Revision b81401c1de0e0fec39f8643ce7a794fda083f7a1 authored by Jeff King on 27 August 2012, 13:27:15 UTC, committed by Junio C Hamano on 27 August 2012, 17:49:09 UTC
All of the smart-http GET requests go through the http_get_* functions, which will prompt for credentials and retry if we see an HTTP 401. POST requests, however, do not go through any central point. Moreover, it is difficult to retry in the general case; we cannot assume the request body fits in memory or is even seekable, and we don't know how much of it was consumed during the attempt. Most of the time, this is not a big deal; for both fetching and pushing, we make a GET request before doing any POSTs, so typically we figure out the credentials during the first request, then reuse them during the POST. However, some servers may allow a client to get the list of refs from receive-pack without authentication, and then require authentication when the client actually tries to POST the pack. This is not ideal, as the client may do a non-trivial amount of work to generate the pack (e.g., delta-compressing objects). However, for a long time it has been the recommended example configuration in git-http-backend(1) for setting up a repository with anonymous fetch and authenticated push. This setup has always been broken without putting a username into the URL. Prior to commit 986bbc0, it did work with a username in the URL, because git would prompt for credentials before making any requests at all. However, post-986bbc0, it is totally broken. Since it has been advertised in the manpage for some time, we should make sure it works. Unfortunately, it is not as easy as simply calling post_rpc again when it fails, due to the input issue mentioned above. However, we can still make this specific case work by retrying in two specific instances: 1. If the request is large (bigger than LARGE_PACKET_MAX), we will first send a probe request with a single flush packet. Since this request is static, we can freely retry it. 2. If the request is small and we are not using gzip, then we have the whole thing in-core, and we can freely retry. That means we will not retry in some instances, including: 1. If we are using gzip. However, we only do so when calling git-upload-pack, so it does not apply to pushes. 2. If we have a large request, the probe succeeds, but then the real POST wants authentication. This is an extremely unlikely configuration and not worth worrying about. While it might be nice to cover those instances, doing so would be significantly more complex for very little real-world gain. In the long run, we will be much better off when curl learns to internally handle authentication as a callback, and we can cleanly handle all cases that way. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
1 parent 8809703
pkt-line.c
#include "cache.h"
#include "pkt-line.h"
static const char *packet_trace_prefix = "git";
static const char trace_key[] = "GIT_TRACE_PACKET";
void packet_trace_identity(const char *prog)
{
packet_trace_prefix = xstrdup(prog);
}
static void packet_trace(const char *buf, unsigned int len, int write)
{
int i;
struct strbuf out;
if (!trace_want(trace_key))
return;
/* +32 is just a guess for header + quoting */
strbuf_init(&out, len+32);
strbuf_addf(&out, "packet: %12s%c ",
packet_trace_prefix, write ? '>' : '<');
if ((len >= 4 && !prefixcmp(buf, "PACK")) ||
(len >= 5 && !prefixcmp(buf+1, "PACK"))) {
strbuf_addstr(&out, "PACK ...");
unsetenv(trace_key);
}
else {
/* XXX we should really handle printable utf8 */
for (i = 0; i < len; i++) {
/* suppress newlines */
if (buf[i] == '\n')
continue;
if (buf[i] >= 0x20 && buf[i] <= 0x7e)
strbuf_addch(&out, buf[i]);
else
strbuf_addf(&out, "\\%o", buf[i]);
}
}
strbuf_addch(&out, '\n');
trace_strbuf(trace_key, &out);
strbuf_release(&out);
}
/*
* Write a packetized stream, where each line is preceded by
* its length (including the header) as a 4-byte hex number.
* A length of 'zero' means end of stream (and a length of 1-3
* would be an error).
*
* This is all pretty stupid, but we use this packetized line
* format to make a streaming format possible without ever
* over-running the read buffers. That way we'll never read
* into what might be the pack data (which should go to another
* process entirely).
*
* The writing side could use stdio, but since the reading
* side can't, we stay with pure read/write interfaces.
*/
ssize_t safe_write(int fd, const void *buf, ssize_t n)
{
ssize_t nn = n;
while (n) {
int ret = xwrite(fd, buf, n);
if (ret > 0) {
buf = (char *) buf + ret;
n -= ret;
continue;
}
if (!ret)
die("write error (disk full?)");
die_errno("write error");
}
return nn;
}
/*
* If we buffered things up above (we don't, but we should),
* we'd flush it here
*/
void packet_flush(int fd)
{
packet_trace("0000", 4, 1);
safe_write(fd, "0000", 4);
}
void packet_buf_flush(struct strbuf *buf)
{
packet_trace("0000", 4, 1);
strbuf_add(buf, "0000", 4);
}
#define hex(a) (hexchar[(a) & 15])
static char buffer[1000];
static unsigned format_packet(const char *fmt, va_list args)
{
static char hexchar[] = "0123456789abcdef";
unsigned n;
n = vsnprintf(buffer + 4, sizeof(buffer) - 4, fmt, args);
if (n >= sizeof(buffer)-4)
die("protocol error: impossibly long line");
n += 4;
buffer[0] = hex(n >> 12);
buffer[1] = hex(n >> 8);
buffer[2] = hex(n >> 4);
buffer[3] = hex(n);
packet_trace(buffer+4, n-4, 1);
return n;
}
void packet_write(int fd, const char *fmt, ...)
{
va_list args;
unsigned n;
va_start(args, fmt);
n = format_packet(fmt, args);
va_end(args);
safe_write(fd, buffer, n);
}
void packet_buf_write(struct strbuf *buf, const char *fmt, ...)
{
va_list args;
unsigned n;
va_start(args, fmt);
n = format_packet(fmt, args);
va_end(args);
strbuf_add(buf, buffer, n);
}
static void safe_read(int fd, void *buffer, unsigned size)
{
ssize_t ret = read_in_full(fd, buffer, size);
if (ret < 0)
die_errno("read error");
else if (ret < size)
die("The remote end hung up unexpectedly");
}
static int packet_length(const char *linelen)
{
int n;
int len = 0;
for (n = 0; n < 4; n++) {
unsigned char c = linelen[n];
len <<= 4;
if (c >= '0' && c <= '9') {
len += c - '0';
continue;
}
if (c >= 'a' && c <= 'f') {
len += c - 'a' + 10;
continue;
}
if (c >= 'A' && c <= 'F') {
len += c - 'A' + 10;
continue;
}
return -1;
}
return len;
}
int packet_read_line(int fd, char *buffer, unsigned size)
{
int len;
char linelen[4];
safe_read(fd, linelen, 4);
len = packet_length(linelen);
if (len < 0)
die("protocol error: bad line length character: %.4s", linelen);
if (!len) {
packet_trace("0000", 4, 0);
return 0;
}
len -= 4;
if (len >= size)
die("protocol error: bad line length %d", len);
safe_read(fd, buffer, len);
buffer[len] = 0;
packet_trace(buffer, len, 0);
return len;
}
int packet_get_line(struct strbuf *out,
char **src_buf, size_t *src_len)
{
int len;
if (*src_len < 4)
return -1;
len = packet_length(*src_buf);
if (len < 0)
return -1;
if (!len) {
*src_buf += 4;
*src_len -= 4;
packet_trace("0000", 4, 0);
return 0;
}
if (*src_len < len)
return -2;
*src_buf += 4;
*src_len -= 4;
len -= 4;
strbuf_add(out, *src_buf, len);
*src_buf += len;
*src_len -= len;
packet_trace(out->buf, out->len, 0);
return len;
}
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