extban: implement helper functions for stackable extbans (part 1) (ref #74)

doc/extban.txt

@@ -88,5 +88,12 @@ The function is called whenever a (local) client needs to be checked against
 a +bqeI entry of the given extban type, and whenever a local client tries to
 add such an entry. (Clients are allowed to add bans matching themselves.)
 
--- 
+There is a convenience function which allows extbans to be stacked:
-$Id: extban.txt 1639 2006-06-04 23:26:47Z jilles $
+extern int match_child(const char *banstr, struct Client *client_p, struct Channel *chptr, long mode_type);
+
+The arguments are as follows:
+banstr: the text after the parent banstr (extb functions already get the mask this way)
+client_p: the client to check; this is always a local client, which may be
+on or off channel
+chptr: the channel
+mode_type: CHFL_BAN, CHFL_QUIET, CHFL_EXCEPTION or CHFL_INVEX

include/channel.h

@@ -266,6 +266,7 @@ extern struct Ban * del_id(struct Channel *chptr, const char *banid, rb_dlink_li
 
 extern ExtbanFunc extban_table[256];
 
+extern int match_child(const char *banstr, struct Client *client_p, struct Channel *chptr, long mode_type);
 extern int match_extban(const char *banstr, struct Client *client_p, struct Channel *chptr, long mode_type);
 extern int valid_extban(const char *banstr, struct Client *client_p, struct Channel *chptr, long mode_type);
 const char * get_extban_string(void);

src/extban.c

@@ -26,9 +26,52 @@
 #include "channel.h"
 #include "client.h"
 #include "common.h"
+#include "ipv4_from_ipv6.h"
 
 ExtbanFunc extban_table[256] = { NULL };
 
+int
+match_child(const char *banstr, struct Client *client_p, struct Channel *chptr, long mode_type)
+{
+	char src_host[NICKLEN + USERLEN + HOSTLEN + 6];
+	char src_iphost[NICKLEN + USERLEN + HOSTLEN + 6];
+	char src_althost[NICKLEN + USERLEN + HOSTLEN + 6];
+	char src_ip4host[NICKLEN + USERLEN + HOSTLEN + 6];
+	struct sockaddr_in ip4;
+	char *s = src_host, *s2 = src_iphost, *s3 = NULL, *s4 = NULL;
+
+	if (*banstr == '$')
+		return match_extban(banstr, client_p, chptr, mode_type) ? EXTBAN_MATCH : EXTBAN_NOMATCH;
+
+	rb_sprintf(src_host, "%s!%s@%s", client_p->name, client_p->username, client_p->host);
+	rb_sprintf(src_iphost, "%s!%s@%s", client_p->name, client_p->username, client_p->sockhost);
+
+	/* handle hostmangling if necessary */
+	if (client_p->localClient->mangledhost != NULL)
+	{
+		if (!strcmp(client_p->host, client_p->localClient->mangledhost))
+			rb_sprintf(src_althost, "%s!%s@%s", client_p->name, client_p->username, client_p->orighost);
+		else if (!IsDynSpoof(client_p))
+			rb_sprintf(src_althost, "%s!%s@%s", client_p->name, client_p->username, client_p->localClient->mangledhost);
+
+		s3 = src_althost;
+	}
+
+#ifdef RB_IPV6
+	/* handle Teredo if necessary */
+	if (client_p->localClient->ip.ss_family == AF_INET6 && ipv4_from_ipv6((const struct sockaddr_in6 *) &client_p->localClient->ip, &ip4))
+	{
+		rb_sprintf(src_ip4host, "%s!%s@", client_p->name, client_p->username);
+		s4 = src_ip4host + strlen(src_ip4host);
+		rb_inet_ntop_sock((struct sockaddr *)&ip4,
+				s4, src_ip4host + sizeof src_ip4host - s4);
+		s4 = src_ip4host;
+	}
+#endif
+
+	return match(banstr, s) || match(banstr, s2) || (s3 != NULL && match(banstr, s3)) || (s4 != NULL && match(banstr, s4)) ? EXTBAN_MATCH : EXTBAN_NOMATCH;
+}
+
 int
 match_extban(const char *banstr, struct Client *client_p, struct Channel *chptr, long mode_type)
 {