common-utils: valid_host_name() should allow (sub)domains starting/ending with a digit

Some (sub)domains start or end with a digit. If this is the case, it
will not be possible to 'gluster peer probe' hosts in that (sub)domain.
This is overly restrictive, and RFC 1912 contains a note that describes
the common use of start/end digits in (sub)domains:
>
> Allowable characters in a label for a host name are only ASCII
> letters, digits, and the `-' character.  Labels may not be all
> numbers, but may have a leading digit  (e.g., 3com.com).  Labels must
> end and begin only with a letter or digit.  See [RFC 1035] and [RFC
> 1123].  (Labels were initially restricted in [RFC 1035] to start with
> a letter, and some older hosts still reportedly have problems with
> the relaxation in [RFC 1123].)  Note there are some Internet
> hostnames which violate this rule (411.org, 1776.com).
>

This change will also allow (sub)domains to consist out of digits only,
like the example of 411.org above. It is still not allowed to start or
and a (sub)domain with a `-' (dash) character.

Change-Id: I7236edfe80fd08f28247536bef5287f63b564a63
BUG: 862297
Signed-off-by: Niels de Vos <ndevos@redhat.com>
Reviewed-on: http://review.gluster.org/4017
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Kaleb KEITHLEY <kkeithle@redhat.com>
Reviewed-by: Jeff Darcy <jdarcy@redhat.com>
Reviewed-by: Anand Avati <avati@redhat.com>

1 files changed, 7 insertions, 23 deletions

diff --git a/libglusterfs/src/common-utils.c b/libglusterfs/src/common-utils.c
index 791ecefe62b..63d7f6e3530 100644
--- a/libglusterfs/src/common-utils.c
+++ b/libglusterfs/src/common-utils.c
@@ -1625,11 +1625,9 @@ get_nth_word (const char *str, int n)
         return word;
 }
 
-/* RFC 1123 & 952 */
-/* Syntax formed combining RFC 1123 & 952                                     *
-   <hname> ::= <first-name>*["."<gen-name>]                                   *
-   <first-name> ::= <let-or-digit> <[*[<let-or-digit-or-hyphen>]<let-or-digit>]
-   <gen-name> ::= <let>[*[<let-or-digit-or-hyphen>]<let-or-digit>]            */
+/* Syntax formed according to RFC 1912 (RFC 1123 & 952 are more restrictive)  *
+   <hname> ::= <gen-name>*["."<gen-name>]                                     *
+   <gen-name> ::= <let-or-digit> <[*[<let-or-digit-or-hyphen>]<let-or-digit>] */
 char
 valid_host_name (char *address, int length)
 {
@@ -1650,27 +1648,13 @@ valid_host_name (char *address, int length)
                 ret = 0;
                 goto out;
         }
-        temp_str = strtok_r (dup_addr,".", &save_ptr);
-
-        /* first-name */
-        if (!temp_str ||
-            !isalnum(temp_str[0]) ||
-            !isalnum (temp_str[strlen(temp_str)-1])) {
-                ret = 0;
-                goto out;
-        }
-        for (i = 1; i < (strlen (temp_str) - 1); i++) {
-                if (!isalnum (temp_str[i]) && (temp_str[i] != '-')) {
-                        ret = 0;
-                        goto out;
-                }
-        }
 
         /* gen-name */
-        while ((temp_str = strtok_r (NULL, ".", &save_ptr))) {
+        temp_str = strtok_r (dup_addr, ".", &save_ptr);
+        do {
                 str_len = strlen (temp_str);
 
-                if (!isalpha (temp_str[0]) ||
+                if (!isalnum (temp_str[0]) ||
                     !isalnum (temp_str[str_len-1])) {
                         ret = 0;
                         goto out;
@@ -1681,7 +1665,7 @@ valid_host_name (char *address, int length)
                                 goto out;
                         }
                 }
-        }
+        } while ((temp_str = strtok_r (NULL, ".", &save_ptr)));
 
 out:
         GF_FREE (dup_addr);