remote: add callback to resolve URLs before connecting

Since libssh2 doesn't read host configuration from the config file,
this callback can be used to hand over URL resolving to the client
without touching the SSH implementation itself.

2 files changed, 44 insertions, 22 deletions

diff --git a/src/remote.c b/src/remote.c
index 3d5555658..3cea7908f 100644
--- a/src/remote.c
+++ b/src/remote.c
@@ -670,21 +670,44 @@ int git_remote_set_pushurl(git_repository *repo, const char *remote, const char*
 	return set_url(repo, remote, CONFIG_PUSHURL_FMT, url);
 }
 
-const char* git_remote__urlfordirection(git_remote *remote, int direction)
+static int resolve_url(git_buf *resolved_url, const char *url, int direction, const git_remote_callbacks *callbacks)
 {
-	assert(remote);
+	int status;
+
+	if (callbacks && callbacks->resolve_url) {
+		git_buf_clear(resolved_url);
+		status = callbacks->resolve_url(resolved_url, url, direction, callbacks->payload);
+		if (status != GIT_PASSTHROUGH) {
+			git_error_set_after_callback_function(status, "git_resolve_url_cb");
+			git_buf_sanitize(resolved_url);
+			return status;
+		}
+	}
 
+	return git_buf_sets(resolved_url, url);
+}
+
+int git_remote__urlfordirection(git_buf *url_out, struct git_remote *remote, int direction, const git_remote_callbacks *callbacks)
+{
+	const char *url = NULL;
+
+	assert(remote);
 	assert(direction == GIT_DIRECTION_FETCH || direction == GIT_DIRECTION_PUSH);
 
 	if (direction == GIT_DIRECTION_FETCH) {
-		return remote->url;
+		url = remote->url;
+	} else if (direction == GIT_DIRECTION_PUSH) {
+		url = remote->pushurl ? remote->pushurl : remote->url;
 	}
 
-	if (direction == GIT_DIRECTION_PUSH) {
-		return remote->pushurl ? remote->pushurl : remote->url;
+	if (!url) {
+		git_error_set(GIT_ERROR_INVALID,
+			"malformed remote '%s' - missing %s URL",
+			remote->name ? remote->name : "(anonymous)",
+			direction == GIT_DIRECTION_FETCH ? "fetch" : "push");
+		return GIT_EINVALID;
 	}
-
-	return NULL;
+	return resolve_url(url_out, url, direction, callbacks);
 }
 
 int set_transport_callbacks(git_transport *t, const git_remote_callbacks *cbs)
@@ -707,7 +730,7 @@ static int set_transport_custom_headers(git_transport *t, const git_strarray *cu
 int git_remote__connect(git_remote *remote, git_direction direction, const git_remote_callbacks *callbacks, const git_remote_connection_opts *conn)
 {
 	git_transport *t;
-	const char *url;
+	git_buf url = GIT_BUF_INIT;
 	int flags = GIT_TRANSPORTFLAGS_NONE;
 	int error;
 	void *payload = NULL;
@@ -728,39 +751,38 @@ int git_remote__connect(git_remote *remote, git_direction direction, const git_r
 
 	t = remote->transport;
 
-	url = git_remote__urlfordirection(remote, direction);
-	if (url == NULL) {
-		git_error_set(GIT_ERROR_INVALID,
-			"Malformed remote '%s' - missing %s URL",
-			remote->name ? remote->name : "(anonymous)",
-			direction == GIT_DIRECTION_FETCH ? "fetch" : "push");
-		return -1;
-	}
+	if ((error = git_remote__urlfordirection(&url, remote, direction, callbacks)) < 0)
+		goto on_error;
 
 	/* If we don't have a transport object yet, and the caller specified a
 	 * custom transport factory, use that */
 	if (!t && transport &&
 		(error = transport(&t, remote, payload)) < 0)
-		return error;
+		goto on_error;
 
 	/* If we still don't have a transport, then use the global
 	 * transport registrations which map URI schemes to transport factories */
-	if (!t && (error = git_transport_new(&t, remote, url)) < 0)
-		return error;
+	if (!t && (error = git_transport_new(&t, remote, url.ptr)) < 0)
+		goto on_error;
 
 	if ((error = set_transport_custom_headers(t, conn->custom_headers)) != 0)
 		goto on_error;
 
 	if ((error = set_transport_callbacks(t, callbacks)) < 0 ||
-	    (error = t->connect(t, url, credentials, payload, conn->proxy, direction, flags)) != 0)
+	    (error = t->connect(t, url.ptr, credentials, payload, conn->proxy, direction, flags)) != 0)
 		goto on_error;
 
 	remote->transport = t;
 
+	git_buf_dispose(&url);
+
 	return 0;
 
 on_error:
-	t->free(t);
+	if (t)
+		t->free(t);
+
+	git_buf_dispose(&url);
 
 	if (t == remote->transport)
 		remote->transport = NULL;
diff --git a/src/remote.h b/src/remote.h
index 15f8d3012..df75ed359 100644
--- a/src/remote.h
+++ b/src/remote.h
@@ -45,7 +45,7 @@ typedef struct git_remote_connection_opts {
 
 int git_remote__connect(git_remote *remote, git_direction direction, const git_remote_callbacks *callbacks, const git_remote_connection_opts *conn);
 
-const char* git_remote__urlfordirection(struct git_remote *remote, int direction);
+int git_remote__urlfordirection(git_buf *url_out, struct git_remote *remote, int direction, const git_remote_callbacks *callbacks);
 int git_remote__get_http_proxy(git_remote *remote, bool use_ssl, char **proxy_url);
 
 git_refspec *git_remote__matching_refspec(git_remote *remote, const char *refname);