Add IRC relay bot

3 files changed, 191 insertions, 0 deletions

diff --git a/bin/irc/.gitignore b/bin/irc/.gitignore
new file mode 100644
index 00000000..32e541af
--- /dev/null
+++ b/bin/irc/.gitignore
@@ -0,0 +1 @@
+relay
diff --git a/bin/irc/Makefile b/bin/irc/Makefile
new file mode 100644
index 00000000..c909f067
--- /dev/null
+++ b/bin/irc/Makefile
@@ -0,0 +1,13 @@
+LIBRESSL_PREFIX = /usr/local
+
+CFLAGS += -Wall -Wextra -Wpedantic
+CFLAGS += -I$(LIBRESSL_PREFIX)/include
+LDFLAGS += -L$(LIBRESSL_PREFIX)/lib
+LDLIBS = -ltls
+
+-include config.mk
+
+relay:
+
+clean:
+	rm -f relay
diff --git a/bin/irc/relay.c b/bin/irc/relay.c
new file mode 100644
index 00000000..b600c3a1
--- /dev/null
+++ b/bin/irc/relay.c
@@ -0,0 +1,177 @@
+/* Copyright (C) 2019  C. 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 <err.h>
+#include <netdb.h>
+#include <netinet/in.h>
+#include <poll.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sysexits.h>
+#include <tls.h>
+#include <unistd.h>
+
+static void clientWrite(struct tls *client, const char *ptr, size_t len) {
+	while (len) {
+		ssize_t ret = tls_write(client, ptr, len);
+		if (ret == TLS_WANT_POLLIN || ret == TLS_WANT_POLLOUT) continue;
+		if (ret < 0) errx(EX_IOERR, "tls_write: %s", tls_error(client));
+		ptr += ret;
+		len -= ret;
+	}
+}
+
+static void clientFormat(struct tls *client, const char *format, ...) {
+	char buf[1024];
+	va_list ap;
+	va_start(ap, format);
+	int len = vsnprintf(buf, sizeof(buf), format, ap);
+	va_end(ap);
+	if ((size_t)len > sizeof(buf) - 1) errx(EX_DATAERR, "message too large");
+	clientWrite(client, buf, len);
+}
+
+static void clientHandle(struct tls *client, const char *chan, char *line) {
+	char *prefix = NULL;
+	if (line[0] == ':') {
+		prefix = strsep(&line, " ") + 1;
+		if (!line) errx(EX_PROTOCOL, "unexpected eol");
+	}
+
+	char *command = strsep(&line, " ");
+	if (!strcmp(command, "001") || !strcmp(command, "INVITE")) {
+		clientFormat(client, "JOIN :%s\r\n", chan);
+	} else if (!strcmp(command, "PING")) {
+		clientFormat(client, "PONG %s\r\n", line);
+	}
+	if (strcmp(command, "PRIVMSG") && strcmp(command, "NOTICE")) return;
+
+	if (!prefix) errx(EX_PROTOCOL, "message without prefix");
+	char *nick = strsep(&prefix, "!");
+
+	if (!line) errx(EX_PROTOCOL, "message without destination");
+	char *dest = strsep(&line, " ");
+	if (strcmp(dest, chan)) return;
+
+	if (!line || line[0] != ':') errx(EX_PROTOCOL, "message without message");
+	line = &line[1];
+
+	if (!strncmp(line, "\1ACTION ", 8)) {
+		line = &line[8];
+		size_t len = strcspn(line, "\1");
+		printf("* %c\u200B%s %.*s\n", nick[0], &nick[1], (int)len, line);
+	} else if (command[0] == 'N') {
+		printf("-%c\u200B%s- %s\n", nick[0], &nick[1], line);
+	} else {
+		printf("<%c\u200B%s> %s\n", nick[0], &nick[1], line);
+	}
+}
+
+int main(int argc, char *argv[]) {
+	int error;
+
+	if (argc < 5) return EX_USAGE;
+	const char *host = argv[1];
+	const char *port = argv[2];
+	const char *nick = argv[3];
+	const char *chan = argv[4];
+
+	setlinebuf(stdout);
+
+	struct tls_config *config = tls_config_new();
+	if (!config) errx(EX_SOFTWARE, "tls_config_new");
+
+	error = tls_config_set_ciphers(config, "compat");
+	if (error) {
+		errx(EX_SOFTWARE, "tls_config_set_ciphers: %s", tls_config_error(config));
+	}
+
+	struct tls *client = tls_client();
+	if (!client) errx(EX_SOFTWARE, "tls_client");
+
+	error = tls_configure(client, config);
+	if (error) errx(EX_SOFTWARE, "tls_configure: %s", tls_error(client));
+	tls_config_free(config);
+
+	struct addrinfo *head;
+	struct addrinfo hints = {
+		.ai_family = AF_UNSPEC,
+		.ai_socktype = SOCK_STREAM,
+		.ai_protocol = IPPROTO_TCP,
+	};
+	error = getaddrinfo(host, port, &hints, &head);
+	if (error) errx(EX_NOHOST, "getaddrinfo: %s", gai_strerror(error));
+
+	int sock = -1;
+	for (struct addrinfo *ai = head; ai; ai = ai->ai_next) {
+		sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
+		if (sock < 0) err(EX_OSERR, "socket");
+
+		error = connect(sock, ai->ai_addr, ai->ai_addrlen);
+		if (!error) break;
+
+		close(sock);
+		sock = -1;
+	}
+	if (sock < 0) err(EX_UNAVAILABLE, "connect");
+	freeaddrinfo(head);
+
+	error = tls_connect_socket(client, sock, host);
+	if (error) errx(EX_PROTOCOL, "tls_connect: %s", tls_error(client));
+
+	clientFormat(client, "NICK :%s\r\nUSER %s 0 * :%s\r\n", nick, nick, nick);
+
+	char *input = NULL;
+	size_t cap = 0;
+
+	char buf[4096];
+	size_t len = 0;
+
+	struct pollfd fds[2] = {
+		{ .events = POLLIN, .fd = STDIN_FILENO },
+		{ .events = POLLIN, .fd = sock },
+	};
+	while (0 < poll(fds, 2, -1)) {
+		if (fds[0].revents) {
+			ssize_t len = getline(&input, &cap, stdin);
+			if (len < 0) err(EX_IOERR, "getline");
+			input[len - 1] = '\0';
+			clientFormat(client, "NOTICE %s :%s\r\n", chan, input);
+		}
+		if (!fds[1].revents) continue;
+
+		ssize_t read = tls_read(client, &buf[len], sizeof(buf) - len);
+		if (read == TLS_WANT_POLLIN || read == TLS_WANT_POLLOUT) continue;
+		if (read < 0) errx(EX_IOERR, "tls_read: %s", tls_error(client));
+		if (!read) return EX_UNAVAILABLE;
+		len += read;
+
+		char *crlf;
+		char *line = buf;
+		for (;;) {
+			crlf = memmem(line, &buf[len] - line, "\r\n", 2);
+			if (!crlf) break;
+			crlf[0] = '\0';
+			clientHandle(client, chan, line);
+			line = &crlf[2];
+		}
+		len -= line - buf;
+		memmove(buf, line, len);
+	}
+	err(EX_IOERR, "poll");
+}