credential: handle `credential.<partial-URL>.<key>` again

In the patches for CVE-2020-11008, the ability to specify credential
settings in the config for partial URLs got lost. For example, it used
to be possible to specify a credential helper for a specific protocol:

	[credential "https://"]
		helper = my-https-helper

Likewise, it used to be possible to configure settings for a specific
host, e.g.:

	[credential "dev.azure.com"]
		useHTTPPath = true

Let's reinstate this behavior.

While at it, increase the test coverage to document and verify the
behavior with a couple other categories of partial URLs.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 27 insertions, 0 deletions

diff --git a/credential.c b/credential.c
index b8f693f..4e7197d 100644
--- a/credential.c
+++ b/credential.c
@@ -37,6 +37,10 @@ int credential_match(const struct credential *want,
 #undef CHECK
 }
 
+
+static int credential_from_potentially_partial_url(struct credential *c,
+						   const char *url);
+
 static int credential_config_callback(const char *var, const char *value,
 				      void *data)
 {
@@ -82,6 +86,22 @@ static int select_all(const struct urlmatch_item *a,
 	return 0;
 }
 
+static int match_partial_url(const char *url, void *cb)
+{
+	struct credential *c = cb;
+	struct credential want = CREDENTIAL_INIT;
+	int matches = 0;
+
+	if (credential_from_potentially_partial_url(&want, url) < 0)
+		warning(_("skipping credential lookup for key: credential.%s"),
+			url);
+	else
+		matches = credential_match(&want, c);
+	credential_clear(&want);
+
+	return matches;
+}
+
 static void credential_apply_config(struct credential *c)
 {
 	char *normalized_url;
@@ -101,6 +121,7 @@ static void credential_apply_config(struct credential *c)
 	config.collect_fn = credential_config_callback;
 	config.cascade_fn = NULL;
 	config.select_fn = select_all;
+	config.fallback_match_fn = match_partial_url;
 	config.cb = c;
 
 	credential_format(c, &url);
@@ -468,6 +489,12 @@ static int credential_from_url_1(struct credential *c, const char *url,
 	return 0;
 }
 
+static int credential_from_potentially_partial_url(struct credential *c,
+						   const char *url)
+{
+	return credential_from_url_1(c, url, 1, 0);
+}
+
 int credential_from_url_gently(struct credential *c, const char *url, int quiet)
 {
 	return credential_from_url_1(c, url, 0, quiet);