[PATCH v2] nss: Implement --no-addrconfig option for getent

[Carlos O'Donell]

On Thu, Sep 15, 2022 at 02:33:41PM +0200, Florian Weimer via Libc-alpha wrote:
> The ahosts, ahostsv4, ahostsv6 commands unconditionally pass
> AI_ADDRCONFIG to getaddrinfo, which is not always desired.

LGTM.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>

> ---
> v2: Reword NEWS and --help output.
>  NEWS         |  5 ++++-
>  nss/getent.c | 11 ++++++++++-
>  2 files changed, 14 insertions(+), 2 deletions(-)
> 
> diff --git a/NEWS b/NEWS
> index ef274d1a42..a64d3eff26 100644
> --- a/NEWS
> +++ b/NEWS
> @@ -9,7 +9,10 @@ Version 2.37
>  
>  Major new features:
>  
> -  [Add new features here]
> +* The getent tool now supports the --no-addrconfig option. The output of
> +  getent with --no-addrconfig may contain addresses of families not
> +  configured on the current host i.e. as-if you had not passed
> +  AI_ADDRCONFIG to getaddrinfo calls.
>  
>  Deprecated and removed features, and other changes affecting compatibility:
>  
> diff --git a/nss/getent.c b/nss/getent.c
> index 8178b4b470..d2d2524b0c 100644
> --- a/nss/getent.c
> +++ b/nss/getent.c
> @@ -58,6 +58,8 @@ static const struct argp_option args_options[] =
>    {
>      { "service", 's', N_("CONFIG"), 0, N_("Service configuration to be used") },
>      { "no-idn", 'i', NULL, 0, N_("disable IDN encoding") },
> +    { "no-addrconfig", 'A', NULL, 0,
> +      N_("do not filter out unsupported IPv4/IPv6 addresses (with ahosts*)") },

OK.

>      { NULL, 0, NULL, 0, NULL },
>    };
>  
> @@ -79,6 +81,9 @@ static struct argp argp =
>  /* Additional getaddrinfo flags for IDN encoding.  */
>  static int idn_flags = AI_IDN | AI_CANONIDN;
>  
> +/* Set to 0 by --no-addrconfig.  */
> +static int addrconfig_flags = AI_ADDRCONFIG;

OK. Default to AI_ADDRCONFIG.

> +
>  /* Print the version information.  */
>  static void
>  print_version (FILE *stream, struct argp_state *state)
> @@ -346,7 +351,7 @@ ahosts_keys_int (int af, int xflags, int number, char *key[])
>  
>    struct addrinfo hint;
>    memset (&hint, '\0', sizeof (hint));
> -  hint.ai_flags = (AI_V4MAPPED | AI_ADDRCONFIG | AI_CANONNAME
> +  hint.ai_flags = (AI_V4MAPPED | addrconfig_flags | AI_CANONNAME

OK.

>  		   | idn_flags | xflags);
>    hint.ai_family = af;
>  
> @@ -905,6 +910,10 @@ parse_option (int key, char *arg, struct argp_state *state)
>        idn_flags = 0;
>        break;
>  
> +    case 'A':
> +      addrconfig_flags = 0;

OK. Zero it.

> +      break;
> +
>      default:
>        return ARGP_ERR_UNKNOWN;
>      }
> 
> base-commit: 05967faf0e3df6aad07f0b05e138e86f82363deb
>