main.c

/*  Copyright (C) 2014 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>

    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/>.
 */

#include <stdlib.h>
#include <string.h>
#include <getopt.h>
#include <uv.h>
#include <assert.h>
#include <contrib/cleanup.h>
#include <contrib/ucw/mempool.h>
#include <contrib/ccan/asprintf/asprintf.h>
#include <libknot/error.h>
#ifdef HAS_SYSTEMD
#include <systemd/sd-daemon.h>
#endif

#include "lib/defines.h"
#include "lib/resolve.h"
#include "lib/dnssec.h"
#include "daemon/network.h"
#include "daemon/worker.h"
#include "daemon/engine.h"
#include "daemon/bindings.h"
#include "daemon/tls.h"

/* We can fork early on Linux 3.9+ and do SO_REUSEPORT for better performance. */
#if defined(UV_VERSION_HEX) && defined(SO_REUSEPORT) && defined(__linux__)
 #define CAN_FORK_EARLY 1
#endif

/*
 * Globals
 */
static bool g_quiet = false;
static bool g_interactive = true;

/*
 * TTY control
 */
static void tty_read(uv_stream_t *stream, ssize_t nread, const uv_buf_t *buf)
{
	/* Set output streams */
	FILE *out = stdout, *outerr = stderr;
	uv_os_fd_t stream_fd = 0;
	if (uv_fileno((uv_handle_t *)stream, &stream_fd)) {
		uv_close((uv_handle_t *)stream, (uv_close_cb) free);
		if (buf) {
			free(buf->base);
		}
		return;
	}
	if (stream_fd != STDIN_FILENO) {
		if (nread <= 0) { /* Close if disconnected */
			uv_close((uv_handle_t *)stream, (uv_close_cb) free);
			if (buf) {
				free(buf->base);
			}
			return;
		}
		uv_os_fd_t dup_fd = dup(stream_fd);
		if (dup_fd >= 0) {
			out = outerr = fdopen(dup_fd, "w");
		}
	}
	/* Execute */
	if (stream && buf && nread > 0) {
		char *cmd = buf->base;
		if (cmd[nread - 1] == '\n') {
			cmd[nread - 1] = '\0';
		}
		struct engine *engine = stream->data;
		lua_State *L = engine->L;
		int ret = engine_cmd(L, cmd, false);
		const char *message = "";
		if (lua_gettop(L) > 0) {
			message = lua_tostring(L, -1);
		}
		/* Log to remote socket if connected */
		const char *delim = g_quiet ? "" : "> ";
		if (stream_fd != STDIN_FILENO) {
			fprintf(stdout, "%s\n", cmd); /* Duplicate command to logs */
			if (message)
				fprintf(out, "%s", message); /* Duplicate output to sender */
			if (message || !g_quiet)
				fprintf(out, "\n");
			fprintf(out, "%s", delim);
		}
		/* Log to standard streams */
		FILE *fp_out = ret ? stderr : stdout;
		if (message)
			fprintf(fp_out, "%s", message);
		if (message || !g_quiet)
			fprintf(fp_out, "\n");
		fprintf(fp_out, "%s", delim);
		lua_settop(L, 0);
	}
	fflush(out);
	if (buf) {
		free(buf->base);
	}
	/* Close if redirected */
	if (stream_fd != STDIN_FILENO) {
		fclose(out); /* outerr is the same */
	}

}

static void tty_alloc(uv_handle_t *handle, size_t suggested, uv_buf_t *buf) {
	buf->len = suggested;
	buf->base = malloc(suggested);
}

static void tty_accept(uv_stream_t *master, int status)
{
	uv_tcp_t *client = malloc(sizeof(*client));
	if (client) {
		 uv_tcp_init(master->loop, client);
		 if (uv_accept(master, (uv_stream_t *)client) != 0) {
			free(client);
			return;
		 }
		 client->data = master->data;
		 uv_read_start((uv_stream_t *)client, tty_alloc, tty_read);
		 /* Write command line */
		 if (!g_quiet) {
		 	uv_buf_t buf = { "> ", 2 };
		 	uv_try_write((uv_stream_t *)client, &buf, 1);
		 }
	}
}

static void ipc_close(uv_handle_t *handle)
{
	free(handle);
}

/* @internal AF_LOCAL reads may still be interrupted, loop it. */
static bool ipc_readall(int fd, char *dst, size_t len)
{
	while (len > 0) {
		int rb = read(fd, dst, len);
		if (rb > 0) {
			dst += rb;
			len -= rb;
		} else if (errno != EAGAIN && errno != EINTR) {
			return false;
		}
	}
	return true;
}

static void ipc_activity(uv_poll_t* handle, int status, int events)
{
	struct engine *engine = handle->data;
	if (status != 0) {
		kr_log_error("[system] ipc: %s\n", uv_strerror(status));
		ipc_close((uv_handle_t *)handle);
		return;
	}
	/* Get file descriptor from handle */
	uv_os_fd_t fd = 0;
	(void) uv_fileno((uv_handle_t *)(handle), &fd);
	/* Read expression from IPC pipe */
	uint32_t len = 0;
	if (ipc_readall(fd, (char *)&len, sizeof(len))) {
		auto_free char *rbuf = NULL;
		if (len < UINT32_MAX) {
			rbuf = malloc(len + 1);
		} else {
			errno = EINVAL;
		}
		if (!rbuf) {
			kr_log_error("[system] ipc: %s\n", strerror(errno));
			engine_stop(engine); /* Panic and stop this fork. */
			return;
		}
		if (ipc_readall(fd, rbuf, len)) {
			rbuf[len] = '\0';
			/* Run expression */
			const char *message = "";
			int ret = engine_ipc(engine, rbuf);
			if (ret > 0) {
				message = lua_tostring(engine->L, -1);
			}
			/* Send response back */
			len = strlen(message);
			if (write(fd, &len, sizeof(len)) != sizeof(len) ||
				write(fd, message, len) != len) {
				kr_log_error("[system] ipc: %s\n", strerror(errno));
			}
			/* Clear the Lua stack */
			lua_settop(engine->L, 0);
		} else {
			kr_log_error("[system] ipc: %s\n", strerror(errno));
		}
	} else {
		kr_log_error("[system] ipc: %s\n", strerror(errno));
	}
}

static bool ipc_watch(uv_loop_t *loop, struct engine *engine, int fd)
{
	uv_poll_t *poller = malloc(sizeof(*poller));
	if (!poller) {
		return false;
	}
	int ret = uv_poll_init(loop, poller, fd);
	if (ret != 0) {
		free(poller);
		return false;
	}
	poller->data = engine;
	ret = uv_poll_start(poller, UV_READABLE, ipc_activity);
	if (ret != 0) {
		free(poller);
		return false;
	}
	/* libuv sets O_NONBLOCK whether we want it or not */
	(void) fcntl(fd, F_SETFD, fcntl(fd, F_GETFL) & ~O_NONBLOCK);
	return true;
}

static void signal_handler(uv_signal_t *handle, int signum)
{
	uv_stop(uv_default_loop());
	uv_signal_stop(handle);
}

static const char *set_addr(char *addr, int *port)
{
	char *p = strchr(addr, '#');
	if (p) {
		*port = atoi(p + 1);
		*p = '\0';
	}

	return addr;
}

/*
 * Server operation.
 */

static int fork_workers(fd_array_t *ipc_set, int forks)
{
	/* Fork subprocesses if requested */
	while (--forks > 0) {
		int sv[2] = {-1, -1};
		if (socketpair(AF_LOCAL, SOCK_STREAM, 0, sv) < 0) {
			perror("[system] socketpair");
			return kr_error(errno);
		}
		int pid = fork();
		if (pid < 0) {
			perror("[system] fork");
			return kr_error(errno);
		}

		/* Forked process */
		if (pid == 0) {
			array_clear(*ipc_set);
			array_push(*ipc_set, sv[0]);
			close(sv[1]);
			return forks;
		/* Parent process */
		} else {
			array_push(*ipc_set, sv[1]);
			/* Do not share parent-end with other forks. */
			(void) fcntl(sv[1], F_SETFD, FD_CLOEXEC);
			close(sv[0]);
		}
	}
	return 0;
}

static void help(int argc, char *argv[])
{
	printf("Usage: %s [parameters] [rundir]\n", argv[0]);
	printf("\nParameters:\n"
	       " -a, --addr=[addr]    Server address (default: localhost#53).\n"
	       " -t, --tls=[addr]     Server address for TLS (default: off).\n"
	       " -S, --fd=[fd]        Listen on given fd (handed out by supervisor).\n"
	       " -T, --tlsfd=[fd]     Listen using TLS on given fd (handed out by supervisor).\n"
	       " -c, --config=[path]  Config file path (relative to [rundir]) (default: config).\n"
	       " -k, --keyfile=[path] File containing trust anchors (DS or DNSKEY).\n"
	       " -f, --forks=N        Start N forks sharing the configuration.\n"
	       " -q, --quiet          Quiet output, no prompt in interactive mode.\n"
	       " -v, --verbose        Run in verbose mode."
#ifdef NOVERBOSELOG
	           " (Recompile without -DNOVERBOSELOG to activate.)"
#endif
	           "\n"
	       " -V, --version        Print version of the server.\n"
	       " -h, --help           Print help and usage.\n"
	       "Options:\n"
	       " [rundir]             Path to the working directory (default: .)\n");
}

static int run_worker(uv_loop_t *loop, struct engine *engine, fd_array_t *ipc_set, bool leader, int control_fd)
{
	/* Control sockets or TTY */
	auto_free char *sock_file = NULL;
	uv_pipe_t pipe;
	uv_pipe_init(loop, &pipe, 0);
	pipe.data = engine;
	if (g_interactive) {
		if (!g_quiet)
			printf("[system] interactive mode\n> ");
		fflush(stdout);
		uv_pipe_open(&pipe, 0);
		uv_read_start((uv_stream_t*) &pipe, tty_alloc, tty_read);
	} else {
		int pipe_ret = -1;
		if (control_fd != -1) {
			pipe_ret = uv_pipe_open(&pipe, control_fd);
		} else {
			(void) mkdir("tty", S_IRWXU|S_IRWXG);
			sock_file = afmt("tty/%ld", getpid());
			if (sock_file) {
				pipe_ret = uv_pipe_bind(&pipe, sock_file);
			}
		}
		if (!pipe_ret)
			uv_listen((uv_stream_t *) &pipe, 16, tty_accept);
	}
	/* Watch IPC pipes (or just assign them if leading the pgroup). */
	if (!leader) {
		for (size_t i = 0; i < ipc_set->len; ++i) {
			if (!ipc_watch(loop, engine, ipc_set->at[i])) {
				kr_log_error("[system] failed to create poller: %s\n", strerror(errno));
				close(ipc_set->at[i]);
			}
		}
	}
	memcpy(&engine->ipc_set, ipc_set, sizeof(*ipc_set));

	tls_setup_logging(kr_verbose_status);
	/* Notify supervisor. */
#ifdef HAS_SYSTEMD
	sd_notify(0, "READY=1");
#endif
	/* Run event loop */
	uv_run(loop, UV_RUN_DEFAULT);
	if (sock_file) {
		unlink(sock_file);
	}
	return kr_ok();
}

void free_sd_socket_names(char **socket_names, int count)
{
	for (int i = 0; i < count; i++) {
		free(socket_names[i]);
	}
	free(socket_names);
}

int main(int argc, char **argv)
{
	int forks = 1;
	array_t(char*) addr_set;
	array_t(char*) tls_set;
	array_init(addr_set);
	array_init(tls_set);
	array_t(int) fd_set;
	array_init(fd_set);
	array_t(int) tls_fd_set;
	array_init(tls_fd_set);
	char *keyfile = NULL;
	const char *config = NULL;
	char *keyfile_buf = NULL;
	int control_fd = -1;

	/* Long options. */
	int c = 0, li = 0, ret = 0;
	struct option opts[] = {
		{"addr", required_argument,   0, 'a'},
		{"tls",  required_argument,   0, 't'},
		{"fd",   required_argument,   0, 'S'},
		{"tlsfd", required_argument,  0, 'T'},
		{"config", required_argument, 0, 'c'},
		{"keyfile",required_argument, 0, 'k'},
		{"forks",required_argument,   0, 'f'},
		{"verbose",    no_argument,   0, 'v'},
		{"quiet",      no_argument,   0, 'q'},
		{"version",   no_argument,    0, 'V'},
		{"help",      no_argument,    0, 'h'},
		{0, 0, 0, 0}
	};
	while ((c = getopt_long(argc, argv, "a:t:S:T:c:f:k:vqVh", opts, &li)) != -1) {
		switch (c)
		{
		case 'a':
			array_push(addr_set, optarg);
			break;
		case 't':
			array_push(tls_set, optarg);
			break;
		case 'S':
			array_push(fd_set,  atoi(optarg));
			break;
		case 'T':
			array_push(tls_fd_set,  atoi(optarg));
			break;
		case 'c':
			config = optarg;
			break;
		case 'f':
			g_interactive = false;
			forks = atoi(optarg);
			if (forks <= 0) {
				kr_log_error("[system] error '-f' requires a positive"
						" number, not '%s'\n", optarg);
				return EXIT_FAILURE;
			}
			break;
		case 'k':
			keyfile_buf = malloc(PATH_MAX);
			if (!keyfile_buf) {
				kr_log_error("[system] not enough memory\n");
				return EXIT_FAILURE;
			}
			/* Check if the path is absolute */
			if (optarg[0] == '/') {
				keyfile = strdup(optarg);
			} else {
				/* Construct absolute path, the file may not exist */
				keyfile = realpath(".", keyfile_buf);
				if (keyfile) {
					int len = strlen(keyfile);
					int namelen = strlen(optarg);
					if (len + namelen < PATH_MAX - 1) {
						keyfile[len] = '/';
						memcpy(keyfile + len + 1, optarg, namelen + 1);
						keyfile = strdup(keyfile); /* Duplicate */
					} else {
						keyfile = NULL; /* Invalidate */
					}
				}
			}
			free(keyfile_buf);
			if (!keyfile) {
				kr_log_error("[system] keyfile '%s':"
					"failed to construct absolute path\n", optarg);
				return EXIT_FAILURE;
			}
			break;
		case 'v':
			kr_verbose_set(true);
#ifdef NOVERBOSELOG
			kr_log_info("--verbose flag has no effect due to compilation with -DNOVERBOSELOG.\n");
#endif
			break;
		case 'q':
			g_quiet = true;
			break;
		case 'V':
			kr_log_info("%s, version %s\n", "Knot DNS Resolver", PACKAGE_VERSION);
			return EXIT_SUCCESS;
		case 'h':
		case '?':
			help(argc, argv);
			return EXIT_SUCCESS;
		default:
			help(argc, argv);
			return EXIT_FAILURE;
		}
	}

#ifdef HAS_SYSTEMD
	/* Accept passed sockets from systemd supervisor. */
	char **socket_names = NULL;
	int sd_nsocks = sd_listen_fds_with_names(0, &socket_names);
	for (int i = 0; i < sd_nsocks; ++i) {
		int fd = SD_LISTEN_FDS_START + i;
		/* when run under systemd supervision, do not use interactive mode */
		g_interactive = false;
		if (forks != 1) {
			kr_log_error("[system] when run under systemd-style supervision, "
				     "use single-process only (bad: --fork=%d).\n", forks);
			free_sd_socket_names(socket_names, sd_nsocks);
			return EXIT_FAILURE;
		}
		if (!strcasecmp("control",socket_names[i])) {
			control_fd = fd;
		} else if (!strcasecmp("tls",socket_names[i])) {
			array_push(tls_fd_set, fd);
		} else {
			array_push(fd_set, fd);
		}
	}
	free_sd_socket_names(socket_names, sd_nsocks);
#endif

	/* Switch to rundir. */
	if (optind < argc) {
		const char *rundir = argv[optind];
		if (access(rundir, W_OK) != 0) {
			kr_log_error("[system] rundir '%s': %s\n", rundir, strerror(errno));
			return EXIT_FAILURE;
		}
		ret = chdir(rundir);
		if (ret != 0) {
			kr_log_error("[system] rundir '%s': %s\n", rundir, strerror(errno));
			return EXIT_FAILURE;
		}
		if(config && strcmp(config, "-") != 0 && access(config, R_OK) != 0) {
			kr_log_error("[system] rundir '%s'\n", rundir);
			kr_log_error("[system] config '%s': %s\n", config, strerror(errno));
			return EXIT_FAILURE;
		}
	}
#ifndef CAN_FORK_EARLY
	/* Forking is currently broken with libuv. We need libuv to bind to
	 * sockets etc. before forking, but at the same time can't touch it before
	 * forking otherwise it crashes, so it's a chicken and egg problem.
	 * Disabling until https://github.com/libuv/libuv/pull/846 is done. */
	 if (forks > 1 && fd_set.len == 0 && tls_fd_set.len == 0) {
	 	kr_log_error("[system] forking >1 workers supported only on Linux 3.9+ or with supervisor\n");
	 	return EXIT_FAILURE;
	 }
#endif

	/* Connect forks with local socket */
	fd_array_t ipc_set;
	array_init(ipc_set);
	/* Fork subprocesses if requested */
	int fork_id = fork_workers(&ipc_set, forks);
	if (fork_id < 0) {
		return EXIT_FAILURE;
	}

	kr_crypto_init();

	/* Create a server engine. */
	knot_mm_t pool = {
		.ctx = mp_new (4096),
		.alloc = (knot_mm_alloc_t) mp_alloc
	};
	struct engine engine;
	ret = engine_init(&engine, &pool);
	if (ret != 0) {
		kr_log_error("[system] failed to initialize engine: %s\n", kr_strerror(ret));
		return EXIT_FAILURE;
	}
	/* Create worker */
	struct worker_ctx *worker = worker_create(&engine, &pool, fork_id, forks);
	if (!worker) {
		kr_log_error("[system] not enough memory\n");
		return EXIT_FAILURE;
	}
	/* Bind to passed fds and run */
	for (size_t i = 0; i < fd_set.len; ++i) {
		ret = network_listen_fd(&engine.net, fd_set.at[i], false);
		if (ret != 0) {
			kr_log_error("[system] listen on fd=%d %s\n", fd_set.at[i], kr_strerror(ret));
			ret = EXIT_FAILURE;
			break;
		}
	}
	/* Do the same for TLS */
	for (size_t i = 0; i < tls_fd_set.len; ++i) {
		ret = network_listen_fd(&engine.net, tls_fd_set.at[i], true);
		if (ret != 0) {
			kr_log_error("[system] TLS listen on fd=%d %s\n", tls_fd_set.at[i], kr_strerror(ret));
			ret = EXIT_FAILURE;
			break;
		}
	}
	/* Bind to sockets and run */
	if (ret == 0) {
		for (size_t i = 0; i < addr_set.len; ++i) {
			int port = 53;
			const char *addr = set_addr(addr_set.at[i], &port);
			ret = network_listen(&engine.net, addr, (uint16_t)port, NET_UDP|NET_TCP);
			if (ret != 0) {
				kr_log_error("[system] bind to '%s#%d' %s\n", addr, port, kr_strerror(ret));
				ret = EXIT_FAILURE;
				break;
			}
		}
	}
	/* Bind to TLS sockets */
	if (ret == 0) {
		for (size_t i = 0; i < tls_set.len; ++i) {
			int port = KR_DNS_TLS_PORT;
			const char *addr = set_addr(tls_set.at[i], &port);
			ret = network_listen(&engine.net, addr, (uint16_t)port, NET_TCP|NET_TLS);
			if (ret != 0) {
				kr_log_error("[system] bind to '%s#%d' (TLS) %s\n", addr, port, kr_strerror(ret));
				ret = EXIT_FAILURE;
				break;
			}
		}
	}

	/* Block signals. */
	uv_loop_t *loop = uv_default_loop();
	uv_signal_t sigint, sigterm;
	uv_signal_init(loop, &sigint);
	uv_signal_init(loop, &sigterm);
	uv_signal_start(&sigint, signal_handler, SIGINT);
	uv_signal_start(&sigterm, signal_handler, SIGTERM);
	/* Start the scripting engine */
	worker->loop = loop;
	loop->data = worker;
	if (ret == 0) {
		ret = engine_start(&engine, config ? config : "config");
		if (ret == 0) {
			if (keyfile) {
				auto_free char *cmd = afmt("trust_anchors.config('%s')", keyfile);
				if (!cmd) {
					kr_log_error("[system] not enough memory\n");
					return EXIT_FAILURE;
				}
				engine_cmd(engine.L, cmd, false);
				lua_settop(engine.L, 0);
			}
			/* Run the event loop */
			ret = run_worker(loop, &engine, &ipc_set, fork_id == 0, control_fd);
		}
		if (ret != 0) {
			perror("[system] worker failed");
			ret = EXIT_FAILURE;
		}
	}
	/* Cleanup. */
	free(keyfile);
	engine_deinit(&engine);
	worker_reclaim(worker);
	mp_delete(pool.ctx);
	array_clear(addr_set);
	array_clear(tls_set);
	kr_crypto_cleanup();
	return ret;
}