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git/http-backend.c
Junio C Hamano ef49a7a012 zlib: zlib can only process 4GB at a time
The size of objects we read from the repository and data we try to put
into the repository are represented in "unsigned long", so that on larger
architectures we can handle objects that weigh more than 4GB.

But the interface defined in zlib.h to communicate with inflate/deflate
limits avail_in (how many bytes of input are we calling zlib with) and
avail_out (how many bytes of output from zlib are we ready to accept)
fields effectively to 4GB by defining their type to be uInt.

In many places in our code, we allocate a large buffer (e.g. mmap'ing a
large loose object file) and tell zlib its size by assigning the size to
avail_in field of the stream, but that will truncate the high octets of
the real size. The worst part of this story is that we often pass around
z_stream (the state object used by zlib) to keep track of the number of
used bytes in input/output buffer by inspecting these two fields, which
practically limits our callchain to the same 4GB limit.

Wrap z_stream in another structure git_zstream that can express avail_in
and avail_out in unsigned long. For now, just die() when the caller gives
a size that cannot be given to a single zlib call. In later patches in the
series, we would make git_inflate() and git_deflate() internally loop to
give callers an illusion that our "improved" version of zlib interface can
operate on a buffer larger than 4GB in one go.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
2011-06-10 11:52:15 -07:00

602 lines
13 KiB
C

#include "cache.h"
#include "refs.h"
#include "pkt-line.h"
#include "object.h"
#include "tag.h"
#include "exec_cmd.h"
#include "run-command.h"
#include "string-list.h"
#include "url.h"
static const char content_type[] = "Content-Type";
static const char content_length[] = "Content-Length";
static const char last_modified[] = "Last-Modified";
static int getanyfile = 1;
static struct string_list *query_params;
struct rpc_service {
const char *name;
const char *config_name;
signed enabled : 2;
};
static struct rpc_service rpc_service[] = {
{ "upload-pack", "uploadpack", 1 },
{ "receive-pack", "receivepack", -1 },
};
static struct string_list *get_parameters(void)
{
if (!query_params) {
const char *query = getenv("QUERY_STRING");
query_params = xcalloc(1, sizeof(*query_params));
while (query && *query) {
char *name = url_decode_parameter_name(&query);
char *value = url_decode_parameter_value(&query);
struct string_list_item *i;
i = string_list_lookup(query_params, name);
if (!i)
i = string_list_insert(query_params, name);
else
free(i->util);
i->util = value;
}
}
return query_params;
}
static const char *get_parameter(const char *name)
{
struct string_list_item *i;
i = string_list_lookup(get_parameters(), name);
return i ? i->util : NULL;
}
__attribute__((format (printf, 2, 3)))
static void format_write(int fd, const char *fmt, ...)
{
static char buffer[1024];
va_list args;
unsigned n;
va_start(args, fmt);
n = vsnprintf(buffer, sizeof(buffer), fmt, args);
va_end(args);
if (n >= sizeof(buffer))
die("protocol error: impossibly long line");
safe_write(fd, buffer, n);
}
static void http_status(unsigned code, const char *msg)
{
format_write(1, "Status: %u %s\r\n", code, msg);
}
static void hdr_str(const char *name, const char *value)
{
format_write(1, "%s: %s\r\n", name, value);
}
static void hdr_int(const char *name, uintmax_t value)
{
format_write(1, "%s: %" PRIuMAX "\r\n", name, value);
}
static void hdr_date(const char *name, unsigned long when)
{
const char *value = show_date(when, 0, DATE_RFC2822);
hdr_str(name, value);
}
static void hdr_nocache(void)
{
hdr_str("Expires", "Fri, 01 Jan 1980 00:00:00 GMT");
hdr_str("Pragma", "no-cache");
hdr_str("Cache-Control", "no-cache, max-age=0, must-revalidate");
}
static void hdr_cache_forever(void)
{
unsigned long now = time(NULL);
hdr_date("Date", now);
hdr_date("Expires", now + 31536000);
hdr_str("Cache-Control", "public, max-age=31536000");
}
static void end_headers(void)
{
safe_write(1, "\r\n", 2);
}
__attribute__((format (printf, 1, 2)))
static NORETURN void not_found(const char *err, ...)
{
va_list params;
http_status(404, "Not Found");
hdr_nocache();
end_headers();
va_start(params, err);
if (err && *err)
vfprintf(stderr, err, params);
va_end(params);
exit(0);
}
__attribute__((format (printf, 1, 2)))
static NORETURN void forbidden(const char *err, ...)
{
va_list params;
http_status(403, "Forbidden");
hdr_nocache();
end_headers();
va_start(params, err);
if (err && *err)
vfprintf(stderr, err, params);
va_end(params);
exit(0);
}
static void select_getanyfile(void)
{
if (!getanyfile)
forbidden("Unsupported service: getanyfile");
}
static void send_strbuf(const char *type, struct strbuf *buf)
{
hdr_int(content_length, buf->len);
hdr_str(content_type, type);
end_headers();
safe_write(1, buf->buf, buf->len);
}
static void send_local_file(const char *the_type, const char *name)
{
const char *p = git_path("%s", name);
size_t buf_alloc = 8192;
char *buf = xmalloc(buf_alloc);
int fd;
struct stat sb;
fd = open(p, O_RDONLY);
if (fd < 0)
not_found("Cannot open '%s': %s", p, strerror(errno));
if (fstat(fd, &sb) < 0)
die_errno("Cannot stat '%s'", p);
hdr_int(content_length, sb.st_size);
hdr_str(content_type, the_type);
hdr_date(last_modified, sb.st_mtime);
end_headers();
for (;;) {
ssize_t n = xread(fd, buf, buf_alloc);
if (n < 0)
die_errno("Cannot read '%s'", p);
if (!n)
break;
safe_write(1, buf, n);
}
close(fd);
free(buf);
}
static void get_text_file(char *name)
{
select_getanyfile();
hdr_nocache();
send_local_file("text/plain", name);
}
static void get_loose_object(char *name)
{
select_getanyfile();
hdr_cache_forever();
send_local_file("application/x-git-loose-object", name);
}
static void get_pack_file(char *name)
{
select_getanyfile();
hdr_cache_forever();
send_local_file("application/x-git-packed-objects", name);
}
static void get_idx_file(char *name)
{
select_getanyfile();
hdr_cache_forever();
send_local_file("application/x-git-packed-objects-toc", name);
}
static int http_config(const char *var, const char *value, void *cb)
{
if (!strcmp(var, "http.getanyfile")) {
getanyfile = git_config_bool(var, value);
return 0;
}
if (!prefixcmp(var, "http.")) {
int i;
for (i = 0; i < ARRAY_SIZE(rpc_service); i++) {
struct rpc_service *svc = &rpc_service[i];
if (!strcmp(var + 5, svc->config_name)) {
svc->enabled = git_config_bool(var, value);
return 0;
}
}
}
/* we are not interested in parsing any other configuration here */
return 0;
}
static struct rpc_service *select_service(const char *name)
{
struct rpc_service *svc = NULL;
int i;
if (prefixcmp(name, "git-"))
forbidden("Unsupported service: '%s'", name);
for (i = 0; i < ARRAY_SIZE(rpc_service); i++) {
struct rpc_service *s = &rpc_service[i];
if (!strcmp(s->name, name + 4)) {
svc = s;
break;
}
}
if (!svc)
forbidden("Unsupported service: '%s'", name);
if (svc->enabled < 0) {
const char *user = getenv("REMOTE_USER");
svc->enabled = (user && *user) ? 1 : 0;
}
if (!svc->enabled)
forbidden("Service not enabled: '%s'", svc->name);
return svc;
}
static void inflate_request(const char *prog_name, int out)
{
git_zstream stream;
unsigned char in_buf[8192];
unsigned char out_buf[8192];
unsigned long cnt = 0;
memset(&stream, 0, sizeof(stream));
git_inflate_init_gzip_only(&stream);
while (1) {
ssize_t n = xread(0, in_buf, sizeof(in_buf));
if (n <= 0)
die("request ended in the middle of the gzip stream");
stream.next_in = in_buf;
stream.avail_in = n;
while (0 < stream.avail_in) {
int ret;
stream.next_out = out_buf;
stream.avail_out = sizeof(out_buf);
ret = git_inflate(&stream, Z_NO_FLUSH);
if (ret != Z_OK && ret != Z_STREAM_END)
die("zlib error inflating request, result %d", ret);
n = stream.total_out - cnt;
if (write_in_full(out, out_buf, n) != n)
die("%s aborted reading request", prog_name);
cnt += n;
if (ret == Z_STREAM_END)
goto done;
}
}
done:
git_inflate_end(&stream);
close(out);
}
static void run_service(const char **argv)
{
const char *encoding = getenv("HTTP_CONTENT_ENCODING");
const char *user = getenv("REMOTE_USER");
const char *host = getenv("REMOTE_ADDR");
char *env[3];
struct strbuf buf = STRBUF_INIT;
int gzipped_request = 0;
struct child_process cld;
if (encoding && !strcmp(encoding, "gzip"))
gzipped_request = 1;
else if (encoding && !strcmp(encoding, "x-gzip"))
gzipped_request = 1;
if (!user || !*user)
user = "anonymous";
if (!host || !*host)
host = "(none)";
memset(&env, 0, sizeof(env));
strbuf_addf(&buf, "GIT_COMMITTER_NAME=%s", user);
env[0] = strbuf_detach(&buf, NULL);
strbuf_addf(&buf, "GIT_COMMITTER_EMAIL=%s@http.%s", user, host);
env[1] = strbuf_detach(&buf, NULL);
env[2] = NULL;
memset(&cld, 0, sizeof(cld));
cld.argv = argv;
cld.env = (const char *const *)env;
if (gzipped_request)
cld.in = -1;
cld.git_cmd = 1;
if (start_command(&cld))
exit(1);
close(1);
if (gzipped_request)
inflate_request(argv[0], cld.in);
else
close(0);
if (finish_command(&cld))
exit(1);
free(env[0]);
free(env[1]);
strbuf_release(&buf);
}
static int show_text_ref(const char *name, const unsigned char *sha1,
int flag, void *cb_data)
{
struct strbuf *buf = cb_data;
struct object *o = parse_object(sha1);
if (!o)
return 0;
strbuf_addf(buf, "%s\t%s\n", sha1_to_hex(sha1), name);
if (o->type == OBJ_TAG) {
o = deref_tag(o, name, 0);
if (!o)
return 0;
strbuf_addf(buf, "%s\t%s^{}\n", sha1_to_hex(o->sha1), name);
}
return 0;
}
static void get_info_refs(char *arg)
{
const char *service_name = get_parameter("service");
struct strbuf buf = STRBUF_INIT;
hdr_nocache();
if (service_name) {
const char *argv[] = {NULL /* service name */,
"--stateless-rpc", "--advertise-refs",
".", NULL};
struct rpc_service *svc = select_service(service_name);
strbuf_addf(&buf, "application/x-git-%s-advertisement",
svc->name);
hdr_str(content_type, buf.buf);
end_headers();
packet_write(1, "# service=git-%s\n", svc->name);
packet_flush(1);
argv[0] = svc->name;
run_service(argv);
} else {
select_getanyfile();
for_each_ref(show_text_ref, &buf);
send_strbuf("text/plain", &buf);
}
strbuf_release(&buf);
}
static void get_info_packs(char *arg)
{
size_t objdirlen = strlen(get_object_directory());
struct strbuf buf = STRBUF_INIT;
struct packed_git *p;
size_t cnt = 0;
select_getanyfile();
prepare_packed_git();
for (p = packed_git; p; p = p->next) {
if (p->pack_local)
cnt++;
}
strbuf_grow(&buf, cnt * 53 + 2);
for (p = packed_git; p; p = p->next) {
if (p->pack_local)
strbuf_addf(&buf, "P %s\n", p->pack_name + objdirlen + 6);
}
strbuf_addch(&buf, '\n');
hdr_nocache();
send_strbuf("text/plain; charset=utf-8", &buf);
strbuf_release(&buf);
}
static void check_content_type(const char *accepted_type)
{
const char *actual_type = getenv("CONTENT_TYPE");
if (!actual_type)
actual_type = "";
if (strcmp(actual_type, accepted_type)) {
http_status(415, "Unsupported Media Type");
hdr_nocache();
end_headers();
format_write(1,
"Expected POST with Content-Type '%s',"
" but received '%s' instead.\n",
accepted_type, actual_type);
exit(0);
}
}
static void service_rpc(char *service_name)
{
const char *argv[] = {NULL, "--stateless-rpc", ".", NULL};
struct rpc_service *svc = select_service(service_name);
struct strbuf buf = STRBUF_INIT;
strbuf_reset(&buf);
strbuf_addf(&buf, "application/x-git-%s-request", svc->name);
check_content_type(buf.buf);
hdr_nocache();
strbuf_reset(&buf);
strbuf_addf(&buf, "application/x-git-%s-result", svc->name);
hdr_str(content_type, buf.buf);
end_headers();
argv[0] = svc->name;
run_service(argv);
strbuf_release(&buf);
}
static NORETURN void die_webcgi(const char *err, va_list params)
{
static int dead;
if (!dead) {
dead = 1;
http_status(500, "Internal Server Error");
hdr_nocache();
end_headers();
vreportf("fatal: ", err, params);
}
exit(0); /* we successfully reported a failure ;-) */
}
static char* getdir(void)
{
struct strbuf buf = STRBUF_INIT;
char *pathinfo = getenv("PATH_INFO");
char *root = getenv("GIT_PROJECT_ROOT");
char *path = getenv("PATH_TRANSLATED");
if (root && *root) {
if (!pathinfo || !*pathinfo)
die("GIT_PROJECT_ROOT is set but PATH_INFO is not");
if (daemon_avoid_alias(pathinfo))
die("'%s': aliased", pathinfo);
end_url_with_slash(&buf, root);
if (pathinfo[0] == '/')
pathinfo++;
strbuf_addstr(&buf, pathinfo);
return strbuf_detach(&buf, NULL);
} else if (path && *path) {
return xstrdup(path);
} else
die("No GIT_PROJECT_ROOT or PATH_TRANSLATED from server");
return NULL;
}
static struct service_cmd {
const char *method;
const char *pattern;
void (*imp)(char *);
} services[] = {
{"GET", "/HEAD$", get_text_file},
{"GET", "/info/refs$", get_info_refs},
{"GET", "/objects/info/alternates$", get_text_file},
{"GET", "/objects/info/http-alternates$", get_text_file},
{"GET", "/objects/info/packs$", get_info_packs},
{"GET", "/objects/[0-9a-f]{2}/[0-9a-f]{38}$", get_loose_object},
{"GET", "/objects/pack/pack-[0-9a-f]{40}\\.pack$", get_pack_file},
{"GET", "/objects/pack/pack-[0-9a-f]{40}\\.idx$", get_idx_file},
{"POST", "/git-upload-pack$", service_rpc},
{"POST", "/git-receive-pack$", service_rpc}
};
int main(int argc, char **argv)
{
char *method = getenv("REQUEST_METHOD");
char *dir;
struct service_cmd *cmd = NULL;
char *cmd_arg = NULL;
int i;
git_extract_argv0_path(argv[0]);
set_die_routine(die_webcgi);
if (!method)
die("No REQUEST_METHOD from server");
if (!strcmp(method, "HEAD"))
method = "GET";
dir = getdir();
for (i = 0; i < ARRAY_SIZE(services); i++) {
struct service_cmd *c = &services[i];
regex_t re;
regmatch_t out[1];
if (regcomp(&re, c->pattern, REG_EXTENDED))
die("Bogus regex in service table: %s", c->pattern);
if (!regexec(&re, dir, 1, out, 0)) {
size_t n;
if (strcmp(method, c->method)) {
const char *proto = getenv("SERVER_PROTOCOL");
if (proto && !strcmp(proto, "HTTP/1.1"))
http_status(405, "Method Not Allowed");
else
http_status(400, "Bad Request");
hdr_nocache();
end_headers();
return 0;
}
cmd = c;
n = out[0].rm_eo - out[0].rm_so;
cmd_arg = xmalloc(n);
memcpy(cmd_arg, dir + out[0].rm_so + 1, n-1);
cmd_arg[n-1] = '\0';
dir[out[0].rm_so] = 0;
break;
}
regfree(&re);
}
if (!cmd)
not_found("Request not supported: '%s'", dir);
setup_path();
if (!enter_repo(dir, 0))
not_found("Not a git repository: '%s'", dir);
if (!getenv("GIT_HTTP_EXPORT_ALL") &&
access("git-daemon-export-ok", F_OK) )
not_found("Repository not exported: '%s'", dir);
git_config(http_config, NULL);
cmd->imp(cmd_arg);
return 0;
}