Merge branch 'mc/credential-helper-auth-headers' into next

Extending credential helper protocol.

* mc/credential-helper-auth-headers:
  credential: add WWW-Authenticate header to cred requests
  http: read HTTP WWW-Authenticate response headers
  http: replace unsafe size_t multiplication with st_mult
  test-http-server: add sending of arbitrary headers
  test-http-server: add simple authentication
  test-http-server: pass Git requests to http-backend
  test-http-server: add HTTP request parsing
  test-http-server: add HTTP error response function
  test-http-server: add stub HTTP server test helper
  daemon: rename some esoteric/laboured terminology
  daemon: libify child process handling functions
  daemon: libify socket setup and option functions

Author: gitster

Documentation/git-credential.txt

@@ -113,7 +113,13 @@ separated by an `=` (equals) sign, followed by a newline.
 The key may contain any bytes except `=`, newline, or NUL. The value may
 contain any bytes except newline or NUL.
 
-In both cases, all bytes are treated as-is (i.e., there is no quoting,
+Attributes with keys that end with C-style array brackets `[]` can have
+multiple values. Each instance of a multi-valued attribute forms an
+ordered list of values - the order of the repeated attributes defines
+the order of the values. An empty multi-valued attribute (`key[]=\n`)
+acts to clear any previous entries and reset the list.
+
+In all cases, all bytes are treated as-is (i.e., there is no quoting,
 and one cannot transmit a value with newline or NUL in it). The list of
 attributes is terminated by a blank line or end-of-file.
 
@@ -160,6 +166,17 @@ empty string.
 Components which are missing from the URL (e.g., there is no
 username in the example above) will be left unset.
 
+`wwwauth[]`::
+
+	When an HTTP response is received by Git that includes one or more
+	'WWW-Authenticate' authentication headers, these will be passed by Git
+	to credential helpers.
++
+Each 'WWW-Authenticate' header value is passed as a multi-valued
+attribute 'wwwauth[]', where the order of the attributes is the same as
+they appear in the HTTP response. This attribute is 'one-way' from Git
+to pass additional information to credential helpers.
+
 Unrecognised attributes are silently discarded.
 
 GIT

Makefile

@@ -867,6 +867,7 @@ TEST_BUILTINS_OBJS += test-xml-encode.o
 # Do not add more tests here unless they have extra dependencies. Add
 # them in TEST_BUILTINS_OBJS above.
 TEST_PROGRAMS_NEED_X += test-fake-ssh
+TEST_PROGRAMS_NEED_X += test-http-server
 TEST_PROGRAMS_NEED_X += test-tool
 
 TEST_PROGRAMS = $(patsubst %,t/helper/%$X,$(TEST_PROGRAMS_NEED_X))
@@ -1005,6 +1006,7 @@ LIB_OBJS += credential.o
 LIB_OBJS += csum-file.o
 LIB_OBJS += ctype.o
 LIB_OBJS += date.o
+LIB_OBJS += daemon-utils.o
 LIB_OBJS += decorate.o
 LIB_OBJS += delta-islands.o
 LIB_OBJS += diagnose.o

contrib/buildsystems/CMakeLists.txt

@@ -961,6 +961,9 @@ if(BUILD_TESTING)
 add_executable(test-fake-ssh ${CMAKE_SOURCE_DIR}/t/helper/test-fake-ssh.c)
 target_link_libraries(test-fake-ssh common-main)
 
+add_executable(test-http-server ${CMAKE_SOURCE_DIR}/t/helper/test-http-server.c)
+target_link_libraries(test-http-server common-main)
+
 #reftable-tests
 parse_makefile_for_sources(test-reftable_SOURCES "REFTABLE_TEST_OBJS")
 list(TRANSFORM test-reftable_SOURCES PREPEND "${CMAKE_SOURCE_DIR}/")
@@ -980,15 +983,19 @@ if(MSVC)
 				PROPERTIES RUNTIME_OUTPUT_DIRECTORY_DEBUG ${CMAKE_BINARY_DIR}/t/helper)
 	set_target_properties(test-fake-ssh test-tool
 				PROPERTIES RUNTIME_OUTPUT_DIRECTORY_RELEASE ${CMAKE_BINARY_DIR}/t/helper)
+
+	set_target_properties(test-http-server
+			PROPERTIES RUNTIME_OUTPUT_DIRECTORY_DEBUG ${CMAKE_BINARY_DIR}/t/helper)
+	set_target_properties(test-http-server
+			PROPERTIES RUNTIME_OUTPUT_DIRECTORY_RELEASE ${CMAKE_BINARY_DIR}/t/helper)
 endif()
 
 #wrapper scripts
 set(wrapper_scripts
 	git git-upload-pack git-receive-pack git-upload-archive git-shell git-remote-ext scalar)
 
 set(wrapper_test_scripts
-	test-fake-ssh test-tool)
-
+	test-http-server test-fake-ssh test-tool)
 
 foreach(script ${wrapper_scripts})
 	file(STRINGS ${CMAKE_SOURCE_DIR}/wrap-for-bin.sh content NEWLINE_CONSUME)

credential.c

@@ -22,6 +22,7 @@ void credential_clear(struct credential *c)
 	free(c->username);
 	free(c->password);
 	string_list_clear(&c->helpers, 0);
+	strvec_clear(&c->wwwauth_headers);
 
 	credential_init(c);
 }
@@ -262,13 +263,24 @@ static void credential_write_item(FILE *fp, const char *key, const char *value,
 	fprintf(fp, "%s=%s\n", key, value);
 }
 
+static void credential_write_strvec(FILE *fp, const char *key,
+				    const struct strvec *vec)
+{
+	char *full_key = xstrfmt("%s[]", key);
+	for (size_t i = 0; i < vec->nr; i++) {
+		credential_write_item(fp, full_key, vec->v[i], 0);
+	}
+	free(full_key);
+}
+
 void credential_write(const struct credential *c, FILE *fp)
 {
 	credential_write_item(fp, "protocol", c->protocol, 1);
 	credential_write_item(fp, "host", c->host, 1);
 	credential_write_item(fp, "path", c->path, 0);
 	credential_write_item(fp, "username", c->username, 0);
 	credential_write_item(fp, "password", c->password, 0);
+	credential_write_strvec(fp, "wwwauth", &c->wwwauth_headers);
 }
 
 static int run_credential_helper(struct credential *c,

credential.h

@@ -2,6 +2,7 @@
 #define CREDENTIAL_H
 
 #include "string-list.h"
+#include "strvec.h"
 
 /**
  * The credentials API provides an abstracted way of gathering username and
@@ -115,6 +116,19 @@ struct credential {
 	 */
 	struct string_list helpers;
 
+	/**
+	 * A `strvec` of WWW-Authenticate header values. Each string
+	 * is the value of a WWW-Authenticate header in an HTTP response,
+	 * in the order they were received in the response.
+	 */
+	struct strvec wwwauth_headers;
+
+	/**
+	 * Internal use only. Used to keep track of split header fields
+	 * in order to fold multiple lines into one value.
+	 */
+	unsigned header_is_last_match:1;
+
 	unsigned approved:1,
 		 configured:1,
 		 quit:1,
@@ -130,6 +144,7 @@ struct credential {
 
 #define CREDENTIAL_INIT { \
 	.helpers = STRING_LIST_INIT_DUP, \
+	.wwwauth_headers = STRVEC_INIT, \
 }
 
 /* Initialize a credential structure, setting all fields to empty. */