HINTS PLEASE: how to determine named-based vhost

["Ralf S. Engelschall" <rs...@engelschall.com>]

A poked around in our http_vhost.c source but couldn't find an API function
which can be used. The problem is this: SSL interfaces like mod_ssl and
Apache-SSL should check whether the configured SSL-vhost is name-based or not.
Because fo SSL it _has_ to be IP-based. So, what's basically needed (and it
would be fine when we could add it for 1.3.2 and not patch it into the code
for mod_ssl, Apache-SSL, etc.) is

     int ap_is_name_based_vhost(server_rec *s);

As it looks it has to search "s" inside the iphash_table from http_vhost and
when it is found it has to look for the "names" attribute.
In other words:

     API_EXPORT int ap_is_name_based_vhost(server_rec *s)
     {
         ipaddr_chain *ic;
         int rc = 0;
         int i;

         for (i = 0; i < IPHASH_TABLE_SIZE; i++) {
             for (ic = iphash_table[i]; ic != NULL; ic = ic->next) {
                 if (ic->server == s) {
                     if (ic->names == NULL)
                         rc = 1;
                     break;
                 }
             }
         }
         return rc;
     }

Is this correct and if yes, is it ok to be added to httpd_vhost.c? Dean?

                                       Ralf S. Engelschall
                                       rse@engelschall.com
                                       www.engelschall.com

Re: HINTS PLEASE: how to determine named-based vhost

[Dean Gaudet <dg...@arctic.org>]

On Wed, 16 Sep 1998, Ralf S. Engelschall wrote:

> A poked around in our http_vhost.c source but couldn't find an API function
> which can be used. The problem is this: SSL interfaces like mod_ssl and
> Apache-SSL should check whether the configured SSL-vhost is name-based or not.
> Because fo SSL it _has_ to be IP-based. So, what's basically needed (and it
> would be fine when we could add it for 1.3.2 and not patch it into the code
> for mod_ssl, Apache-SSL, etc.) is
> 
>      int ap_is_name_based_vhost(server_rec *s);

This is an impossible question to answer.  Consider:

NameVirtualHost 10.1.1.1
<VirtualHost 10.1.1.1 10.1.1.2>
    ServerName foobar
    blah blah
</VirtualHost>
<VirtualHost 10.1.1.1>
    ServerName whatever
    ...
</VirtualHost>

Is foobar a name-vhost or not?

> As it looks it has to search "s" inside the iphash_table from http_vhost and
> when it is found it has to look for the "names" attribute.
> In other words:
> 
>      API_EXPORT int ap_is_name_based_vhost(server_rec *s)
>      {
>          ipaddr_chain *ic;
>          int rc = 0;
>          int i;
> 
>          for (i = 0; i < IPHASH_TABLE_SIZE; i++) {
>              for (ic = iphash_table[i]; ic != NULL; ic = ic->next) {
>                  if (ic->server == s) {
>                      if (ic->names == NULL)
>                          rc = 1;
>                      break;
>                  }
>              }
>          }
>          return rc;
>      }

This code doesn't do what you want... it answers the question: for
one of the IP:port pairs that s can respond to requests on, is it an
*ip*-based vhost.

I'm not sure if the real question you want to ask is:

    - does this server have exactly one IP address and is that addr
      shared with no other server?

or

    - are all of this server's addresses unique to this server

To do the first you'll want to look at s->addrs... in either case you
always have to scan the entire hash table... which is ugly O(n^2) if you
have to do it for every server.  So you may want to instead add a field
to server_rec, and add the calculation of these answers to the hashing
process in ap_fini_vhost_config().

Dean