DOWNGRADE(1)
General Commands Manual
DOWNGRADE(1)
downgrade —
IRC features for all
downgrade |
[-iv] [-c
cert] [-j
join] [-k
priv] [-n
nick] [-p
port] host |
The downgrade IRC bot downgrades new IRC
“features” so
everyone
can see them. It supports typing notifications, message reactions and
message replies.
The arguments are as follows:
-c
cert- Load the TLS client certificate from cert and
authenticate using SASL EXTERNAL.
-i- Accept invites to channels.
-j
join- Join the channel list join.
-k
priv- Load the TLS client private key from priv. The
default is the same path as cert.
-n
nick- Set the nickname and username to nick. The default
is
downgrade.
-p
port- Connect to port. The default is 6697.
-v- Log IRC protocol.
- host
- Connect to host.
-downgrade- * guest-n4 is typing...
<guest-n4> wtf
-downgrade- * june reacted to guest-n4's message ("wtf") with "👍"
-downgrade- * guest-n4 is typing...
-downgrade- * guest-n4 has given up :(
<june> ,bef
-downgrade- * tildebot is typing...
<tildebot> [Ducks] june: There was no duck!
-downgrade- * tildebot was replying to june's message (",bef")
- Kiyoshi Aman,
Kyle Fuller, Stéphan
Kochen, Alexey Sokolov, and
James Wheare, Message
Tags,
https://ircv3.net/specs/extensions/message-tags.
- MuffinMedic and
James Wheare, typing client
tag,
https://ircv3.net/specs/client-tags/typing.
- Daniel Oaks,
Bot Mode,
https://ircv3.net/specs/extensions/bot-mode.
- James Wheare,
Message IDs,
https://ircv3.net/specs/extensions/message-ids.
- James Wheare,
react client tag,
https://ircv3.net/specs/client-tags/react.
- James Wheare,
reply client tag,
https://ircv3.net/specs/client-tags/reply.
downgrade.c in git
/* Copyright (C) 2021 June McEnroe <june@causal.agency>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <assert.h>
#include <err.h>
#include <signal.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <tls.h>
#include <unistd.h>
#ifdef __FreeBSD__
#include <capsicum_helpers.h>
#endif
enum { BufferCap = 8192 + 512 };
static bool verbose;
static struct tls *client;
static void clientWrite(const char *ptr, size_t len) {
if (verbose) printf("%.*s", (int)len, ptr);
while (len) {
ssize_t ret = tls_write(client, ptr, len);
if (ret == TLS_WANT_POLLIN || ret == TLS_WANT_POLLOUT) continue;
if (ret < 0) errx(1, "tls_write: %s", tls_error(client));
ptr += ret;
len -= ret;
}
}
static void format(const char *format, ...) {
char buf[BufferCap];
va_list ap;
va_start(ap, format);
int len = vsnprintf(buf, sizeof(buf), format, ap);
va_end(ap);
assert((size_t)len < sizeof(buf));
clientWrite(buf, len);
}
static bool invite;
static const char *join;
enum { Cap = 1024 };
static struct Message {
char *id;
char *nick;
char *chan;
char *mesg;
} msgs[Cap];
static size_t m;
static void push(struct Message msg) {
struct Message *dst = &msgs[m++ % Cap];
free(dst->id);
free(dst->nick);
free(dst->chan);
free(dst->mesg);
dst->id = strdup(msg.id);
dst->nick = strdup(msg.nick);
dst->chan = strdup(msg.chan);
if (!dst->id || !dst->nick || !dst->chan) err(1, "strdup");
dst->mesg = NULL;
if (msg.mesg) {
dst->mesg = strdup(msg.mesg);
if (!dst->mesg) err(1, "strdup");
}
}
static struct Message *find(const char *id) {
for (size_t i = 0; i < Cap; ++i) {
if (!msgs[i].id) return NULL;
if (!strcmp(msgs[i].id, id)) return &msgs[i];
}
return NULL;
}
static void handle(char *ptr) {
char *tags = NULL;
char *origin = NULL;
if (ptr && *ptr == '@') tags = 1 + strsep(&ptr, " ");
if (ptr && *ptr == ':') origin = 1 + strsep(&ptr, " ");
char *cmd = strsep(&ptr, " ");
if (!cmd) return;
if (!strcmp(cmd, "CAP")) {
strsep(&ptr, " ");
char *sub = strsep(&ptr, " ");
if (!sub) errx(1, "CAP without subcommand");
if (!strcmp(sub, "NAK")) {
errx(1, "server does not support %s", ptr);
} else if (!strcmp(sub, "ACK")) {
if (!ptr) errx(1, "CAP ACK without caps");
if (*ptr == ':') ptr++;
if (!strcmp(ptr, "sasl")) format("AUTHENTICATE EXTERNAL\r\n");
}
} else if (!strcmp(cmd, "AUTHENTICATE")) {
format("AUTHENTICATE +\r\nCAP END\r\n");
} else if (!strcmp(cmd, "433")) {
strsep(&ptr, " ");
char *nick = strsep(&ptr, " ");
if (!nick) errx(1, "ERR_NICKNAMEINUSE missing nick");
format("NICK %s_\r\n", nick);
} else if (!strcmp(cmd, "001")) {
if (join) format("JOIN %s\r\n", join);
} else if (!strcmp(cmd, "005")) {
char *self = strsep(&ptr, " ");
if (!self) errx(1, "RPL_ISUPPORT missing nick");
while (ptr && *ptr != ':') {
char *tok = strsep(&ptr, " ");
char *key = strsep(&tok, "=");
if (!strcmp(key, "BOT") && tok) {
format("MODE %s +%s\r\n", self, tok);
}
}
} else if (!strcmp(cmd, "INVITE") && invite) {
strsep(&ptr, " ");
if (!ptr) errx(1, "INVITE missing channel");
if (*ptr == ':') ptr++;
format("JOIN %s\r\n", ptr);
} else if (!strcmp(cmd, "PING")) {
if (!ptr) errx(1, "PING missing parameter");
format("PONG %s\r\n", ptr);
} else if (!strcmp(cmd, "ERROR")) {
if (!ptr) errx(1, "ERROR missing parameter");
if (*ptr == ':') ptr++;
errx(1, "%s", ptr);
}
if (
strcmp(cmd, "PRIVMSG") &&
strcmp(cmd, "NOTICE") &&
strcmp(cmd, "TAGMSG")
) return;
if (!origin) errx(1, "%s missing origin", cmd);
struct Message msg = {
.nick = strsep(&origin, "!"),
.chan = strsep(&ptr, " "),
};
if (!msg.chan) errx(1, "%s missing target", cmd);
if (msg.chan[0] == ':') msg.chan++;
if (msg.chan[0] != '#') return;
if (strcmp(cmd, "TAGMSG")) msg.mesg = (*ptr == ':' ? &ptr[1] : ptr);
if (msg.mesg) {
if (!strncmp(msg.mesg, "\1ACTION ", 8)) msg.mesg += 8;
size_t len = strlen(msg.mesg);
if (msg.mesg[len-1] == '\1') msg.mesg[len-1] = '\0';
}
char *reply = NULL;
char *react = NULL;
char *typing = NULL;
if (!tags) return;
while (tags) {
char *tag = strsep(&tags, ";");
char *key = strsep(&tag, "=");
if (!strcmp(key, "msgid")) {
if (tag) msg.id = tag;
} else if (!strcmp(key, "+draft/reply")) {
if (tag) reply = tag;
} else if (!strcmp(key, "+draft/react")) {
if (!tag) continue;
for (char *ptr = tag; (ptr = strchr(ptr, '\\')); ptr += !!*ptr) {
switch (ptr[1]) {
break; case ':': ptr[1] = ';';
break; case 's': ptr[1] = ' ';
//break; case 'r': ptr[1] = '\r';
//break; case 'n': ptr[1] = '\n';
}
memmove(ptr, &ptr[1], strlen(&ptr[1]) + 1);
}
react = tag;
} else if (!strcmp(key, "+typing") || !strcmp(key, "+draft/typing")) {
if (tag) typing = tag;
}
}
if (msg.id) push(msg);
if (typing) {
if (!strcmp(typing, "active")) {
format("NOTICE %s :* %s is typing...\r\n", msg.chan, msg.nick);
} else if (!strcmp(typing, "paused")) {
format(
"NOTICE %s :* %s is thinking hard...\r\n", msg.chan, msg.nick
);
} else if (!strcmp(typing, "done")) {
format("NOTICE %s :* %s has given up :(\r\n", msg.chan, msg.nick);
} else {
format(
"NOTICE %s :* %s is doing some wacky %s typing!\r\n",
msg.chan, msg.nick, typing
);
}
} else if (react && reply) {
struct Message *to = find(reply);
format("NOTICE %s :* %s reacted to ", msg.chan, msg.nick);
if (to && strcmp(to->chan, msg.chan)) {
format("a message in another channel");
} else if (to && to->mesg) {
size_t len = 0;
for (size_t n; to->mesg[len]; len += n) {
n = 1 + strcspn(&to->mesg[len+1], " ");
if (len + n > 50) break;
}
format(
"%s's message (\"%.*s\"%s)",
to->nick, (int)len, to->mesg, (to->mesg[len] ? "..." : "")
);
} else if (to) {
format("%s's reaction", to->nick);
} else {
format("an unknown message");
}
format(" with \"%s\"\r\n", react);
} else if (react) {
format(
"NOTICE %s :* %s reacted to nothing with \"%s\"\r\n",
msg.chan, msg.nick, react
);
} else if (reply) {
struct Message *to = find(reply);
format("NOTICE %s :* %s was replying to ", msg.chan, msg.nick);
if (to && strcmp(to->chan, msg.chan)) {
format("a message in another channel!\r\n");
} else if (to && to->mesg) {
size_t len = 0;
for (size_t n; to->mesg[len]; len += n) {
n = 1 + strcspn(&to->mesg[len+1], " ");
if (len + n > 50) break;
}
format(
"%s's message (\"%.*s\"%s)\r\n",
to->nick, (int)len, to->mesg, (to->mesg[len] ? "..." : "")
);
} else if (to) {
format("%s's reaction\r\n", to->nick);
} else {
format("an unknown message!\r\n");
}
}
}
static void quit(int sig) {
(void)sig;
format("QUIT\r\n");
tls_close(client);
exit(0);
}
int main(int argc, char *argv[]) {
const char *host = NULL;
const char *port = "6697";
const char *nick = "downgrade";
const char *cert = NULL;
const char *priv = NULL;
for (int opt; 0 < (opt = getopt(argc, argv, "c:ij:k:n:p:v"));) {
switch (opt) {
break; case 'c': cert = optarg;
break; case 'i': invite = true;
break; case 'j': join = optarg;
break; case 'k': priv = optarg;
break; case 'n': nick = optarg;
break; case 'p': port = optarg;
break; case 'v': verbose = true;
break; default: return 1;
}
}
if (optind == argc) errx(1, "host required");
host = argv[optind];
client = tls_client();
if (!client) errx(1, "tls_client");
struct tls_config *config = tls_config_new();
if (!config) errx(1, "tls_config_new");
if (cert) {
if (!priv) priv = cert;
int error = tls_config_set_keypair_file(config, cert, priv);
if (error) errx(1, "%s: %s", cert, tls_config_error(config));
}
int error = tls_configure(client, config);
if (error) errx(1, "tls_configure: %s", tls_error(client));
error = tls_connect(client, host, port);
if (error) errx(1, "tls_connect: %s", tls_error(client));
do {
error = tls_handshake(client);
} while (error == TLS_WANT_POLLIN || error == TLS_WANT_POLLOUT);
if (error) errx(1, "tls_handshake: %s", tls_error(client));
tls_config_clear_keys(config);
#ifdef __OpenBSD__
error = pledge("stdio", NULL);
if (error) err(1, "pledge");
#endif
#ifdef __FreeBSD__
error = caph_enter() || caph_limit_stdio();
if (error) err(1, "caph_enter");
#endif
signal(SIGHUP, quit);
signal(SIGINT, quit);
signal(SIGTERM, quit);
format(
"CAP REQ :echo-message message-tags\r\n"
"NICK %s\r\n"
"USER %s 0 * :https://causal.agency/bin/downgrade.html\r\n",
nick, nick
);
if (cert) {
format("CAP REQ sasl\r\n");
} else {
format("CAP END\r\n");
}
size_t len = 0;
char buf[BufferCap];
for (;;) {
ssize_t n = tls_read(client, &buf[len], sizeof(buf) - len);
if (n == TLS_WANT_POLLIN || n == TLS_WANT_POLLOUT) continue;
if (n < 0) errx(1, "tls_read: %s", tls_error(client));
if (!n) errx(1, "disconnected");
len += n;
char *ptr = buf;
for (
char *crlf;
(crlf = memmem(ptr, &buf[len] - ptr, "\r\n", 2));
ptr = crlf + 2
) {
*crlf = '\0';
if (verbose) printf("%s\n", ptr);
handle(ptr);
}
len -= ptr - buf;
memmove(buf, ptr, len);
}
}