mirror of https://github.com/pissnet/pissircd.git
157 lines
4.8 KiB
C
157 lines
4.8 KiB
C
/*
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* IRC - Internet Relay Chat, src/modules/message-ids.c
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* (C) 2019 Syzop & The UnrealIRCd Team
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*
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* See file AUTHORS in IRC package for additional names of
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* the programmers.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 1, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include "unrealircd.h"
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ModuleHeader MOD_HEADER
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= {
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"message-ids",
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"5.0",
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"msgid CAP",
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"UnrealIRCd Team",
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"unrealircd-6",
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};
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/* Variables */
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long CAP_ACCOUNT_TAG = 0L;
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int msgid_mtag_is_ok(Client *client, const char *name, const char *value);
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void mtag_add_or_inherit_msgid(Client *sender, MessageTag *recv_mtags, MessageTag **mtag_list, const char *signature);
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MOD_INIT()
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{
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MessageTagHandlerInfo mtag;
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MARK_AS_OFFICIAL_MODULE(modinfo);
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memset(&mtag, 0, sizeof(mtag));
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mtag.name = "msgid";
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mtag.is_ok = msgid_mtag_is_ok;
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mtag.flags = MTAG_HANDLER_FLAGS_NO_CAP_NEEDED;
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MessageTagHandlerAdd(modinfo->handle, &mtag);
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HookAddVoid(modinfo->handle, HOOKTYPE_NEW_MESSAGE, 0, mtag_add_or_inherit_msgid);
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return MOD_SUCCESS;
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}
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MOD_LOAD()
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{
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return MOD_SUCCESS;
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}
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MOD_UNLOAD()
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{
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return MOD_SUCCESS;
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}
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/** This function verifies if the client sending
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* 'msgid' is permitted to do so and uses a permitted
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* syntax.
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* We simply allow msgid ONLY from servers and with any syntax.
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*/
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int msgid_mtag_is_ok(Client *client, const char *name, const char *value)
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{
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if (IsServer(client) && !BadPtr(value))
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return 1;
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return 0;
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}
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/** Generate a msgid.
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* @returns a MessageTag struct that you can use directly.
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* @note
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* Apparently there has been some discussion on what method to use to
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* generate msgid's. I am not going to list them here. Just saying that
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* they have been considered and we chose to go for a string that contains
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* 128+ bits of randomness, which has an extremely low chance of colissions.
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* Or, to quote wikipedia on the birthday attack problem:
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* "For comparison, 10^-18 to 10^-15 is the uncorrectable bit error rate
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* of a typical hard disk. In theory, hashes or UUIDs being 128 bits,
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* should stay within that range until about 820 billion outputs"
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* For reference, 10^-15 is 0.000000000000001%
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* The main reasons for this choice are: that it is extremely simple,
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* the chance of making a mistake in an otherwise complex implementation
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* is nullified and we don't risk "leaking" any details.
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*/
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MessageTag *mtag_generate_msgid(void)
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{
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MessageTag *m = safe_alloc(sizeof(MessageTag));
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safe_strdup(m->name, "msgid");
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m->value = safe_alloc(MSGIDLEN+1);
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gen_random_alnum(m->value, MSGIDLEN);
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return m;
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}
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void mtag_add_or_inherit_msgid(Client *sender, MessageTag *recv_mtags, MessageTag **mtag_list, const char *signature)
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{
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MessageTag *m = find_mtag(recv_mtags, "msgid");
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if (m)
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m = duplicate_mtag(m);
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else
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m = mtag_generate_msgid();
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if (signature)
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{
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/* Special case:
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* Some commands will receive a single msgid from
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* a remote server for multiple events.
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* Take for example SJOIN which may contain 5 joins,
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* 3 bans setting, 2 invites, and setting a few modes.
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* This way we can still generate unique msgid's
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* for such sub-events. It is a hash of the subevent
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* concatenated to the existing msgid.
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* The hash is the first half of a SHA256 hash, then
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* base64'd, and with the == suffix removed.
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*/
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char prefix[MSGIDLEN+1], *p;
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strlcpy(prefix, m->value, sizeof(prefix));
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p = strchr(prefix, '-');
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if (p)
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{
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/* It is possible that we have more stacking.
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* IOTW: we are already stacked like xxx-yyy
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* and it would have become an xxx-yyy-zzz
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* sequence. Instead, we strip the yyy-
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* so the end result will be xxx-zzz.
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*
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* One example code path would be when someone joins
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* and the issecure module sets -Z.
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*/
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*p = '\0';
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}
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SHA256_CTX hash;
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char binaryhash[SHA256_DIGEST_LENGTH];
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char b64hash[SHA256_DIGEST_LENGTH*2+1];
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char newbuf[256];
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memset(&binaryhash, 0, sizeof(binaryhash));
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memset(&b64hash, 0, sizeof(b64hash));
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sha256hash_binary(binaryhash, signature, strlen(signature));
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b64_encode(binaryhash, sizeof(binaryhash)/2, b64hash, sizeof(b64hash));
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b64hash[22] = '\0'; /* cut off at '=' */
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snprintf(newbuf, sizeof(newbuf), "%s-%s", prefix, b64hash);
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safe_strdup(m->value, newbuf);
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}
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AddListItem(m, *mtag_list);
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}
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