From 7d31fef29eefca30a8b8be668eebf1694e4df4a5 Mon Sep 17 00:00:00 2001
From: Bogdan-Andrei Iancu <bogdan@opensips.org>
Date: Tue, 17 Dec 2024 12:50:24 +0200
Subject: [PATCH] [dns_cache] Fix restoring IP array in hostend struct

When restoring (from cache) a hostend structure, be sure you end the "aliases" and "addresses" arrays with a NULL element.
Without that NULL terminator, when doing DNS-based failover on a cached hostend, OpenSIPS will use garbage IPs from the addresses array.
---
 modules/dns_cache/dns_cache.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/modules/dns_cache/dns_cache.c b/modules/dns_cache/dns_cache.c
index d9a4a95ff7..2964568cae 100644
--- a/modules/dns_cache/dns_cache.c
+++ b/modules/dns_cache/dns_cache.c
@@ -150,6 +150,8 @@ static void destroy(void)
 static int rdata_struct_len=sizeof(struct rdata)-sizeof(void *) -
 		sizeof(struct rdata *);
 
+#define MAXALIASES		36
+#define MAXADDRS 		36
 static unsigned char *he_buf=NULL;
 static int he_buf_len=0;
 static char* serialize_he_rdata(struct hostent *he,int *buf_len,int do_encoding)
@@ -165,7 +167,7 @@ static char* serialize_he_rdata(struct hostent *he,int *buf_len,int do_encoding)
 		len+=strlen(he->h_name)+1;
 
 	if (he->h_aliases)
-       		for (i=0;he->h_aliases[i];i++) {
+		for (i=0;he->h_aliases[i]&&alias_no<MAXALIASES-1;i++) {
 			/* integer with len + len bytes of alias */
 			len+=strlen(he->h_aliases[i])+1+sizeof(int);
 			alias_no++;
@@ -174,7 +176,7 @@ static char* serialize_he_rdata(struct hostent *he,int *buf_len,int do_encoding)
 
 	i=0;
 	if (he->h_addr_list)
-       		for (i=0;he->h_addr_list[i];i++) {
+		for (i=0;he->h_addr_list[i]&&addr_no<MAXADDRS-1;i++) {
 			len+=he->h_length;
 			addr_no++;
 		}
@@ -219,7 +221,7 @@ static char* serialize_he_rdata(struct hostent *he,int *buf_len,int do_encoding)
 
 	/* copy aliases, if any */
 	if (he->h_aliases)
-       		for (i=0;he->h_aliases[i];i++) {
+		for (i=0;he->h_aliases[i];i++) {
 			len=strlen(he->h_aliases[i])+1;
 			/* copy alias length */
 			memcpy(p,&len,sizeof(int));
@@ -235,7 +237,7 @@ static char* serialize_he_rdata(struct hostent *he,int *buf_len,int do_encoding)
 
 	/* copy addresses */
 	if (he->h_addr_list)
-       		for (i=0;he->h_addr_list[i];i++) {
+		for (i=0;he->h_addr_list[i];i++) {
 			/* copy addreses. length will be known from the addrtype field */
 			len=he->h_length;
 			memcpy(p,he->h_addr_list[i],len);
@@ -261,8 +263,6 @@ static char* serialize_he_rdata(struct hostent *he,int *buf_len,int do_encoding)
 static unsigned char *dec_he_buf=NULL;
 static int dec_he_buf_len=0;
 static struct hostent dec_global_he;
-#define MAXALIASES		36
-#define MAXADDRS 		36
 static char *h_addr_ptrs[MAXADDRS];
 static char *host_aliases[MAXALIASES];
 static struct hostent* deserialize_he_rdata(char *buff,int buf_len,int do_decoding)
@@ -291,10 +291,8 @@ static struct hostent* deserialize_he_rdata(char *buff,int buf_len,int do_decodi
 
 	/* set pointer in dec_global_he */
 	ap = host_aliases;
-	*ap = NULL;
 	dec_global_he.h_aliases = host_aliases;
 	hap = h_addr_ptrs;
-	*hap = NULL;
 	dec_global_he.h_addr_list = h_addr_ptrs;
 
 	if (do_decoding) {
@@ -331,6 +329,7 @@ static struct hostent* deserialize_he_rdata(char *buff,int buf_len,int do_decodi
 		*ap++ = (char *)p;
 		p+=len;
 	}
+	*ap = NULL;
 
 	/* get number of addresses */
 	memcpy(&addr_no,p,sizeof(int));
@@ -341,6 +340,7 @@ static struct hostent* deserialize_he_rdata(char *buff,int buf_len,int do_decodi
 		*hap++ = (char *)p;
 		p+=dec_global_he.h_length;
 	}
+	*hap = NULL;
 
 	return &dec_global_he;
 }