1 files changed, 353 insertions, 0 deletions
diff --git a/notify.c b/notify.c
new file mode 100644
index 0000000..935ba26
--- /dev/null
+++ b/notify.c
@@ -0,0 +1,353 @@
+/* Copyright (C) 2021  C. McEnroe <june@causal.agency>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ * Additional permission under GNU GPL version 3 section 7:
+ *
+ * If you modify this Program, or any covered work, by linking or
+ * combining it with OpenSSL (or a modified version of that library),
+ * containing parts covered by the terms of the OpenSSL License and the
+ * original SSLeay license, the licensors of this Program grant you
+ * additional permission to convey the resulting work. Corresponding
+ * Source for a non-source form of such a combination shall include the
+ * source code for the parts of OpenSSL used as well as that of the
+ * covered work.
+ */
+
+#include <assert.h>
+#include <ctype.h>
+#include <err.h>
+#include <signal.h>
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/wait.h>
+#include <sysexits.h>
+#include <time.h>
+#include <tls.h>
+#include <unistd.h>
+
+#define ARRAY_LEN(a) (sizeof(a) / sizeof((a)[0]))
+
+static bool verbose;
+static struct tls *client;
+
+static void clientWrite(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 format(const char *format, ...) {
+	char buf[1024];
+	va_list ap;
+	va_start(ap, format);
+	int len = vsnprintf(buf, sizeof(buf), format, ap);
+	va_end(ap);
+	assert((size_t)len < sizeof(buf));
+	if (verbose) fprintf(stderr, "%s", buf);
+	clientWrite(buf, len);
+}
+
+enum { ParamCap = 2 };
+struct Message {
+	char *time;
+	char *nick;
+	char *user;
+	char *host;
+	char *cmd;
+	char *params[ParamCap];
+};
+
+static struct Message parse(char *line) {
+	if (verbose) fprintf(stderr, "%s\n", line);
+	struct Message msg = {0};
+	if (line[0] == '@') {
+		char *tags = 1 + strsep(&line, " ");
+		while (tags) {
+			char *tag = strsep(&tags, ";");
+			char *key = strsep(&tag, "=");
+			if (!strcmp(key, "time")) msg.time = tag;
+		}
+	}
+	if (line[0] == ':') {
+		char *origin = 1 + strsep(&line, " ");
+		msg.nick = strsep(&origin, "!");
+		msg.user = strsep(&origin, "@");
+		msg.host = origin;
+	}
+	msg.cmd = strsep(&line, " ");
+	for (size_t i = 0; line && i < ParamCap; ++i) {
+		if (line[0] == ':') {
+			msg.params[i] = &line[1];
+			break;
+		}
+		msg.params[i] = strsep(&line, " ");
+	}
+	return msg;
+}
+
+static void require(const struct Message *msg, bool nick, size_t len) {
+	if (nick && !msg->nick) errx(EX_PROTOCOL, "%s missing origin", msg->cmd);
+	for (size_t i = 0; i < len; ++i) {
+		if (msg->params[i]) continue;
+		errx(EX_PROTOCOL, "%s missing parameter %zu", msg->cmd, 1 + i);
+	}
+}
+
+typedef void Handler(struct Message *msg);
+
+static void handlePing(struct Message *msg) {
+	require(msg, false, 1);
+	format("PONG :%s\r\n", msg->params[0]);
+}
+
+static void handleError(struct Message *msg) {
+	require(msg, false, 1);
+	errx(EX_UNAVAILABLE, "%s", msg->params[0]);
+}
+
+static char *nick;
+static bool away;
+
+static void handleReplyWelcome(struct Message *msg) {
+	require(msg, false, 1);
+	free(nick);
+	nick = strdup(msg->params[0]);
+	if (!nick) err(EX_OSERR, "strdup");
+	format("USERHOST %s\r\n", nick);
+}
+
+static void handleNick(struct Message *msg) {
+	require(msg, true, 1);
+	if (nick && !strcmp(msg->nick, nick)) {
+		free(nick);
+		nick = strdup(msg->params[0]);
+		if (!nick) err(EX_OSERR, "strdup");
+	}
+}
+
+static void handleReplyUserHost(struct Message *msg) {
+	require(msg, false, 2);
+	while (msg->params[1]) {
+		char *reply = strsep(&msg->params[1], " ");
+		char *replyNick = strsep(&reply, "*=");
+		if (strcmp(replyNick, nick)) continue;
+		if (reply && !reply[0]) strsep(&msg->params[1], "=");
+		if (!reply) errx(EX_PROTOCOL, "invalid USERHOST reply");
+		away = (reply[0] == '-');
+		break;
+	}
+}
+
+static void handleReplyNowAway(struct Message *msg) {
+	(void)msg;
+	away = true;
+}
+
+static void handleReplyUnaway(struct Message *msg) {
+	(void)msg;
+	away = false;
+}
+
+static const char *command;
+
+static void handlePrivmsg(struct Message *msg) {
+	require(msg, true, 2);
+	if (!nick || !away) return;
+
+	if (!msg->time) return;
+	struct tm tm = {0};
+	strptime(msg->time, "%FT%T", &tm);
+	time_t then = timegm(&tm);
+	if (time(NULL) - then > 60) return;
+
+	bool query = (msg->params[0][0] != '#');
+	bool mention = false;
+	size_t len = strlen(nick);
+	for (
+		char *match = msg->params[1];
+		NULL != (match = strstr(match, nick));
+		match = &match[len]
+	) {
+		char a = (match > msg->params[1] ? match[-1] : ' ');
+		char b = (match[len] ? match[len] : ' ');
+		if (b == '\1') b = ' ';
+		if ((isspace(a) || ispunct(a)) && (isspace(b) || ispunct(b))) {
+			mention = true;
+			break;
+		}
+		match = &match[len];
+	}
+	if (!query && !mention) return;
+
+	pid_t pid = fork();
+	if (pid < 0) err(EX_OSERR, "fork");
+	if (pid) return;
+
+	setenv("NOTIFY_TIME", msg->time, 1);
+	setenv("NOTIFY_NICK", msg->nick, 1);
+	if (msg->user) setenv("NOTIFY_USER", msg->user, 1);
+	if (msg->host) setenv("NOTIFY_HOST", msg->host, 1);
+	if (!query) setenv("NOTIFY_CHANNEL", msg->params[0], 1);
+	setenv("NOTIFY_MESSAGE", msg->params[1], 1);
+
+	const char *shell = getenv("SHELL");
+	if (!shell) shell = "/bin/sh";
+	execl(shell, "sh", "-c", command, NULL);
+	err(EX_OSERR, "%s", shell);
+}
+
+static const struct {
+	const char *cmd;
+	Handler *fn;
+} Handlers[] = {
+	{ "001", handleReplyWelcome },
+	{ "302", handleReplyUserHost },
+	{ "305", handleReplyUnaway },
+	{ "306", handleReplyNowAway },
+	{ "ERROR", handleError },
+	{ "NICK", handleNick },
+	{ "PING", handlePing },
+	{ "PRIVMSG", handlePrivmsg },
+};
+
+static void handle(struct Message *msg) {
+	if (!msg->cmd) return;
+	for (size_t i = 0; i < ARRAY_LEN(Handlers); ++i) {
+		if (strcmp(msg->cmd, Handlers[i].cmd)) continue;
+		Handlers[i].fn(msg);
+		break;
+	}
+}
+
+static void reap(int sig) {
+	(void)sig;
+	int status;
+	wait(&status);
+}
+
+static void quit(int sig) {
+	(void)sig;
+	format("QUIT\r\n");
+	tls_close(client);
+	_exit(EX_OK);
+}
+
+int main(int argc, char *argv[]) {
+	bool insecure = false;
+	const char *cert = NULL;
+	const char *priv = NULL;
+	const char *host = NULL;
+	const char *port = "6697";
+	const char *pass = NULL;
+	const char *trust = NULL;
+	const char *user = "pounce-notify";
+
+	for (int opt; 0 < (opt = getopt(argc, argv, "!c:k:p:t:u:vw:"));) {
+		switch (opt) {
+			break; case '!': insecure = true;
+			break; case 'c': cert = optarg;
+			break; case 'k': priv = optarg;
+			break; case 'p': port = optarg;
+			break; case 't': trust = optarg;
+			break; case 'u': user = optarg;
+			break; case 'v': verbose = true;
+			break; case 'w': pass = optarg;
+			break; default:  return EX_USAGE;
+		}
+	}
+	if (argc - optind < 1) errx(EX_USAGE, "host required");
+	if (argc - optind < 2) errx(EX_USAGE, "command required");
+	host = argv[optind++];
+	command = argv[optind];
+
+	setenv("POUNCE_HOST", host, 1);
+	setenv("POUNCE_PORT", port, 1);
+
+	client = tls_client();
+	if (!client) errx(EX_SOFTWARE, "tls_client");
+
+	struct tls_config *config = tls_config_new();
+	if (!config) errx(EX_SOFTWARE, "tls_config_new");
+
+	if (insecure) {
+		tls_config_insecure_noverifycert(config);
+		tls_config_insecure_noverifyname(config);
+	}
+
+	int error;
+	if (trust) {
+		tls_config_insecure_noverifyname(config);
+		error = tls_config_set_ca_file(config, trust);
+		if (error) errx(EX_NOINPUT, "%s: %s", trust, tls_config_error(config));
+	}
+	if (cert) {
+		error = tls_config_set_keypair_file(config, cert, (priv ? priv : cert));
+		if (error) {
+			errx(
+				EX_NOINPUT, "tls_config_set_keypair_file: %s",
+				tls_config_error(config)
+			);
+		}
+	}
+
+	error = tls_configure(client, config);
+	if (error) errx(EX_SOFTWARE, "tls_configure: %s", tls_error(client));
+	tls_config_free(config);
+
+	error = tls_connect(client, host, port);
+	if (error) errx(EX_UNAVAILABLE, "tls_connect: %s", tls_error(client));
+
+	if (pass) format("PASS :%s\r\n", pass);
+	format(
+		"CAP REQ :causal.agency/passive server-time\r\n"
+		"CAP END\r\n"
+		"NICK *\r\n"
+		"USER %s 0 * :pounce-notify\r\n",
+		user
+	);
+
+	signal(SIGINT, quit);
+	signal(SIGTERM, quit);
+	signal(SIGCHLD, reap);
+
+	size_t len = 0;
+	char buf[8191 + 512];
+	for (;;) {
+		ssize_t ret = tls_read(client, &buf[len], sizeof(buf) - len);
+		if (ret == TLS_WANT_POLLIN || ret == TLS_WANT_POLLOUT) continue;
+		if (ret < 0) errx(EX_IOERR, "tls_read: %s", tls_error(client));
+		if (!ret) errx(EX_PROTOCOL, "server closed connection");
+		len += ret;
+
+		char *line = buf;
+		for (;;) {
+			char *crlf = memmem(line, &buf[len] - line, "\r\n", 2);
+			if (!crlf) break;
+			*crlf = '\0';
+			struct Message msg = parse(line);
+			handle(&msg);
+			line = crlf + 2;
+		}
+		len -= line - buf;
+		memmove(buf, line, len);
+	}
+}