(getnameinfo_verified): handle the case of forward but no backward DNS

information, and also describe the desired behaviour.  from Love
<lha@stacken.kth.se>


git-svn-id: svn://svn.h5l.se/heimdal/trunk/heimdal@11395 ec53bebd-3082-4978-b11e-865c3cabbd6b

lib/roken/getnameinfo_verified.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1999 - 2001 Kungliga Tekniska H<>gskolan
+ * Copyright (c) 1999 - 2002 Kungliga Tekniska H<>gskolan
  * (Royal Institute of Technology, Stockholm, Sweden).
  * All rights reserved.
  * 
@@ -38,6 +38,14 @@ RCSID("$Id$");
 
 #include "roken.h"
 
+/*
+ * Try to obtain a verified name for the address in `sa, salen' (much
+ * similar to getnameinfo).
+ * Verified in this context means that forwards and backwards lookups
+ * in DNS are consistent.  If that fails, return an error if the
+ * NI_NAMEREQD flag is set or return the numeric address as a string.
+ */
+
 int
 getnameinfo_verified(const struct sockaddr *sa, socklen_t salen,
 		     char *host, size_t hostlen,
@@ -60,13 +68,13 @@ getnameinfo_verified(const struct sockaddr *sa, socklen_t salen,
     ret = getnameinfo (sa, salen, host, hostlen, serv, servlen,
 		       flags | NI_NUMERICSERV);
     if (ret)
-	return ret;
+	goto fail;
 
     memset (&hints, 0, sizeof(hints));
     hints.ai_socktype = SOCK_STREAM;
     ret = getaddrinfo (host, serv, &hints, &ai);
     if (ret)
-	return ret;
+	goto fail;
     for (a = ai; a != NULL; a = a->ai_next) {
 	if (a->ai_addrlen == salen
 	    && memcmp (a->ai_addr, sa, salen) == 0) {
@@ -75,6 +83,7 @@ getnameinfo_verified(const struct sockaddr *sa, socklen_t salen,
 	}
     }
     freeaddrinfo (ai);
+ fail:
     if (flags & NI_NAMEREQD)
 	return EAI_NONAME;
     ret = getnameinfo (sa, salen, host, hostlen, serv, servlen,