From 6ecccd26449e021e6e2bce3256d2475e8bc4a238 Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Sun, 24 Jul 2005 21:42:00 +0000 Subject: [PATCH] add reverse lookup check --- src/ngircd/resolve.c | 25 +++++++++++++++++++++---- 1 file changed, 21 insertions(+), 4 deletions(-) diff --git a/src/ngircd/resolve.c b/src/ngircd/resolve.c index d261fd0a..5529f168 100644 --- a/src/ngircd/resolve.c +++ b/src/ngircd/resolve.c @@ -14,7 +14,7 @@ #include "portab.h" -static char UNUSED id[] = "$Id: resolve.c,v 1.13 2005/07/07 18:39:08 fw Exp $"; +static char UNUSED id[] = "$Id: resolve.c,v 1.14 2005/07/24 21:42:00 fw Exp $"; #include "imp.h" #include @@ -185,8 +185,10 @@ Do_ResolveAddr( struct sockaddr_in *Addr, int w_fd ) * pipe to parent. */ char hostname[HOST_LEN]; + char ipstr[HOST_LEN]; struct hostent *h; size_t len; + struct in_addr *addr; #ifdef IDENTAUTH char *res; #endif @@ -194,15 +196,30 @@ Do_ResolveAddr( struct sockaddr_in *Addr, int w_fd ) /* Resolve IP address */ Log_Resolver( LOG_DEBUG, "Now resolving %s ...", inet_ntoa( Addr->sin_addr )); h = gethostbyaddr( (char *)&Addr->sin_addr, sizeof( Addr->sin_addr ), AF_INET ); - if( h ) strlcpy( hostname, h->h_name, sizeof( hostname )); - else - { + if (!h) { #ifdef h_errno Log_Resolver( LOG_WARNING, "Can't resolve address \"%s\": %s!", inet_ntoa( Addr->sin_addr ), Get_Error( h_errno )); #else Log_Resolver( LOG_WARNING, "Can't resolve address \"%s\"!", inet_ntoa( Addr->sin_addr )); #endif strlcpy( hostname, inet_ntoa( Addr->sin_addr ), sizeof( hostname )); + } else { + strlcpy( hostname, h->h_name, sizeof( hostname )); + + h = gethostbyname( hostname ); + if ( h ) { + if (memcmp(h->h_addr, &Addr->sin_addr, sizeof (struct in_addr))) { + addr = (struct in_addr*) h->h_addr; + strlcpy(ipstr, inet_ntoa(*addr), sizeof ipstr); + Log(LOG_WARNING,"Possible forgery: %s resolved to %s (which is at ip %s!)", + inet_ntoa( Addr->sin_addr), hostname, ipstr); + strlcpy( hostname, inet_ntoa( Addr->sin_addr ), sizeof( hostname )); + } + } else { + Log(LOG_WARNING, "Possible forgery: %s resolved to %s (which has no ip address)", + inet_ntoa( Addr->sin_addr ), hostname); + strlcpy( hostname, inet_ntoa( Addr->sin_addr ), sizeof( hostname )); + } } Log_Resolver( LOG_DEBUG, "Ok, translated %s to \"%s\".", inet_ntoa( Addr->sin_addr ), hostname ); -- 2.39.2