More detailed error message for 403 forbidden.

Currently, if user tried to access a git repository via HTTP and it fails because the user's permission is not enough to access the repository, git client tells that http request failed and the error was 403 forbidden.

But It is not enough for user to understand why it fails, especially if the user don't know the username because git-credential-osxkeychain authenticate implicitly without user knowing.

It would be much better if git client shows response body which might include an explanation of the failure. For example,

before:

$ git clone http://localhost/foo/bar error: The requested URL returned error: 403 while accessing http://localhost/foo/bar fatal: HTTP request failed

after:

$ git clone http://localhost/foo/bar error: The requested URL returned error: 403 while accessing http://localhost/foo/bar remote: User 'me' does not have enough permission to access the repository. fatal: HTTP request failed

On Wed, Mar 27, 2013 at 12:29:57PM +0900, Yi, EungJun wrote:

The situations in which you'll get a 403 depend on how the server is configured. For instance, on github.com, if you successfully authenticate but are not authorized to access a repository, you get a 404 (we do this to avoid leaking information about which private repositories exist). But we do provide a 403 if you try to access the repository with a non-smart-http client.

So the "403 forbidden" there is not about your account, but about the method; if git is going to give a more verbose message, it needs to be careful not to mislead the user.

I agree that is the best way forward, as that means the server is telling us what is going on, and we are not guessing about the meaning of the 403.

One problem is that the content body sent along with the error is not necessarily appropriate for showing to the user (e.g., if it is HTML, it is probably not a good idea to show it on the terminal). So I think we would want to only show it when the server has indicated via the content-type that the message is meant to be shown to the user. I'm thinking the server would generate something like:

   HTTP/1.1 403 Forbidden
   Content-type: application/x-git-error-message

   User 'me' does not have enough permission to access the repository.

which would produce the example you showed above.

-Peff

Jeff King wrote:

Would it make sense to use text/plain this way?

Curious, Jonathan

On Thu, Mar 28, 2013 at 11:41:20AM -0700, Jonathan Nieder wrote:

Maybe. But I would worry somewhat about sites which provide a useless and verbose text/plain message. Ideally an x-git-error-message would be no more than few lines, suitable for the error message of a terminal program. I would not want a site-branded "Your page cannot be found. Here's a complete navigation bar" page to be spewed to the terminal. Those tend to be text/html, though, so we may be safe. It's just that we're gambling on what random servers do, and if we show useless spew even some of the time, that would be a regression.

-Peff

I completely agree with you.

And should git client need to add x-git-error-message in Accept header and/or perhaps language preference in Accept-Language header?

    Accept: x-git-error-message, */*;q=0.8
    Accept-Language: ko,en;q=0.8

Jeff King <peff@peff.net> writes:

Actually, isn't the human-readable part of the server response meant for this kind of thing? I.e.

	HTTP/1.1 403 User 'me' not allowed to accept the repository.

On Thu, Mar 28, 2013 at 12:11:55PM -0700, Junio C Hamano wrote:

In theory, yes. But I don't think that most servers make it very easy to use custom "reason phrases" (that is the rfc 2616 term for them). At least I could not easily figure out how to make Apache do so. You can do so from CGIs, but I think you'd want to customize some of this at the HTTP server level (e.g., overriding 404s with a custom message). There's much better support at that level for custom error documents (e.g., Apache's ErrorDocument).

I do not configure http servers very often, though, so I could be wrong about what is normal practice, and what is easy to do.

-Peff