udp_multicast_example: better handling wrong addresses

inet_aton returns 0 on failure, but socket_add_ipv4_multicast_group has to return negative values for failures
getaddrinfo sets res to zero of address could not resolved, but doesn't necessarily return an
error. res is now checked for zero before dereferencing

Merges https://github.com/espressif/esp-idf/pull/2814

diff --git a/examples/protocols/sockets/udp_multicast/main/udp_multicast_example_main.c b/examples/protocols/sockets/udp_multicast/main/udp_multicast_example_main.c
index e3bb7428400b7d782319f7703058e7b3156ef563..03025125becda1450591b1012ff61b8fd4eed518 100644 (file)
--- a/examples/protocols/sockets/udp_multicast/main/udp_multicast_example_main.c
+++ b/examples/protocols/sockets/udp_multicast/main/udp_multicast_example_main.c
@@ -74,6 +74,8 @@ static int socket_add_ipv4_multicast_group(int sock, bool assign_source_if)
     err = inet_aton(MULTICAST_IPV4_ADDR, &imreq.imr_multiaddr.s_addr);
     if (err != 1) {
         ESP_LOGE(V4TAG, "Configured IPV4 multicast address '%s' is invalid.", MULTICAST_IPV4_ADDR);
+        // Errors in the return value have to be negative
+        err = -1;
         goto err;
     }
     ESP_LOGI(TAG, "Configured IPV4 Multicast address %s", inet_ntoa(imreq.imr_multiaddr.s_addr));
@@ -426,6 +428,10 @@ static void mcast_example_task(void *pvParameters)
                     ESP_LOGE(TAG, "getaddrinfo() failed for IPV4 destination address. error: %d", err);
                     break;
                 }
+                if (res == 0) {
+                    ESP_LOGE(TAG, "getaddrinfo() did not return any addresses");
+                    break;
+                }
 #ifdef CONFIG_EXAMPLE_IPV4_ONLY
                 ((struct sockaddr_in *)res->ai_addr)->sin_port = htons(UDP_PORT);
                 inet_ntoa_r(((struct sockaddr_in *)res->ai_addr)->sin_addr, addrbuf, sizeof(addrbuf)-1);