extensions: implement @jevolk's spamfilter core module

extensions/Makefile.am

@@ -13,6 +13,7 @@ extension_LTLIBRARIES =		\
   chm_nonotice.la		\
   chm_operpeace.la		\
   chm_quietunreg_compat.la	\
+  chm_spamfilter.la		\
   chm_sslonly.la		\
   chm_sslonly_compat.la		\
   createauthonly.la		\

extensions/chm_spamfilter.c

@@ -0,0 +1,162 @@
+/************************************************************************
+ * charybdis: an advanced ircd. extensions/chm_spamfilter.c
+ * Copyright (C) 2016 Jason Volk
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
+ * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
+ * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "stdinc.h"
+#include "s_conf.h"
+#include "modules.h"
+#include "hook.h"
+#include "send.h"
+#include "chmode.h"
+#include "newconf.h"
+#include "substitution.h"
+#include "spamfilter.h"
+
+
+int chm_spamfilter;
+int h_spamfilter_query;
+int h_spamfilter_reject;
+
+char reject_reason[BUFSIZE - CHANNELLEN - 32];
+
+
+static
+void hook_privmsg_channel(hook_data_privmsg_channel *const hook)
+{
+	// Check for mootness by other hooks first
+	if(hook->approved != 0 || EmptyString(hook->text))
+		return;
+
+	// Assess channel related
+	if(~hook->chptr->mode.mode & chm_spamfilter)
+		return;
+
+	// Assess client related
+	if(IsExemptSpambot(hook->source_p))
+		return;
+
+	// Assess type related
+	if(hook->msgtype != MESSAGE_TYPE_NOTICE && hook->msgtype != MESSAGE_TYPE_PRIVMSG)
+		return;
+
+	// Invoke the active spamfilters
+	call_hook(h_spamfilter_query, hook);
+	if(hook->approved == 0)
+		return;
+
+	call_hook(h_spamfilter_reject, hook);
+	sendto_realops_snomask(SNO_REJ|SNO_BOTS, L_NETWIDE,
+	                       "spamfilter: REJECT %s[%s@%s] on %s to %s (%s)",
+	                       hook->source_p->name,
+	                       hook->source_p->username,
+	                       hook->source_p->orighost,
+	                       hook->source_p->servptr->name,
+	                       hook->chptr->chname,
+	                       hook->reason?: "filter gave no reason");
+
+	hook->reason = reject_reason;
+}
+
+
+static
+void substitute_reject_reason(void)
+{
+	rb_dlink_list subs = {0};
+	substitution_append_var(&subs, "network-name", ServerInfo.network_name?: "${network-name}");
+	substitution_append_var(&subs, "admin-email", AdminInfo.email?: "${admin-email}");
+	const char *const substituted = substitution_parse(reject_reason, &subs);
+	rb_strlcpy(reject_reason, substituted, sizeof(reject_reason));
+	substitution_free(&subs);
+}
+
+
+static
+void set_reject_reason(void *const str)
+{
+	rb_strlcpy(reject_reason, str, sizeof(reject_reason));
+	substitute_reject_reason();
+}
+
+
+struct ConfEntry conf_spamfilter[] =
+{
+	{ "reject_reason",     CF_QSTRING,   set_reject_reason, 0,  NULL },
+	{ "\0",                0,            NULL,              0,  NULL }
+};
+
+
+static
+int modinit(void)
+{
+	chm_spamfilter = cflag_add(MODE_SPAMFILTER, CHM_D, chm_simple);
+	if(!chm_spamfilter)
+		return -1;
+
+	add_top_conf("spamfilter", NULL, NULL, conf_spamfilter);
+	return 0;
+}
+
+
+static
+void modfini(void)
+{
+	remove_top_conf("spamfilter");
+	cflag_orphan(MODE_SPAMFILTER);
+}
+
+
+mapi_hlist_av1 hlist[] =
+{
+	{ "spamfilter_query", &h_spamfilter_query,        },
+	{ "spamfilter_reject", &h_spamfilter_reject,      },
+	{ NULL, NULL                                      }
+};
+
+mapi_hfn_list_av1 hfnlist[] =
+{
+	{ "privmsg_channel", (hookfn)hook_privmsg_channel      },
+	{ NULL, NULL                                           }
+};
+
+static const char chm_spamfilter_desc[] =
+	"Adds channel mode +Y which enables various spam mitigations";
+
+DECLARE_MODULE_AV2
+(
+	chm_spamfilter,
+	modinit,
+	modfini,
+	NULL,
+	hlist,
+	hfnlist,
+	NULL,
+	NULL,
+	chm_spamfilter_desc
+);

extensions/spamfilter.h

@@ -0,0 +1,33 @@
+/************************************************************************
+ * charybdis: an advanced ircd. extensions/spamfilter.h
+ * Copyright (C) 2016 Jason Volk
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
+ * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
+ * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#define MODE_SPAMFILTER      'Y'
+#define STATCHAR_SPAMFILTER  'S'