Re: Request for detailed documentation of git pack protocol

From: Jakub Narebski <jnareb@gmail.com>
Date: Jun 3, 2009, 15:39 UTC
Message-ID: <200906031739.49682.jnareb@gmail.com>
In-Reply-To: <20090603150746.GF3355@spearce.org>

On Wed, 3 Jun 2009, Shawn O. Pearce wrote:

> "Shawn O. Pearce" <spearce@spearce.org> wrote:
> > Jakub Narebski <jnareb@gmail.com> wrote:

Show 7 quoted lines

> > > What options besides (required?) "host=<server>[:<port>]" are supported?
> > 
> > Currently only host is supported.  And yea, it takes the :<port> if
> > the client included the port number in the URL (git://foo:8813/path).
> 
> Ok, I'm wrong.  It *doesn't* send the port.  The reason is obtuse,
> but git_tcp_connect() clobbers the port number out of the host

What about git_proxy_connect()? Does it clobber port number either?

> name string, so that later when git_connect() sends this "host=%s",
> only the host name is transmitted.

Hmmm... so does that mean that in the following fragment of deamon.c on branch is dead in practice?

  if (strncasecmp("host=", extra_args, 5) == 0) {
    val = extra_args + 5;
    vallen = strlen(val) + 1;
    if (*val) {
      /* Split <host>:<port> at colon. */
      char *host = val;
      char *port = strrchr(host, ':');
      if (port) {
        *port = 0;
        port++;
        free(tcp_port);
        tcp_port = xstrdup(port);
      }
      free(hostname);
      hostname = xstrdup_tolower(host);
    }

    /* On to the next one */
    extra_args = val + vallen;
  }

> > Actually, I just realized JGit isn't compliant here.  It doesn't
> > send the :<port> like C Git would.
> 
> So, actually JGit is compliant here.

Well, we can take the stance that C Git isn't compliant either ;-)

Show 18 quoted lines

>  
> > > Do I understand correctly that "host=<host>" information is required
> > > for core.gitProxy to work, isn't it?
> 
> If core.gitProxy or GIT_PROXY_COMMAND are set, you can lie to the
> remote git daemon about the host.  E.g.:
> 
>   $ cat proxy.sh
>   #!/bin/sh
>   exec nc git.kernel.org 9418
> 
>   GIT_PROXY_COMMAND=proxy.sh git ls-remote git://github.com/foo.git
> 
> During that kernel.org receives "\0host=github.com\0" host header,
> which is not the name you connected to it as.  :-)
> 
> In practice I doubt anyone would do that, but, you can confuse
> yourself.  I guess about equally as well as url.insteadof.  :-)

A question: do compliant implementation MUST not fail on receiving arguments it doesn't understand, e.g.:

   003bgit-upload-pack /project.git\0host=myserver.com\0user=me\0

or can it go hang the client, or silently fail?

-- 
Jakub Narebski
Poland