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psyclpc/mudlib/dns_resolve.c
2009-03-03 04:27:01 +01:00

112 lines
3.1 KiB
C

void
dns_resolve (string hostname, closure callback)
// Try to lookup the IP for the fully qualified <hostname> using direct ERQ
// communication. Once the name is resolved, call callback() with the
// resolved name as parameter.
//
// Note: If the ERQ is unavailable, callback() is called with the original
// hostname.
//
// preferably to be installed as "simul efun." latest version available
// in world/net/library.i of psycMUVE (download from http://muve.pages.de)
// this version runs with broken and fixed erq's alike.
//
// Written by Tobias@Heldensaga and Arne@Elridion.
{
closure c;
if (sscanf(hostname,"%~D.%~D.%~D.%~D") == 4) {
// hostname is an IP already. Just call the callback.
funcall(callback, hostname);
return;
}
c = lambda( ({ 'name }), ({
(#'switch), ({ #'sizeof, 'name }),
({ 4 }), // ERQ: name resolved!
({ (#',),
({ (#'=),'name,({ (#'map),'name,#'&,255 }) }),
({ (#'=),'name,
({
(#'sprintf),"%d.%d.%d.%d",
({ #'[, 'name, 0 }),
({ #'[, 'name, 1 }),
({ #'[, 'name, 2 }),
({ #'[, 'name, 3 })
})
}),
({ (#'funcall), callback, 'name })
}),
(#'break),
({ 6 + strlen(hostname) }), // XERQ
({ (#',),
({ (#'=),'name,({ (#'map),'name,#'&,255 }) }),
({ (#'=),'name,
({
(#'sprintf),"%d.%d.%d.%d",
({ #'[, 'name, 1
}),
({ #'[, 'name, 2
}),
({ #'[, 'name, 3
}),
({ #'[, 'name, 4 })
})
}),
({ (#'funcall), callback, 'name })
}),
(#'break),
({ #'default }),
({
#'debug_message, "FATAL: ERQ could not resolve \""
+ hostname + "\". The callback will not be called.\n"
}),
(#'break)
})
);
#ifdef THEDAYWEARESURENOONERUNSABUGGYERQ
if (!send_erq(ERQ_LOOKUP, hostname, c))
#else
// appending the zero byte fixes a bug in erq. sick!
if (!send_erq(ERQ_LOOKUP, to_array(hostname) + ({ 0 }), c))
#endif
{
// if we cannot resolve using erq, we'll send back the hostname,
// so the driver can do a blocking resolve itself (needed for
// net_connect())
funcall(callback, hostname);
}
}
#if 0
/*------------------------------------------------------------------------*/
// typical usage example taken from PSYCmuve world/net/irc/gatebot.c
// this ensures a non-blocking connect to a remote service even by name.
//
connect(host, port) {
unless (host) host = IRCNET_HOST;
unless (port) port = IRCNET_PORT;
D2( D("IRCgate resolving hostname "+ host +"\n"); )
dns_resolve(host, lambda(({ 'result }),
({ #'connect2, 'result, port })));
}
connect2(host, port) {
#if __EFUN_DEFINED__(net_connect)
int res;
D0( D(S("IRCgate attempting connect to %O:%O\n", host, port)); )
res = net_connect(host, port);
if (res) monitor_report("_failure_network_connect_call",
"ircbot: connect to "+host+" returns "+ res);
return res;
#else
D2( D("IRCgate * Oh, driver does not provide net_connect()\n"); )
return -9;
#endif
}
#endif /* EXAMPLE */