gaih_inet: Simplify canon name resolution

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.

Signed-off-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
Reviewed-by: DJ Delorie <dj@redhat.com>
(cherry picked from commit d01411f6bc61429fc027c38827bf3103b48eef2e)

1 files changed, 75 insertions, 55 deletions

diff --git a/sysdeps/posix/getaddrinfo.c b/sysdeps/posix/getaddrinfo.c
index 3d9bea60c6..0629fd147b 100644
--- a/sysdeps/posix/getaddrinfo.c
+++ b/sysdeps/posix/getaddrinfo.c
@@ -285,7 +285,7 @@ convert_hostent_to_gaih_addrtuple (const struct addrinfo *req,
 									      \
       if (localcanon != NULL && canon == NULL)				      \
 	{								      \
-	  canonbuf = __strdup (localcanon);				      \
+	  char *canonbuf = __strdup (localcanon);			      \
 	  if (canonbuf == NULL)						      \
 	    {								      \
 	      __resolv_context_put (res_ctx);				      \
@@ -323,6 +323,41 @@ getcanonname (nss_action_list nip, struct gaih_addrtuple *at, const char *name)
   return __strdup (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;
+}
+
 static int
 gaih_inet (const char *name, const struct gaih_service *service,
 	   const struct addrinfo *req, struct addrinfo **pai,
@@ -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;
   const char *orig_name = name;
 
   /* Reserve stack memory for the scratch buffer in the getaddrinfo
@@ -453,7 +488,6 @@ gaih_inet (const char *name, const struct gaih_service *service,
 
   bool malloc_name = false;
   struct gaih_addrtuple *addrmem = NULL;
-  char *canonbuf = NULL;
   int result = 0;
 
   if (name != NULL)
@@ -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;
+	    }
 
 	  goto process_list;
 	}
@@ -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;
+	    }
 
 	  goto process_list;
 	}
@@ -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);
 			  if (canonbuf == NULL)
 			    {
 			      result = -EAI_MEMORY;
@@ -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;
 	      got_ipv6 = false;
 
@@ -805,7 +855,16 @@ 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;
+			}
 
 		      struct gaih_addrtuple **pat = &at;
 
@@ -893,7 +952,7 @@ 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);
 			      if (canonbuf == NULL)
 				{
 				  __resolv_context_put (res_ctx);
@@ -1004,6 +1063,10 @@ 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;
+
     struct gaih_servtuple *st2;
     struct gaih_addrtuple *at2 = at;
     size_t socklen;
@@ -1014,48 +1077,6 @@ 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;
-		      }
-		  }
-	      }
-	  }
-
 	family = at2->family;
 	if (family == AF_INET6)
 	  {
@@ -1078,7 +1099,6 @@ gaih_inet (const char *name, const struct gaih_service *service,
 	    ai = *pai = malloc (sizeof (struct addrinfo) + socklen);
 	    if (ai == NULL)
 	      {
-		free ((char *) canon);
 		result = -EAI_MEMORY;
 		goto free_and_return;
 	      }
@@ -1138,7 +1158,7 @@ gaih_inet (const char *name, const struct gaih_service *service,
   if (malloc_name)
     free ((char *) name);
   free (addrmem);
-  free (canonbuf);
+  free (canon);
 
   return result;
 }