Use socket_errno and socket_strerror() to include helpful error

descriptions in socket error messages in a cross-platform
(i.e. WinSock-compatible) manner.

src/xpdev/ini_file.c

@@ -1532,13 +1532,13 @@ int iniGetSocketOptions(str_list_t list, const char* section, SOCKET sock
 
 	len=sizeof(type);
 	if((result=getsockopt(sock, SOL_SOCKET, SO_TYPE, (char*)&type, &len)) != 0) {
-		safe_snprintf(error,errlen,"%d getting socket type", ERROR_VALUE);
+		safe_snprintf(error,errlen,"%d (%s) getting socket type", ERROR_VALUE, socket_strerror(socket_errno));
 		return(result);
 	}
 #ifdef IPPROTO_IPV6
 	len=sizeof(addr);
 	if((result=getsockname(sock, &addr.addr, &len)) != 0) {
-		safe_snprintf(error,errlen,"%d getting socket name", ERROR_VALUE);
+		safe_snprintf(error,errlen,"%d (%s) getting socket name", ERROR_VALUE, socket_strerror(socket_errno));
 		return(result);
 	}
 #endif
@@ -1573,8 +1573,8 @@ int iniGetSocketOptions(str_list_t list, const char* section, SOCKET sock
 		}
 
 		if((result=setsockopt(sock,level,option,(const char *)vp,len)) != 0) {
-			safe_snprintf(error,errlen,"%d setting socket option (%s, %d) to %d"
-				,ERROR_VALUE, name, option, value);
+			safe_snprintf(error,errlen,"%d (%s) setting socket option (%s, %d) to %d"
+				,ERROR_VALUE, socket_strerror(socket_errno), name, option, value);
 			return(result);
 		}
 	}

src/xpdev/multisock.c

@@ -152,8 +152,9 @@ BOOL DLLCALL xpms_add(struct xpms_set *xpms_set, int domain, int type,
 		if(type != SOCK_DGRAM) {
 			if(listen(xpms_set->socks[xpms_set->sock_count].sock, SOMAXCONN)==-1) {
 				if(xpms_set->lprintf)
-					xpms_set->lprintf(LOG_WARNING, "%04d !%s ERROR %d listen()ing on port %d"
-							,xpms_set->socks[xpms_set->sock_count].sock, prot, ERROR_VALUE, port);
+					xpms_set->lprintf(LOG_WARNING, "%04d !%s ERROR %d (%s) listening on port %d"
+						,xpms_set->socks[xpms_set->sock_count].sock, prot, ERROR_VALUE
+						,socket_strerror(socket_errno), port);
 				closesocket(xpms_set->socks[xpms_set->sock_count].sock);
 				FREE_AND_NULL(xpms_set->socks[xpms_set->sock_count].address);
 				FREE_AND_NULL(xpms_set->socks[xpms_set->sock_count].prot);