cidr: Implement simplified IPv6 formats

* include/mailutils/cidr.h (MU_CIDR_FMT_SIMPLIFY): New format flag.
* libmailutils/cidr/tostr.c (format_ipv6_bytes): Take additional
argument, indicating whether to simplify the output.
(format_ipv6_bytes_normal)
(format_ipv6_bytes_simplified): New static functions.
(mu_cidr_to_string): Select appropriate ipv6 printer depending on
the MU_CIDR_FMT_SIMPLIFY bit.
* libmailutils/tests/cidr.c (main): New options -s and -S

@@ -42,6 +42,7 @@ int mu_cidr_from_sockaddr (struct mu_cidr *cp, const struct sockaddr *sa);
 int mu_cidr_from_string (struct mu_cidr *cp, const char *str);
 
 #define MU_CIDR_FMT_ADDRONLY 0x01
+#define MU_CIDR_FMT_SIMPLIFY 0x02
   
 int mu_cidr_to_string (struct mu_cidr *cidr, int flags, char *buf, size_t size,
 		       size_t *pret);

@@ -34,33 +34,102 @@ to_xdig (unsigned char b)
 
 static size_t
 format_ipv6_bytes (const unsigned char *bytes, int len, 
-		   char *buf, size_t size)
+		   char *buf, size_t size, int simplify)
 {
   size_t total = 0;
   int i;
+  int run_count = 0;
+  char *p;
   
   for (i = 0; i < len; i += 2)
     {
-      if (i)
+      if (bytes[0] == 0 && bytes[1] == 0)
+	{
+	  if (simplify)
+	    run_count++;
+	  else
+	    {
+	      if (i && total++ < size)
+		*buf++ = ':';
+	      if (total++ < size)
+		*buf++ = '0';
+	    }
+	  bytes += 2;
+	}
+      else
+	{
+	  if (run_count)
+	    {
+	      if (run_count == 1)
+		{
+		  if (i && total++ < size)
+		    *buf++ = ':';
+		  if (total++ < size)
+		    *buf++ = '0';
+		}
+	      else
+		{
+		  if (total++ < size)
+		    *buf++ = ':';
+		  simplify = 0;
+		}
+	      run_count = 0;
+	    }
+	  
+	  if (i && total++ < size)
+	    *buf++ = ':';
+
+	  p = buf;
+	  if ((*bytes & 0xf0) && total++ < size)
+	    *buf++ = to_xdig (*bytes >> 4);
+	  if ((buf > p || (*bytes & 0xf)) && total++ < size)
+	    *buf++ = to_xdig (*bytes & 0xf);
+	  bytes++;
+	  if ((buf > p || (*bytes & 0xf0)) && total++ < size)
+	    *buf++ = to_xdig (*bytes >> 4);
+	  if ((buf > p || (*bytes & 0xf)) && total++ < size)
+	    *buf++ = to_xdig (*bytes & 0xf);
+	  bytes++;
+	}
+    }
+
+  if (run_count)
+    {
+      if (run_count == 1)
+	{
+	  if (i && total++ < size)
+	    *buf++ = ':';
+	  if (total++ < size)
+	    *buf++ = '0';
+	}
+      else
 	{
 	  if (total++ < size)
 	    *buf++ = ':';
+	  if (total++ < size)
+	    *buf++ = ':';
 	}
-      if (total++ < size)
-	*buf++ = to_xdig (*bytes >> 4);
-      if (total++ < size)
-	*buf++ = to_xdig (*bytes & 0xf);
-      bytes++;
-      if (total++ < size)
-	*buf++ = to_xdig (*bytes >> 4);
-      if (total++ < size)
-	*buf++ = to_xdig (*bytes & 0xf);
-      bytes++;
     }
+  
   return total;
 }
 
 static size_t
+format_ipv6_bytes_normal (const unsigned char *bytes, int len, 
+			  char *buf, size_t size)
+{
+  return format_ipv6_bytes (bytes, len, buf, size, 0);
+}
+
+static size_t
+format_ipv6_bytes_simplified (const unsigned char *bytes, int len, 
+			      char *buf, size_t size)
+{
+  return format_ipv6_bytes (bytes, len, buf, size, 1);
+}
+
+
+static size_t
 format_ipv4_bytes (const unsigned char *bytes, int len, 
 		   char *buf, size_t size)
 {
@@ -114,7 +183,8 @@ mu_cidr_to_string (struct mu_cidr *cidr, int flags,
       
 #ifdef MAILUTILS_IPV6
     case AF_INET6:
-      fmt = format_ipv6_bytes;
+      fmt = (flags & MU_CIDR_FMT_SIMPLIFY) ?
+	         format_ipv6_bytes_simplified : format_ipv6_bytes_normal;
       break;
 #endif
 

@@ -33,10 +33,12 @@ print_bytes (unsigned char *b, size_t l)
 int
 main (int argc, char **argv)
 {
+  int flags = 0;
+  
   mu_set_program_name (argv[0]);
   if (argc < 2)
     {
-      mu_error ("usage: %s CIDR [CIDR...]", argv[0]);
+      mu_error ("usage: %s [-sS] CIDR [CIDR...]", argv[0]);
       return 1;
     }
 
@@ -46,7 +48,18 @@ main (int argc, char **argv)
       struct mu_cidr cidr;
       int rc;
       char *str;
-      
+
+      if (strcmp (arg, "-s") == 0)
+	{
+	  flags |= MU_CIDR_FMT_SIMPLIFY;
+	  continue;
+	}
+      else if (strcmp (arg, "-S") == 0)
+	{
+	  flags &= ~MU_CIDR_FMT_SIMPLIFY;
+	  continue;
+	}
+	       
       rc = mu_cidr_from_string (&cidr, arg);
       if (rc)
 	{
@@ -61,7 +74,7 @@ main (int argc, char **argv)
       print_bytes (cidr.address, cidr.len);
       printf ("netmask =");
       print_bytes (cidr.netmask, cidr.len);
-      rc = mu_cidr_format (&cidr, 0, &str);
+      rc = mu_cidr_format (&cidr, flags, &str);
       if (rc)
 	{
 	  mu_error ("cannot covert to string: %s", mu_strerror (rc));