Revision 2501aff8b7516115c409cb34cc50305cdde40a47 authored by Jeff King on 28 September 2013, 08:31:45 UTC, committed by Jonathan Nieder on 14 October 2013, 23:55:13 UTC
When we are handling a curl response code in http_request or in the remote-curl RPC code, we use the handle_curl_result helper to translate curl's response into an easy-to-use code. When we see an HTTP 401, we do one of two things: 1. If we already had a filled-in credential, we mark it as rejected, and then return HTTP_NOAUTH to indicate to the caller that we failed. 2. If we didn't, then we ask for a new credential and tell the caller HTTP_REAUTH to indicate that they may want to try again. Rejecting in the first case makes sense; it is the natural result of the request we just made. However, prompting for more credentials in the second step does not always make sense. We do not know for sure that the caller is going to make a second request, and nor are we sure that it will be to the same URL. Logically, the prompt belongs not to the request we just finished, but to the request we are (maybe) about to make. In practice, it is very hard to trigger any bad behavior. Currently, if we make a second request, it will always be to the same URL (even in the face of redirects, because curl handles the redirects internally). And we almost always retry on HTTP_REAUTH these days. The one exception is if we are streaming a large RPC request to the server (e.g., a pushed packfile), in which case we cannot restart. It's extremely unlikely to see a 401 response at this stage, though, as we would typically have seen it when we sent a probe request, before streaming the data. This patch drops the automatic prompt out of case 2, and instead requires the caller to do it. This is a few extra lines of code, and the bug it fixes is unlikely to come up in practice. But it is conceptually cleaner, and paves the way for better handling of credentials across redirects. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
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git-credential.txt
git-credential(1)
=================
NAME
----
git-credential - Retrieve and store user credentials
SYNOPSIS
--------
------------------
git credential <fill|approve|reject>
------------------
DESCRIPTION
-----------
Git has an internal interface for storing and retrieving credentials
from system-specific helpers, as well as prompting the user for
usernames and passwords. The git-credential command exposes this
interface to scripts which may want to retrieve, store, or prompt for
credentials in the same manner as Git. The design of this scriptable
interface models the internal C API; see
link:technical/api-credentials.txt[the Git credential API] for more
background on the concepts.
git-credential takes an "action" option on the command-line (one of
`fill`, `approve`, or `reject`) and reads a credential description
on stdin (see <<IOFMT,INPUT/OUTPUT FORMAT>>).
If the action is `fill`, git-credential will attempt to add "username"
and "password" attributes to the description by reading config files,
by contacting any configured credential helpers, or by prompting the
user. The username and password attributes of the credential
description are then printed to stdout together with the attributes
already provided.
If the action is `approve`, git-credential will send the description
to any configured credential helpers, which may store the credential
for later use.
If the action is `reject`, git-credential will send the description to
any configured credential helpers, which may erase any stored
credential matching the description.
If the action is `approve` or `reject`, no output should be emitted.
TYPICAL USE OF GIT CREDENTIAL
-----------------------------
An application using git-credential will typically use `git
credential` following these steps:
1. Generate a credential description based on the context.
+
For example, if we want a password for
`https://example.com/foo.git`, we might generate the following
credential description (don't forget the blank line at the end; it
tells `git credential` that the application finished feeding all the
information it has):
protocol=https
host=example.com
path=foo.git
2. Ask git-credential to give us a username and password for this
description. This is done by running `git credential fill`,
feeding the description from step (1) to its standard input. The complete
credential description (including the credential per se, i.e. the
login and password) will be produced on standard output, like:
protocol=https
host=example.com
username=bob
password=secr3t
+
In most cases, this means the attributes given in the input will be
repeated in the output, but Git may also modify the credential
description, for example by removing the `path` attribute when the
protocol is HTTP(s) and `credential.useHttpPath` is false.
+
If the `git credential` knew about the password, this step may
not have involved the user actually typing this password (the
user may have typed a password to unlock the keychain instead,
or no user interaction was done if the keychain was already
unlocked) before it returned `password=secr3t`.
3. Use the credential (e.g., access the URL with the username and
password from step (2)), and see if it's accepted.
4. Report on the success or failure of the password. If the
credential allowed the operation to complete successfully, then
it can be marked with an "approve" action to tell `git
credential` to reuse it in its next invocation. If the credential
was rejected during the operation, use the "reject" action so
that `git credential` will ask for a new password in its next
invocation. In either case, `git credential` should be fed with
the credential description obtained from step (2) (which also
contain the ones provided in step (1)).
[[IOFMT]]
INPUT/OUTPUT FORMAT
-------------------
`git credential` reads and/or writes (depending on the action used)
credential information in its standard input/output. This information
can correspond either to keys for which `git credential` will obtain
the login/password information (e.g. host, protocol, path), or to the
actual credential data to be obtained (login/password).
The credential is split into a set of named attributes, with one
attribute per line. Each attribute is
specified by a key-value pair, separated by an `=` (equals) sign,
followed by a newline. The key may contain any bytes except `=`,
newline, or NUL. The value may contain any bytes except newline or NUL.
In both cases, all bytes are treated as-is (i.e., there is no quoting,
and one cannot transmit a value with newline or NUL in it). The list of
attributes is terminated by a blank line or end-of-file.
Git understands the following attributes:
`protocol`::
The protocol over which the credential will be used (e.g.,
`https`).
`host`::
The remote hostname for a network credential.
`path`::
The path with which the credential will be used. E.g., for
accessing a remote https repository, this will be the
repository's path on the server.
`username`::
The credential's username, if we already have one (e.g., from a
URL, from the user, or from a previously run helper).
`password`::
The credential's password, if we are asking it to be stored.
`url`::
When this special attribute is read by `git credential`, the
value is parsed as a URL and treated as if its constituent parts
were read (e.g., `url=https://example.com` would behave as if
`protocol=https` and `host=example.com` had been provided). This
can help callers avoid parsing URLs themselves. Note that any
components which are missing from the URL (e.g., there is no
username in the example above) will be set to empty; if you want
to provide a URL and override some attributes, provide the URL
attribute first, followed by any overrides.
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