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

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

[Florian Weimer]

The ahosts, ahostsv4, ahostsv6 commands unconditionally pass
AI_ADDRCONFIG to getaddrinfo, which is not always desired.

---
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*)") },
     { 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;
+
 /* 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
 		   | 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;
+      break;
+
     default:
       return ARGP_ERR_UNKNOWN;
     }

base-commit: 05967faf0e3df6aad07f0b05e138e86f82363deb

Re: [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
>