1 files changed, 116 insertions, 0 deletions
diff --git a/tunnel.c b/tunnel.c
new file mode 100644
index 0000000..56bdcdd
--- /dev/null
+++ b/tunnel.c
@@ -0,0 +1,116 @@
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/un.h>
+
+#include <stddef.h>
+#include <unistd.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <err.h>
+
+#include "tunnel.h"
+#include "macro.h"
+
+int tunnel_socket(struct sockaddr **sa, socklen_t *salen)
+{
+	int sock = socket(AF_UNIX, SOCK_SEQPACKET, 0);
+	if (sock < 0) {
+		warn("socket");
+		return -1;
+	}
+
+	struct sockaddr_un sun = {
+		.sun_family = AF_UNIX
+	};
+
+	const char *path = TUNNEL_SOCK_PATH;
+
+	int n = snprintf(sun.sun_path, sizeof(sun.sun_path), "%s", path);
+	socklen_t len = offsetof(struct sockaddr_un, sun_path) + n + 1;
+
+	if (len > sizeof(sun)) {
+		warnx("too large unix path");
+		close(sock);
+		return -1;
+	}
+
+	*sa = _copy(&sun, len);
+	*salen = len;
+
+	return sock;
+}
+
+int tunnel_listen(int sock, struct sockaddr *sa, socklen_t salen)
+{
+	if (bind(sock, sa, salen) < 0) {
+		warn("bind");
+		return -1;
+	}
+
+	if (listen(sock, 0) < 0) {
+		warn("listen");
+		return -1;
+	}
+
+	return 0;
+}
+
+int tunnel_server(void)
+{
+	struct sockaddr *sa = NULL;
+	socklen_t salen = 0;
+
+	int sock = tunnel_socket(&sa, &salen);
+	if (sock < 0)
+		return -1;
+
+	defer {
+		close(sock);
+		free(sa);
+	}
+
+	if (tunnel_listen(sock, sa, salen) < 0)
+		return -1;
+
+	if (tunnel_daemon(sock) < 0)
+		return -1;
+
+	return 0;
+}
+
+int tunnel_connect(int sock, struct sockaddr *sa, socklen_t salen)
+{
+	if (connect(sock, sa, salen) < 0) {
+		if (errno == ENOENT) {
+			if (tunnel_server() < 0)
+				return -1;
+		}
+
+		if (errno != ENOENT || connect(sock, sa, salen) < 0) {
+			warn("connect");
+			return -1;
+		}
+	}
+
+	return 0;
+}
+
+int tunnel_client(void)
+{
+	struct sockaddr *sa = NULL;
+	socklen_t salen = 0;
+
+	int sock = tunnel_socket(&sa, &salen);
+	if (sock < 0)
+		return -1;
+
+	defer { free(sa); }
+
+	if (tunnel_connect(sock, sa, salen) < 0) {
+		close(sock);
+		return -1;
+	}
+
+	return sock;
+}