1 files changed, 319 insertions, 0 deletions
diff --git a/builtin/credential-cache--daemon.c b/builtin/credential-cache--daemon.c
new file mode 100644
index 0000000..f3c8983
--- /dev/null
+++ b/builtin/credential-cache--daemon.c
@@ -0,0 +1,319 @@
+#include "builtin.h"
+#include "parse-options.h"
+
+#ifndef NO_UNIX_SOCKETS
+
+#include "config.h"
+#include "tempfile.h"
+#include "credential.h"
+#include "unix-socket.h"
+
+struct credential_cache_entry {
+	struct credential item;
+	timestamp_t expiration;
+};
+static struct credential_cache_entry *entries;
+static int entries_nr;
+static int entries_alloc;
+
+static void cache_credential(struct credential *c, int timeout)
+{
+	struct credential_cache_entry *e;
+
+	ALLOC_GROW(entries, entries_nr + 1, entries_alloc);
+	e = &entries[entries_nr++];
+
+	/* take ownership of pointers */
+	memcpy(&e->item, c, sizeof(*c));
+	memset(c, 0, sizeof(*c));
+	e->expiration = time(NULL) + timeout;
+}
+
+static struct credential_cache_entry *lookup_credential(const struct credential *c)
+{
+	int i;
+	for (i = 0; i < entries_nr; i++) {
+		struct credential *e = &entries[i].item;
+		if (credential_match(c, e))
+			return &entries[i];
+	}
+	return NULL;
+}
+
+static void remove_credential(const struct credential *c)
+{
+	struct credential_cache_entry *e;
+
+	e = lookup_credential(c);
+	if (e)
+		e->expiration = 0;
+}
+
+static timestamp_t check_expirations(void)
+{
+	static timestamp_t wait_for_entry_until;
+	int i = 0;
+	timestamp_t now = time(NULL);
+	timestamp_t next = TIME_MAX;
+
+	/*
+	 * Initially give the client 30 seconds to actually contact us
+	 * and store a credential before we decide there's no point in
+	 * keeping the daemon around.
+	 */
+	if (!wait_for_entry_until)
+		wait_for_entry_until = now + 30;
+
+	while (i < entries_nr) {
+		if (entries[i].expiration <= now) {
+			entries_nr--;
+			credential_clear(&entries[i].item);
+			if (i != entries_nr)
+				memcpy(&entries[i], &entries[entries_nr], sizeof(*entries));
+			/*
+			 * Stick around 30 seconds in case a new credential
+			 * shows up (e.g., because we just removed a failed
+			 * one, and we will soon get the correct one).
+			 */
+			wait_for_entry_until = now + 30;
+		}
+		else {
+			if (entries[i].expiration < next)
+				next = entries[i].expiration;
+			i++;
+		}
+	}
+
+	if (!entries_nr) {
+		if (wait_for_entry_until <= now)
+			return 0;
+		next = wait_for_entry_until;
+	}
+
+	return next - now;
+}
+
+static int read_request(FILE *fh, struct credential *c,
+			struct strbuf *action, int *timeout)
+{
+	static struct strbuf item = STRBUF_INIT;
+	const char *p;
+
+	strbuf_getline_lf(&item, fh);
+	if (!skip_prefix(item.buf, "action=", &p))
+		return error("client sent bogus action line: %s", item.buf);
+	strbuf_addstr(action, p);
+
+	strbuf_getline_lf(&item, fh);
+	if (!skip_prefix(item.buf, "timeout=", &p))
+		return error("client sent bogus timeout line: %s", item.buf);
+	*timeout = atoi(p);
+
+	if (credential_read(c, fh) < 0)
+		return -1;
+	return 0;
+}
+
+static void serve_one_client(FILE *in, FILE *out)
+{
+	struct credential c = CREDENTIAL_INIT;
+	struct strbuf action = STRBUF_INIT;
+	int timeout = -1;
+
+	if (read_request(in, &c, &action, &timeout) < 0)
+		/* ignore error */ ;
+	else if (!strcmp(action.buf, "get")) {
+		struct credential_cache_entry *e = lookup_credential(&c);
+		if (e) {
+			fprintf(out, "username=%s\n", e->item.username);
+			fprintf(out, "password=%s\n", e->item.password);
+		}
+	}
+	else if (!strcmp(action.buf, "exit")) {
+		/*
+		 * It's important that we clean up our socket first, and then
+		 * signal the client only once we have finished the cleanup.
+		 * Calling exit() directly does this, because we clean up in
+		 * our atexit() handler, and then signal the client when our
+		 * process actually ends, which closes the socket and gives
+		 * them EOF.
+		 */
+		exit(0);
+	}
+	else if (!strcmp(action.buf, "erase"))
+		remove_credential(&c);
+	else if (!strcmp(action.buf, "store")) {
+		if (timeout < 0)
+			warning("cache client didn't specify a timeout");
+		else if (!c.username || !c.password)
+			warning("cache client gave us a partial credential");
+		else {
+			remove_credential(&c);
+			cache_credential(&c, timeout);
+		}
+	}
+	else
+		warning("cache client sent unknown action: %s", action.buf);
+
+	credential_clear(&c);
+	strbuf_release(&action);
+}
+
+static int serve_cache_loop(int fd)
+{
+	struct pollfd pfd;
+	timestamp_t wakeup;
+
+	wakeup = check_expirations();
+	if (!wakeup)
+		return 0;
+
+	pfd.fd = fd;
+	pfd.events = POLLIN;
+	if (poll(&pfd, 1, 1000 * wakeup) < 0) {
+		if (errno != EINTR)
+			die_errno("poll failed");
+		return 1;
+	}
+
+	if (pfd.revents & POLLIN) {
+		int client, client2;
+		FILE *in, *out;
+
+		client = accept(fd, NULL, NULL);
+		if (client < 0) {
+			warning_errno("accept failed");
+			return 1;
+		}
+		client2 = dup(client);
+		if (client2 < 0) {
+			warning_errno("dup failed");
+			close(client);
+			return 1;
+		}
+
+		in = xfdopen(client, "r");
+		out = xfdopen(client2, "w");
+		serve_one_client(in, out);
+		fclose(in);
+		fclose(out);
+	}
+	return 1;
+}
+
+static void serve_cache(const char *socket_path, int debug)
+{
+	struct unix_stream_listen_opts opts = UNIX_STREAM_LISTEN_OPTS_INIT;
+	int fd;
+
+	fd = unix_stream_listen(socket_path, &opts);
+	if (fd < 0)
+		die_errno("unable to bind to '%s'", socket_path);
+
+	printf("ok\n");
+	fclose(stdout);
+	if (!debug) {
+		if (!freopen("/dev/null", "w", stderr))
+			die_errno("unable to point stderr to /dev/null");
+	}
+
+	while (serve_cache_loop(fd))
+		; /* nothing */
+
+	close(fd);
+}
+
+static const char permissions_advice[] = N_(
+"The permissions on your socket directory are too loose; other\n"
+"users may be able to read your cached credentials. Consider running:\n"
+"\n"
+"	chmod 0700 %s");
+static void init_socket_directory(const char *path)
+{
+	struct stat st;
+	char *path_copy = xstrdup(path);
+	char *dir = dirname(path_copy);
+
+	if (!stat(dir, &st)) {
+		if (st.st_mode & 077)
+			die(_(permissions_advice), dir);
+	} else {
+		/*
+		 * We must be sure to create the directory with the correct mode,
+		 * not just chmod it after the fact; otherwise, there is a race
+		 * condition in which somebody can chdir to it, sleep, then try to open
+		 * our protected socket.
+		 */
+		if (safe_create_leading_directories_const(dir) < 0)
+			die_errno("unable to create directories for '%s'", dir);
+		if (mkdir(dir, 0700) < 0)
+			die_errno("unable to mkdir '%s'", dir);
+	}
+
+	if (chdir(dir))
+		/*
+		 * We don't actually care what our cwd is; we chdir here just to
+		 * be a friendly daemon and avoid tying up our original cwd.
+		 * If this fails, it's OK to just continue without that benefit.
+		 */
+		;
+
+	free(path_copy);
+}
+
+int cmd_credential_cache_daemon(int argc, const char **argv, const char *prefix)
+{
+	struct tempfile *socket_file;
+	const char *socket_path;
+	int ignore_sighup = 0;
+	static const char *usage[] = {
+		"git credential-cache--daemon [--debug] <socket-path>",
+		NULL
+	};
+	int debug = 0;
+	const struct option options[] = {
+		OPT_BOOL(0, "debug", &debug,
+			 N_("print debugging messages to stderr")),
+		OPT_END()
+	};
+
+	git_config_get_bool("credentialcache.ignoresighup", &ignore_sighup);
+
+	argc = parse_options(argc, argv, prefix, options, usage, 0);
+	socket_path = argv[0];
+
+	if (!socket_path)
+		usage_with_options(usage, options);
+
+	if (!is_absolute_path(socket_path))
+		die("socket directory must be an absolute path");
+
+	init_socket_directory(socket_path);
+	socket_file = register_tempfile(socket_path);
+
+	if (ignore_sighup)
+		signal(SIGHUP, SIG_IGN);
+
+	serve_cache(socket_path, debug);
+	delete_tempfile(&socket_file);
+
+	return 0;
+}
+
+#else
+
+int cmd_credential_cache_daemon(int argc, const char **argv, const char *prefix)
+{
+	const char * const usage[] = {
+		"git credential-cache--daemon [--debug] <socket-path>",
+		"",
+		"credential-cache--daemon is disabled in this build of Git",
+		NULL
+	};
+	struct option options[] = { OPT_END() };
+
+	argc = parse_options(argc, argv, prefix, options, usage, 0);
+	die(_("credential-cache--daemon unavailable; no unix socket support"));
+}
+
+#endif /* NO_UNIX_SOCKET */