Implement support for systemd(8) "socket activation"

[ngircd-alex.git] / src / ngircd / conn.c

diff --git a/src/ngircd/conn.c b/src/ngircd/conn.c
index 14d337b9408265b1213a157cd36cf66a8efc057e..378509f96f09bc35eb9e3ebc2eb12140c24509fb 100644 (file)
--- a/src/ngircd/conn.c
+++ b/src/ngircd/conn.c
@@ -82,6 +82,8 @@
 #define MAX_COMMANDS_SERVER_MIN 10
 #define MAX_COMMANDS_SERVICE 10
 
+#define SD_LISTEN_FDS_START 3
+
 
 static bool Handle_Write PARAMS(( CONN_ID Idx ));
 static bool Conn_Write PARAMS(( CONN_ID Idx, char *Data, size_t Len ));
@@ -120,6 +122,40 @@ static void cb_Connect_to_Server PARAMS((int sock, UNUSED short what));
 static void cb_clientserver PARAMS((int sock, short what));
 
 
+/**
+ * Get number of sockets available from systemd(8).
+ *
+ * ngIRCd needs to implement its own sd_listen_fds(3) function and can't
+ * use the one provided by systemd itself, becaus the sockets will be
+ * used in a forked child process with a new PID, and this would trigger
+ * an error in the standard implementation.
+ *
+ * @return Number of sockets available, -1 if sockets have already been
+ *         initialized, or 0 when no sockets have been passed.
+ */
+static int
+my_sd_listen_fds(void)
+{
+       const char *e;
+       long count;
+
+       /* Check if LISTEN_PID exists; but we ignore the result, because
+        * normally ngircd forks a child before checking this, and therefore
+        * the PID set in the environment is always wrong ... */
+       e = getenv("LISTEN_PID");
+       if (!e || !*e)
+               return 0;
+
+       e = getenv("LISTEN_FDS");
+       if (!e || !*e)
+               return -1;
+       count = atol(e);
+       unsetenv("LISTEN_FDS");
+
+       return count;
+}
+
+
 /**
  * IO callback for listening sockets: handle new connections. This callback
  * gets called when a new non-SSL connection should be accepted.
@@ -495,9 +531,38 @@ Conn_InitListeners( void )
        /* Initialize ports on which the server should accept connections */
        unsigned int created = 0;
        char *copy, *listen_addr;
+       int count, fd, i;
 
        assert(Conf_ListenAddress);
 
+       count = my_sd_listen_fds();
+       if (count < 0) {
+               Log(LOG_INFO,
+                   "Not re-initializing listening sockets of systemd(8) ...");
+               return 0;
+       }
+       if (count > 0) {
+               /* systemd(8) passed sockets to us, so don't try to initialize
+                * listening sockets on our own but use the passed ones */
+               LogDebug("Initializing %d systemd sockets ...", count);
+               for (i = 0; i < count; i++) {
+                       fd = SD_LISTEN_FDS_START + i;
+                       Init_Socket(fd);
+                       if (!io_event_create(fd, IO_WANTREAD, cb_listen)) {
+                               Log(LOG_ERR,
+                                   "io_event_create(): Can't add fd %d: %s!",
+                                   fd, strerror(errno));
+                               continue;
+                       }
+                       Log(LOG_INFO,
+                           "Initialized socket %d from systemd.", fd);
+                       created++;
+               }
+               return created;
+       }
+
+       /* not using systemd socket activation, initialize listening sockets: */
+
        /* can't use Conf_ListenAddress directly, see below */
        copy = strdup(Conf_ListenAddress);
        if (!copy) {
@@ -541,7 +606,12 @@ Conn_ExitListeners( void )
        int *fd;
        size_t arraylen;
 
+       /* Get number of listening sockets to shut down. There can be none
+        * if ngIRCd has been "socket activated" by systemd. */
        arraylen = array_length(&My_Listeners, sizeof (int));
+       if (arraylen < 1)
+               return;
+
        Log(LOG_INFO,
            "Shutting down all listening sockets (%d total) ...", arraylen);
        fd = array_start(&My_Listeners);