Merge branch 'ap/http-preserve-wwwauth-redirect' into jch

When an HTTP request triggers a redirect and the target yields an
authentication challenge, the WWW-Authenticate headers received
during the redirect are now explicitly preserved across the
credential URL update, fixing an issue where they were incorrectly
cleared.

* ap/http-preserve-wwwauth-redirect:
  http: preserve wwwauth_headers across redirects

credential.c

@@ -708,3 +708,19 @@ void credential_from_url(struct credential *c, const char *url)
 	if (credential_from_url_gently(c, url, 0) < 0)
 		die(_("credential url cannot be parsed: %s"), url);
 }
+
+void credential_update_url(struct credential *c, const char *url)
+{
+	struct strvec wwwauth_headers = STRVEC_INIT;
+
+	/*
+	 * credential_from_url() clears the whole credential. Preserve the
+	 * WWW-Authenticate list, which is derived from the server's original
+	 * response rather than from the URL and is required to authenticate to
+	 * the new URL.
+	 */
+	SWAP(wwwauth_headers, c->wwwauth_headers);
+	credential_from_url(c, url);
+	SWAP(c->wwwauth_headers, wwwauth_headers);
+	strvec_clear(&wwwauth_headers);
+}

credential.h

@@ -305,6 +305,14 @@ void credential_write(const struct credential *, FILE *,
 void credential_from_url(struct credential *, const char *url);
 int credential_from_url_gently(struct credential *, const char *url, int quiet);
 
+/*
+ * Update the URL-derived fields (protocol, host, path) of an existing
+ * credential to match a new URL. Unlike credential_from_url(), this function
+ * preserves state that was derived from a server's HTTP redirect response,
+ * such as the WWW-Authenticate headers.
+ */
+void credential_update_url(struct credential *c, const char *url);
+
 int credential_match(const struct credential *want,
 		     const struct credential *have, int match_password);
 

http.c

@@ -2429,7 +2429,14 @@ static int http_request_recoverable(const char *url,
 	if (options->effective_url && options->base_url) {
 		if (update_url_from_redirect(options->base_url,
 					     url, options->effective_url)) {
-			credential_from_url(&http_auth, options->base_url->buf);
+			/*
+			 * Use credential_update_url() rather than
+			 * credential_from_url() so that the WWW-Authenticate
+			 * challenge the server sent with the redirect target's
+			 * response is preserved and handed to the credential
+			 * helper.
+			 */
+			credential_update_url(&http_auth, options->base_url->buf);
 			url = options->effective_url->buf;
 		}
 	}

t/lib-httpd/apache.conf

@@ -203,6 +203,7 @@ RewriteRule ^/dumb-redir/(.*)$ /dumb/$1 [R=301]
 RewriteRule ^/smart-redir-perm/(.*)$ /smart/$1 [R=301]
 RewriteRule ^/smart-redir-temp/(.*)$ /smart/$1 [R=302]
 RewriteRule ^/smart-redir-auth/(.*)$ /auth/smart/$1 [R=301]
+RewriteRule ^/custom_auth_redir/(.*)$ /custom_auth/$1 [R=302]
 RewriteRule ^/smart-redir-limited/(.*)/info/refs$ /smart/$1/info/refs [R=301]
 RewriteRule ^/ftp-redir/(.*)$ ftp://localhost:1000/$1 [R=302]
 

t/t5563-simple-http-auth.sh

@@ -557,6 +557,51 @@ test_expect_success 'access using bearer auth' '
 	EOF
 '
 
+test_expect_success 'bearer auth after redirect preserves wwwauth headers' '
+	test_when_finished "per_test_cleanup" &&
+
+	set_credential_reply get <<-EOF &&
+	capability[]=authtype
+	authtype=Bearer
+	credential=YS1naXQtdG9rZW4=
+	EOF
+
+	cat >"$HTTPD_ROOT_PATH/custom-auth.valid" <<-EOF &&
+	id=1 creds=Bearer YS1naXQtdG9rZW4=
+	EOF
+
+	cat >"$HTTPD_ROOT_PATH/custom-auth.challenge" <<-EOF &&
+	id=1 status=200
+	id=default response=WWW-Authenticate: FooBar param1="value1" param2="value2"
+	id=default response=WWW-Authenticate: Bearer authorize_uri="id.example.com" p=1 q=0
+	id=default response=WWW-Authenticate: Basic realm="example.com"
+	EOF
+
+	test_config_global credential.helper test-helper &&
+	test_config_global credential.useHttpPath true &&
+	git ls-remote "$HTTPD_URL/custom_auth_redir/repo.git" &&
+
+	expect_credential_query get <<-EOF &&
+	capability[]=authtype
+	capability[]=state
+	protocol=http
+	host=$HTTPD_DEST
+	path=custom_auth/repo.git
+	wwwauth[]=FooBar param1="value1" param2="value2"
+	wwwauth[]=Bearer authorize_uri="id.example.com" p=1 q=0
+	wwwauth[]=Basic realm="example.com"
+	EOF
+
+	expect_credential_query store <<-EOF
+	capability[]=authtype
+	authtype=Bearer
+	credential=YS1naXQtdG9rZW4=
+	protocol=http
+	host=$HTTPD_DEST
+	path=custom_auth/repo.git
+	EOF
+'
+
 test_expect_success 'access using bearer auth with invalid credentials' '
 	test_when_finished "per_test_cleanup" &&