esp8266-mqtt-ipv6.patch

diff --git a/components/tcp_transport/transport_tcp.c b/components/tcp_transport/transport_tcp.c
index 5bfb99dd..cdae5bf0 100644
--- a/components/tcp_transport/transport_tcp.c
+++ b/components/tcp_transport/transport_tcp.c
@@ -32,60 +32,51 @@ typedef struct {
     int sock;
 } transport_tcp_t;
 
-static int resolve_dns(const char *host, struct sockaddr_in *ip) {
-
-    struct hostent *he;
-    struct in_addr **addr_list;
-    he = gethostbyname(host);
-    if (he == NULL) {
-        return ESP_FAIL;
-    }
-    addr_list = (struct in_addr **)he->h_addr_list;
-    if (addr_list[0] == NULL) {
-        return ESP_FAIL;
-    }
-    ip->sin_family = AF_INET;
-    memcpy(&ip->sin_addr, addr_list[0], sizeof(ip->sin_addr));
-    return ESP_OK;
-}
-
 static int tcp_connect(esp_transport_handle_t t, const char *host, int port, int timeout_ms)
 {
-    struct sockaddr_in remote_ip;
+    struct addrinfo* addr;
+    struct addrinfo hints;
     struct timeval tv = { 0 };
     transport_tcp_t *tcp = esp_transport_get_context_data(t);
 
-    bzero(&remote_ip, sizeof(struct sockaddr_in));
-
-    //if stream_host is not ip address, resolve it AF_INET,servername,&serveraddr.sin_addr
-    if (inet_pton(AF_INET, host, &remote_ip.sin_addr) != 1) {
-        if (resolve_dns(host, &remote_ip) < 0) {
-            return -1;
-        }
+    memset(&hints, 0, sizeof(hints));
+    hints.ai_socktype = SOCK_STREAM;
+    hints.ai_family = AF_UNSPEC;
+    char buf[6];
+    sprintf(buf, "%d", port);
+    if (getaddrinfo(host, buf, &hints, &addr) != 0) {
+        ESP_LOGE(TAG, "Error getaddrinfo()");
+	return -1;
     }
 
-    tcp->sock = socket(PF_INET, SOCK_STREAM, 0);
+    tcp->sock = socket(addr->ai_family, addr->ai_socktype, addr->ai_protocol);
 
     if (tcp->sock < 0) {
         ESP_LOGE(TAG, "Error create socket");
         return -1;
     }
 
-    remote_ip.sin_family = AF_INET;
-    remote_ip.sin_port = htons(port);
-
     esp_transport_utils_ms_to_timeval(timeout_ms, &tv); // if timeout=-1, tv is unchanged, 0, i.e. waits forever
 
     setsockopt(tcp->sock, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv));
     setsockopt(tcp->sock, SOL_SOCKET, SO_SNDTIMEO, &tv, sizeof(tv));
 
-    ESP_LOGD(TAG, "[sock=%d],connecting to server IP:%s,Port:%d...",
-             tcp->sock, ipaddr_ntoa((const ip_addr_t*)&remote_ip.sin_addr.s_addr), port);
-    if (connect(tcp->sock, (struct sockaddr *)(&remote_ip), sizeof(struct sockaddr)) != 0) {
+#if LWIP_IPV6
+    if (addr->ai_family == AF_INET6) {
+        struct sockaddr_in6* addr6 = (struct sockaddr_in6*)addr->ai_addr;
+	if (addr6->sin6_addr.s6_addr[0] == 0xfe && addr6->sin6_addr.s6_addr[1] == 0x80) { // link local
+	    addr6->sin6_scope_id = 2;
+	}
+    }
+#endif
+
+    if (connect(tcp->sock, addr->ai_addr, addr->ai_addrlen) != 0) {
         close(tcp->sock);
         tcp->sock = -1;
+	freeaddrinfo(addr);
         return -1;
     }
+    freeaddrinfo(addr);
     return tcp->sock;
 }