Re: [PATCH v2 02/12] gaih_inet: Simplify canon name resolution

[DJ Delorie <dj@redhat.com>]

Siddhesh Poyarekar via Libc-alpha <libc-alpha@sourceware.org> writes:
> Simplify logic for allocation of canon to remove the canonbuf variable;
> canon now always points to an allocated block.  Also pull the canon name
> set into a separate function.

LGTM.

Reviewed-by: DJ Delorie <dj@redhat.com>

> diff --git a/sysdeps/posix/getaddrinfo.c b/sysdeps/posix/getaddrinfo.c
> -	  canonbuf = __strdup (localcanon);				      \
> +	  char *canonbuf = __strdup (localcanon);			      \

Ok.

> @@ -323,6 +323,41 @@ getcanonname (nss_action_list nip, struct gaih_addrtuple *at, const char *name)
> +/* Process looked up canonical name and if necessary, decode to IDNA.  Result
> +   is a new string written to CANONP and the earlier string is freed.  */
> +
> +static int
> +process_canonname (const struct addrinfo *req, const char *orig_name,
> +		   char **canonp)
> +{
> +  char *canon = *canonp;
> +
> +  if ((req->ai_flags & AI_CANONNAME) != 0)
> +    {
> +      bool do_idn = req->ai_flags & AI_CANONIDN;
> +      if (do_idn)
> +	{
> +	  char *out;
> +	  int rc = __idna_from_dns_encoding (canon ?: orig_name, &out);
> +	  if (rc == 0)
> +	    {
> +	      free (canon);
> +	      canon = out;
> +	    }
> +	  else if (rc == EAI_IDN_ENCODE)
> +	    /* Use the punycode name as a fallback.  */
> +	    do_idn = false;
> +	  else
> +	    return -rc;
> +	}
> +      if (!do_idn && canon == NULL && (canon = __strdup (orig_name)) == NULL)
> +	return -EAI_MEMORY;
> +    }
> +
> +  *canonp = canon;
> +  return 0;
> +}

Moved from below, ok.

> @@ -332,7 +367,7 @@ gaih_inet (const char *name, const struct gaih_service *service,
>    struct gaih_servtuple *st = (struct gaih_servtuple *) &nullserv;
>    struct gaih_addrtuple *at = NULL;
>    bool got_ipv6 = false;
> -  const char *canon = NULL;
> +  char *canon = NULL;

Ok.

> -  char *canonbuf = NULL;

Ok.


> @@ -495,7 +529,15 @@ gaih_inet (const char *name, const struct gaih_service *service,
>  	    }
>  
>  	  if (req->ai_flags & AI_CANONNAME)
> -	    canon = name;
> +	    {
> +	      char *canonbuf = __strdup (name);
> +	      if (canonbuf == NULL)
> +		{
> +		  result = -EAI_MEMORY;
> +		  goto free_and_return;
> +		}
> +	      canon = canonbuf;
> +	    }

Ok.

> @@ -545,7 +587,15 @@ gaih_inet (const char *name, const struct gaih_service *service,
>  	    }
>  
>  	  if (req->ai_flags & AI_CANONNAME)
> -	    canon = name;
> +	    {
> +	      char *canonbuf = __strdup (name);
> +	      if (canonbuf == NULL)
> +		{
> +		  result = -EAI_MEMORY;
> +		  goto free_and_return;
> +		}
> +	      canon = canonbuf;
> +	    }

Ok.

> @@ -676,9 +726,9 @@ gaih_inet (const char *name, const struct gaih_service *service,
>  		      (*pat)->next = NULL;
>  		      if (added_canon || air->canon == NULL)
>  			(*pat)->name = NULL;
> -		      else if (canonbuf == NULL)
> +		      else if (canon == NULL)
>  			{
> -			  canonbuf = __strdup (air->canon);
> +			  char *canonbuf = __strdup (air->canon);

Ok.

> @@ -748,9 +798,9 @@ gaih_inet (const char *name, const struct gaih_service *service,
>  	      /* Always start afresh; continue should discard previous results
>  		 and the hosts database does not support merge.  */
>  	      at = NULL;
> -	      free (canonbuf);
> +	      free (canon);
>  	      free (addrmem);
> -	      canon = canonbuf = NULL;
> +	      canon = NULL;
>  	      addrmem = NULL;

Ok.

> @@ -804,7 +854,16 @@ gaih_inet (const char *name, const struct gaih_service *service,
>  		      no_data = 1;
>  
>  		      if ((req->ai_flags & AI_CANONNAME) != 0 && canon == NULL)
> -			canon = at->name;
> +			{
> +			  char *canonbuf = __strdup (at->name);
> +			  if (canonbuf == NULL)
> +			    {
> +			      __resolv_context_put (res_ctx);
> +			      result = -EAI_MEMORY;
> +			      goto free_and_return;
> +			    }
> +			  canon = canonbuf;
> +			}

Ok.

> @@ -892,7 +951,7 @@ gaih_inet (const char *name, const struct gaih_service *service,
>  			  if ((req->ai_flags & AI_CANONNAME) != 0
>  			      && canon == NULL)
>  			    {
> -			      canonbuf = getcanonname (nip, at, name);
> +			      char *canonbuf = getcanonname (nip, at, name);

Ok.

> @@ -1003,6 +1062,10 @@ gaih_inet (const char *name, const struct gaih_service *service,
>      }
>  
>    {
> +    /* Set up the canonical name if we need it.  */
> +    if ((result = process_canonname (req, orig_name, &canon)) != 0)
> +      goto free_and_return;
> +

Ok.

> @@ -1013,48 +1076,6 @@ gaih_inet (const char *name, const struct gaih_service *service,
>       */
>      while (at2 != NULL)
>        {
> -	/* Only the first entry gets the canonical name.  */
> -	if (at2 == at && (req->ai_flags & AI_CANONNAME) != 0)
> -	  {
> -	    if (canon == NULL)
> -	      /* If the canonical name cannot be determined, use
> -		 the passed in string.  */
> -	      canon = orig_name;
> -
> -	    bool do_idn = req->ai_flags & AI_CANONIDN;
> -	    if (do_idn)
> -	      {
> -		char *out;
> -		int rc = __idna_from_dns_encoding (canon, &out);
> -		if (rc == 0)
> -		  canon = out;
> -		else if (rc == EAI_IDN_ENCODE)
> -		  /* Use the punycode name as a fallback.  */
> -		  do_idn = false;
> -		else
> -		  {
> -		    result = -rc;
> -		    goto free_and_return;
> -		  }
> -	      }
> -	    if (!do_idn)
> -	      {
> -		if (canonbuf != NULL)
> -		  /* We already allocated the string using malloc, but
> -		     the buffer is now owned by canon.  */
> -		  canonbuf = NULL;
> -		else
> -		  {
> -		    canon = __strdup (canon);
> -		    if (canon == NULL)
> -		      {
> -			result = -EAI_MEMORY;
> -			goto free_and_return;
> -		      }
> -		  }
> -	      }
> -	  }
> -

Moved above; ok.

> @@ -1077,7 +1098,6 @@ gaih_inet (const char *name, const struct gaih_service *service,
>  	    ai = *pai = malloc (sizeof (struct addrinfo) + socklen);
>  	    if (ai == NULL)
>  	      {
> -		free ((char *) canon);

Ok.
> @@ -1137,7 +1157,7 @@ gaih_inet (const char *name, const struct gaih_service *service,
>    if (malloc_name)
>      free ((char *) name);
>    free (addrmem);
> -  free (canonbuf);
> +  free (canon);

Ok.