Patch by Matěj Cepl <mcepl@redhat.com> for bitlbee >= 3.2 to avoid static linking

to a private glibc function, that is normally visible as libc.so.6(GLIBC_PRIVATE)

in the binary RPM package. Glibc >= 2.9 allows dynamic linking using -lresolv for

ns_initparse()/ns_parserr(), but Red Hat Enterprise Linux 5 (including derivates)

is shipping glibc 2.5. A few more information and details regarding this patch in

Red Hat Bugzilla ID #439047: https://bugzilla.redhat.com/show_bug.cgi?id=439047

--- bitlbee-3.2.1/configure			2013-11-27 23:54:54.000000000 +0100

+++ bitlbee-3.2.1/configure.libresolv		2013-12-18 21:56:14.000000000 +0100

@@ -364,10 +364,10 @@

 	TMPFILE=$(mktemp /tmp/bitlbee-configure.XXXXXX)

 	ret=1

 	for i in $systemlibdirs; do

-		if [ -f $i/libresolv.a ]; then

+		if [ -f $i/libresolv.so ]; then

 			echo "$RESOLV_TESTCODE" | $CC -o $TMPFILE -x c - -Wl,$i/libresolv.a >/dev/null 2>/dev/null

 			if [ "$?" = "0" ]; then

-				echo 'EFLAGS+='$i'/libresolv.a' >> Makefile.settings

+				echo 'EFLAGS+=-lresolv' >> Makefile.settings

 				ret=0

 			fi

 		fi

--- bitlbee-3.2.1/lib/misc.c			2013-11-27 23:54:54.000000000 +0100

+++ bitlbee-3.2.1/lib/misc.c.libresolv		2013-12-18 22:10:45.000000000 +0100

--- bitlbee-3.2.1/lib/misc.c	2013-11-27 23:54:54.000000000 +0100

+++ bitlbee-3.2.1/lib/misc.c.libresolv.c	2013-12-18 22:18:29.000000000 +0100

@@ -30,6 +30,12 @@

   Suite 330, Boston, MA  02111-1307  USA

 */

+#undef TEST

+

+#ifdef TEST

+#define HAVE_RESOLV_A

+#endif

+

 #define BITLBEE_CORE

 #include "nogaim.h"

 #include "base64.h"

@@ -42,13 +48,17 @@

 #include <time.h>

 #ifdef HAVE_RESOLV_A

-#include <arpa/nameser.h>

 #include <resolv.h>

 #endif

 #include "md5.h"

 #include "ssl_client.h"

+/* Not every installation has gotten around to supporting SRVs yet... */

+#ifndef T_SRV

+#define T_SRV 33

+#endif

+

 void strip_linefeed(gchar *text)

 {

 	int i, j;

@@ -514,66 +524,6 @@

 	return 0;

 }

-struct ns_srv_reply **srv_lookup( char *service, char *protocol, char *domain )

-{	

-	struct ns_srv_reply **replies = NULL;

-#ifdef HAVE_RESOLV_A

-	struct ns_srv_reply *reply = NULL;

-	char name[1024];

-	unsigned char querybuf[1024];

-	const unsigned char *buf;

-	ns_msg nsh;

-	ns_rr rr;

-	int i, n, len, size;

-	

-	g_snprintf( name, sizeof( name ), "_%s._%s.%s", service, protocol, domain );

-	

-	if( ( size = res_query( name, ns_c_in, ns_t_srv, querybuf, sizeof( querybuf ) ) ) <= 0 )

-		return NULL;

-	

-	if( ns_initparse( querybuf, size, &nsh ) != 0 )

-		return NULL;

-	

-	n = 0;

-	while( ns_parserr( &nsh, ns_s_an, n, &rr ) == 0 )

-	{

-		size = ns_rr_rdlen( rr );

-		buf = ns_rr_rdata( rr );

-		

-		len = 0;

-		for( i = 6; i < size && buf[i]; i += buf[i] + 1 )

-			len += buf[i] + 1;

-		

-		if( i > size )

-			break;

-		

-		reply = g_malloc( sizeof( struct ns_srv_reply ) + len );

-		memcpy( reply->name, buf + 7, len );

-		

-		for( i = buf[6]; i < len && buf[7+i]; i += buf[7+i] + 1 )

-			reply->name[i] = '.';

-		

-		if( i > len )

-		{

-			g_free( reply );

-			break;

-		}

-		

-		reply->prio = ( buf[0] << 8 ) | buf[1];

-		reply->weight = ( buf[2] << 8 ) | buf[3];

-		reply->port = ( buf[4] << 8 ) | buf[5];

-		

-		n ++;

-		replies = g_renew( struct ns_srv_reply *, replies, n + 1 );

-		replies[n-1] = reply;

-	}

-	if( replies )

-		replies[n] = NULL;

-#endif

-	

-	return replies;

-}

-

 void srv_free( struct ns_srv_reply **srv )

 {

 	int i;

@@ -586,6 +536,136 @@

 	g_free( srv );

 }

+static int srv_compare( const void *a, const void *b )

+{

+	int prio;

+	const struct ns_srv_reply *sa = *(struct ns_srv_reply **) a;

+	const struct ns_srv_reply *sb = *(struct ns_srv_reply **) b;

+

+	prio = sa->prio - sb->prio;

+	if( prio == 0 )

+	{

+		/* Place weight 0 entries first. */

+		if( sa->weight == 0 )

+			return -1;

+		if( sb->weight == 0 )

+			return 1;

+	}

+

+	return prio;

+}

+

+struct ns_srv_reply **srv_lookup( char *service, char *protocol, char *domain )

+{

+	struct ns_srv_reply **results = NULL;

+	struct ns_srv_reply *reply = NULL;

+	char name[1024];

+

+	/* PACKETSZ is a maximum packet size and

+	   defined in arpa/nameser_compat.h as 512 */

+	unsigned char answer[PACKETSZ];

+	int len;

+	HEADER *header;

+	unsigned char *p;

+	unsigned char *end;

+	unsigned int count;

+	size_t n;

+

+	uint16_t type;

+	uint16_t class;

+	uint32_t ttl;

+	uint16_t rdlength;

+

+	g_snprintf( name, sizeof( name ), "_%s._%s.%s", service, protocol, domain );

+

+	len = res_query( name, C_IN, T_SRV, answer, PACKETSZ );

+	if( len == -1 )

+	{

+		goto fail;

+	}

+

+	header = (HEADER *) answer;

+	p = answer + sizeof( HEADER );

+	end = answer + len;

+

+	if( header->rcode != NOERROR )

+	{

+		goto fail;

+	}

+

+	len = dn_skipname( p, end );

+	if( len == -1 )

+	{

+		goto fail;

+	}

+	p += len + QFIXEDSZ;

+

+	count = ntohs( header->ancount );

+

+	n = 0;

+	while( count-- > 0 && p < end )

+	{

+		len = dn_skipname( p, end );

+		if( len == -1 )

+		{

+			goto fail;

+		}

+		p += len;

+

+		GETSHORT( type, p );

+		GETSHORT( class, p );

+		GETLONG( ttl, p );

+		GETSHORT( rdlength, p );

+

+		if( type != T_SRV || class != C_IN )

+		{

+			p += rdlength;

+			continue;

+		}

+

+		/* This is an overestimate of the needed size. */

+		reply = g_malloc( sizeof( struct ns_srv_reply ) + rdlength + 1 );

+

+		GETSHORT( reply->prio, p );

+		GETSHORT( reply->weight, p );

+		GETSHORT( reply->port, p );

+

+		len = dn_expand( answer, end, p, reply->name, rdlength + 1 );

+		if( len == -1 )

+		{

+			g_free( reply );

+			goto fail;

+		}

+		p += len;

+

+		/* n + 2 includes an entry for the terminating NULL. */

+		results = g_renew( struct ns_srv_reply *, results, n + 2 );

+		results[n++] = reply;

+	}

+

+	if( results != NULL )

+	{

+		results[n] = NULL;

+

+		/* Order by priority. */

+		qsort( results, n, sizeof( struct ns_srv_reply * ), srv_compare );

+	}

+

+	return results;

+

+fail:

+	if( results )

+	{

+		while( n-- > 0 )

+		{

+			g_free( results[n] );

+		}

+		g_free( results );

+	}

+

+	return NULL;

+}

+

 /* Word wrapping. Yes, I know this isn't UTF-8 clean. I'm willing to take the risk. */

 char *word_wrap( const char *msg, int line_len )

 {

@@ -783,3 +863,24 @@

 	return NULL;

 }

+

+#ifdef TEST

+int main()

+{

+	struct ns_srv_reply **srv;

+	int i;

+

+	srv = srv_lookup( "xmpp-client", "tcp", "jabber.org" );

+	for( i = 0; srv[i]; ++i )

+	{

+		printf( "priority=%hu\n", srv[i]->prio );

+		printf( "weight=%hu\n", srv[i]->weight );

+		printf( "port=%hu\n", srv[i]->port );

+		printf( "target=%s\n", srv[i]->name );

+		printf( "\n" );

+	}

+	srv_free( srv );

+

+	return 0;

+}

+#endif /* TEST */