Add argument parsing and dumb TLS server

I can connect to this from Textual using a localhost certificate I
manually made on macOS, at least.

3 files changed, 169 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..1532716
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,5 @@
+*.o
+*.pem
+config.mk
+linger
+tags
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..9ae0ed7
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,10 @@
+LIBRESSL_PREFIX = /usr/local
+
+CFLAGS += -std=c11 -Wall -Wextra -Wpedantic
+CFLAGS += -I${LIBRESSL_PREFIX}/include
+LDFLAGS += -L${LIBRESSL_PREFIX}/lib
+LDLIBS = -ltls
+
+-include config.mk
+
+linger:
diff --git a/linger.c b/linger.c
new file mode 100644
index 0000000..960886d
--- /dev/null
+++ b/linger.c
@@ -0,0 +1,154 @@
+/* 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 <limits.h>
+#include <netdb.h>
+#include <netinet/in.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <sysexits.h>
+#include <tls.h>
+#include <unistd.h>
+
+#ifndef DEFAULT_CERT_PATH
+#define DEFAULT_CERT_PATH "/usr/local/etc/letsencrypt/live/%s/fullchain.pem"
+#endif
+
+#ifndef DEFAULT_PRIV_PATH
+#define DEFAULT_PRIV_PATH "/usr/local/etc/letsencrypt/live/%s/privkey.pem"
+#endif
+
+static char *censor(char *arg) {
+	char *dup = strdup(arg);
+	if (!dup) err(EX_OSERR, "strdup");
+	memset(arg, '*', strlen(dup));
+	return dup;
+}
+
+int main(int argc, char *argv[]) {
+	const char *localHost = "localhost";
+	const char *localPort = "6697";
+	const char *localPass = NULL;
+	char certPath[PATH_MAX] = "";
+	char privPath[PATH_MAX] = "";
+
+	const char *host = NULL;
+	const char *port = "6697";
+	const char *pass = NULL;
+	const char *auth = NULL;
+	const char *nick = NULL;
+	const char *user = NULL;
+	const char *real = NULL;
+	const char *join = NULL;
+
+	int opt;
+	while (0 < (opt = getopt(argc, argv, "C:H:K:P:W:a:h:j:n:p:r:u:w:"))) {
+		switch (opt) {
+			break; case 'C': strlcpy(certPath, optarg, sizeof(certPath));
+			break; case 'H': localHost = optarg;
+			break; case 'K': strlcpy(privPath, optarg, sizeof(privPath));
+			break; case 'P': localPort = optarg;
+			break; case 'W': localPass = censor(optarg);
+			break; case 'a': auth = censor(optarg);
+			break; case 'h': host = optarg;
+			break; case 'j': join = optarg;
+			break; case 'n': nick = optarg;
+			break; case 'p': port = optarg;
+			break; case 'r': real = optarg;
+			break; case 'u': user = optarg;
+			break; case 'w': pass = censor(optarg);
+			break; default:  return EX_USAGE;
+		}
+	}
+
+	if (!certPath[0]) {
+		snprintf(certPath, sizeof(certPath), DEFAULT_CERT_PATH, localHost);
+	}
+	if (!privPath[0]) {
+		snprintf(privPath, sizeof(privPath), DEFAULT_PRIV_PATH, localHost);
+	}
+
+	if (!host) errx(EX_USAGE, "no host");
+	if (!nick) {
+		nick = getenv("USER");
+		if (!nick) errx(EX_CONFIG, "USER unset");
+	}
+	if (!user) user = nick;
+	if (!real) real = nick;
+
+	int error;
+
+	struct tls_config *config = tls_config_new();
+	if (!config) errx(EX_SOFTWARE, "tls_config_new");
+
+	error = tls_config_set_keypair_file(config, certPath, privPath);
+	if (error) {
+		errx(
+			EX_CONFIG, "tls_config_set_keypair_file: %s",
+			tls_config_error(config)
+		);
+	}
+
+	struct tls *server = tls_server();
+	if (!server) errx(EX_SOFTWARE, "tls_server");
+
+	error = tls_configure(server, config);
+	if (error) errx(EX_SOFTWARE, "tls_configure: %s", tls_error(server));
+	tls_config_free(config);
+
+	struct addrinfo *head;
+	struct addrinfo hints = {
+		.ai_family = AF_UNSPEC,
+		.ai_socktype = SOCK_STREAM,
+		.ai_protocol = IPPROTO_TCP,
+	};
+	error = getaddrinfo(localHost, localPort, &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 = bind(sock, ai->ai_addr, ai->ai_addrlen);
+		if (!error) break;
+
+		close(sock);
+		sock = -1;
+	}
+	if (sock < 0) err(EX_UNAVAILABLE, "bind");
+	freeaddrinfo(head);
+
+	error = listen(sock, 1);
+	if (error) err(EX_IOERR, "listen");
+
+	int client = accept(sock, NULL, NULL);
+	if (client < 0) err(EX_IOERR, "accept");
+
+	struct tls *tls;
+	error = tls_accept_socket(server, &tls, client);
+	if (error) errx(EX_SOFTWARE, "tls_accept_socket: %s", tls_error(server));
+
+	char buf[4096];
+	ssize_t len = tls_read(tls, buf, sizeof(buf));
+	if (len < 0) errx(EX_IOERR, "tls_read: %s", tls_error(tls));
+
+	buf[len] = '\0';
+	printf("%s", buf);
+}