[PATCH 13/16] promisor-remote: introduce promisor.acceptFromServerUrl

[Christian Couder <christian.couder@gmail.com>]

The "promisor-remote" protocol capability allows servers to advertise
promisor remotes, but doesn't allow these remotes to be automatically
configured on the client.

Let's introduce a new `promisor.acceptFromServerUrl` config variable
which contains a glob pattern, so that advertised remotes with a URL
matching that pattern will be automatically configured.

The glob pattern can optionally be prefixed with a remote name which
will be used as the name of the new local remote.

For now though, let's only introduce the functions to read and validate
the glob patterns and the optional prefixes.

Checking if the URLs of the advertised remotes match the glob patterns
and taking the appropriate action is left for a following commit.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
---
 promisor-remote.c | 73 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 73 insertions(+)

diff --git a/promisor-remote.c b/promisor-remote.c
index c2f0eb7223..4cb18e1a6a 100644
--- a/promisor-remote.c
+++ b/promisor-remote.c
@@ -12,6 +12,7 @@
 #include "packfile.h"
 #include "environment.h"
 #include "url.h"
+#include "urlmatch.h"
 #include "version.h"
 
 struct promisor_remote_config {
@@ -656,6 +657,76 @@ static bool has_control_char(const char *s)
 	return false;
 }
 
+struct allowed_url {
+	char *remote_name;
+	char *url_pattern;
+};
+
+static struct allowed_url *valid_accept_url(const char *url)
+{
+	char *dup, *p;
+	struct allowed_url *allowed;
+
+	if (!url)
+		return NULL;
+
+	dup = xstrdup(url);
+	p = strchr(dup, '=');
+	if (p) {
+		*p = '\0';
+		if (!valid_remote_name(dup)) {
+			warning(_("invalid remote name '%s' before '=' sign "
+				  "in '%s' from promisor.acceptFromServerUrl config"),
+				dup, url);
+			free(dup);
+			return NULL;
+		}
+		p++;
+	} else {
+		p = dup;
+	}
+
+	if (has_control_char(p) || !url_is_valid_pattern(p)) {
+		warning(_("invalid url pattern '%s' "
+			  "in '%s' from promisor.acceptFromServerUrl config"), p, url);
+		free(dup);
+		return NULL;
+	}
+
+	allowed = xmalloc(sizeof(*allowed));
+	allowed->remote_name = (p == dup) ? NULL : dup;
+	allowed->url_pattern = p;
+
+	return allowed;
+}
+
+static struct string_list *accept_from_server_url(struct repository *repo)
+{
+	static struct string_list accept_urls = STRING_LIST_INIT_DUP;
+	static int initialized;
+	const struct string_list *config_urls;
+
+	if (initialized)
+		return &accept_urls;
+
+	initialized = 1;
+
+	if (!repo_config_get_string_multi(repo, "promisor.acceptfromserverurl", &config_urls)) {
+		struct string_list_item *item;
+
+		for_each_string_list_item(item, config_urls) {
+			struct allowed_url *allowed = valid_accept_url(item->string);
+			if (allowed) {
+				struct string_list_item *new;
+				new = string_list_append(&accept_urls, item->string);
+				new->util = allowed;
+			}
+		}
+	}
+
+	return &accept_urls;
+}
+
 static int should_accept_remote(enum accept_promisor accept,
 				struct promisor_info *advertised,
 				struct string_list *config_info)
@@ -901,6 +972,8 @@ static void filter_promisor_remote(struct repository *repo,
 	struct string_list_item *item;
 	bool reload_config = false;
 	enum accept_promisor accept = accept_from_server(repo);
+	/* Pre-load and validate the acceptFromServerUrl config */
+	(void)accept_from_server_url(repo);
 
 	if (accept == ACCEPT_NONE)
 		return;
-- 
2.53.0.625.g20f70b52bb