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-rw-r--r--src/socket-proxy/socket-proxyd.c665
1 files changed, 665 insertions, 0 deletions
diff --git a/src/socket-proxy/socket-proxyd.c b/src/socket-proxy/socket-proxyd.c
new file mode 100644
index 0000000..bac5c16
--- /dev/null
+++ b/src/socket-proxy/socket-proxyd.c
@@ -0,0 +1,665 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <getopt.h>
+#include <netdb.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <unistd.h>
+
+#include "sd-daemon.h"
+#include "sd-event.h"
+#include "sd-resolve.h"
+
+#include "alloc-util.h"
+#include "fd-util.h"
+#include "log.h"
+#include "main-func.h"
+#include "parse-util.h"
+#include "path-util.h"
+#include "pretty-print.h"
+#include "resolve-private.h"
+#include "set.h"
+#include "socket-util.h"
+#include "string-util.h"
+#include "util.h"
+
+#define BUFFER_SIZE (256 * 1024)
+static unsigned arg_connections_max = 256;
+
+static const char *arg_remote_host = NULL;
+
+typedef struct Context {
+ sd_event *event;
+ sd_resolve *resolve;
+
+ Set *listen;
+ Set *connections;
+} Context;
+
+typedef struct Connection {
+ Context *context;
+
+ int server_fd, client_fd;
+ int server_to_client_buffer[2]; /* a pipe */
+ int client_to_server_buffer[2]; /* a pipe */
+
+ size_t server_to_client_buffer_full, client_to_server_buffer_full;
+ size_t server_to_client_buffer_size, client_to_server_buffer_size;
+
+ sd_event_source *server_event_source, *client_event_source;
+
+ sd_resolve_query *resolve_query;
+} Connection;
+
+static void connection_free(Connection *c) {
+ assert(c);
+
+ if (c->context)
+ set_remove(c->context->connections, c);
+
+ sd_event_source_unref(c->server_event_source);
+ sd_event_source_unref(c->client_event_source);
+
+ safe_close(c->server_fd);
+ safe_close(c->client_fd);
+
+ safe_close_pair(c->server_to_client_buffer);
+ safe_close_pair(c->client_to_server_buffer);
+
+ sd_resolve_query_unref(c->resolve_query);
+
+ free(c);
+}
+
+static void context_clear(Context *context) {
+ assert(context);
+
+ set_free_with_destructor(context->listen, sd_event_source_unref);
+ set_free_with_destructor(context->connections, connection_free);
+
+ sd_event_unref(context->event);
+ sd_resolve_unref(context->resolve);
+}
+
+static int connection_create_pipes(Connection *c, int buffer[static 2], size_t *sz) {
+ int r;
+
+ assert(c);
+ assert(buffer);
+ assert(sz);
+
+ if (buffer[0] >= 0)
+ return 0;
+
+ r = pipe2(buffer, O_CLOEXEC|O_NONBLOCK);
+ if (r < 0)
+ return log_error_errno(errno, "Failed to allocate pipe buffer: %m");
+
+ (void) fcntl(buffer[0], F_SETPIPE_SZ, BUFFER_SIZE);
+
+ r = fcntl(buffer[0], F_GETPIPE_SZ);
+ if (r < 0)
+ return log_error_errno(errno, "Failed to get pipe buffer size: %m");
+
+ assert(r > 0);
+ *sz = r;
+
+ return 0;
+}
+
+static int connection_shovel(
+ Connection *c,
+ int *from, int buffer[2], int *to,
+ size_t *full, size_t *sz,
+ sd_event_source **from_source, sd_event_source **to_source) {
+
+ bool shoveled;
+
+ assert(c);
+ assert(from);
+ assert(buffer);
+ assert(buffer[0] >= 0);
+ assert(buffer[1] >= 0);
+ assert(to);
+ assert(full);
+ assert(sz);
+ assert(from_source);
+ assert(to_source);
+
+ do {
+ ssize_t z;
+
+ shoveled = false;
+
+ if (*full < *sz && *from >= 0 && *to >= 0) {
+ z = splice(*from, NULL, buffer[1], NULL, *sz - *full, SPLICE_F_MOVE|SPLICE_F_NONBLOCK);
+ if (z > 0) {
+ *full += z;
+ shoveled = true;
+ } else if (z == 0 || IN_SET(errno, EPIPE, ECONNRESET)) {
+ *from_source = sd_event_source_unref(*from_source);
+ *from = safe_close(*from);
+ } else if (!IN_SET(errno, EAGAIN, EINTR))
+ return log_error_errno(errno, "Failed to splice: %m");
+ }
+
+ if (*full > 0 && *to >= 0) {
+ z = splice(buffer[0], NULL, *to, NULL, *full, SPLICE_F_MOVE|SPLICE_F_NONBLOCK);
+ if (z > 0) {
+ *full -= z;
+ shoveled = true;
+ } else if (z == 0 || IN_SET(errno, EPIPE, ECONNRESET)) {
+ *to_source = sd_event_source_unref(*to_source);
+ *to = safe_close(*to);
+ } else if (!IN_SET(errno, EAGAIN, EINTR))
+ return log_error_errno(errno, "Failed to splice: %m");
+ }
+ } while (shoveled);
+
+ return 0;
+}
+
+static int connection_enable_event_sources(Connection *c);
+
+static int traffic_cb(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
+ Connection *c = userdata;
+ int r;
+
+ assert(s);
+ assert(fd >= 0);
+ assert(c);
+
+ r = connection_shovel(c,
+ &c->server_fd, c->server_to_client_buffer, &c->client_fd,
+ &c->server_to_client_buffer_full, &c->server_to_client_buffer_size,
+ &c->server_event_source, &c->client_event_source);
+ if (r < 0)
+ goto quit;
+
+ r = connection_shovel(c,
+ &c->client_fd, c->client_to_server_buffer, &c->server_fd,
+ &c->client_to_server_buffer_full, &c->client_to_server_buffer_size,
+ &c->client_event_source, &c->server_event_source);
+ if (r < 0)
+ goto quit;
+
+ /* EOF on both sides? */
+ if (c->server_fd == -1 && c->client_fd == -1)
+ goto quit;
+
+ /* Server closed, and all data written to client? */
+ if (c->server_fd == -1 && c->server_to_client_buffer_full <= 0)
+ goto quit;
+
+ /* Client closed, and all data written to server? */
+ if (c->client_fd == -1 && c->client_to_server_buffer_full <= 0)
+ goto quit;
+
+ r = connection_enable_event_sources(c);
+ if (r < 0)
+ goto quit;
+
+ return 1;
+
+quit:
+ connection_free(c);
+ return 0; /* ignore errors, continue serving */
+}
+
+static int connection_enable_event_sources(Connection *c) {
+ uint32_t a = 0, b = 0;
+ int r;
+
+ assert(c);
+
+ if (c->server_to_client_buffer_full > 0)
+ b |= EPOLLOUT;
+ if (c->server_to_client_buffer_full < c->server_to_client_buffer_size)
+ a |= EPOLLIN;
+
+ if (c->client_to_server_buffer_full > 0)
+ a |= EPOLLOUT;
+ if (c->client_to_server_buffer_full < c->client_to_server_buffer_size)
+ b |= EPOLLIN;
+
+ if (c->server_event_source)
+ r = sd_event_source_set_io_events(c->server_event_source, a);
+ else if (c->server_fd >= 0)
+ r = sd_event_add_io(c->context->event, &c->server_event_source, c->server_fd, a, traffic_cb, c);
+ else
+ r = 0;
+
+ if (r < 0)
+ return log_error_errno(r, "Failed to set up server event source: %m");
+
+ if (c->client_event_source)
+ r = sd_event_source_set_io_events(c->client_event_source, b);
+ else if (c->client_fd >= 0)
+ r = sd_event_add_io(c->context->event, &c->client_event_source, c->client_fd, b, traffic_cb, c);
+ else
+ r = 0;
+
+ if (r < 0)
+ return log_error_errno(r, "Failed to set up client event source: %m");
+
+ return 0;
+}
+
+static int connection_complete(Connection *c) {
+ int r;
+
+ assert(c);
+
+ r = connection_create_pipes(c, c->server_to_client_buffer, &c->server_to_client_buffer_size);
+ if (r < 0)
+ goto fail;
+
+ r = connection_create_pipes(c, c->client_to_server_buffer, &c->client_to_server_buffer_size);
+ if (r < 0)
+ goto fail;
+
+ r = connection_enable_event_sources(c);
+ if (r < 0)
+ goto fail;
+
+ return 0;
+
+fail:
+ connection_free(c);
+ return 0; /* ignore errors, continue serving */
+}
+
+static int connect_cb(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
+ Connection *c = userdata;
+ socklen_t solen;
+ int error, r;
+
+ assert(s);
+ assert(fd >= 0);
+ assert(c);
+
+ solen = sizeof(error);
+ r = getsockopt(fd, SOL_SOCKET, SO_ERROR, &error, &solen);
+ if (r < 0) {
+ log_error_errno(errno, "Failed to issue SO_ERROR: %m");
+ goto fail;
+ }
+
+ if (error != 0) {
+ log_error_errno(error, "Failed to connect to remote host: %m");
+ goto fail;
+ }
+
+ c->client_event_source = sd_event_source_unref(c->client_event_source);
+
+ return connection_complete(c);
+
+fail:
+ connection_free(c);
+ return 0; /* ignore errors, continue serving */
+}
+
+static int connection_start(Connection *c, struct sockaddr *sa, socklen_t salen) {
+ int r;
+
+ assert(c);
+ assert(sa);
+ assert(salen);
+
+ c->client_fd = socket(sa->sa_family, SOCK_STREAM|SOCK_NONBLOCK|SOCK_CLOEXEC, 0);
+ if (c->client_fd < 0) {
+ log_error_errno(errno, "Failed to get remote socket: %m");
+ goto fail;
+ }
+
+ r = connect(c->client_fd, sa, salen);
+ if (r < 0) {
+ if (errno == EINPROGRESS) {
+ r = sd_event_add_io(c->context->event, &c->client_event_source, c->client_fd, EPOLLOUT, connect_cb, c);
+ if (r < 0) {
+ log_error_errno(r, "Failed to add connection socket: %m");
+ goto fail;
+ }
+
+ r = sd_event_source_set_enabled(c->client_event_source, SD_EVENT_ONESHOT);
+ if (r < 0) {
+ log_error_errno(r, "Failed to enable oneshot event source: %m");
+ goto fail;
+ }
+ } else {
+ log_error_errno(errno, "Failed to connect to remote host: %m");
+ goto fail;
+ }
+ } else {
+ r = connection_complete(c);
+ if (r < 0)
+ goto fail;
+ }
+
+ return 0;
+
+fail:
+ connection_free(c);
+ return 0; /* ignore errors, continue serving */
+}
+
+static int resolve_handler(sd_resolve_query *q, int ret, const struct addrinfo *ai, Connection *c) {
+ assert(q);
+ assert(c);
+
+ if (ret != 0) {
+ log_error("Failed to resolve host: %s", gai_strerror(ret));
+ goto fail;
+ }
+
+ c->resolve_query = sd_resolve_query_unref(c->resolve_query);
+
+ return connection_start(c, ai->ai_addr, ai->ai_addrlen);
+
+fail:
+ connection_free(c);
+ return 0; /* ignore errors, continue serving */
+}
+
+static int resolve_remote(Connection *c) {
+
+ static const struct addrinfo hints = {
+ .ai_family = AF_UNSPEC,
+ .ai_socktype = SOCK_STREAM,
+ .ai_flags = AI_ADDRCONFIG
+ };
+
+ union sockaddr_union sa = {};
+ const char *node, *service;
+ int r;
+
+ if (IN_SET(arg_remote_host[0], '/', '@')) {
+ int salen;
+
+ salen = sockaddr_un_set_path(&sa.un, arg_remote_host);
+ if (salen < 0) {
+ log_error_errno(salen, "Specified address doesn't fit in an AF_UNIX address, refusing: %m");
+ goto fail;
+ }
+
+ return connection_start(c, &sa.sa, salen);
+ }
+
+ service = strrchr(arg_remote_host, ':');
+ if (service) {
+ node = strndupa(arg_remote_host, service - arg_remote_host);
+ service++;
+ } else {
+ node = arg_remote_host;
+ service = "80";
+ }
+
+ log_debug("Looking up address info for %s:%s", node, service);
+ r = resolve_getaddrinfo(c->context->resolve, &c->resolve_query, node, service, &hints, resolve_handler, NULL, c);
+ if (r < 0) {
+ log_error_errno(r, "Failed to resolve remote host: %m");
+ goto fail;
+ }
+
+ return 0;
+
+fail:
+ connection_free(c);
+ return 0; /* ignore errors, continue serving */
+}
+
+static int add_connection_socket(Context *context, int fd) {
+ Connection *c;
+ int r;
+
+ assert(context);
+ assert(fd >= 0);
+
+ if (set_size(context->connections) > arg_connections_max) {
+ log_warning("Hit connection limit, refusing connection.");
+ safe_close(fd);
+ return 0;
+ }
+
+ r = set_ensure_allocated(&context->connections, NULL);
+ if (r < 0) {
+ log_oom();
+ return 0;
+ }
+
+ c = new0(Connection, 1);
+ if (!c) {
+ log_oom();
+ return 0;
+ }
+
+ c->context = context;
+ c->server_fd = fd;
+ c->client_fd = -1;
+ c->server_to_client_buffer[0] = c->server_to_client_buffer[1] = -1;
+ c->client_to_server_buffer[0] = c->client_to_server_buffer[1] = -1;
+
+ r = set_put(context->connections, c);
+ if (r < 0) {
+ free(c);
+ log_oom();
+ return 0;
+ }
+
+ return resolve_remote(c);
+}
+
+static int accept_cb(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
+ _cleanup_free_ char *peer = NULL;
+ Context *context = userdata;
+ int nfd = -1, r;
+
+ assert(s);
+ assert(fd >= 0);
+ assert(revents & EPOLLIN);
+ assert(context);
+
+ nfd = accept4(fd, NULL, NULL, SOCK_NONBLOCK|SOCK_CLOEXEC);
+ if (nfd < 0) {
+ if (errno != -EAGAIN)
+ log_warning_errno(errno, "Failed to accept() socket: %m");
+ } else {
+ getpeername_pretty(nfd, true, &peer);
+ log_debug("New connection from %s", strna(peer));
+
+ r = add_connection_socket(context, nfd);
+ if (r < 0) {
+ log_error_errno(r, "Failed to accept connection, ignoring: %m");
+ safe_close(fd);
+ }
+ }
+
+ r = sd_event_source_set_enabled(s, SD_EVENT_ONESHOT);
+ if (r < 0) {
+ log_error_errno(r, "Error while re-enabling listener with ONESHOT: %m");
+ sd_event_exit(context->event, r);
+ return r;
+ }
+
+ return 1;
+}
+
+static int add_listen_socket(Context *context, int fd) {
+ sd_event_source *source;
+ int r;
+
+ assert(context);
+ assert(fd >= 0);
+
+ r = set_ensure_allocated(&context->listen, NULL);
+ if (r < 0) {
+ log_oom();
+ return r;
+ }
+
+ r = sd_is_socket(fd, 0, SOCK_STREAM, 1);
+ if (r < 0)
+ return log_error_errno(r, "Failed to determine socket type: %m");
+ if (r == 0)
+ return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
+ "Passed in socket is not a stream socket.");
+
+ r = fd_nonblock(fd, true);
+ if (r < 0)
+ return log_error_errno(r, "Failed to mark file descriptor non-blocking: %m");
+
+ r = sd_event_add_io(context->event, &source, fd, EPOLLIN, accept_cb, context);
+ if (r < 0)
+ return log_error_errno(r, "Failed to add event source: %m");
+
+ r = set_put(context->listen, source);
+ if (r < 0) {
+ log_error_errno(r, "Failed to add source to set: %m");
+ sd_event_source_unref(source);
+ return r;
+ }
+
+ /* Set the watcher to oneshot in case other processes are also
+ * watching to accept(). */
+ r = sd_event_source_set_enabled(source, SD_EVENT_ONESHOT);
+ if (r < 0)
+ return log_error_errno(r, "Failed to enable oneshot mode: %m");
+
+ return 0;
+}
+
+static int help(void) {
+ _cleanup_free_ char *link = NULL;
+ int r;
+
+ r = terminal_urlify_man("systemd-socket-proxyd", "8", &link);
+ if (r < 0)
+ return log_oom();
+
+ printf("%1$s [HOST:PORT]\n"
+ "%1$s [SOCKET]\n\n"
+ "Bidirectionally proxy local sockets to another (possibly remote) socket.\n\n"
+ " -c --connections-max= Set the maximum number of connections to be accepted\n"
+ " -h --help Show this help\n"
+ " --version Show package version\n"
+ "\nSee the %2$s for details.\n"
+ , program_invocation_short_name
+ , link
+ );
+
+ return 0;
+}
+
+static int parse_argv(int argc, char *argv[]) {
+
+ enum {
+ ARG_VERSION = 0x100,
+ ARG_IGNORE_ENV
+ };
+
+ static const struct option options[] = {
+ { "connections-max", required_argument, NULL, 'c' },
+ { "help", no_argument, NULL, 'h' },
+ { "version", no_argument, NULL, ARG_VERSION },
+ {}
+ };
+
+ int c, r;
+
+ assert(argc >= 0);
+ assert(argv);
+
+ while ((c = getopt_long(argc, argv, "c:h", options, NULL)) >= 0)
+
+ switch (c) {
+
+ case 'h':
+ return help();
+
+ case ARG_VERSION:
+ return version();
+
+ case 'c':
+ r = safe_atou(optarg, &arg_connections_max);
+ if (r < 0) {
+ log_error("Failed to parse --connections-max= argument: %s", optarg);
+ return r;
+ }
+
+ if (arg_connections_max < 1)
+ return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
+ "Connection limit is too low.");
+
+ break;
+
+ case '?':
+ return -EINVAL;
+
+ default:
+ assert_not_reached("Unhandled option");
+ }
+
+ if (optind >= argc)
+ return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
+ "Not enough parameters.");
+
+ if (argc != optind+1)
+ return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
+ "Too many parameters.");
+
+ arg_remote_host = argv[optind];
+ return 1;
+}
+
+static int run(int argc, char *argv[]) {
+ _cleanup_(context_clear) Context context = {};
+ int r, n, fd;
+
+ log_parse_environment();
+ log_open();
+
+ r = parse_argv(argc, argv);
+ if (r <= 0)
+ return r;
+
+ r = sd_event_default(&context.event);
+ if (r < 0)
+ return log_error_errno(r, "Failed to allocate event loop: %m");
+
+ r = sd_resolve_default(&context.resolve);
+ if (r < 0)
+ return log_error_errno(r, "Failed to allocate resolver: %m");
+
+ r = sd_resolve_attach_event(context.resolve, context.event, 0);
+ if (r < 0)
+ return log_error_errno(r, "Failed to attach resolver: %m");
+
+ sd_event_set_watchdog(context.event, true);
+
+ r = sd_listen_fds(1);
+ if (r < 0)
+ return log_error_errno(r, "Failed to receive sockets from parent.");
+ if (r == 0)
+ return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Didn't get any sockets passed in.");
+
+ n = r;
+
+ for (fd = SD_LISTEN_FDS_START; fd < SD_LISTEN_FDS_START + n; fd++) {
+ r = add_listen_socket(&context, fd);
+ if (r < 0)
+ return r;
+ }
+
+ r = sd_event_loop(context.event);
+ if (r < 0)
+ return log_error_errno(r, "Failed to run event loop: %m");
+
+ return 0;
+}
+
+DEFINE_MAIN_FUNCTION(run);
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-23 02:41:10 +0000