net: refactor gitno redirect handling

Move the redirect handling into `git_net_url` for consistency.

1 files changed, 106 insertions, 0 deletions

diff --git a/src/net.c b/src/net.c
index 24b85c0b5..bb7664366 100644
--- a/src/net.c
+++ b/src/net.c
@@ -153,6 +153,112 @@ done:
 	return error;
 }
 
+/*
+ * Some servers strip the query parameters from the Location header
+ * when sending a redirect. Others leave it in place.
+ * Check for both, starting with the stripped case first,
+ * since it appears to be more common.
+ */
+static void remove_service_suffix(
+	git_net_url *url,
+	const char *service_suffix)
+{
+	const char *service_query = strchr(service_suffix, '?');
+	size_t full_suffix_len = strlen(service_suffix);
+	size_t suffix_len = service_query ?
+		(size_t)(service_query - service_suffix) : full_suffix_len;
+	size_t path_len = strlen(url->path);
+	ssize_t truncate = -1;
+
+	/*
+	 * Check for a redirect without query parameters,
+	 * like "/newloc/info/refs"'
+	 */
+	if (suffix_len && path_len >= suffix_len) {
+		size_t suffix_offset = path_len - suffix_len;
+
+		if (git__strncmp(url->path + suffix_offset, service_suffix, suffix_len) == 0 &&
+		    (!service_query || git__strcmp(url->query, service_query + 1) == 0)) {
+			truncate = suffix_offset;
+		}
+	}
+
+	/*
+	 * If we haven't already found where to truncate to remove the
+	 * suffix, check for a redirect with query parameters, like
+	 * "/newloc/info/refs?service=git-upload-pack"
+	 */
+	if (truncate < 0 && git__suffixcmp(url->path, service_suffix) == 0)
+		truncate = path_len - full_suffix_len;
+
+	/* Ensure we leave a minimum of '/' as the path */
+	if (truncate == 0)
+		truncate++;
+
+	if (truncate > 0) {
+		url->path[truncate] = '\0';
+
+		git__free(url->query);
+		url->query = NULL;
+	}
+}
+
+int git_net_url_apply_redirect(
+	git_net_url *url,
+	const char *redirect_location,
+	const char *service_suffix)
+{
+	git_net_url tmp = GIT_NET_URL_INIT;
+	int error = 0;
+
+	assert(url && redirect_location);
+
+	if (redirect_location[0] == '/') {
+		git__free(url->path);
+
+		if ((url->path = git__strdup(redirect_location)) == NULL) {
+			error = -1;
+			goto done;
+		}
+	} else {
+		git_net_url *original = url;
+
+		if ((error = git_net_url_parse(&tmp, redirect_location)) < 0)
+			goto done;
+
+		/* Validate that this is a legal redirection */
+
+		if (original->scheme &&
+			strcmp(original->scheme, tmp.scheme) != 0 &&
+			strcmp(tmp.scheme, "https") != 0) {
+			git_error_set(GIT_ERROR_NET, "cannot redirect from '%s' to '%s'",
+				original->scheme, tmp.scheme);
+
+			error = -1;
+			goto done;
+		}
+
+		if (original->host &&
+		    git__strcasecmp(original->host, tmp.host) != 0) {
+			git_error_set(GIT_ERROR_NET, "cannot redirect from '%s' to '%s'",
+				original->host, tmp.host);
+
+			error = -1;
+			goto done;
+		}
+
+		git_net_url_swap(url, &tmp);
+	}
+
+	/* Remove the service suffix if it was given to us */
+	if (service_suffix)
+		remove_service_suffix(url, service_suffix);
+
+done:
+	git_net_url_dispose(&tmp);
+	return error;
+}
+
 bool git_net_url_valid(git_net_url *url)
 {
 	return (url->host && url->port && url->path);