git/credential-cache--daemon.c

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#include "cache.h"
#include "tempfile.h"
#include "credential.h"
#include "unix-socket.h"
#include "parse-options.h"
static struct tempfile socket_file;
struct credential_cache_entry {
struct credential item;
unsigned long 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 int check_expirations(void)
{
static unsigned long wait_for_entry_until;
int i = 0;
unsigned long now = time(NULL);
unsigned long next = (unsigned long)-1;
/*
* 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;
unsigned long 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)
{
int fd;
fd = unix_stream_listen(socket_path);
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);
}
add an extra level of indirection to main() There are certain startup tasks that we expect every git process to do. In some cases this is just to improve the quality of the program (e.g., setting up gettext()). In others it is a requirement for using certain functions in libgit.a (e.g., system_path() expects that you have called git_extract_argv0_path()). Most commands are builtins and are covered by the git.c version of main(). However, there are still a few external commands that use their own main(). Each of these has to remember to include the correct startup sequence, and we are not always consistent. Rather than just fix the inconsistencies, let's make this harder to get wrong by providing a common main() that can run this standard startup. We basically have two options to do this: - the compat/mingw.h file already does something like this by adding a #define that replaces the definition of main with a wrapper that calls mingw_startup(). The upside is that the code in each program doesn't need to be changed at all; it's rewritten on the fly by the preprocessor. The downside is that it may make debugging of the startup sequence a bit more confusing, as the preprocessor is quietly inserting new code. - the builtin functions are all of the form cmd_foo(), and git.c's main() calls them. This is much more explicit, which may make things more obvious to somebody reading the code. It's also more flexible (because of course we have to figure out _which_ cmd_foo() to call). The downside is that each of the builtins must define cmd_foo(), instead of just main(). This patch chooses the latter option, preferring the more explicit approach, even though it is more invasive. We introduce a new file common-main.c, with the "real" main. It expects to call cmd_main() from whatever other objects it is linked against. We link common-main.o against anything that links against libgit.a, since we know that such programs will need to do this setup. Note that common-main.o can't actually go inside libgit.a, as the linker would not pick up its main() function automatically (it has no callers). The rest of the patch is just adjusting all of the various external programs (mostly in t/helper) to use cmd_main(). I've provided a global declaration for cmd_main(), which means that all of the programs also need to match its signature. In particular, many functions need to switch to "const char **" instead of "char **" for argv. This effect ripples out to a few other variables and functions, as well. This makes the patch even more invasive, but the end result is much better. We should be treating argv strings as const anyway, and now all programs conform to the same signature (which also matches the way builtins are defined). Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-07-01 05:58:58 +00:00
int cmd_main(int argc, const char **argv)
{
const char *socket_path;
int ignore_sighup = 0;
static const char *usage[] = {
"git-credential-cache--daemon [opts] <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, NULL, 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);
register_tempfile(&socket_file, socket_path);
if (ignore_sighup)
signal(SIGHUP, SIG_IGN);
serve_cache(socket_path, debug);
delete_tempfile(&socket_file);
return 0;
}