From: Guus Sliepen <guus@meshlink.io>
Date: Sat, 29 Feb 2020 15:19:44 +0000 (+0100)
Subject: Add meshlink_set_external_address_discovery_url().
X-Git-Url: https://git.meshlink.io/?a=commitdiff_plain;h=11d4da4957cb576abe9ee79c9893809a34f1f3d9;p=meshlink

Add meshlink_set_external_address_discovery_url().

This function can be used to override the default meshlink.io service to
query a host's own externally visible address.
---

diff --git a/src/meshlink++.h b/src/meshlink++.h
index 4d900448..11e7eabb 100644
--- a/src/meshlink++.h
+++ b/src/meshlink++.h
@@ -1030,6 +1030,17 @@ public:
 		meshlink_set_inviter_commits_first(handle, inviter_commits_first);
 	}
 
+	/// Set the URL used to discover the host's external address
+	/** For generating invitation URLs, MeshLink can look up the externally visible address of the local node.
+	 *  It does so by querying an external service. By default, this is http://meshlink.io/host.cgi.
+	 *  Only URLs starting with http:// are supported.
+	 *
+	 *  @param url   The URL to use for external address queries, or NULL to revert back to the default URL.
+	 */
+	void set_external_address_discovery_url(const char *url) {
+		meshlink_set_external_address_discovery_url(handle, url);
+	}
+
 private:
 	// non-copyable:
 	mesh(const mesh &) /* TODO: C++11: = delete */;
diff --git a/src/meshlink.c b/src/meshlink.c
index def3e6ef..3ebaee01 100644
--- a/src/meshlink.c
+++ b/src/meshlink.c
@@ -221,12 +221,42 @@ char *meshlink_get_external_address(meshlink_handle_t *mesh) {
 }
 
 char *meshlink_get_external_address_for_family(meshlink_handle_t *mesh, int family) {
-	char *hostname = NULL;
+	const char *url = mesh->external_address_url;
+
+	if(!url) {
+		url = "http://meshlink.io/host.cgi";
+	}
+
+	/* Find the hostname part between the slashes */
+	if(strncmp(url, "http://", 7)) {
+		abort();
+		meshlink_errno = MESHLINK_EINTERNAL;
+		return NULL;
+	}
+
+	const char *begin = url + 7;
+
+	const char *end = strchr(begin, '/');
+
+	if(!end) {
+		end = begin + strlen(begin);
+	}
+
+	/* Make a copy */
+	char host[end - begin + 1];
+	strncpy(host, begin, end - begin);
+	host[end - begin] = 0;
+
+	char *port = strchr(host, ':');
+
+	if(port) {
+		*port++ = 0;
+	}
 
 	logger(mesh, MESHLINK_DEBUG, "Trying to discover externally visible hostname...\n");
-	struct addrinfo *ai = str2addrinfo("meshlink.io", "80", SOCK_STREAM);
-	static const char request[] = "GET http://www.meshlink.io/host.cgi HTTP/1.0\r\n\r\n";
+	struct addrinfo *ai = str2addrinfo(host, port ? port : "80", SOCK_STREAM);
 	char line[256];
+	char *hostname = NULL;
 
 	for(struct addrinfo *aip = ai; aip; aip = aip->ai_next) {
 		if(family != AF_UNSPEC && aip->ai_family != family) {
@@ -245,7 +275,9 @@ char *meshlink_get_external_address_for_family(meshlink_handle_t *mesh, int fami
 		}
 
 		if(s >= 0) {
-			send(s, request, sizeof(request) - 1, 0);
+			send(s, "GET ", 4, 0);
+			send(s, url, strlen(url), 0);
+			send(s, " HTTP/1.0\r\n\r\n", 13, 0);
 			int len = recv(s, line, sizeof(line) - 1, MSG_WAITALL);
 
 			if(len > 0) {
@@ -1754,6 +1786,7 @@ void meshlink_close(meshlink_handle_t *mesh) {
 	free(mesh->appname);
 	free(mesh->confbase);
 	free(mesh->config_key);
+	free(mesh->external_address_url);
 	ecdsa_free(mesh->private_key);
 
 	main_config_unlock(mesh);
@@ -3986,6 +4019,23 @@ extern void meshlink_set_inviter_commits_first(struct meshlink_handle *mesh, boo
 	pthread_mutex_unlock(&mesh->mutex);
 }
 
+void meshlink_set_external_address_discovery_url(struct meshlink_handle *mesh, const char *url) {
+	if(!mesh) {
+		meshlink_errno = EINVAL;
+		return;
+	}
+
+	if(url && (strncmp(url, "http://", 7) || strchr(url, ' '))) {
+		meshlink_errno = EINVAL;
+		return;
+	}
+
+	pthread_mutex_lock(&mesh->mutex);
+	free(mesh->external_address_url);
+	mesh->external_address_url = url ? xstrdup(url) : NULL;
+	pthread_mutex_unlock(&mesh->mutex);
+}
+
 void handle_network_change(meshlink_handle_t *mesh, bool online) {
 	(void)online;
 
diff --git a/src/meshlink.h b/src/meshlink.h
index 385c12ce..2877c64e 100644
--- a/src/meshlink.h
+++ b/src/meshlink.h
@@ -1562,6 +1562,17 @@ extern void meshlink_set_dev_class_fast_retry_period(struct meshlink_handle *mes
  */
 extern void meshlink_set_inviter_commits_first(struct meshlink_handle *mesh, bool inviter_commits_first);
 
+/// Set the URL used to discover the host's external address
+/** For generating invitation URLs, MeshLink can look up the externally visible address of the local node.
+ *  It does so by querying an external service. By default, this is http://meshlink.io/host.cgi.
+ *  Only URLs starting with http:// are supported.
+ *
+ *  \memberof meshlink_handle
+ *  @param mesh  A handle which represents an instance of MeshLink.
+ *  @param url   The URL to use for external address queries, or NULL to revert back to the default URL.
+ */
+extern void meshlink_set_external_address_discovery_url(struct meshlink_handle *mesh, const char *url);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/src/meshlink.sym b/src/meshlink.sym
index de640c0c..6c4dd572 100644
--- a/src/meshlink.sym
+++ b/src/meshlink.sym
@@ -70,6 +70,7 @@ meshlink_set_default_blacklist
 meshlink_set_dev_class_fast_retry_period
 meshlink_set_dev_class_timeouts
 meshlink_set_error_cb
+meshlink_set_external_address_discovery_url
 meshlink_set_invitation_timeout
 meshlink_set_inviter_commits_first
 meshlink_set_log_cb
diff --git a/src/meshlink_internal.h b/src/meshlink_internal.h
index f895e02f..8c67aa3e 100644
--- a/src/meshlink_internal.h
+++ b/src/meshlink_internal.h
@@ -174,6 +174,7 @@ struct meshlink_handle {
 	char *confbase;
 	FILE *lockfile;
 	void *config_key;
+	char *external_address_url;
 
 	// Thread management
 	pthread_t thread;