Re: [PATCH] connect: also update offset for features without values

> From: Andrzej Hunt <andrzej@ahunt.org>
> 
> parse_feature_value() does not update offset if the feature being
> searched for does not specify a value. A loop that uses
> parse_feature_value() to find a feature which was specified without a
> value therefore might never exit (such loops will typically use
> next_server_feature_value() as opposed to parse_feature_value() itself).
> This usually isn't an issue: there's no point in using
> next_server_feature_value() to search for repeated instances of the same
> capability unless that capability typically specifies a value - but a
> broken server could send a response that omits the value for a feature
> even when we are expecting a value.
> 
> Therefore we add an offset update calculation for the no-value case,
> which helps ensure that loops using next_server_feature_value() will
> always terminate.
> 
> next_server_feature_value(), and the offset calculation, were first
> added in 2.28 in:
>   2c6a403d96 (connect: add function to parse multiple v1 capability values, 2020-05-25)
> 
> Thanks to Peff for authoring the test.

>     Note: I modified the test by adding and object-format=... to the
>     injected server response, because the oid that we're using is the
>     default hash (which will be e.g. sha256 for some CI jobs), but our
>     protocol handler assumes sha1 unless a different hash has been
>     explicitly specified. I'm open to alternative suggestions.

>     ATB,
>     
>     Andrzej
> 
> Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-1091%2Fahunt%2Fconnectloop-v1
> Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-1091/ahunt/connectloop-v1
> Pull-Request: https://github.com/git/git/pull/1091
> 
>  connect.c                      |  2 ++
>  t/t5704-protocol-violations.sh | 13 +++++++++++++
>  2 files changed, 15 insertions(+)
> 
> diff --git a/connect.c b/connect.c
> index aff13a270e6..eaf7d6d2618 100644
> --- a/connect.c
> +++ b/connect.c
> @@ -557,6 +557,8 @@ const char *parse_feature_value(const char *feature_list, const char *feature, i
>  			if (!*value || isspace(*value)) {
>  				if (lenp)
>  					*lenp = 0;
> +				if (offset)
> +					*offset = found + len - feature_list;