core: test if ipv6 address starts with [ for subst snd lumps

- safer than the test against cached socket address known to be without
[], allowing to pass any address value to be used
- reported by GH #1315

src/core/msg_translator.c

@@ -678,8 +678,8 @@ static inline int lumps_len(struct sip_msg* msg, struct lump* lumps,
 			case SUBST_SND_IP: \
 				if (send_sock){ \
 					new_len+=send_address_str->len; \
-					if (send_sock->address.af!=AF_INET && \
-							send_address_str==&(send_sock->address_str)) \
+					if (send_sock->address.af==AF_INET6 && \
+							send_address_str->s[0]!='[') \
 						new_len+=2; \
 				}else{ \
 					LM_CRIT("FIXME: null send_sock\n"); \
@@ -724,8 +724,8 @@ static inline int lumps_len(struct sip_msg* msg, struct lump* lumps,
 			case SUBST_SND_ALL: \
 				if (send_sock){ \
 					new_len+=send_address_str->len; \
-					if ((send_sock->address.af!=AF_INET) && \
-							(send_address_str==&(send_sock->address_str))) \
+					if ((send_sock->address.af==AF_INET6) && \
+							(send_address_str->s[0]!='[')) \
 						new_len+=2; \
 					if ((send_sock->port_no!=SIP_PORT) || \
 							(send_port_str!=&(send_sock->port_no_str))){ \
@@ -766,7 +766,7 @@ static inline int lumps_len(struct sip_msg* msg, struct lump* lumps,
 			default: \
 				LM_CRIT("unknown subst type %d\n", (subst_l)->u.subst); \
 		}
-	
+
 	if (send_info){
 		send_sock=send_info->send_sock;
 	}else{
@@ -935,7 +935,7 @@ void process_lumps( struct sip_msg* msg,
 					default:\
 						LM_CRIT("unknown comp %d\n", msg->rcv.comp); \
 				}
-	
+
 	#define SENDCOMP_PARAM_ADD \
 				/* add ;comp=xxxx */ \
 				switch(send_info->comp){ \
@@ -956,7 +956,7 @@ void process_lumps( struct sip_msg* msg,
 						break;\
 					default:\
 						LM_CRIT("unknown comp %d\n", msg->rcv.comp); \
-				} 
+				}
 #else
 	#define RCVCOMP_PARAM_ADD
 	#define SENDCOMP_PARAM_ADD
@@ -1057,14 +1057,14 @@ void process_lumps( struct sip_msg* msg,
 		case SUBST_SND_IP: \
 			if (send_sock){  \
 				if ((send_sock->address.af!=AF_INET) && \
-						(send_address_str==&(send_sock->address_str))){\
+						(send_address_str->s[0]!='[')){\
 					new_buf[offset]='['; offset++; \
 				}\
 				memcpy(new_buf+offset, send_address_str->s, \
 									send_address_str->len); \
 				offset+=send_address_str->len; \
 				if ((send_sock->address.af!=AF_INET) && \
-						(send_address_str==&(send_sock->address_str))){\
+						(send_address_str->s[0]!='[')){\
 					new_buf[offset]=']'; offset++; \
 				}\
 			}else{  \
@@ -1086,14 +1086,14 @@ void process_lumps( struct sip_msg* msg,
 			if (send_sock){  \
 				/* address */ \
 				if ((send_sock->address.af!=AF_INET) && \
-						(send_address_str==&(send_sock->address_str))){\
+						(send_address_str->s[0]!='[')){\
 					new_buf[offset]='['; offset++; \
 				}\
 				memcpy(new_buf+offset, send_address_str->s, \
 						send_address_str->len); \
 				offset+=send_address_str->len; \
 				if ((send_sock->address.af!=AF_INET) && \
-						(send_address_str==&(send_sock->address_str))){\
+						(send_address_str->s[0]!='[')){\
 					new_buf[offset]=']'; offset++; \
 				}\
 				/* :port */ \