]> arthur.barton.de Git - netdata.git/blobdiff - src/registry.c
Merge branch 'master' into ab-debian
[netdata.git] / src / registry.c
index 988ed78d67a3c8203efadbeea141b73ff392bb8d..ed9be984881d770d29c873285207cb2f076ca8f8 100644 (file)
 #include "common.h"
 
-// ----------------------------------------------------------------------------
-// TODO
-//
-// 1. the default tracking cookie expires in 1 year, but the persons are not
-//    removed from the db - this means the database only grows - ideally the
-//    database should be cleaned in registry_save() for both on-disk and
-//    on-memory entries.
-//
-//    Cleanup:
-//    i. Find all the PERSONs that have expired cookie
-//    ii. For each of their PERSON_URLs:
-//     - decrement the linked MACHINE links
-//     - if the linked MACHINE has no other links, remove the linked MACHINE too
-//     - remove the PERSON_URL
-//
-// 2. add protection to prevent abusing the registry by flooding it with
-//    requests to fill the memory and crash it.
-//
-//    Possible protections:
-//    - limit the number of URLs per person
-//    - limit the number of URLs per machine
-//    - limit the number of persons
-//    - limit the number of machines
-//    - [DONE] limit the size of URLs
-//    - [DONE] limit the size of PERSON_URL names
-//    - limit the number of requests that add data to the registry,
-//      per client IP per hour
-
-
-
-#define REGISTRY_URL_FLAGS_DEFAULT 0x00
-#define REGISTRY_URL_FLAGS_EXPIRED 0x01
-
-#define DICTIONARY_FLAGS DICTIONARY_FLAG_VALUE_LINK_DONT_CLONE | DICTIONARY_FLAG_NAME_LINK_DONT_CLONE
-
-// ----------------------------------------------------------------------------
-// COMMON structures
-
-struct registry {
-       int enabled;
-
-       char machine_guid[36 + 1];
-
-       // entries counters / statistics
-       unsigned long long persons_count;
-       unsigned long long machines_count;
-       unsigned long long usages_count;
-       unsigned long long urls_count;
-       unsigned long long persons_urls_count;
-       unsigned long long machines_urls_count;
-       unsigned long long log_count;
-
-       // memory counters / statistics
-       unsigned long long persons_memory;
-       unsigned long long machines_memory;
-       unsigned long long urls_memory;
-       unsigned long long persons_urls_memory;
-       unsigned long long machines_urls_memory;
-
-       // configuration
-       unsigned long long save_registry_every_entries;
-       char *registry_domain;
-       char *hostname;
-       char *registry_to_announce;
-       time_t persons_expiration; // seconds to expire idle persons
-       int verify_cookies_redirects;
-
-       size_t max_url_length;
-       size_t max_name_length;
-
-       // file/path names
-       char *pathname;
-       char *db_filename;
-       char *log_filename;
-       char *machine_guid_filename;
-
-       // open files
-       FILE *log_fp;
-
-       // the database
-       DICTIONARY *persons;    // dictionary of PERSON *, with key the PERSON.guid
-       DICTIONARY *machines;   // dictionary of MACHINE *, with key the MACHINE.guid
-       DICTIONARY *urls;               // dictionary of URL *, with key the URL.url
-
-       // concurrency locking
-       // we keep different locks for different things
-       // so that many tasks can be completed in parallel
-       pthread_mutex_t persons_lock;
-       pthread_mutex_t machines_lock;
-       pthread_mutex_t urls_lock;
-       pthread_mutex_t person_urls_lock;
-       pthread_mutex_t machine_urls_lock;
-       pthread_mutex_t log_lock;
-} registry;
-
-
-// ----------------------------------------------------------------------------
-// URL structures
-// Save memory by de-duplicating URLs
-// so instead of storing URLs all over the place
-// we store them here and we keep pointers elsewhere
-
-struct url {
-       uint32_t links; // the number of links to this URL - when none is left, we free it
-       uint16_t len;   // the length of the URL in bytes
-       char url[1];    // the URL - dynamically allocated to more size
-};
-typedef struct url URL;
-
-
-// ----------------------------------------------------------------------------
-// MACHINE structures
-
-// For each MACHINE-URL pair we keep this
-struct machine_url {
-       URL *url;                                       // de-duplicated URL
-//     DICTIONARY *persons;            // dictionary of PERSON *
-
-       uint8_t flags;
-       uint32_t first_t;                       // the first time we saw this
-       uint32_t last_t;                        // the last time we saw this
-       uint32_t usages;                        // how many times this has been accessed
-};
-typedef struct machine_url MACHINE_URL;
-
-// A machine
-struct machine {
-       char guid[36 + 1];                      // the GUID
-
-       uint32_t links;                         // the number of PERSON_URLs linked to this machine
-
-       DICTIONARY *urls;                       // MACHINE_URL *
-
-       uint32_t first_t;                       // the first time we saw this
-       uint32_t last_t;                        // the last time we saw this
-       uint32_t usages;                        // how many times this has been accessed
-};
-typedef struct machine MACHINE;
-
-
-// ----------------------------------------------------------------------------
-// PERSON structures
-
-// for each PERSON-URL pair we keep this
-struct person_url {
-       URL *url;                                       // de-duplicated URL
-       MACHINE *machine;                       // link the MACHINE of this URL
-
-       uint8_t flags;
-       uint32_t first_t;                       // the first time we saw this
-       uint32_t last_t;                        // the last time we saw this
-       uint32_t usages;                        // how many times this has been accessed
-
-       char name[1];                           // the name of the URL, as known by the user
-                                                               // dynamically allocated to fit properly
-};
-typedef struct person_url PERSON_URL;
-
-// A person
-struct person {
-       char guid[36 + 1];                      // the person GUID
-
-       DICTIONARY *urls;                       // dictionary of PERSON_URL *
-
-       uint32_t first_t;                       // the first time we saw this
-       uint32_t last_t;                        // the last time we saw this
-       uint32_t usages;                        // how many times this has been accessed
-};
-typedef struct person PERSON;
+#include "registry_internals.h"
 
+#define REGISTRY_STATUS_OK "ok"
+#define REGISTRY_STATUS_FAILED "failed"
+#define REGISTRY_STATUS_DISABLED "disabled"
 
 // ----------------------------------------------------------------------------
 // REGISTRY concurrency locking
 
-static inline void registry_persons_lock(void) {
-       pthread_mutex_lock(&registry.persons_lock);
-}
-
-static inline void registry_persons_unlock(void) {
-       pthread_mutex_unlock(&registry.persons_lock);
-}
-
-static inline void registry_machines_lock(void) {
-       pthread_mutex_lock(&registry.machines_lock);
-}
-
-static inline void registry_machines_unlock(void) {
-       pthread_mutex_unlock(&registry.machines_lock);
-}
-
-static inline void registry_urls_lock(void) {
-       pthread_mutex_lock(&registry.urls_lock);
-}
-
-static inline void registry_urls_unlock(void) {
-       pthread_mutex_unlock(&registry.urls_lock);
-}
-
-// ideally, we should not lock the whole registry for
-// updating a person's urls.
-// however, to save the memory required for keeping a
-// mutex (40 bytes) per person, we do...
-static inline void registry_person_urls_lock(PERSON *p) {
-       (void)p;
-       pthread_mutex_lock(&registry.person_urls_lock);
-}
-
-static inline void registry_person_urls_unlock(PERSON *p) {
-       (void)p;
-       pthread_mutex_unlock(&registry.person_urls_lock);
-}
-
-// ideally, we should not lock the whole registry for
-// updating a machine's urls.
-// however, to save the memory required for keeping a
-// mutex (40 bytes) per machine, we do...
-static inline void registry_machine_urls_lock(MACHINE *m) {
-       (void)m;
-       pthread_mutex_lock(&registry.machine_urls_lock);
-}
-
-static inline void registry_machine_urls_unlock(MACHINE *m) {
-       (void)m;
-       pthread_mutex_unlock(&registry.machine_urls_lock);
-}
-
-static inline void registry_log_lock(void) {
-       pthread_mutex_lock(&registry.log_lock);
-}
-
-static inline void registry_log_unlock(void) {
-       pthread_mutex_unlock(&registry.log_lock);
-}
-
-
-// ----------------------------------------------------------------------------
-// common functions
-
-// parse a GUID and re-generated to be always lower case
-// this is used as a protection against the variations of GUIDs
-static inline int registry_regenerate_guid(const char *guid, char *result) {
-       uuid_t uuid;
-       if(unlikely(uuid_parse(guid, uuid) == -1)) {
-               info("Registry: GUID '%s' is not a valid GUID.", guid);
-               return -1;
-       }
-       else {
-               uuid_unparse_lower(uuid, result);
-
-#ifdef NETDATA_INTERNAL_CHECKS
-               if(strcmp(guid, result))
-                       info("Registry: source GUID '%s' and re-generated GUID '%s' differ!", guid, result);
-#endif /* NETDATA_INTERNAL_CHECKS */
-       }
-
-       return 0;
-}
-
-// make sure the names of the machines / URLs do not contain any tabs
-// (which are used as our separator in the database files)
-// and are properly trimmed (before and after)
-static inline char *registry_fix_machine_name(char *name, size_t *len) {
-       char *s = name?name:"";
-
-       // skip leading spaces
-       while(*s && isspace(*s)) s++;
-
-       // make sure all spaces are a SPACE
-       char *t = s;
-       while(*t) {
-               if(unlikely(isspace(*t)))
-                       *t = ' ';
-
-               t++;
-       }
-
-       // remove trailing spaces
-       while(--t >= s) {
-               if(*t == ' ')
-                       *t = '\0';
-               else
-                       break;
-       }
-       t++;
-
-       if(likely(len))
-               *len = (t - s);
-
-       return s;
-}
-
-static inline char *registry_fix_url(char *url, size_t *len) {
-       return registry_fix_machine_name(url, len);
-}
-
-
-// ----------------------------------------------------------------------------
-// forward definition of functions
-
-extern PERSON *registry_request_access(char *person_guid, char *machine_guid, char *url, char *name, time_t when);
-extern PERSON *registry_request_delete(char *person_guid, char *machine_guid, char *url, char *delete_url, time_t when);
-
-
-// ----------------------------------------------------------------------------
-// URL
-
-static inline URL *registry_url_allocate_nolock(const char *url, size_t urllen) {
-       // protection from too big URLs
-       if(urllen > registry.max_url_length)
-               urllen = registry.max_url_length;
-
-       debug(D_REGISTRY, "Registry: registry_url_allocate_nolock('%s'): allocating %zu bytes", url, sizeof(URL) + urllen);
-       URL *u = mallocz(sizeof(URL) + urllen);
-
-       // a simple strcpy() should do the job
-       // but I prefer to be safe, since the caller specified urllen
-       u->len = (uint16_t)urllen;
-       strncpyz(u->url, url, u->len);
-       u->links = 0;
-
-       registry.urls_memory += sizeof(URL) + urllen;
-
-       debug(D_REGISTRY, "Registry: registry_url_allocate_nolock('%s'): indexing it", url);
-       dictionary_set(registry.urls, u->url, u, sizeof(URL));
-
-       return u;
-}
-
-static inline URL *registry_url_get(const char *url, size_t urllen) {
-       debug(D_REGISTRY, "Registry: registry_url_get('%s')", url);
-
-       registry_urls_lock();
-
-       URL *u = dictionary_get(registry.urls, url);
-       if(!u) {
-               u = registry_url_allocate_nolock(url, urllen);
-               registry.urls_count++;
-       }
-
-       registry_urls_unlock();
-
-       return u;
-}
-
-static inline void registry_url_link_nolock(URL *u) {
-       u->links++;
-       debug(D_REGISTRY, "Registry: registry_url_link_nolock('%s'): URL has now %u links", u->url, u->links);
-}
-
-static inline void registry_url_unlink_nolock(URL *u) {
-       u->links--;
-       if(!u->links) {
-               debug(D_REGISTRY, "Registry: registry_url_unlink_nolock('%s'): No more links for this URL", u->url);
-               dictionary_del(registry.urls, u->url);
-               freez(u);
-       }
-       else
-               debug(D_REGISTRY, "Registry: registry_url_unlink_nolock('%s'): URL has %u links left", u->url, u->links);
-}
-
-
-// ----------------------------------------------------------------------------
-// MACHINE
-
-static inline MACHINE *registry_machine_find(const char *machine_guid) {
-       debug(D_REGISTRY, "Registry: registry_machine_find('%s')", machine_guid);
-       return dictionary_get(registry.machines, machine_guid);
-}
-
-static inline MACHINE_URL *registry_machine_url_allocate(MACHINE *m, URL *u, time_t when) {
-       debug(D_REGISTRY, "registry_machine_link_to_url('%s', '%s'): allocating %zu bytes", m->guid, u->url, sizeof(MACHINE_URL));
-
-       MACHINE_URL *mu = mallocz(sizeof(MACHINE_URL));
-
-       // mu->persons = dictionary_create(DICTIONARY_FLAGS);
-       // dictionary_set(mu->persons, p->guid, p, sizeof(PERSON));
-
-       mu->first_t = mu->last_t = (uint32_t)when;
-       mu->usages = 1;
-       mu->url = u;
-       mu->flags = REGISTRY_URL_FLAGS_DEFAULT;
-
-       registry.machines_urls_memory += sizeof(MACHINE_URL);
-
-       debug(D_REGISTRY, "registry_machine_link_to_url('%s', '%s'): indexing URL in machine", m->guid, u->url);
-       dictionary_set(m->urls, u->url, mu, sizeof(MACHINE_URL));
-       registry_url_link_nolock(u);
-
-       return mu;
-}
-
-static inline MACHINE *registry_machine_allocate(const char *machine_guid, time_t when) {
-       debug(D_REGISTRY, "Registry: registry_machine_allocate('%s'): creating new machine, sizeof(MACHINE)=%zu", machine_guid, sizeof(MACHINE));
-
-       MACHINE *m = mallocz(sizeof(MACHINE));
-
-       strncpyz(m->guid, machine_guid, 36);
-
-       debug(D_REGISTRY, "Registry: registry_machine_allocate('%s'): creating dictionary of urls", machine_guid);
-       m->urls = dictionary_create(DICTIONARY_FLAGS);
-
-       m->first_t = m->last_t = (uint32_t)when;
-       m->usages = 0;
-
-       registry.machines_memory += sizeof(MACHINE);
-
-       registry.machines_count++;
-       dictionary_set(registry.machines, m->guid, m, sizeof(MACHINE));
-
-       return m;
-}
-
-// 1. validate machine GUID
-// 2. if it is valid, find it or create it and return it
-// 3. if it is not valid, return NULL
-static inline MACHINE *registry_machine_get(const char *machine_guid, time_t when) {
-       MACHINE *m = NULL;
-
-       registry_machines_lock();
-
-       if(likely(machine_guid && *machine_guid)) {
-               // validate it is a GUID
-               char buf[36 + 1];
-               if(unlikely(registry_regenerate_guid(machine_guid, buf) == -1))
-                       info("Registry: machine guid '%s' is not a valid guid. Ignoring it.", machine_guid);
-               else {
-                       machine_guid = buf;
-                       m = registry_machine_find(machine_guid);
-                       if(!m) m = registry_machine_allocate(machine_guid, when);
-               }
-       }
-
-       registry_machines_unlock();
-
-       return m;
-}
-
-
-// ----------------------------------------------------------------------------
-// PERSON
-
-static inline PERSON *registry_person_find(const char *person_guid) {
-       debug(D_REGISTRY, "Registry: registry_person_find('%s')", person_guid);
-       return dictionary_get(registry.persons, person_guid);
-}
-
-static inline PERSON_URL *registry_person_url_allocate(PERSON *p, MACHINE *m, URL *u, char *name, size_t namelen, time_t when) {
-       // protection from too big names
-       if(namelen > registry.max_name_length)
-               namelen = registry.max_name_length;
-
-       debug(D_REGISTRY, "registry_person_url_allocate('%s', '%s', '%s'): allocating %zu bytes", p->guid, m->guid, u->url,
-                 sizeof(PERSON_URL) + namelen);
-
-       PERSON_URL *pu = mallocz(sizeof(PERSON_URL) + namelen);
-
-       // a simple strcpy() should do the job
-       // but I prefer to be safe, since the caller specified urllen
-       strncpyz(pu->name, name, namelen);
-
-       pu->machine = m;
-       pu->first_t = pu->last_t = when;
-       pu->usages = 1;
-       pu->url = u;
-       pu->flags = REGISTRY_URL_FLAGS_DEFAULT;
-       m->links++;
-
-       registry.persons_urls_memory += sizeof(PERSON_URL) + namelen;
-
-       debug(D_REGISTRY, "registry_person_url_allocate('%s', '%s', '%s'): indexing URL in person", p->guid, m->guid, u->url);
-       dictionary_set(p->urls, u->url, pu, sizeof(PERSON_URL));
-       registry_url_link_nolock(u);
-
-       return pu;
-}
-
-static inline PERSON_URL *registry_person_url_reallocate(PERSON *p, MACHINE *m, URL *u, char *name, size_t namelen, time_t when, PERSON_URL *pu) {
-       // this function is needed to change the name of a PERSON_URL
-
-       debug(D_REGISTRY, "registry_person_url_reallocate('%s', '%s', '%s'): allocating %zu bytes", p->guid, m->guid, u->url,
-                 sizeof(PERSON_URL) + namelen);
-
-       PERSON_URL *tpu = registry_person_url_allocate(p, m, u, name, namelen, when);
-       tpu->first_t = pu->first_t;
-       tpu->last_t = pu->last_t;
-       tpu->usages = pu->usages;
-
-       // ok, these are a hack - since the registry_person_url_allocate() is
-       // adding these, we have to subtract them
-       tpu->machine->links--;
-       registry.persons_urls_memory -= sizeof(PERSON_URL) + strlen(pu->name);
-       registry_url_unlink_nolock(u);
-
-       freez(pu);
-
-       return tpu;
-}
-
-static inline PERSON *registry_person_allocate(const char *person_guid, time_t when) {
-       PERSON *p = NULL;
-
-       debug(D_REGISTRY, "Registry: registry_person_allocate('%s'): allocating new person, sizeof(PERSON)=%zu", (person_guid)?person_guid:"", sizeof(PERSON));
-
-       p = mallocz(sizeof(PERSON));
-
-       if(!person_guid) {
-               for (; ;) {
-                       uuid_t uuid;
-                       uuid_generate(uuid);
-                       uuid_unparse_lower(uuid, p->guid);
-
-                       debug(D_REGISTRY, "Registry: Checking if the generated person guid '%s' is unique", p->guid);
-                       if (!dictionary_get(registry.persons, p->guid)) {
-                               debug(D_REGISTRY, "Registry: generated person guid '%s' is unique", p->guid);
-                               break;
-                       }
-                       else
-                               info("Registry: generated person guid '%s' found in the registry. Retrying...", p->guid);
-               }
-       }
-       else
-               strncpyz(p->guid, person_guid, 36);
-
-       debug(D_REGISTRY, "Registry: registry_person_allocate('%s'): creating dictionary of urls", p->guid);
-       p->urls = dictionary_create(DICTIONARY_FLAGS);
-
-       p->first_t = p->last_t = when;
-       p->usages = 0;
-
-       registry.persons_memory += sizeof(PERSON);
-
-       registry.persons_count++;
-       dictionary_set(registry.persons, p->guid, p, sizeof(PERSON));
-
-       return p;
+static inline void registry_lock(void) {
+    netdata_mutex_lock(&registry.lock);
 }
 
-
-// 1. validate person GUID
-// 2. if it is valid, find it
-// 3. if it is not valid, create a new one
-// 4. return it
-static inline PERSON *registry_person_get(const char *person_guid, time_t when) {
-       PERSON *p = NULL;
-
-       registry_persons_lock();
-
-       if(person_guid && *person_guid) {
-               char buf[36 + 1];
-               // validate it is a GUID
-               if(unlikely(registry_regenerate_guid(person_guid, buf) == -1))
-                       info("Registry: person guid '%s' is not a valid guid. Ignoring it.", person_guid);
-               else {
-                       person_guid = buf;
-                       p = registry_person_find(person_guid);
-                       if(!p) person_guid = NULL;
-               }
-       }
-
-       if(!p) p = registry_person_allocate(NULL, when);
-
-       registry_persons_unlock();
-
-       return p;
-}
-
-// ----------------------------------------------------------------------------
-// LINKING OF OBJECTS
-
-static inline PERSON_URL *registry_person_link_to_url(PERSON *p, MACHINE *m, URL *u, char *name, size_t namelen, time_t when) {
-       debug(D_REGISTRY, "registry_person_link_to_url('%s', '%s', '%s'): searching for URL in person", p->guid, m->guid, u->url);
-
-       registry_person_urls_lock(p);
-
-       PERSON_URL *pu = dictionary_get(p->urls, u->url);
-       if(!pu) {
-               debug(D_REGISTRY, "registry_person_link_to_url('%s', '%s', '%s'): not found", p->guid, m->guid, u->url);
-               pu = registry_person_url_allocate(p, m, u, name, namelen, when);
-               registry.persons_urls_count++;
-       }
-       else {
-               debug(D_REGISTRY, "registry_person_link_to_url('%s', '%s', '%s'): found", p->guid, m->guid, u->url);
-               pu->usages++;
-               if(likely(pu->last_t < (uint32_t)when)) pu->last_t = when;
-
-               if(pu->machine != m) {
-                       MACHINE_URL *mu = dictionary_get(pu->machine->urls, u->url);
-                       if(mu) {
-                               info("registry_person_link_to_url('%s', '%s', '%s'): URL switched machines (old was '%s') - expiring it from previous machine.",
-                                        p->guid, m->guid, u->url, pu->machine->guid);
-                               mu->flags |= REGISTRY_URL_FLAGS_EXPIRED;
-                       }
-                       else {
-                               info("registry_person_link_to_url('%s', '%s', '%s'): URL switched machines (old was '%s') - but the URL is not linked to the old machine.",
-                                        p->guid, m->guid, u->url, pu->machine->guid);
-                       }
-
-                       pu->machine->links--;
-                       pu->machine = m;
-               }
-
-               if(strcmp(pu->name, name)) {
-                       // the name of the PERSON_URL has changed !
-                       pu = registry_person_url_reallocate(p, m, u, name, namelen, when, pu);
-               }
-       }
-
-       p->usages++;
-       if(likely(p->last_t < (uint32_t)when)) p->last_t = when;
-
-       if(pu->flags & REGISTRY_URL_FLAGS_EXPIRED) {
-               info("registry_person_link_to_url('%s', '%s', '%s'): accessing an expired URL. Re-enabling URL.", p->guid, m->guid, u->url);
-               pu->flags &= ~REGISTRY_URL_FLAGS_EXPIRED;
-       }
-
-       registry_person_urls_unlock(p);
-
-       return pu;
+static inline void registry_unlock(void) {
+    netdata_mutex_unlock(&registry.lock);
 }
 
-static inline MACHINE_URL *registry_machine_link_to_url(PERSON *p, MACHINE *m, URL *u, time_t when) {
-       debug(D_REGISTRY, "registry_machine_link_to_url('%s', '%s', '%s'): searching for URL in machine", p->guid, m->guid, u->url);
-
-       registry_machine_urls_lock(m);
-
-       MACHINE_URL *mu = dictionary_get(m->urls, u->url);
-       if(!mu) {
-               debug(D_REGISTRY, "registry_machine_link_to_url('%s', '%s', '%s'): not found", p->guid, m->guid, u->url);
-               mu = registry_machine_url_allocate(m, u, when);
-               registry.machines_urls_count++;
-       }
-       else {
-               debug(D_REGISTRY, "registry_machine_link_to_url('%s', '%s', '%s'): found", p->guid, m->guid, u->url);
-               mu->usages++;
-               if(likely(mu->last_t < (uint32_t)when)) mu->last_t = when;
-       }
-
-       //debug(D_REGISTRY, "registry_machine_link_to_url('%s', '%s', '%s'): indexing person in machine", p->guid, m->guid, u->url);
-       //dictionary_set(mu->persons, p->guid, p, sizeof(PERSON));
-
-       m->usages++;
-       if(likely(m->last_t < (uint32_t)when)) m->last_t = when;
-
-       if(mu->flags & REGISTRY_URL_FLAGS_EXPIRED) {
-               info("registry_machine_link_to_url('%s', '%s', '%s'): accessing an expired URL.", p->guid, m->guid, u->url);
-               mu->flags &= ~REGISTRY_URL_FLAGS_EXPIRED;
-       }
-
-       registry_machine_urls_unlock(m);
-
-       return mu;
-}
 
 // ----------------------------------------------------------------------------
-// REGISTRY LOG LOAD/SAVE
-
-static inline int registry_should_save_db(void) {
-       debug(D_REGISTRY, "log entries %llu, max %llu", registry.log_count, registry.save_registry_every_entries);
-       return registry.log_count > registry.save_registry_every_entries;
-}
-
-static inline void registry_log(const char action, PERSON *p, MACHINE *m, URL *u, char *name) {
-       if(likely(registry.log_fp)) {
-               // we lock only if the file is open
-               // to allow replaying the log at registry_log_load()
-               registry_log_lock();
-
-               if(unlikely(fprintf(registry.log_fp, "%c\t%08x\t%s\t%s\t%s\t%s\n",
-                               action,
-                               p->last_t,
-                               p->guid,
-                               m->guid,
-                               name,
-                               u->url) < 0))
-                       error("Registry: failed to save log. Registry data may be lost in case of abnormal restart.");
-
-               // we increase the counter even on failures
-               // so that the registry will be saved periodically
-               registry.log_count++;
-
-               registry_log_unlock();
-
-               // this must be outside the log_lock(), or a deadlock will happen.
-               // registry_save() checks the same inside the log_lock, so only
-               // one thread will save the db
-               if(unlikely(registry_should_save_db()))
-                       registry_save();
-       }
-}
-
-static inline int registry_log_open_nolock(void) {
-       if(registry.log_fp)
-               fclose(registry.log_fp);
-
-       registry.log_fp = fopen(registry.log_filename, "a");
-
-       if(registry.log_fp) {
-               if (setvbuf(registry.log_fp, NULL, _IOLBF, 0) != 0)
-                       error("Cannot set line buffering on registry log file.");
-               return 0;
-       }
-
-       error("Cannot open registry log file '%s'. Registry data will be lost in case of netdata or server crash.", registry.log_filename);
-       return -1;
-}
-
-static inline void registry_log_close_nolock(void) {
-       if(registry.log_fp) {
-               fclose(registry.log_fp);
-               registry.log_fp = NULL;
-       }
-}
-
-static inline void registry_log_recreate_nolock(void) {
-       if(registry.log_fp != NULL) {
-               registry_log_close_nolock();
+// COOKIES
 
-               // open it with truncate
-               registry.log_fp = fopen(registry.log_filename, "w");
-               if(registry.log_fp) fclose(registry.log_fp);
-               else error("Cannot truncate registry log '%s'", registry.log_filename);
+static void registry_set_cookie(struct web_client *w, const char *guid) {
+    char edate[100];
+    time_t et = now_realtime_sec() + registry.persons_expiration;
+    struct tm etmbuf, *etm = gmtime_r(&et, &etmbuf);
+    strftime(edate, sizeof(edate), "%a, %d %b %Y %H:%M:%S %Z", etm);
 
-               registry.log_fp = NULL;
+    snprintfz(w->cookie1, COOKIE_MAX, NETDATA_REGISTRY_COOKIE_NAME "=%s; Expires=%s", guid, edate);
 
-               registry_log_open_nolock();
-       }
+    if(registry.registry_domain && registry.registry_domain[0])
+        snprintfz(w->cookie2, COOKIE_MAX, NETDATA_REGISTRY_COOKIE_NAME "=%s; Domain=%s; Expires=%s", guid, registry.registry_domain, edate);
 }
 
-int registry_log_load(void) {
-       char *s, buf[4096 + 1];
-       size_t line = -1;
-
-       // closing the log is required here
-       // otherwise we will append to it the values we read
-       registry_log_close_nolock();
-
-       debug(D_REGISTRY, "Registry: loading active db from: %s", registry.log_filename);
-       FILE *fp = fopen(registry.log_filename, "r");
-       if(!fp)
-               error("Registry: cannot open registry file: %s", registry.log_filename);
-       else {
-               line = 0;
-               size_t len = 0;
-               while ((s = fgets_trim_len(buf, 4096, fp, &len))) {
-                       line++;
-
-                       switch (s[0]) {
-                               case 'A': // accesses
-                               case 'D': // deletes
-
-                                       // verify it is valid
-                                       if (unlikely(len < 85 || s[1] != '\t' || s[10] != '\t' || s[47] != '\t' || s[84] != '\t')) {
-                                               error("Registry: log line %zu is wrong (len = %zu).", line, len);
-                                               continue;
-                                       }
-                                       s[1] = s[10] = s[47] = s[84] = '\0';
-
-                                       // get the variables
-                                       time_t when = strtoul(&s[2], NULL, 16);
-                                       char *person_guid = &s[11];
-                                       char *machine_guid = &s[48];
-                                       char *name = &s[85];
-
-                                       // skip the name to find the url
-                                       char *url = name;
-                                       while(*url && *url != '\t') url++;
-                                       if(!*url) {
-                                               error("Registry: log line %zu does not have a url.", line);
-                                               continue;
-                                       }
-                                       *url++ = '\0';
-
-                                       // make sure the person exists
-                                       // without this, a new person guid will be created
-                                       PERSON *p = registry_person_find(person_guid);
-                                       if(!p) p = registry_person_allocate(person_guid, when);
-
-                                       if(s[0] == 'A')
-                                               registry_request_access(p->guid, machine_guid, url, name, when);
-                                       else
-                                               registry_request_delete(p->guid, machine_guid, url, name, when);
-
-                                       break;
-
-                               default:
-                                       error("Registry: ignoring line %zu of filename '%s': %s.", line, registry.log_filename, s);
-                                       break;
-                       }
-               }
-               
-               fclose(fp);
-       }
-
-       // open the log again
-       registry_log_open_nolock();
-
-       return line;
-}
-
-
-// ----------------------------------------------------------------------------
-// REGISTRY REQUESTS
-
-PERSON *registry_request_access(char *person_guid, char *machine_guid, char *url, char *name, time_t when) {
-       debug(D_REGISTRY, "registry_request_access('%s', '%s', '%s'): NEW REQUEST", (person_guid)?person_guid:"", machine_guid, url);
-
-       MACHINE *m = registry_machine_get(machine_guid, when);
-       if(!m) return NULL;
-
-       // make sure the name is valid
-       size_t namelen;
-       name = registry_fix_machine_name(name, &namelen);
-
-       size_t urllen;
-       url = registry_fix_url(url, &urllen);
-
-       URL *u = registry_url_get(url, urllen);
-       PERSON *p = registry_person_get(person_guid, when);
-
-       registry_person_link_to_url(p, m, u, name, namelen, when);
-       registry_machine_link_to_url(p, m, u, when);
-
-       registry_log('A', p, m, u, name);
-
-       registry.usages_count++;
-       return p;
-}
-
-// verify the person, the machine and the URL exist in our DB
-PERSON_URL *registry_verify_request(char *person_guid, char *machine_guid, char *url, PERSON **pp, MACHINE **mm) {
-       char pbuf[36 + 1], mbuf[36 + 1];
-
-       if(!person_guid || !*person_guid || !machine_guid || !*machine_guid || !url || !*url) {
-               info("Registry Request Verification: invalid request! person: '%s', machine '%s', url '%s'", person_guid?person_guid:"UNSET", machine_guid?machine_guid:"UNSET", url?url:"UNSET");
-               return NULL;
-       }
-
-       // normalize the url
-       url = registry_fix_url(url, NULL);
-
-       // make sure the person GUID is valid
-       if(registry_regenerate_guid(person_guid, pbuf) == -1) {
-               info("Registry Request Verification: invalid person GUID, person: '%s', machine '%s', url '%s'", person_guid, machine_guid, url);
-               return NULL;
-       }
-       person_guid = pbuf;
-
-       // make sure the machine GUID is valid
-       if(registry_regenerate_guid(machine_guid, mbuf) == -1) {
-               info("Registry Request Verification: invalid machine GUID, person: '%s', machine '%s', url '%s'", person_guid, machine_guid, url);
-               return NULL;
-       }
-       machine_guid = mbuf;
-
-       // make sure the machine exists
-       MACHINE *m = registry_machine_find(machine_guid);
-       if(!m) {
-               info("Registry Request Verification: machine not found, person: '%s', machine '%s', url '%s'", person_guid, machine_guid, url);
-               return NULL;
-       }
-       if(mm) *mm = m;
-
-       // make sure the person exist
-       PERSON *p = registry_person_find(person_guid);
-       if(!p) {
-               info("Registry Request Verification: person not found, person: '%s', machine '%s', url '%s'", person_guid, machine_guid, url);
-               return NULL;
-       }
-       if(pp) *pp = p;
-
-       PERSON_URL *pu = dictionary_get(p->urls, url);
-       if(!pu) {
-               info("Registry Request Verification: URL not found for person, person: '%s', machine '%s', url '%s'", person_guid, machine_guid, url);
-               return NULL;
-       }
-       return pu;
-}
-
-PERSON *registry_request_delete(char *person_guid, char *machine_guid, char *url, char *delete_url, time_t when) {
-       (void)when;
-
-       PERSON *p = NULL;
-       MACHINE *m = NULL;
-       PERSON_URL *pu = registry_verify_request(person_guid, machine_guid, url, &p, &m);
-       if(!pu || !p || !m) return NULL;
-
-       // normalize the url
-       delete_url = registry_fix_url(delete_url, NULL);
-
-       // make sure the user is not deleting the url it uses
-       if(!strcmp(delete_url, pu->url->url)) {
-               info("Registry Delete Request: delete URL is the one currently accessed, person: '%s', machine '%s', url '%s', delete url '%s'", p->guid, m->guid, pu->url->url, delete_url);
-               return NULL;
-       }
-
-       registry_person_urls_lock(p);
-
-       PERSON_URL *dpu = dictionary_get(p->urls, delete_url);
-       if(!dpu) {
-               info("Registry Delete Request: URL not found for person: '%s', machine '%s', url '%s', delete url '%s'", p->guid, m->guid, pu->url->url, delete_url);
-               registry_person_urls_unlock(p);
-               return NULL;
-       }
-
-       registry_log('D', p, m, pu->url, dpu->url->url);
-
-       dictionary_del(p->urls, dpu->url->url);
-       registry_url_unlink_nolock(dpu->url);
-       freez(dpu);
-
-       registry_person_urls_unlock(p);
-       return p;
-}
-
-
-// a structure to pass to the dictionary_get_all() callback handler
-struct machine_request_callback_data {
-       MACHINE *find_this_machine;
-       PERSON_URL *result;
-};
-
-// the callback function
-// this will be run for every PERSON_URL of this PERSON
-int machine_request_callback(void *entry, void *data) {
-       PERSON_URL *mypu = (PERSON_URL *)entry;
-       struct machine_request_callback_data *myrdata = (struct machine_request_callback_data *)data;
-
-       if(mypu->machine == myrdata->find_this_machine) {
-               myrdata->result = mypu;
-               return -1; // this will also stop the walk through
-       }
-
-       return 0; // continue
-}
-
-MACHINE *registry_request_machine(char *person_guid, char *machine_guid, char *url, char *request_machine, time_t when) {
-       (void)when;
-
-       char mbuf[36 + 1];
-
-       PERSON *p = NULL;
-       MACHINE *m = NULL;
-       PERSON_URL *pu = registry_verify_request(person_guid, machine_guid, url, &p, &m);
-       if(!pu || !p || !m) return NULL;
-
-       // make sure the machine GUID is valid
-       if(registry_regenerate_guid(request_machine, mbuf) == -1) {
-               info("Registry Machine URLs request: invalid machine GUID, person: '%s', machine '%s', url '%s', request machine '%s'", p->guid, m->guid, pu->url->url, request_machine);
-               return NULL;
-       }
-       request_machine = mbuf;
-
-       // make sure the machine exists
-       m = registry_machine_find(request_machine);
-       if(!m) {
-               info("Registry Machine URLs request: machine not found, person: '%s', machine '%s', url '%s', request machine '%s'", p->guid, m->guid, pu->url->url, request_machine);
-               return NULL;
-       }
-
-       // Verify the user has in the past accessed this machine
-       // We will walk through the PERSON_URLs to find the machine
-       // linking to our machine
-
-       // a structure to pass to the dictionary_get_all() callback handler
-       struct machine_request_callback_data rdata = { m, NULL };
-
-       // request a walk through on the dictionary
-       // no need for locking here, the underlying dictionary has its own
-       dictionary_get_all(p->urls, machine_request_callback, &rdata);
-
-       if(rdata.result)
-               return m;
-
-       return NULL;
+static inline void registry_set_person_cookie(struct web_client *w, REGISTRY_PERSON *p) {
+    registry_set_cookie(w, p->guid);
 }
 
 
 // ----------------------------------------------------------------------------
-// REGISTRY JSON generation
+// JSON GENERATION
 
-#define REGISTRY_STATUS_OK "ok"
-#define REGISTRY_STATUS_FAILED "failed"
-#define REGISTRY_STATUS_DISABLED "disabled"
-
-int registry_verify_cookies_redirects(void) {
-       return registry.verify_cookies_redirects;
-}
-
-const char *registry_to_announce(void) {
-       return registry.registry_to_announce;
-}
-
-void registry_set_cookie(struct web_client *w, const char *guid) {
-       char edate[100];
-       time_t et = time(NULL) + registry.persons_expiration;
-       struct tm etmbuf, *etm = gmtime_r(&et, &etmbuf);
-       strftime(edate, sizeof(edate), "%a, %d %b %Y %H:%M:%S %Z", etm);
-
-       snprintfz(w->cookie1, COOKIE_MAX, NETDATA_REGISTRY_COOKIE_NAME "=%s; Expires=%s", guid, edate);
-
-       if(registry.registry_domain && registry.registry_domain[0])
-               snprintfz(w->cookie2, COOKIE_MAX, NETDATA_REGISTRY_COOKIE_NAME "=%s; Domain=%s; Expires=%s", guid, registry.registry_domain, edate);
-}
-
-static inline void registry_set_person_cookie(struct web_client *w, PERSON *p) {
-       registry_set_cookie(w, p->guid);
-}
-
-static inline void registry_json_header(struct web_client *w, const char *action, const char *status) {
-       buffer_flush(w->response.data);
-       w->response.data->contenttype = CT_APPLICATION_JSON;
-       buffer_sprintf(w->response.data, "{\n\t\"action\": \"%s\",\n\t\"status\": \"%s\",\n\t\"hostname\": \"%s\",\n\t\"machine_guid\": \"%s\"",
-                                  action, status, registry.hostname, registry.machine_guid);
+static inline void registry_json_header(RRDHOST *host, struct web_client *w, const char *action, const char *status) {
+    buffer_flush(w->response.data);
+    w->response.data->contenttype = CT_APPLICATION_JSON;
+    buffer_sprintf(w->response.data, "{\n\t\"action\": \"%s\",\n\t\"status\": \"%s\",\n\t\"hostname\": \"%s\",\n\t\"machine_guid\": \"%s\"",
+            action, status, (host == localhost)?registry.hostname:host->hostname, host->machine_guid);
 }
 
 static inline void registry_json_footer(struct web_client *w) {
-       buffer_strcat(w->response.data, "\n}\n");
+    buffer_strcat(w->response.data, "\n}\n");
 }
 
-int registry_request_hello_json(struct web_client *w) {
-       registry_json_header(w, "hello", REGISTRY_STATUS_OK);
+static inline int registry_json_disabled(RRDHOST *host, struct web_client *w, const char *action) {
+    registry_json_header(host, w, action, REGISTRY_STATUS_DISABLED);
 
-       buffer_sprintf(w->response.data, ",\n\t\"registry\": \"%s\"",
-                                  registry.registry_to_announce);
+    buffer_sprintf(w->response.data, ",\n\t\"registry\": \"%s\"",
+            registry.registry_to_announce);
 
-       registry_json_footer(w);
-       return 200;
+    registry_json_footer(w);
+    return 200;
 }
 
-static inline int registry_json_disabled(struct web_client *w, const char *action) {
-       registry_json_header(w, action, REGISTRY_STATUS_DISABLED);
 
-       buffer_sprintf(w->response.data, ",\n\t\"registry\": \"%s\"",
-                                  registry.registry_to_announce);
-
-       registry_json_footer(w);
-       return 200;
-}
+// ----------------------------------------------------------------------------
+// CALLBACKS FOR WALKING THROUGH REGISTRY OBJECTS
 
 // structure used be the callbacks below
 struct registry_json_walk_person_urls_callback {
-       PERSON *p;
-       MACHINE *m;
-       struct web_client *w;
-       int count;
+    REGISTRY_PERSON *p;
+    REGISTRY_MACHINE *m;
+    struct web_client *w;
+    int count;
 };
 
 // callback for rendering PERSON_URLs
-static inline int registry_json_person_url_callback(void *entry, void *data) {
-       PERSON_URL *pu = (PERSON_URL *)entry;
-       struct registry_json_walk_person_urls_callback *c = (struct registry_json_walk_person_urls_callback *)data;
-       struct web_client *w = c->w;
+static int registry_json_person_url_callback(void *entry, void *data) {
+    REGISTRY_PERSON_URL *pu = (REGISTRY_PERSON_URL *)entry;
+    struct registry_json_walk_person_urls_callback *c = (struct registry_json_walk_person_urls_callback *)data;
+    struct web_client *w = c->w;
 
-       if(unlikely(c->count++))
-               buffer_strcat(w->response.data, ",");
+    if(unlikely(c->count++))
+        buffer_strcat(w->response.data, ",");
 
-       buffer_sprintf(w->response.data, "\n\t\t[ \"%s\", \"%s\", %u000, %u, \"%s\" ]",
-                                  pu->machine->guid, pu->url->url, pu->last_t, pu->usages, pu->name);
+    buffer_sprintf(w->response.data, "\n\t\t[ \"%s\", \"%s\", %u000, %u, \"%s\" ]",
+            pu->machine->guid, pu->url->url, pu->last_t, pu->usages, pu->machine_name);
 
-       return 1;
+    return 0;
 }
 
 // callback for rendering MACHINE_URLs
-static inline int registry_json_machine_url_callback(void *entry, void *data) {
-       MACHINE_URL *mu = (MACHINE_URL *)entry;
-       struct registry_json_walk_person_urls_callback *c = (struct registry_json_walk_person_urls_callback *)data;
-       struct web_client *w = c->w;
-       MACHINE *m = c->m;
-
-       if(unlikely(c->count++))
-               buffer_strcat(w->response.data, ",");
+static int registry_json_machine_url_callback(void *entry, void *data) {
+    REGISTRY_MACHINE_URL *mu = (REGISTRY_MACHINE_URL *)entry;
+    struct registry_json_walk_person_urls_callback *c = (struct registry_json_walk_person_urls_callback *)data;
+    struct web_client *w = c->w;
+    REGISTRY_MACHINE *m = c->m;
 
-       buffer_sprintf(w->response.data, "\n\t\t[ \"%s\", \"%s\", %u000, %u ]",
-                                  m->guid, mu->url->url, mu->last_t, mu->usages);
-
-       return 1;
-}
+    if(unlikely(c->count++))
+        buffer_strcat(w->response.data, ",");
 
+    buffer_sprintf(w->response.data, "\n\t\t[ \"%s\", \"%s\", %u000, %u ]",
+            m->guid, mu->url->url, mu->last_t, mu->usages);
 
-// the main method for registering an access
-int registry_request_access_json(struct web_client *w, char *person_guid, char *machine_guid, char *url, char *name, time_t when) {
-       if(!registry.enabled)
-               return registry_json_disabled(w, "access");
-
-       PERSON *p = registry_request_access(person_guid, machine_guid, url, name, when);
-       if(!p) {
-               registry_json_header(w, "access", REGISTRY_STATUS_FAILED);
-               registry_json_footer(w);
-               return 412;
-       }
-
-       // set the cookie
-       registry_set_person_cookie(w, p);
-
-       // generate the response
-       registry_json_header(w, "access", REGISTRY_STATUS_OK);
-
-       buffer_sprintf(w->response.data, ",\n\t\"person_guid\": \"%s\",\n\t\"urls\": [", p->guid);
-       struct registry_json_walk_person_urls_callback c = { p, NULL, w, 0 };
-       dictionary_get_all(p->urls, registry_json_person_url_callback, &c);
-       buffer_strcat(w->response.data, "\n\t]\n");
-
-       registry_json_footer(w);
-       return 200;
+    return 1;
 }
 
-// the main method for deleting a URL from a person
-int registry_request_delete_json(struct web_client *w, char *person_guid, char *machine_guid, char *url, char *delete_url, time_t when) {
-       if(!registry.enabled)
-               return registry_json_disabled(w, "delete");
-
-       PERSON *p = registry_request_delete(person_guid, machine_guid, url, delete_url, when);
-       if(!p) {
-               registry_json_header(w, "delete", REGISTRY_STATUS_FAILED);
-               registry_json_footer(w);
-               return 412;
-       }
-
-       // generate the response
-       registry_json_header(w, "delete", REGISTRY_STATUS_OK);
-       registry_json_footer(w);
-       return 200;
-}
-
-// the main method for searching the URLs of a netdata
-int registry_request_search_json(struct web_client *w, char *person_guid, char *machine_guid, char *url, char *request_machine, time_t when) {
-       if(!registry.enabled)
-               return registry_json_disabled(w, "search");
-
-       MACHINE *m = registry_request_machine(person_guid, machine_guid, url, request_machine, when);
-       if(!m) {
-               registry_json_header(w, "search", REGISTRY_STATUS_FAILED);
-               registry_json_footer(w);
-               return 404;
-       }
-
-       registry_json_header(w, "search", REGISTRY_STATUS_OK);
-
-       buffer_strcat(w->response.data, ",\n\t\"urls\": [");
-       struct registry_json_walk_person_urls_callback c = { NULL, m, w, 0 };
-       dictionary_get_all(m->urls, registry_json_machine_url_callback, &c);
-       buffer_strcat(w->response.data, "\n\t]\n");
-
-       registry_json_footer(w);
-       return 200;
-}
+// ----------------------------------------------------------------------------
 
 // structure used be the callbacks below
 struct registry_person_url_callback_verify_machine_exists_data {
-       MACHINE *m;
-       int count;
+    REGISTRY_MACHINE *m;
+    int count;
 };
 
-int registry_person_url_callback_verify_machine_exists(void *entry, void *data) {
-       struct registry_person_url_callback_verify_machine_exists_data *d = (struct registry_person_url_callback_verify_machine_exists_data *)data;
-       PERSON_URL *pu = (PERSON_URL *)entry;
-       MACHINE *m = d->m;
+static inline int registry_person_url_callback_verify_machine_exists(void *entry, void *data) {
+    struct registry_person_url_callback_verify_machine_exists_data *d = (struct registry_person_url_callback_verify_machine_exists_data *)data;
+    REGISTRY_PERSON_URL *pu = (REGISTRY_PERSON_URL *)entry;
+    REGISTRY_MACHINE *m = d->m;
 
-       if(pu->machine == m)
-               d->count++;
+    if(pu->machine == m)
+        d->count++;
 
-       return 0;
+    return 0;
 }
 
-// the main method for switching user identity
-int registry_request_switch_json(struct web_client *w, char *person_guid, char *machine_guid, char *url, char *new_person_guid, time_t when) {
-       (void)url;
-       (void)when;
-
-       if(!registry.enabled)
-               return registry_json_disabled(w, "switch");
-
-       PERSON *op = registry_person_find(person_guid);
-       if(!op) {
-               registry_json_header(w, "switch", REGISTRY_STATUS_FAILED);
-               registry_json_footer(w);
-               return 430;
-       }
-
-       PERSON *np = registry_person_find(new_person_guid);
-       if(!np) {
-               registry_json_header(w, "switch", REGISTRY_STATUS_FAILED);
-               registry_json_footer(w);
-               return 431;
-       }
-
-       MACHINE *m = registry_machine_find(machine_guid);
-       if(!m) {
-               registry_json_header(w, "switch", REGISTRY_STATUS_FAILED);
-               registry_json_footer(w);
-               return 432;
-       }
-
-       struct registry_person_url_callback_verify_machine_exists_data data = { m, 0 };
-
-       // verify the old person has access to this machine
-       dictionary_get_all(op->urls, registry_person_url_callback_verify_machine_exists, &data);
-       if(!data.count) {
-               registry_json_header(w, "switch", REGISTRY_STATUS_FAILED);
-               registry_json_footer(w);
-               return 433;
-       }
-
-       // verify the new person has access to this machine
-       data.count = 0;
-       dictionary_get_all(np->urls, registry_person_url_callback_verify_machine_exists, &data);
-       if(!data.count) {
-               registry_json_header(w, "switch", REGISTRY_STATUS_FAILED);
-               registry_json_footer(w);
-               return 434;
-       }
-
-       // set the cookie of the new person
-       // the user just switched identity
-       registry_set_person_cookie(w, np);
-
-       // generate the response
-       registry_json_header(w, "switch", REGISTRY_STATUS_OK);
-       buffer_sprintf(w->response.data, ",\n\t\"person_guid\": \"%s\"", np->guid);
-       registry_json_footer(w);
-       return 200;
-}
-
-
 // ----------------------------------------------------------------------------
-// REGISTRY THIS MACHINE UNIQUE ID
-
-char *registry_get_this_machine_guid(void) {
-       if(likely(registry.machine_guid[0]))
-               return registry.machine_guid;
-
-       // read it from disk
-       int fd = open(registry.machine_guid_filename, O_RDONLY);
-       if(fd != -1) {
-               char buf[36 + 1];
-               if(read(fd, buf, 36) != 36)
-                       error("Failed to read machine GUID from '%s'", registry.machine_guid_filename);
-               else {
-                       buf[36] = '\0';
-                       if(registry_regenerate_guid(buf, registry.machine_guid) == -1) {
-                               error("Failed to validate machine GUID '%s' from '%s'. Ignoring it - this might mean this netdata will appear as duplicate in the registry.",
-                                         buf, registry.machine_guid_filename);
-
-                               registry.machine_guid[0] = '\0';
-                       }
-               }
-               close(fd);
-       }
-
-       // generate a new one?
-       if(!registry.machine_guid[0]) {
-               uuid_t uuid;
-
-               uuid_generate_time(uuid);
-               uuid_unparse_lower(uuid, registry.machine_guid);
-               registry.machine_guid[36] = '\0';
-
-               // save it
-               fd = open(registry.machine_guid_filename, O_WRONLY|O_CREAT|O_TRUNC, 444);
-               if(fd == -1)
-                       fatal("Cannot create unique machine id file '%s'. Please fix this.", registry.machine_guid_filename);
-
-               if(write(fd, registry.machine_guid, 36) != 36)
-                       fatal("Cannot write the unique machine id file '%s'. Please fix this.", registry.machine_guid_filename);
-
-               close(fd);
-       }
-
-       return registry.machine_guid;
-}
-
-
-// ----------------------------------------------------------------------------
-// REGISTRY LOAD/SAVE
-
-int registry_machine_save_url(void *entry, void *file) {
-       MACHINE_URL *mu = entry;
-       FILE *fp = file;
+// public HELLO request
 
-       debug(D_REGISTRY, "Registry: registry_machine_save_url('%s')", mu->url->url);
+int registry_request_hello_json(RRDHOST *host, struct web_client *w) {
+    registry_json_header(host, w, "hello", REGISTRY_STATUS_OK);
 
-       int ret = fprintf(fp, "V\t%08x\t%08x\t%08x\t%02x\t%s\n",
-                       mu->first_t,
-                       mu->last_t,
-                       mu->usages,
-                       mu->flags,
-                       mu->url->url
-       );
+    buffer_sprintf(w->response.data, ",\n\t\"registry\": \"%s\"",
+            registry.registry_to_announce);
 
-       // error handling is done at registry_save()
-
-       return ret;
+    registry_json_footer(w);
+    return 200;
 }
 
-int registry_machine_save(void *entry, void *file) {
-       MACHINE *m = entry;
-       FILE *fp = file;
-
-       debug(D_REGISTRY, "Registry: registry_machine_save('%s')", m->guid);
-
-       int ret = fprintf(fp, "M\t%08x\t%08x\t%08x\t%s\n",
-                       m->first_t,
-                       m->last_t,
-                       m->usages,
-                       m->guid
-       );
-
-       if(ret >= 0) {
-               int ret2 = dictionary_get_all(m->urls, registry_machine_save_url, fp);
-               if(ret2 < 0) return ret2;
-               ret += ret2;
-       }
-
-       // error handling is done at registry_save()
-
-       return ret;
-}
-
-static inline int registry_person_save_url(void *entry, void *file) {
-       PERSON_URL *pu = entry;
-       FILE *fp = file;
+// ----------------------------------------------------------------------------
+//public ACCESS request
 
-       debug(D_REGISTRY, "Registry: registry_person_save_url('%s')", pu->url->url);
+#define REGISTRY_VERIFY_COOKIES_GUID "give-me-back-this-cookie-now--please"
 
-       int ret = fprintf(fp, "U\t%08x\t%08x\t%08x\t%02x\t%s\t%s\t%s\n",
-                       pu->first_t,
-                       pu->last_t,
-                       pu->usages,
-                       pu->flags,
-                       pu->machine->guid,
-                       pu->name,
-                       pu->url->url
-       );
+// the main method for registering an access
+int registry_request_access_json(RRDHOST *host, struct web_client *w, char *person_guid, char *machine_guid, char *url, char *name, time_t when) {
+    if(unlikely(!registry.enabled))
+        return registry_json_disabled(host, w, "access");
 
-       // error handling is done at registry_save()
+    // ------------------------------------------------------------------------
+    // verify the browser supports cookies
 
-       return ret;
-}
+    if(registry.verify_cookies_redirects > 0 && !person_guid[0]) {
+        buffer_flush(w->response.data);
+        registry_set_cookie(w, REGISTRY_VERIFY_COOKIES_GUID);
+        w->response.data->contenttype = CT_APPLICATION_JSON;
+        buffer_sprintf(w->response.data, "{ \"status\": \"redirect\", \"registry\": \"%s\" }", registry.registry_to_announce);
+        return 200;
+    }
 
-static inline int registry_person_save(void *entry, void *file) {
-       PERSON *p = entry;
-       FILE *fp = file;
+    if(unlikely(person_guid[0] && !strcmp(person_guid, REGISTRY_VERIFY_COOKIES_GUID)))
+        person_guid[0] = '\0';
 
-       debug(D_REGISTRY, "Registry: registry_person_save('%s')", p->guid);
+    // ------------------------------------------------------------------------
 
-       int ret = fprintf(fp, "P\t%08x\t%08x\t%08x\t%s\n",
-                       p->first_t,
-                       p->last_t,
-                       p->usages,
-                       p->guid
-       );
+    registry_lock();
 
-       if(ret >= 0) {
-               int ret2 = dictionary_get_all(p->urls, registry_person_save_url, fp);
-               if (ret2 < 0) return ret2;
-               ret += ret2;
-       }
+    REGISTRY_PERSON *p = registry_request_access(person_guid, machine_guid, url, name, when);
+    if(!p) {
+        registry_json_header(host, w, "access", REGISTRY_STATUS_FAILED);
+        registry_json_footer(w);
+        registry_unlock();
+        return 412;
+    }
 
-       // error handling is done at registry_save()
+    // set the cookie
+    registry_set_person_cookie(w, p);
 
-       return ret;
-}
+    // generate the response
+    registry_json_header(host, w, "access", REGISTRY_STATUS_OK);
 
-int registry_save(void) {
-       if(!registry.enabled) return -1;
-
-       // make sure the log is not updated
-       registry_log_lock();
-
-       if(unlikely(!registry_should_save_db())) {
-               registry_log_unlock();
-               return -2;
-       }
-
-       char tmp_filename[FILENAME_MAX + 1];
-       char old_filename[FILENAME_MAX + 1];
-
-       snprintfz(old_filename, FILENAME_MAX, "%s.old", registry.db_filename);
-       snprintfz(tmp_filename, FILENAME_MAX, "%s.tmp", registry.db_filename);
-
-       debug(D_REGISTRY, "Registry: Creating file '%s'", tmp_filename);
-       FILE *fp = fopen(tmp_filename, "w");
-       if(!fp) {
-               error("Registry: Cannot create file: %s", tmp_filename);
-               registry_log_unlock();
-               return -1;
-       }
-
-       // dictionary_get_all() has its own locking, so this is safe to do
-
-       debug(D_REGISTRY, "Saving all machines");
-       int bytes1 = dictionary_get_all(registry.machines, registry_machine_save, fp);
-       if(bytes1 < 0) {
-               error("Registry: Cannot save registry machines - return value %d", bytes1);
-               fclose(fp);
-               registry_log_unlock();
-               return bytes1;
-       }
-       debug(D_REGISTRY, "Registry: saving machines took %d bytes", bytes1);
-
-       debug(D_REGISTRY, "Saving all persons");
-       int bytes2 = dictionary_get_all(registry.persons, registry_person_save, fp);
-       if(bytes2 < 0) {
-               error("Registry: Cannot save registry persons - return value %d", bytes2);
-               fclose(fp);
-               registry_log_unlock();
-               return bytes2;
-       }
-       debug(D_REGISTRY, "Registry: saving persons took %d bytes", bytes2);
-
-       // save the totals
-       fprintf(fp, "T\t%016llx\t%016llx\t%016llx\t%016llx\t%016llx\t%016llx\n",
-                       registry.persons_count,
-                       registry.machines_count,
-                       registry.usages_count + 1, // this is required - it is lost on db rotation
-                       registry.urls_count,
-                       registry.persons_urls_count,
-                       registry.machines_urls_count
-       );
-
-       fclose(fp);
-
-       errno = 0;
-
-       // remove the .old db
-       debug(D_REGISTRY, "Registry: Removing old db '%s'", old_filename);
-       if(unlink(old_filename) == -1 && errno != ENOENT)
-               error("Registry: cannot remove old registry file '%s'", old_filename);
-
-       // rename the db to .old
-       debug(D_REGISTRY, "Registry: Link current db '%s' to .old: '%s'", registry.db_filename, old_filename);
-       if(link(registry.db_filename, old_filename) == -1 && errno != ENOENT)
-               error("Registry: cannot move file '%s' to '%s'. Saving registry DB failed!", tmp_filename, registry.db_filename);
-
-       else {
-               // remove the database (it is saved in .old)
-               debug(D_REGISTRY, "Registry: removing db '%s'", registry.db_filename);
-               if (unlink(registry.db_filename) == -1 && errno != ENOENT)
-                       error("Registry: cannot remove old registry file '%s'", registry.db_filename);
-
-               // move the .tmp to make it active
-               debug(D_REGISTRY, "Registry: linking tmp db '%s' to active db '%s'", tmp_filename, registry.db_filename);
-               if (link(tmp_filename, registry.db_filename) == -1) {
-                       error("Registry: cannot move file '%s' to '%s'. Saving registry DB failed!", tmp_filename,
-                                 registry.db_filename);
-
-                       // move the .old back
-                       debug(D_REGISTRY, "Registry: linking old db '%s' to active db '%s'", old_filename, registry.db_filename);
-                       if(link(old_filename, registry.db_filename) == -1)
-                               error("Registry: cannot move file '%s' to '%s'. Recovering the old registry DB failed!", old_filename, registry.db_filename);
-               }
-               else {
-                       debug(D_REGISTRY, "Registry: removing tmp db '%s'", tmp_filename);
-                       if(unlink(tmp_filename) == -1)
-                               error("Registry: cannot remove tmp registry file '%s'", tmp_filename);
-
-                       // it has been moved successfully
-                       // discard the current registry log
-                       registry_log_recreate_nolock();
-
-                       registry.log_count = 0;
-               }
-       }
-
-       // continue operations
-       registry_log_unlock();
-
-       return -1;
-}
+    buffer_sprintf(w->response.data, ",\n\t\"person_guid\": \"%s\",\n\t\"urls\": [", p->guid);
+    struct registry_json_walk_person_urls_callback c = { p, NULL, w, 0 };
+    avl_traverse(&p->person_urls, registry_json_person_url_callback, &c);
+    buffer_strcat(w->response.data, "\n\t]\n");
 
-static inline size_t registry_load(void) {
-       char *s, buf[4096 + 1];
-       PERSON *p = NULL;
-       MACHINE *m = NULL;
-       URL *u = NULL;
-       size_t line = 0;
-
-       debug(D_REGISTRY, "Registry: loading active db from: '%s'", registry.db_filename);
-       FILE *fp = fopen(registry.db_filename, "r");
-       if(!fp) {
-               error("Registry: cannot open registry file: '%s'", registry.db_filename);
-               return 0;
-       }
-
-       size_t len = 0;
-       buf[4096] = '\0';
-       while((s = fgets_trim_len(buf, 4096, fp, &len))) {
-               line++;
-
-               debug(D_REGISTRY, "Registry: read line %zu to length %zu: %s", line, len, s);
-               switch(*s) {
-                       case 'T': // totals
-                               if(unlikely(len != 103 || s[1] != '\t' || s[18] != '\t' || s[35] != '\t' || s[52] != '\t' || s[69] != '\t' || s[86] != '\t' || s[103] != '\0')) {
-                                       error("Registry totals line %zu is wrong (len = %zu).", line, len);
-                                       continue;
-                               }
-                               registry.persons_count = strtoull(&s[2], NULL, 16);
-                               registry.machines_count = strtoull(&s[19], NULL, 16);
-                               registry.usages_count = strtoull(&s[36], NULL, 16);
-                               registry.urls_count = strtoull(&s[53], NULL, 16);
-                               registry.persons_urls_count = strtoull(&s[70], NULL, 16);
-                               registry.machines_urls_count = strtoull(&s[87], NULL, 16);
-                               break;
-
-                       case 'P': // person
-                               m = NULL;
-                               // verify it is valid
-                               if(unlikely(len != 65 || s[1] != '\t' || s[10] != '\t' || s[19] != '\t' || s[28] != '\t' || s[65] != '\0')) {
-                                       error("Registry person line %zu is wrong (len = %zu).", line, len);
-                                       continue;
-                               }
-
-                               s[1] = s[10] = s[19] = s[28] = '\0';
-                               p = registry_person_allocate(&s[29], strtoul(&s[2], NULL, 16));
-                               p->last_t = strtoul(&s[11], NULL, 16);
-                               p->usages = strtoul(&s[20], NULL, 16);
-                               debug(D_REGISTRY, "Registry loaded person '%s', first: %u, last: %u, usages: %u", p->guid, p->first_t, p->last_t, p->usages);
-                               break;
-
-                       case 'M': // machine
-                               p = NULL;
-                               // verify it is valid
-                               if(unlikely(len != 65 || s[1] != '\t' || s[10] != '\t' || s[19] != '\t' || s[28] != '\t' || s[65] != '\0')) {
-                                       error("Registry person line %zu is wrong (len = %zu).", line, len);
-                                       continue;
-                               }
-
-                               s[1] = s[10] = s[19] = s[28] = '\0';
-                               m = registry_machine_allocate(&s[29], strtoul(&s[2], NULL, 16));
-                               m->last_t = strtoul(&s[11], NULL, 16);
-                               m->usages = strtoul(&s[20], NULL, 16);
-                               debug(D_REGISTRY, "Registry loaded machine '%s', first: %u, last: %u, usages: %u", m->guid, m->first_t, m->last_t, m->usages);
-                               break;
-
-                       case 'U': // person URL
-                               if(unlikely(!p)) {
-                                       error("Registry: ignoring line %zu, no person loaded: %s", line, s);
-                                       continue;
-                               }
-
-                               // verify it is valid
-                               if(len < 69 || s[1] != '\t' || s[10] != '\t' || s[19] != '\t' || s[28] != '\t' || s[31] != '\t' || s[68] != '\t') {
-                                       error("Registry person URL line %zu is wrong (len = %zu).", line, len);
-                                       continue;
-                               }
-
-                               s[1] = s[10] = s[19] = s[28] = s[31] = s[68] = '\0';
-
-                               // skip the name to find the url
-                               char *url = &s[69];
-                               while(*url && *url != '\t') url++;
-                               if(!*url) {
-                                       error("Registry person URL line %zu does not have a url.", line);
-                                       continue;
-                               }
-                               *url++ = '\0';
-
-                               u = registry_url_allocate_nolock(url, strlen(url));
-
-                               time_t first_t = strtoul(&s[2], NULL, 16);
-
-                               m = registry_machine_find(&s[32]);
-                               if(!m) m = registry_machine_allocate(&s[32], first_t);
-
-                               PERSON_URL *pu = registry_person_url_allocate(p, m, u, &s[69], strlen(&s[69]), first_t);
-                               pu->last_t = strtoul(&s[11], NULL, 16);
-                               pu->usages = strtoul(&s[20], NULL, 16);
-                               pu->flags = strtoul(&s[29], NULL, 16);
-                               debug(D_REGISTRY, "Registry loaded person URL '%s' with name '%s' of machine '%s', first: %u, last: %u, usages: %u, flags: %02x", u->url, pu->name, m->guid, pu->first_t, pu->last_t, pu->usages, pu->flags);
-                               break;
-
-                       case 'V': // machine URL
-                               if(unlikely(!m)) {
-                                       error("Registry: ignoring line %zu, no machine loaded: %s", line, s);
-                                       continue;
-                               }
-
-                               // verify it is valid
-                               if(len < 32 || s[1] != '\t' || s[10] != '\t' || s[19] != '\t' || s[28] != '\t' || s[31] != '\t') {
-                                       error("Registry person URL line %zu is wrong (len = %zu).", line, len);
-                                       continue;
-                               }
-
-                               s[1] = s[10] = s[19] = s[28] = s[31] = '\0';
-                               u = registry_url_allocate_nolock(&s[32], strlen(&s[32]));
-
-                               MACHINE_URL *mu = registry_machine_url_allocate(m, u, strtoul(&s[2], NULL, 16));
-                               mu->last_t = strtoul(&s[11], NULL, 16);
-                               mu->usages = strtoul(&s[20], NULL, 16);
-                               mu->flags = strtoul(&s[29], NULL, 16);
-                               debug(D_REGISTRY, "Registry loaded machine URL '%s', machine '%s', first: %u, last: %u, usages: %u, flags: %02x", u->url, m->guid, mu->first_t, mu->last_t, mu->usages, mu->flags);
-                               break;
-
-                       default:
-                               error("Registry: ignoring line %zu of filename '%s': %s.", line, registry.db_filename, s);
-                               break;
-               }
-       }
-       fclose(fp);
-
-       return line;
+    registry_json_footer(w);
+    registry_unlock();
+    return 200;
 }
 
 // ----------------------------------------------------------------------------
-// REGISTRY
-
-int registry_init(void) {
-       char filename[FILENAME_MAX + 1];
-
-       // registry enabled?
-       registry.enabled = config_get_boolean("registry", "enabled", 0);
-
-       if(mkdir(VARLIB_DIR, 0755) == -1 && errno != EEXIST)
-               error("Cannot create directory '" VARLIB_DIR "'");
-
-       // pathnames
-       registry.pathname = config_get("registry", "registry db directory", VARLIB_DIR "/registry");
-       if(mkdir(registry.pathname, 0755) == -1 && errno != EEXIST) {
-               error("Cannot create directory '%s'. Registry disabled.", registry.pathname);
-               registry.enabled = 0;
-               return -1;
-       }
-
-       // filenames
-       snprintfz(filename, FILENAME_MAX, "%s/netdata.public.unique.id", registry.pathname);
-       registry.machine_guid_filename = config_get("registry", "netdata unique id file", filename);
-       registry_get_this_machine_guid();
-
-       snprintfz(filename, FILENAME_MAX, "%s/registry.db", registry.pathname);
-       registry.db_filename = config_get("registry", "registry db file", filename);
-
-       snprintfz(filename, FILENAME_MAX, "%s/registry-log.db", registry.pathname);
-       registry.log_filename = config_get("registry", "registry log file", filename);
-
-       // configuration options
-       registry.save_registry_every_entries = config_get_number("registry", "registry save db every new entries", 1000000);
-       registry.persons_expiration = config_get_number("registry", "registry expire idle persons days", 365) * 86400;
-       registry.registry_domain = config_get("registry", "registry domain", "");
-       registry.registry_to_announce = config_get("registry", "registry to announce", "https://registry.my-netdata.io");
-       registry.hostname = config_get("registry", "registry hostname", config_get("global", "hostname", hostname));
-       registry.verify_cookies_redirects = config_get_boolean("registry", "verify browser cookies support", 1);
-
-       registry.max_url_length = config_get_number("registry", "max URL length", 1024);
-       if(registry.max_url_length < 10) {
-               registry.max_url_length = 10;
-               config_set_number("registry", "max URL length", registry.max_url_length);
-       }
-
-       registry.max_name_length = config_get_number("registry", "max URL name length", 50);
-       if(registry.max_name_length < 10) {
-               registry.max_name_length = 10;
-               config_set_number("registry", "max URL name length", registry.max_name_length);
-       }
-
-       // initialize entries counters
-       registry.persons_count = 0;
-       registry.machines_count = 0;
-       registry.usages_count = 0;
-       registry.urls_count = 0;
-       registry.persons_urls_count = 0;
-       registry.machines_urls_count = 0;
-
-       // initialize memory counters
-       registry.persons_memory = 0;
-       registry.machines_memory = 0;
-       registry.urls_memory = 0;
-       registry.persons_urls_memory = 0;
-       registry.machines_urls_memory = 0;
-
-       // initialize locks
-       pthread_mutex_init(&registry.persons_lock, NULL);
-       pthread_mutex_init(&registry.machines_lock, NULL);
-       pthread_mutex_init(&registry.urls_lock, NULL);
-       pthread_mutex_init(&registry.person_urls_lock, NULL);
-       pthread_mutex_init(&registry.machine_urls_lock, NULL);
-
-       // create dictionaries
-       registry.persons = dictionary_create(DICTIONARY_FLAGS);
-       registry.machines = dictionary_create(DICTIONARY_FLAGS);
-       registry.urls = dictionary_create(DICTIONARY_FLAGS);
-
-       // load the registry database
-       if(registry.enabled) {
-               registry_log_open_nolock();
-               registry_load();
-               registry_log_load();
-       }
-
-       return 0;
-}
-
-void registry_free(void) {
-       if(!registry.enabled) return;
-
-       // we need to destroy the dictionaries ourselves
-       // since the dictionaries use memory we allocated
-
-       while(registry.persons->values_index.root) {
-               PERSON *p = ((NAME_VALUE *)registry.persons->values_index.root)->value;
-
-               // fprintf(stderr, "\nPERSON: '%s', first: %u, last: %u, usages: %u\n", p->guid, p->first_t, p->last_t, p->usages);
+// public DELETE request
 
-               while(p->urls->values_index.root) {
-                       PERSON_URL *pu = ((NAME_VALUE *)p->urls->values_index.root)->value;
-
-                       // fprintf(stderr, "\tURL: '%s', first: %u, last: %u, usages: %u, flags: 0x%02x\n", pu->url->url, pu->first_t, pu->last_t, pu->usages, pu->flags);
-
-                       debug(D_REGISTRY, "Registry: deleting url '%s' from person '%s'", pu->url->url, p->guid);
-                       dictionary_del(p->urls, pu->url->url);
-
-                       debug(D_REGISTRY, "Registry: unlinking url '%s' from person", pu->url->url);
-                       registry_url_unlink_nolock(pu->url);
-
-                       debug(D_REGISTRY, "Registry: freeing person url");
-                       freez(pu);
-               }
-
-               debug(D_REGISTRY, "Registry: deleting person '%s' from persons registry", p->guid);
-               dictionary_del(registry.persons, p->guid);
-
-               debug(D_REGISTRY, "Registry: destroying URL dictionary of person '%s'", p->guid);
-               dictionary_destroy(p->urls);
-
-               debug(D_REGISTRY, "Registry: freeing person '%s'", p->guid);
-               freez(p);
-       }
-
-       while(registry.machines->values_index.root) {
-               MACHINE *m = ((NAME_VALUE *)registry.machines->values_index.root)->value;
-
-               // fprintf(stderr, "\nMACHINE: '%s', first: %u, last: %u, usages: %u\n", m->guid, m->first_t, m->last_t, m->usages);
-
-               while(m->urls->values_index.root) {
-                       MACHINE_URL *mu = ((NAME_VALUE *)m->urls->values_index.root)->value;
+// the main method for deleting a URL from a person
+int registry_request_delete_json(RRDHOST *host, struct web_client *w, char *person_guid, char *machine_guid, char *url, char *delete_url, time_t when) {
+    if(!registry.enabled)
+        return registry_json_disabled(host, w, "delete");
 
-                       // fprintf(stderr, "\tURL: '%s', first: %u, last: %u, usages: %u, flags: 0x%02x\n", mu->url->url, mu->first_t, mu->last_t, mu->usages, mu->flags);
+    registry_lock();
 
-                       //debug(D_REGISTRY, "Registry: destroying persons dictionary from url '%s'", mu->url->url);
-                       //dictionary_destroy(mu->persons);
+    REGISTRY_PERSON *p = registry_request_delete(person_guid, machine_guid, url, delete_url, when);
+    if(!p) {
+        registry_json_header(host, w, "delete", REGISTRY_STATUS_FAILED);
+        registry_json_footer(w);
+        registry_unlock();
+        return 412;
+    }
 
-                       debug(D_REGISTRY, "Registry: deleting url '%s' from person '%s'", mu->url->url, m->guid);
-                       dictionary_del(m->urls, mu->url->url);
+    // generate the response
+    registry_json_header(host, w, "delete", REGISTRY_STATUS_OK);
+    registry_json_footer(w);
+    registry_unlock();
+    return 200;
+}
 
-                       debug(D_REGISTRY, "Registry: unlinking url '%s' from machine", mu->url->url);
-                       registry_url_unlink_nolock(mu->url);
+// ----------------------------------------------------------------------------
+// public SEARCH request
 
-                       debug(D_REGISTRY, "Registry: freeing machine url");
-                       freez(mu);
-               }
+// the main method for searching the URLs of a netdata
+int registry_request_search_json(RRDHOST *host, struct web_client *w, char *person_guid, char *machine_guid, char *url, char *request_machine, time_t when) {
+    if(!registry.enabled)
+        return registry_json_disabled(host, w, "search");
 
-               debug(D_REGISTRY, "Registry: deleting machine '%s' from machines registry", m->guid);
-               dictionary_del(registry.machines, m->guid);
+    registry_lock();
 
-               debug(D_REGISTRY, "Registry: destroying URL dictionary of machine '%s'", m->guid);
-               dictionary_destroy(m->urls);
+    REGISTRY_MACHINE *m = registry_request_machine(person_guid, machine_guid, url, request_machine, when);
+    if(!m) {
+        registry_json_header(host, w, "search", REGISTRY_STATUS_FAILED);
+        registry_json_footer(w);
+        registry_unlock();
+        return 404;
+    }
 
-               debug(D_REGISTRY, "Registry: freeing machine '%s'", m->guid);
-               freez(m);
-       }
+    registry_json_header(host, w, "search", REGISTRY_STATUS_OK);
 
-       // and free the memory of remaining dictionary structures
+    buffer_strcat(w->response.data, ",\n\t\"urls\": [");
+    struct registry_json_walk_person_urls_callback c = { NULL, m, w, 0 };
+    dictionary_get_all(m->machine_urls, registry_json_machine_url_callback, &c);
+    buffer_strcat(w->response.data, "\n\t]\n");
 
-       debug(D_REGISTRY, "Registry: destroying persons dictionary");
-       dictionary_destroy(registry.persons);
+    registry_json_footer(w);
+    registry_unlock();
+    return 200;
+}
 
-       debug(D_REGISTRY, "Registry: destroying machines dictionary");
-       dictionary_destroy(registry.machines);
+// ----------------------------------------------------------------------------
+// SWITCH REQUEST
 
-       debug(D_REGISTRY, "Registry: destroying urls dictionary");
-       dictionary_destroy(registry.urls);
+// the main method for switching user identity
+int registry_request_switch_json(RRDHOST *host, struct web_client *w, char *person_guid, char *machine_guid, char *url, char *new_person_guid, time_t when) {
+    if(!registry.enabled)
+        return registry_json_disabled(host, w, "switch");
+
+    (void)url;
+    (void)when;
+
+    registry_lock();
+
+    REGISTRY_PERSON *op = registry_person_find(person_guid);
+    if(!op) {
+        registry_json_header(host, w, "switch", REGISTRY_STATUS_FAILED);
+        registry_json_footer(w);
+        registry_unlock();
+        return 430;
+    }
+
+    REGISTRY_PERSON *np = registry_person_find(new_person_guid);
+    if(!np) {
+        registry_json_header(host, w, "switch", REGISTRY_STATUS_FAILED);
+        registry_json_footer(w);
+        registry_unlock();
+        return 431;
+    }
+
+    REGISTRY_MACHINE *m = registry_machine_find(machine_guid);
+    if(!m) {
+        registry_json_header(host, w, "switch", REGISTRY_STATUS_FAILED);
+        registry_json_footer(w);
+        registry_unlock();
+        return 432;
+    }
+
+    struct registry_person_url_callback_verify_machine_exists_data data = { m, 0 };
+
+    // verify the old person has access to this machine
+    avl_traverse(&op->person_urls, registry_person_url_callback_verify_machine_exists, &data);
+    if(!data.count) {
+        registry_json_header(host, w, "switch", REGISTRY_STATUS_FAILED);
+        registry_json_footer(w);
+        registry_unlock();
+        return 433;
+    }
+
+    // verify the new person has access to this machine
+    data.count = 0;
+    avl_traverse(&np->person_urls, registry_person_url_callback_verify_machine_exists, &data);
+    if(!data.count) {
+        registry_json_header(host, w, "switch", REGISTRY_STATUS_FAILED);
+        registry_json_footer(w);
+        registry_unlock();
+        return 434;
+    }
+
+    // set the cookie of the new person
+    // the user just switched identity
+    registry_set_person_cookie(w, np);
+
+    // generate the response
+    registry_json_header(host, w, "switch", REGISTRY_STATUS_OK);
+    buffer_sprintf(w->response.data, ",\n\t\"person_guid\": \"%s\"", np->guid);
+    registry_json_footer(w);
+
+    registry_unlock();
+    return 200;
 }
 
 // ----------------------------------------------------------------------------
 // STATISTICS
 
 void registry_statistics(void) {
-       if(!registry.enabled) return;
-
-       static RRDSET *sts = NULL, *stc = NULL, *stm = NULL;
-
-       if(!sts) sts = rrdset_find("netdata.registry_sessions");
-       if(!sts) {
-               sts = rrdset_create("netdata", "registry_sessions", NULL, "registry", NULL, "NetData Registry Sessions", "session", 131000, rrd_update_every, RRDSET_TYPE_LINE);
-
-               rrddim_add(sts, "sessions",  NULL,  1, 1, RRDDIM_ABSOLUTE);
-       }
-       else rrdset_next(sts);
-
-       rrddim_set(sts, "sessions", registry.usages_count);
-       rrdset_done(sts);
-
-       // ------------------------------------------------------------------------
-
-       if(!stc) stc = rrdset_find("netdata.registry_entries");
-       if(!stc) {
-               stc = rrdset_create("netdata", "registry_entries", NULL, "registry", NULL, "NetData Registry Entries", "entries", 131100, rrd_update_every, RRDSET_TYPE_LINE);
-
-               rrddim_add(stc, "persons",        NULL,  1, 1, RRDDIM_ABSOLUTE);
-               rrddim_add(stc, "machines",       NULL,  1, 1, RRDDIM_ABSOLUTE);
-               rrddim_add(stc, "urls",           NULL,  1, 1, RRDDIM_ABSOLUTE);
-               rrddim_add(stc, "persons_urls",   NULL,  1, 1, RRDDIM_ABSOLUTE);
-               rrddim_add(stc, "machines_urls",  NULL,  1, 1, RRDDIM_ABSOLUTE);
-       }
-       else rrdset_next(stc);
-
-       rrddim_set(stc, "persons",       registry.persons_count);
-       rrddim_set(stc, "machines",      registry.machines_count);
-       rrddim_set(stc, "urls",          registry.urls_count);
-       rrddim_set(stc, "persons_urls",  registry.persons_urls_count);
-       rrddim_set(stc, "machines_urls", registry.machines_urls_count);
-       rrdset_done(stc);
-
-       // ------------------------------------------------------------------------
-
-       if(!stm) stm = rrdset_find("netdata.registry_mem");
-       if(!stm) {
-               stm = rrdset_create("netdata", "registry_mem", NULL, "registry", NULL, "NetData Registry Memory", "KB", 131300, rrd_update_every, RRDSET_TYPE_STACKED);
-
-               rrddim_add(stm, "persons",        NULL,  1, 1024, RRDDIM_ABSOLUTE);
-               rrddim_add(stm, "machines",       NULL,  1, 1024, RRDDIM_ABSOLUTE);
-               rrddim_add(stm, "urls",           NULL,  1, 1024, RRDDIM_ABSOLUTE);
-               rrddim_add(stm, "persons_urls",   NULL,  1, 1024, RRDDIM_ABSOLUTE);
-               rrddim_add(stm, "machines_urls",  NULL,  1, 1024, RRDDIM_ABSOLUTE);
-       }
-       else rrdset_next(stm);
-
-       rrddim_set(stm, "persons",       registry.persons_memory + registry.persons_count * sizeof(NAME_VALUE) + sizeof(DICTIONARY));
-       rrddim_set(stm, "machines",      registry.machines_memory + registry.machines_count * sizeof(NAME_VALUE) + sizeof(DICTIONARY));
-       rrddim_set(stm, "urls",          registry.urls_memory + registry.urls_count * sizeof(NAME_VALUE) + sizeof(DICTIONARY));
-       rrddim_set(stm, "persons_urls",  registry.persons_urls_memory + registry.persons_count * sizeof(DICTIONARY) + registry.persons_urls_count * sizeof(NAME_VALUE));
-       rrddim_set(stm, "machines_urls", registry.machines_urls_memory + registry.machines_count * sizeof(DICTIONARY) + registry.machines_urls_count * sizeof(NAME_VALUE));
-       rrdset_done(stm);
+    if(!registry.enabled) return;
+
+    static RRDSET *sts = NULL, *stc = NULL, *stm = NULL;
+
+    if(!sts) sts = rrdset_find_localhost("netdata.registry_sessions");
+    if(!sts) {
+        sts = rrdset_create_localhost("netdata", "registry_sessions", NULL, "registry", NULL
+                                      , "NetData Registry Sessions", "session", 131000, localhost->rrd_update_every
+                                      , RRDSET_TYPE_LINE);
+
+        rrddim_add(sts, "sessions",  NULL,  1, 1, RRD_ALGORITHM_ABSOLUTE);
+    }
+    else rrdset_next(sts);
+
+    rrddim_set(sts, "sessions", registry.usages_count);
+    rrdset_done(sts);
+
+    // ------------------------------------------------------------------------
+
+    if(!stc) stc = rrdset_find_localhost("netdata.registry_entries");
+    if(!stc) {
+        stc = rrdset_create_localhost("netdata", "registry_entries", NULL, "registry", NULL, "NetData Registry Entries"
+                                      , "entries", 131100, localhost->rrd_update_every, RRDSET_TYPE_LINE);
+
+        rrddim_add(stc, "persons",        NULL,  1, 1, RRD_ALGORITHM_ABSOLUTE);
+        rrddim_add(stc, "machines",       NULL,  1, 1, RRD_ALGORITHM_ABSOLUTE);
+        rrddim_add(stc, "urls",           NULL,  1, 1, RRD_ALGORITHM_ABSOLUTE);
+        rrddim_add(stc, "persons_urls",   NULL,  1, 1, RRD_ALGORITHM_ABSOLUTE);
+        rrddim_add(stc, "machines_urls",  NULL,  1, 1, RRD_ALGORITHM_ABSOLUTE);
+    }
+    else rrdset_next(stc);
+
+    rrddim_set(stc, "persons",       registry.persons_count);
+    rrddim_set(stc, "machines",      registry.machines_count);
+    rrddim_set(stc, "urls",          registry.urls_count);
+    rrddim_set(stc, "persons_urls",  registry.persons_urls_count);
+    rrddim_set(stc, "machines_urls", registry.machines_urls_count);
+    rrdset_done(stc);
+
+    // ------------------------------------------------------------------------
+
+    if(!stm) stm = rrdset_find_localhost("netdata.registry_mem");
+    if(!stm) {
+        stm = rrdset_create_localhost("netdata", "registry_mem", NULL, "registry", NULL, "NetData Registry Memory", "KB"
+                                      , 131300, localhost->rrd_update_every, RRDSET_TYPE_STACKED);
+
+        rrddim_add(stm, "persons",        NULL,  1, 1024, RRD_ALGORITHM_ABSOLUTE);
+        rrddim_add(stm, "machines",       NULL,  1, 1024, RRD_ALGORITHM_ABSOLUTE);
+        rrddim_add(stm, "urls",           NULL,  1, 1024, RRD_ALGORITHM_ABSOLUTE);
+        rrddim_add(stm, "persons_urls",   NULL,  1, 1024, RRD_ALGORITHM_ABSOLUTE);
+        rrddim_add(stm, "machines_urls",  NULL,  1, 1024, RRD_ALGORITHM_ABSOLUTE);
+    }
+    else rrdset_next(stm);
+
+    rrddim_set(stm, "persons",       registry.persons_memory + registry.persons_count * sizeof(NAME_VALUE) + sizeof(DICTIONARY));
+    rrddim_set(stm, "machines",      registry.machines_memory + registry.machines_count * sizeof(NAME_VALUE) + sizeof(DICTIONARY));
+    rrddim_set(stm, "urls",          registry.urls_memory);
+    rrddim_set(stm, "persons_urls",  registry.persons_urls_memory);
+    rrddim_set(stm, "machines_urls", registry.machines_urls_memory + registry.machines_count * sizeof(DICTIONARY) + registry.machines_urls_count * sizeof(NAME_VALUE));
+    rrdset_done(stm);
 }