Print HTTP port number in the logs during startup.

This provides a way to start webdis with dynamic port allocation and
discover HTTP port number by simply grepping logs i.e. without need to
use netstat or sockstat that are not available on some architectures.

Dynamic port allocation is a feature that can be used to run webdis
ad-hoc for testing purpose.

src/server.c

@@ -25,6 +25,7 @@ socket_setup(struct server *s, const char *ip, int port) {
 
 	int reuse = 1;
 	struct sockaddr_in addr;
+	socklen_t len = sizeof(addr);
 	int fd, ret;
 
 	memset(&addr, 0, sizeof(addr));
@@ -60,7 +61,7 @@ socket_setup(struct server *s, const char *ip, int port) {
 	}
 
 	/* bind */
-	ret = bind(fd, (struct sockaddr*)&addr, sizeof(addr));
+	ret = bind(fd, (struct sockaddr*)&addr, len);
 	if (0 != ret) {
 		slog(s, WEBDIS_ERROR, strerror(errno), 0);
 		return -1;
@@ -73,6 +74,18 @@ socket_setup(struct server *s, const char *ip, int port) {
 		return -1;
 	}
 
+	if (getsockname(fd, (struct sockaddr *)&addr, &len) != -1) {
+		const char* comment = "Webdis listening on port %d";
+		int port_num = ntohs(addr.sin_port);
+
+		char* buffer = malloc(strlen(comment) -2 + strlen("65535") + 1);
+		sprintf(buffer, comment, port_num);
+
+		slog(s, WEBDIS_INFO, buffer , 0);
+
+        free(buffer);
+    }
+
 	/* there you go, ready to accept! */
 	return fd;
 }