diff options
Diffstat (limited to 'src/sabridge')
| -rw-r--r-- | src/sabridge/Makefile | 28 | ||||
| -rw-r--r-- | src/sabridge/sabridge.c | 575 |
2 files changed, 603 insertions, 0 deletions
diff --git a/src/sabridge/Makefile b/src/sabridge/Makefile new file mode 100644 index 0000000000..9d07505194 --- /dev/null +++ b/src/sabridge/Makefile @@ -0,0 +1,28 @@ +# This file is part of systemd. +# +# Copyright 2010 Lennart Poettering +# +# systemd is free software; you can redistribute it and/or modify it +# under the terms of the GNU Lesser General Public License as published by +# the Free Software Foundation; either version 2.1 of the License, or +# (at your option) any later version. +# +# systemd 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 +# Lesser General Public License for more details. +# +# You should have received a copy of the GNU Lesser General Public License +# along with systemd; If not, see <http://www.gnu.org/licenses/>. + +# This file is a dirty trick to simplify compilation from within +# emacs. This file is not intended to be distributed. So, don't touch +# it, even better ignore it! + +all: + $(MAKE) -C .. + +clean: + $(MAKE) -C .. clean + +.PHONY: all clean diff --git a/src/sabridge/sabridge.c b/src/sabridge/sabridge.c new file mode 100644 index 0000000000..0589871870 --- /dev/null +++ b/src/sabridge/sabridge.c @@ -0,0 +1,575 @@ +/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ + +/*** + This file is part of systemd. + + Copyright 2013 David Strauss + + systemd is free software; you can redistribute it and/or modify it + under the terms of the GNU Lesser General Public License as published by + the Free Software Foundation; either version 2.1 of the License, or + (at your option) any later version. + + systemd 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 + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public License + along with systemd; If not, see <http://www.gnu.org/licenses/>. + ***/ + +#include <arpa/inet.h> +#include <errno.h> +#include <getopt.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <netdb.h> +#include <sys/fcntl.h> +#include <sys/socket.h> +#include <sys/un.h> +#include <unistd.h> + +#include "log.h" +#include "sd-daemon.h" +#include "sd-event.h" +#include "socket-util.h" +#include "util.h" + +#define BUFFER_SIZE 4096 +#define _cleanup_freeaddrinfo_ _cleanup_(freeaddrinfop) + +unsigned int total_clients = 0; + +DEFINE_TRIVIAL_CLEANUP_FUNC(struct addrinfo *, freeaddrinfo); + +struct proxy { + int listen_fd; + bool ignore_env; + bool remote_is_inet; + const char *remote_host; + const char *remote_service; +}; + +struct connection { + int fd; + sd_event_source *w_recv; + sd_event_source *w_send; + struct connection *c_destination; + size_t buffer_filled_len; + size_t buffer_sent_len; + char buffer[BUFFER_SIZE]; +}; + +static void free_connection(struct connection *c) { + log_debug("Freeing fd=%d (conn %p).", c->fd, c); + sd_event_source_unref(c->w_recv); + sd_event_source_unref(c->w_send); + close(c->fd); + free(c); +} + +static int send_buffer(struct connection *sender) { + struct connection *receiver = sender->c_destination; + ssize_t len; + int r = 0; + + /* We cannot assume that even a partial send() indicates that + * the next send() will block. Loop until it does. */ + while (sender->buffer_filled_len > sender->buffer_sent_len) { + len = send(receiver->fd, sender->buffer + sender->buffer_sent_len, sender->buffer_filled_len - sender->buffer_sent_len, 0); + log_debug("send(%d, ...)=%ld", receiver->fd, len); + if (len < 0) { + if (errno != EWOULDBLOCK && errno != EAGAIN) { + log_error("Error %d in send to fd=%d: %m", errno, receiver->fd); + return -errno; + } + else { + /* send() is in a blocking state. */ + break; + } + } + + /* len < 0 can't occur here. len == 0 is possible but + * undefined behavior for nonblocking send(). */ + assert(len > 0); + sender->buffer_sent_len += len; + } + + log_debug("send(%d, ...) completed with %lu bytes still buffered.", receiver->fd, sender->buffer_filled_len - sender->buffer_sent_len); + + /* Detect a would-block state or partial send. */ + if (sender->buffer_filled_len > sender->buffer_sent_len) { + + /* If the buffer is full, disable events coming for recv. */ + if (sender->buffer_filled_len == BUFFER_SIZE) { + r = sd_event_source_set_enabled(sender->w_recv, SD_EVENT_OFF); + if (r < 0) { + log_error("Error %d disabling recv for fd=%d: %s", r, sender->fd, strerror(-r)); + return r; + } + } + + /* Watch for when the recipient can be sent data again. */ + r = sd_event_source_set_enabled(receiver->w_send, SD_EVENT_ON); + if (r < 0) { + log_error("Error %d enabling send for fd=%d: %s", r, receiver->fd, strerror(-r)); + return r; + } + log_debug("Done with recv for fd=%d. Waiting on send for fd=%d.", sender->fd, receiver->fd); + return r; + } + + /* If we sent everything without blocking, the buffer is now empty. */ + sender->buffer_filled_len = 0; + sender->buffer_sent_len = 0; + + /* Unmute the sender, in case the buffer was full. */ + r = sd_event_source_set_enabled(sender->w_recv, SD_EVENT_ON); + if (r < 0) { + log_error("Error %d enabling recv for fd=%d: %s", r, sender->fd, strerror(-r)); + return r; + } + + /* Mute the recipient, as we have no data to send now. */ + r = sd_event_source_set_enabled(receiver->w_send, SD_EVENT_OFF); + if (r < 0) { + log_error("Error %d disabling send for fd=%d: %s", r, receiver->fd, strerror(-r)); + return r; + } + + return 0; +} + +static int transfer_data_cb(sd_event_source *s, int fd, uint32_t revents, void *userdata) { + struct connection *c = (struct connection *) userdata; + int r = 0; + ssize_t len; + + assert(revents & (EPOLLIN | EPOLLOUT)); + assert(fd == c->fd); + + log_debug("Got event revents=%d from fd=%d (conn %p).", revents, fd, c); + + if (revents & EPOLLIN) { + log_debug("About to recv up to %lu bytes from fd=%d (%lu/BUFFER_SIZE).", BUFFER_SIZE - c->buffer_filled_len, fd, c->buffer_filled_len); + + assert(s == c->w_recv); + + /* Receive until the buffer's full, there's no more data, + * or the client/server disconnects. */ + while (c->buffer_filled_len < BUFFER_SIZE) { + len = recv(fd, c->buffer + c->buffer_filled_len, BUFFER_SIZE - c->buffer_filled_len, 0); + log_debug("recv(%d, ...)=%ld", fd, len); + if (len < 0) { + if (errno != EWOULDBLOCK && errno != EAGAIN) { + log_error("Error %d in recv from fd=%d: %m", errno, fd); + return -errno; + } + else { + /* recv() is in a blocking state. */ + break; + } + } + else if (len == 0) { + log_debug("Clean disconnection from fd=%d", fd); + total_clients--; + free_connection(c->c_destination); + free_connection(c); + return 0; + } + + assert(len > 0); + log_debug("Recording that the buffer got %ld more bytes full.", len); + c->buffer_filled_len += len; + log_debug("Buffer now has %ld bytes full.", c->buffer_filled_len); + } + + /* Try sending the data immediately. */ + return send_buffer(c); + } + else { + assert(s == c->w_send); + return send_buffer(c->c_destination); + } + + return r; +} + +/* Once sending to the server is unblocked, set up the real watchers. */ +static int connected_to_server_cb(sd_event_source *s, int fd, uint32_t revents, void *userdata) { + struct sd_event *e = NULL; + struct connection *c_server_to_client = (struct connection *) userdata; + struct connection *c_client_to_server = c_server_to_client->c_destination; + int r; + + assert(revents & EPOLLOUT); + + e = sd_event_get(s); + + /* Cancel the initial write watcher for the server. */ + sd_event_source_unref(s); + + log_debug("Connected to server. Initializing watchers for receiving data."); + + /* A disabled send watcher for the server. */ + r = sd_event_add_io(e, c_server_to_client->fd, EPOLLOUT, transfer_data_cb, c_server_to_client, &c_server_to_client->w_send); + if (r < 0) { + log_error("Error %d creating send watcher for fd=%d: %s", r, c_server_to_client->fd, strerror(-r)); + goto fail; + } + r = sd_event_source_set_enabled(c_server_to_client->w_send, SD_EVENT_OFF); + if (r < 0) { + log_error("Error %d muting send for fd=%d: %s", r, c_server_to_client->fd, strerror(-r)); + goto finish; + } + + /* A recv watcher for the server. */ + r = sd_event_add_io(e, c_server_to_client->fd, EPOLLIN, transfer_data_cb, c_server_to_client, &c_server_to_client->w_recv); + if (r < 0) { + log_error("Error %d creating recv watcher for fd=%d: %s", r, c_server_to_client->fd, strerror(-r)); + goto fail; + } + + /* A disabled send watcher for the client. */ + r = sd_event_add_io(e, c_client_to_server->fd, EPOLLOUT, transfer_data_cb, c_client_to_server, &c_client_to_server->w_send); + if (r < 0) { + log_error("Error %d creating send watcher for fd=%d: %s", r, c_client_to_server->fd, strerror(-r)); + goto fail; + } + r = sd_event_source_set_enabled(c_client_to_server->w_send, SD_EVENT_OFF); + if (r < 0) { + log_error("Error %d muting send for fd=%d: %s", r, c_client_to_server->fd, strerror(-r)); + goto finish; + } + + /* A recv watcher for the client. */ + r = sd_event_add_io(e, c_client_to_server->fd, EPOLLIN, transfer_data_cb, c_client_to_server, &c_client_to_server->w_recv); + if (r < 0) { + log_error("Error %d creating recv watcher for fd=%d: %s", r, c_client_to_server->fd, strerror(-r)); + goto fail; + } + +goto finish; + +fail: + free_connection(c_client_to_server); + free_connection(c_server_to_client); + +finish: + return r; +} + +static int get_server_connection_fd(const struct proxy *proxy) { + int server_fd; + int r = -EBADF; + int len; + + if (proxy->remote_is_inet) { + int s; + _cleanup_freeaddrinfo_ struct addrinfo *result = NULL; + struct addrinfo hints = {.ai_family = AF_UNSPEC, + .ai_socktype = SOCK_STREAM, + .ai_flags = AI_PASSIVE}; + + log_debug("Looking up address info for %s:%s", proxy->remote_host, proxy->remote_service); + s = getaddrinfo(proxy->remote_host, proxy->remote_service, &hints, &result); + if (s != 0) { + log_error("getaddrinfo error (%d): %s", s, gai_strerror(s)); + return r; + } + + if (result == NULL) { + log_error("getaddrinfo: no result"); + return r; + } + + /* @TODO: Try connecting to all results instead of just the first. */ + server_fd = socket(result->ai_family, result->ai_socktype | SOCK_NONBLOCK, result->ai_protocol); + if (server_fd < 0) { + log_error("Error %d creating socket: %m", errno); + return r; + } + + r = connect(server_fd, result->ai_addr, result->ai_addrlen); + /* Ignore EINPROGRESS errors because they're expected for a nonblocking socket. */ + if (r < 0 && errno != EINPROGRESS) { + log_error("Error %d while connecting to socket %s:%s: %m", errno, proxy->remote_host, proxy->remote_service); + return r; + } + } + else { + struct sockaddr_un remote; + + server_fd = socket(AF_UNIX, SOCK_STREAM | SOCK_NONBLOCK, 0); + if (server_fd < 0) { + log_error("Error %d creating socket: %m", errno); + return -EBADFD; + } + + remote.sun_family = AF_UNIX; + strncpy(remote.sun_path, proxy->remote_host, sizeof(remote.sun_path)); + len = strlen(remote.sun_path) + sizeof(remote.sun_family); + r = connect(server_fd, (struct sockaddr *) &remote, len); + if (r < 0 && errno != EINPROGRESS) { + log_error("Error %d while connecting to Unix domain socket %s: %m", errno, proxy->remote_host); + return -EBADFD; + } + } + + log_debug("Server connection is fd=%d", server_fd); + return server_fd; +} + +static int accept_cb(sd_event_source *s, int fd, uint32_t revents, void *userdata) { + struct proxy *proxy = (struct proxy *) userdata; + struct connection *c_server_to_client; + struct connection *c_client_to_server; + int r = 0; + union sockaddr_union sa; + socklen_t salen = sizeof(sa); + + assert(revents & EPOLLIN); + + c_server_to_client = malloc0(sizeof(struct connection)); + if (c_server_to_client == NULL) { + log_oom(); + goto fail; + } + + c_client_to_server = malloc0(sizeof(struct connection)); + if (c_client_to_server == NULL) { + log_oom(); + goto fail; + } + + c_server_to_client->fd = get_server_connection_fd(proxy); + if (c_server_to_client->fd < 0) { + log_error("Error initiating server connection."); + goto fail; + } + + c_client_to_server->fd = accept(fd, (struct sockaddr *) &sa, &salen); + if (c_client_to_server->fd < 0) { + log_error("Error accepting client connection."); + goto fail; + } + + /* Unlike on BSD, client sockets do not inherit nonblocking status + * from the listening socket. */ + r = fd_nonblock(c_client_to_server->fd, true); + if (r < 0) { + log_error("Error %d marking client connection as nonblocking: %s", r, strerror(-r)); + goto fail; + } + + if (sa.sa.sa_family == AF_INET || sa.sa.sa_family == AF_INET6) { + char sa_str[INET6_ADDRSTRLEN]; + const char *success; + + success = inet_ntop(sa.sa.sa_family, &sa.in6.sin6_addr, sa_str, INET6_ADDRSTRLEN); + if (success == NULL) + log_warning("Error %d calling inet_ntop: %m", errno); + else + log_debug("Accepted client connection from %s as fd=%d", sa_str, c_client_to_server->fd); + } + else { + log_debug("Accepted client connection (non-IP) as fd=%d", c_client_to_server->fd); + } + + total_clients++; + log_debug("Client fd=%d (conn %p) successfully connected. Total clients: %u", c_client_to_server->fd, c_client_to_server, total_clients); + log_debug("Server fd=%d (conn %p) successfully initialized.", c_server_to_client->fd, c_server_to_client); + + /* Initialize watcher for send to server; this shows connectivity. */ + r = sd_event_add_io(sd_event_get(s), c_server_to_client->fd, EPOLLOUT, connected_to_server_cb, c_server_to_client, &c_server_to_client->w_send); + if (r < 0) { + log_error("Error %d creating connectivity watcher for fd=%d: %s", r, c_server_to_client->fd, strerror(-r)); + goto fail; + } + + /* Allow lookups of the opposite connection. */ + c_server_to_client->c_destination = c_client_to_server; + c_client_to_server->c_destination = c_server_to_client; + + goto finish; + +fail: + log_warning("Accepting a client connection or connecting to the server failed."); + free_connection(c_client_to_server); + free_connection(c_server_to_client); + +finish: + /* Preserve the main loop even if a single proxy setup fails. */ + return 0; +} + +static int run_main_loop(struct proxy *proxy) { + int r = EXIT_SUCCESS; + struct sd_event *e = NULL; + sd_event_source *w_accept = NULL; + + r = sd_event_new(&e); + if (r < 0) + goto finish; + + r = fd_nonblock(proxy->listen_fd, true); + if (r < 0) + goto finish; + + log_debug("Initializing main listener fd=%d", proxy->listen_fd); + + sd_event_add_io(e, proxy->listen_fd, EPOLLIN, accept_cb, proxy, &w_accept); + + log_debug("Initialized main listener. Entering loop."); + + sd_event_loop(e); + +finish: + sd_event_source_unref(w_accept); + sd_event_unref(e); + + return r; +} + +static int help(void) { + + printf("%s hostname-or-ip port-or-service\n" + "%s unix-domain-socket-path\n\n" + "Inherit a socket. Bidirectionally proxy.\n\n" + " -h --help Show this help\n" + " --version Print version and exit\n" + " --ignore-env Ignore expected systemd environment\n", + program_invocation_short_name, + program_invocation_short_name); + + return 0; +} + +static void version(void) { + puts(PACKAGE_STRING " sabridge"); +} + +static int parse_argv(int argc, char *argv[], struct proxy *p) { + + enum { + ARG_VERSION = 0x100, + ARG_IGNORE_ENV + }; + + static const struct option options[] = { + { "help", no_argument, NULL, 'h' }, + { "version", no_argument, NULL, ARG_VERSION }, + { "ignore-env", no_argument, NULL, ARG_IGNORE_ENV}, + { NULL, 0, NULL, 0 } + }; + + int c; + + assert(argc >= 0); + assert(argv); + + while ((c = getopt_long(argc, argv, "h", options, NULL)) >= 0) { + + switch (c) { + + case 'h': + help(); + return 0; + + case '?': + return -EINVAL; + + case ARG_VERSION: + version(); + return 0; + + case ARG_IGNORE_ENV: + p->ignore_env = true; + continue; + + default: + log_error("Unknown option code %c", c); + return -EINVAL; + } + } + + if (optind + 1 != argc && optind + 2 != argc) { + log_error("Incorrect number of positional arguments."); + help(); + return -EINVAL; + } + + p->remote_host = argv[optind]; + assert(p->remote_host); + + p->remote_is_inet = p->remote_host[0] != '/'; + + if (optind == argc - 2) { + if (!p->remote_is_inet) { + log_error("A port or service is not allowed for Unix socket destinations."); + help(); + return -EINVAL; + } + p->remote_service = argv[optind + 1]; + assert(p->remote_service); + } else if (p->remote_is_inet) { + log_error("A port or service is required for IP destinations."); + help(); + return -EINVAL; + } + + return 1; +} + +int main(int argc, char *argv[]) { + struct proxy p = {}; + int r; + + log_parse_environment(); + log_open(); + + r = parse_argv(argc, argv, &p); + if (r <= 0) + goto finish; + + p.listen_fd = SD_LISTEN_FDS_START; + + if (!p.ignore_env) { + int n; + n = sd_listen_fds(1); + if (n == 0) { + log_error("Found zero inheritable sockets. Are you sure this is running as a socket-activated service?"); + r = EXIT_FAILURE; + goto finish; + } else if (n < 0) { + log_error("Error %d while finding inheritable sockets: %s", n, strerror(-n)); + r = EXIT_FAILURE; + goto finish; + } else if (n > 1) { + log_error("Can't listen on more than one socket."); + r = EXIT_FAILURE; + goto finish; + } + } + + /* @TODO: Check if this proxy can work with datagram sockets. */ + r = sd_is_socket(p.listen_fd, 0, SOCK_STREAM, 1); + if (r < 0) { + log_error("Error %d while checking inherited socket: %s", r, strerror(-r)); + goto finish; + } + + log_info("Starting the socket activation bridge with listener fd=%d.", p.listen_fd); + + r = run_main_loop(&p); + if (r < 0) { + log_error("Error %d from main loop.", r); + goto finish; + } + +finish: + log_close(); + return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS; +} |