Resolve network name for socket output

When the address provided in the configuration is not an IPV4 address
(such as w.x.y.z) we now try to resolve the network name before
connecting.
This will allow using the socket output in environments where IP
addresses are dynamically provided and not known when configuring the
sensor (e.g. docker compose or k8s).

Author: PierreRustOrange

src/storage_socket.c

@@ -90,30 +90,91 @@ socket_connection(struct socket_context *ctx)
   return -1;
 }
 
+/* Attemp to resolve network name from config.address and connect. */
 static int
-socket_initialize(struct storage_module *module)
+socket_resolve_and_connect(struct socket_context *ctx)
 {
-    struct socket_context *ctx = module->context;
-
-    if (module->is_initialized)
-        return -1;
-
-    if(addr_init(ctx->config, &(ctx->address)) == 0){
-        zsys_error("socket: failed to parse uri: %s", ctx->config.address);
+    struct addrinfo *result, *rp;
+    struct addrinfo hints;
+    int s;
+    char portstr[8];
+    bool is_connected = false;
+
+    memset(&hints, 0, sizeof(hints));
+    hints.ai_family = AF_INET;    /*  IPv4 */
+    hints.ai_socktype = SOCK_STREAM;
+    hints.ai_flags = 0;
+    hints.ai_protocol = 0;
+    hints.ai_canonname = NULL;
+    hints.ai_addr = NULL;
+    hints.ai_next = NULL;
+
+    bson_snprintf (portstr, sizeof portstr, "%hu", ctx->config.port);
+
+    s = getaddrinfo(ctx->config.address, portstr, &hints, &result);
+    if (s!= 0) {
+        zsys_error("unable to get addr info from %s", ctx->config.address);
         goto error;
     }
 
+    zsys_debug("Name %s resolved, attempt connecting", ctx->config.address);
     ctx->socket = socket(PF_INET, SOCK_STREAM, 0);
     if(ctx->socket == -1) {
         zsys_error("socket: failed create socket");
         goto error;
     }
-
-    if(socket_connection(ctx) == -1){
-        zsys_error("socket: unable to connect to %s", ctx->config.address);
+    // attemps to connect to the first possible result from getaddrinfo
+    for (rp = result; rp; rp = rp->ai_next) {
+        memcpy(&ctx->address, rp->ai_addr, rp->ai_addrlen);
+        if(socket_connection(ctx) == -1){
+            zsys_warning("socket: unable to connect to %s", ctx->config.address);
+        } else {
+            zsys_info("Connected !!");
+            is_connected = true;
+            break;
+        }
+    }
+    freeaddrinfo (result);
+    if (! is_connected) {
+         zsys_error("Could not connect to any resolved address for  %s", ctx->config.address);
         goto error;
     }
 
+    return 0;
+
+error:
+    return -1;
+}
+
+static int
+socket_initialize(struct storage_module *module)
+{
+    struct socket_context *ctx = module->context;
+
+    if (module->is_initialized)
+        return -1;
+
+    if(addr_init(ctx->config, &(ctx->address)) == 1){
+        // ctx.address is a valid IP address, attempt connecting:
+        ctx->socket = socket(PF_INET, SOCK_STREAM, 0);
+        if(ctx->socket == -1) {
+            zsys_error("socket: failed create socket");
+            goto error;
+        }
+        if(socket_connection(ctx) == -1){
+            zsys_error("socket: unable to connect to %s", ctx->config.address);
+            goto error;
+        }
+
+    } else {
+
+        zsys_info("socket: failed to parse uri: %s, trying to resolve name", ctx->config.address);
+        if (socket_resolve_and_connect(ctx) == -1) {
+            zsys_error("Could not resolve and connect to %s", ctx->config.address);
+            goto error;
+        }
+    }
+
     module->is_initialized = true;
     return 0;