[Cvs-cvs] Changes to ccvs/lib/canon-host.c

[Derek Robert Price]

Index: ccvs/lib/canon-host.c
diff -u ccvs/lib/canon-host.c:1.1 ccvs/lib/canon-host.c:1.2
--- ccvs/lib/canon-host.c:1.1   Sun Sep  4 15:21:27 2005
+++ ccvs/lib/canon-host.c       Tue Sep  6 04:50:04 2005
@@ -1,9 +1,9 @@
 /* Host name canonicalization
 
-   Copyright (C) 1995, 1999, 2000, 2002, 2003, 2004, 2005 Free Software
+   Copyright (C) 2005 Free Software
    Foundation, Inc.
 
-   Written by Miles Bader <address@hidden>
+   Written by Derek Price <address@hidden>.
 
    This program is free software; you can redistribute it and/or
    modify it under the terms of the GNU General Public License as
@@ -23,105 +23,76 @@
 # include <config.h>
 #endif
 
-#include <sys/types.h>
-#ifdef HAVE_UNISTD_H
-# include <unistd.h>
-#endif
-#include <stdlib.h>
-#include <string.h>
-#ifdef HAVE_NETDB_H
-# include <netdb.h>
-#endif
-#ifdef HAVE_SYS_SOCKET_H
-# include <sys/socket.h>
-#endif
-
-#ifdef HAVE_NETINET_IN_H
-# include <netinet/in.h>
-#endif
-#ifdef HAVE_ARPA_INET_H
-# include <arpa/inet.h>
-#endif
+#include "canon-host.h"
 
+#include "getaddrinfo.h"
 #include "strdup.h"
 
-/* Returns the canonical hostname associated with HOST (allocated in a static
-   buffer), or NULL if it can't be determined.  */
+
+
+/* Store the last error for the single-threaded version of this function.  */
+static int last_cherror;
+
+
+
+/* Single-threaded of wrapper for canon_host_r.  After a NULL return, error
+   messages may be retrieved via ch_strerror().
+ */
 char *
-canon_host (char const *host)
+canon_host (const char *host)
 {
-  char *h_addr_copy = NULL;
+    return canon_host_r (host, &last_cherror);
+}
 
-#if HAVE_GETADDRINFO
-  {
-    struct addrinfo hint = { 0, };
+
+
+/* Returns a malloc'd string containing the canonical hostname associated with
+   HOST, or NULL if a canonical name cannot be determined.  On NULL return, if
+   CHERROR is not NULL, *CHERROR will be set to an error code as returned by
+   getaddrinfo().  Error codes from CHERROR may be converted to a string
+   suitable for error messages by ch_strerror_r() or gai_strerror().
+
+   WARNINGS
+     HOST must be a string representation of a resolvable name for this host.
+     Strings containing an IP address in dotted decimal notation will be
+     returned as-is, without further resolution.
+
+     The use of the word "canonical" in this context is unfortunate but
+     entrenched.  The value returned by this function will be the end result
+     of the resolution of any CNAME chains in the DNS.  There may only be one
+     such value for any given hostname, though the actual IP address
+     referenced by this value and the device using that IP address may each
+     actually have any number of such "canonical" hostnames.  See the POSIX
+     getaddrinfo spec <http://www.opengroup.org/susv3xsh/getaddrinfo.html";>,
+     RFC 1034 <http://www.faqs.org/rfcs/rfc1034.html>, & RFC 2181
+     <http://www.faqs.org/rfcs/rfc2181.html> for more on what this confusing
+     term really refers to.
+ */
+char *
+canon_host_r (char const *host, int *cherror)
+{
+    char *retval = NULL;
+    static struct addrinfo hints = { .ai_flags = AI_CANONNAME, };
     struct addrinfo *res = NULL;
-    hint.ai_flags = AI_CANONNAME;
-    if (getaddrinfo (host, NULL, &hint, &res) == 0)
-      {
-       h_addr_copy = strdup (res->ai_canonname);
+    int status;
+
+    status = getaddrinfo (host, NULL, &hints, &res);
+    if (!status)
+    {
+       retval = strdup (res->ai_canonname);
        freeaddrinfo (res);
-      }
-  }
-#elif HAVE_GETHOSTBYNAME
-  {
-    struct hostent *he = gethostbyname (host);
-
-    if (he)
-      {
-# ifdef HAVE_GETHOSTBYADDR
-       char *addr = NULL;
-
-       /* Try and get an ascii version of the numeric host address.  */
-       switch (he->h_addrtype)
-         {
-#  ifdef HAVE_INET_NTOA
-         case AF_INET:
-           addr = inet_ntoa (*(struct in_addr *) he->h_addr);
-           break;
-#  endif /* HAVE_INET_NTOA */
-         }
-
-       if (addr && strcmp (he->h_name, addr) == 0)
-         {
-           /* gethostbyname has returned a string representation of the IP
-              address, for example, "127.0.0.1".  So now, look up the host
-              name via the address.  Although it may seem reasonable to look
-              up the host name via the address, we must not pass `he->h_addr'
-              directly to gethostbyaddr because on some systems he->h_addr
-              is located in a static library buffer that is reused in the
-              gethostbyaddr call.  Make a copy and use that instead.  */
-           h_addr_copy = (char *) malloc (he->h_length);
-           if (h_addr_copy == NULL)
-             he = NULL;
-           else
-             {
-               memcpy (h_addr_copy, he->h_addr, he->h_length);
-               he = gethostbyaddr (h_addr_copy, he->h_length, he->h_addrtype);
-               free (h_addr_copy);
-             }
-         }
-# endif /* HAVE_GETHOSTBYADDR */
-
-       if (he)
-         h_addr_copy = strdup (he->h_name);
-      }
-  }
-#endif /* HAVE_GETHOSTBYNAME */
+    }
+    else if (cherror)
+       *cherror = status;
 
-  return h_addr_copy;
+    return retval;
 }
 
-#ifdef TEST_CANON_HOST
-int
-main (int argc, char **argv)
+
+
+/* Return a string describing the last error encountered by canon_host.  */
+const char *
+ch_strerror (void)
 {
-  int i;
-  for (i = 1; i < argc; i++)
-    {
-      char *s = canon_host (argv[i]);
-      printf ("%s: %s\n", argv[i], (s ? s : "<undef>"));
-    }
-  exit (0);
+    return gai_strerror (last_cherror);
 }
-#endif /* TEST_CANON_HOST */