442 lines
14 KiB
C
442 lines
14 KiB
C
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
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/***
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This file is part of systemd.
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Copyright 2013 Zbigniew Jędrzejewski-Szmek
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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***/
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#include <getopt.h>
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#include <sys/epoll.h>
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#include <sys/prctl.h>
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#include <sys/socket.h>
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#include <sys/wait.h>
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#include <unistd.h>
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#include "sd-daemon.h"
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#include "alloc-util.h"
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#include "fd-util.h"
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#include "log.h"
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#include "macro.h"
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#include "signal-util.h"
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#include "socket-util.h"
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#include "string-util.h"
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#include "strv.h"
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static char** arg_listen = NULL;
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static bool arg_accept = false;
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static char** arg_args = NULL;
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static char** arg_setenv = NULL;
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static const char *arg_fdname = NULL;
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static int add_epoll(int epoll_fd, int fd) {
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struct epoll_event ev = {
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.events = EPOLLIN
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};
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int r;
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assert(epoll_fd >= 0);
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assert(fd >= 0);
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ev.data.fd = fd;
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r = epoll_ctl(epoll_fd, EPOLL_CTL_ADD, fd, &ev);
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if (r < 0)
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return log_error_errno(errno, "Failed to add event on epoll fd:%d for fd:%d: %m", epoll_fd, fd);
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return 0;
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}
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static int open_sockets(int *epoll_fd, bool accept) {
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char **address;
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int n, fd, r;
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int count = 0;
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n = sd_listen_fds(true);
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if (n < 0)
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return log_error_errno(n, "Failed to read listening file descriptors from environment: %m");
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if (n > 0) {
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log_info("Received %i descriptors via the environment.", n);
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for (fd = SD_LISTEN_FDS_START; fd < SD_LISTEN_FDS_START + n; fd++) {
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r = fd_cloexec(fd, arg_accept);
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if (r < 0)
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return r;
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count ++;
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}
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}
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/* Close logging and all other descriptors */
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if (arg_listen) {
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int except[3 + n];
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for (fd = 0; fd < SD_LISTEN_FDS_START + n; fd++)
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except[fd] = fd;
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log_close();
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close_all_fds(except, 3 + n);
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}
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/** Note: we leak some fd's on error here. I doesn't matter
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* much, since the program will exit immediately anyway, but
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* would be a pain to fix.
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*/
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STRV_FOREACH(address, arg_listen) {
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fd = make_socket_fd(LOG_DEBUG, *address, SOCK_STREAM | (arg_accept*SOCK_CLOEXEC));
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if (fd < 0) {
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log_open();
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return log_error_errno(fd, "Failed to open '%s': %m", *address);
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}
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assert(fd == SD_LISTEN_FDS_START + count);
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count ++;
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}
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if (arg_listen)
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log_open();
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*epoll_fd = epoll_create1(EPOLL_CLOEXEC);
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if (*epoll_fd < 0)
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return log_error_errno(errno, "Failed to create epoll object: %m");
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for (fd = SD_LISTEN_FDS_START; fd < SD_LISTEN_FDS_START + count; fd++) {
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_cleanup_free_ char *name = NULL;
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getsockname_pretty(fd, &name);
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log_info("Listening on %s as %i.", strna(name), fd);
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r = add_epoll(*epoll_fd, fd);
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if (r < 0)
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return r;
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}
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return count;
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}
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static int launch(char* name, char **argv, char **env, int fds) {
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static const char* tocopy[] = {"TERM=", "PATH=", "USER=", "HOME="};
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_cleanup_strv_free_ char **envp = NULL;
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_cleanup_free_ char *tmp = NULL;
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unsigned n_env = 0, length;
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char **s;
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unsigned i;
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length = strv_length(arg_setenv);
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/* PATH, TERM, HOME, USER, LISTEN_FDS, LISTEN_PID, LISTEN_FDNAMES, NULL */
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envp = new0(char *, length + 8);
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if (!envp)
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return log_oom();
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STRV_FOREACH(s, arg_setenv) {
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if (strchr(*s, '='))
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envp[n_env++] = *s;
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else {
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_cleanup_free_ char *p;
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p = strappend(*s, "=");
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if (!p)
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return log_oom();
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envp[n_env] = strv_find_prefix(env, p);
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if (envp[n_env])
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n_env ++;
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}
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}
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for (i = 0; i < ELEMENTSOF(tocopy); i++) {
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envp[n_env] = strv_find_prefix(env, tocopy[i]);
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if (envp[n_env])
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n_env ++;
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}
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if ((asprintf((char**)(envp + n_env++), "LISTEN_FDS=%d", fds) < 0) ||
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(asprintf((char**)(envp + n_env++), "LISTEN_PID=%d", getpid()) < 0))
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return log_oom();
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if (arg_fdname) {
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char *e;
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e = strappend("LISTEN_FDNAMES=", arg_fdname);
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if (!e)
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return log_oom();
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for (i = 1; i < (unsigned) fds; i++) {
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char *c;
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c = strjoin(e, ":", arg_fdname, NULL);
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if (!c) {
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free(e);
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return log_oom();
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}
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free(e);
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e = c;
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}
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envp[n_env++] = e;
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}
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tmp = strv_join(argv, " ");
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if (!tmp)
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return log_oom();
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log_info("Execing %s (%s)", name, tmp);
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execvpe(name, argv, envp);
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return log_error_errno(errno, "Failed to execp %s (%s): %m", name, tmp);
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}
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static int launch1(const char* child, char** argv, char **env, int fd) {
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_cleanup_free_ char *tmp = NULL;
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pid_t parent_pid, child_pid;
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int r;
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tmp = strv_join(argv, " ");
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if (!tmp)
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return log_oom();
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parent_pid = getpid();
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child_pid = fork();
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if (child_pid < 0)
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return log_error_errno(errno, "Failed to fork: %m");
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/* In the child */
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if (child_pid == 0) {
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(void) reset_all_signal_handlers();
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(void) reset_signal_mask();
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r = dup2(fd, STDIN_FILENO);
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if (r < 0) {
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log_error_errno(errno, "Failed to dup connection to stdin: %m");
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_exit(EXIT_FAILURE);
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}
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r = dup2(fd, STDOUT_FILENO);
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if (r < 0) {
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log_error_errno(errno, "Failed to dup connection to stdout: %m");
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_exit(EXIT_FAILURE);
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}
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r = close(fd);
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if (r < 0) {
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log_error_errno(errno, "Failed to close dupped connection: %m");
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_exit(EXIT_FAILURE);
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}
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/* Make sure the child goes away when the parent dies */
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if (prctl(PR_SET_PDEATHSIG, SIGTERM) < 0)
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_exit(EXIT_FAILURE);
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/* Check whether our parent died before we were able
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* to set the death signal */
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if (getppid() != parent_pid)
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_exit(EXIT_SUCCESS);
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execvp(child, argv);
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log_error_errno(errno, "Failed to exec child %s: %m", child);
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_exit(EXIT_FAILURE);
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}
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log_info("Spawned %s (%s) as PID %d", child, tmp, child_pid);
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return 0;
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}
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static int do_accept(const char* name, char **argv, char **envp, int fd) {
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_cleanup_free_ char *local = NULL, *peer = NULL;
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_cleanup_close_ int fd2 = -1;
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fd2 = accept(fd, NULL, NULL);
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if (fd2 < 0) {
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log_error_errno(errno, "Failed to accept connection on fd:%d: %m", fd);
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return fd2;
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}
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getsockname_pretty(fd2, &local);
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getpeername_pretty(fd2, &peer);
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log_info("Connection from %s to %s", strna(peer), strna(local));
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return launch1(name, argv, envp, fd2);
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}
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/* SIGCHLD handler. */
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static void sigchld_hdl(int sig, siginfo_t *t, void *data) {
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PROTECT_ERRNO;
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log_info("Child %d died with code %d", t->si_pid, t->si_status);
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/* Wait for a dead child. */
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waitpid(t->si_pid, NULL, 0);
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}
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static int install_chld_handler(void) {
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int r;
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struct sigaction act = {
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.sa_flags = SA_SIGINFO,
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.sa_sigaction = sigchld_hdl,
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};
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r = sigaction(SIGCHLD, &act, 0);
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if (r < 0)
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log_error_errno(errno, "Failed to install SIGCHLD handler: %m");
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return r;
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}
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static void help(void) {
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printf("%s [OPTIONS...]\n\n"
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"Listen on sockets and launch child on connection.\n\n"
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"Options:\n"
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" -l --listen=ADDR Listen for raw connections at ADDR\n"
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" -a --accept Spawn separate child for each connection\n"
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" -h --help Show this help and exit\n"
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" -E --setenv=NAME[=VALUE] Pass an environment variable to children\n"
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" --version Print version string and exit\n"
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"\n"
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"Note: file descriptors from sd_listen_fds() will be passed through.\n"
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, program_invocation_short_name);
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}
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static int parse_argv(int argc, char *argv[]) {
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enum {
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ARG_VERSION = 0x100,
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ARG_FDNAME,
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};
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static const struct option options[] = {
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{ "help", no_argument, NULL, 'h' },
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{ "version", no_argument, NULL, ARG_VERSION },
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{ "listen", required_argument, NULL, 'l' },
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{ "accept", no_argument, NULL, 'a' },
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{ "setenv", required_argument, NULL, 'E' },
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{ "environment", required_argument, NULL, 'E' }, /* legacy alias */
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{ "fdname", required_argument, NULL, ARG_FDNAME },
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{}
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};
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int c, r;
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assert(argc >= 0);
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assert(argv);
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while ((c = getopt_long(argc, argv, "+hl:aE:", options, NULL)) >= 0)
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switch(c) {
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case 'h':
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help();
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return 0;
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case ARG_VERSION:
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return version();
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case 'l':
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r = strv_extend(&arg_listen, optarg);
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if (r < 0)
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return log_oom();
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break;
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case 'a':
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arg_accept = true;
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break;
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case 'E':
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r = strv_extend(&arg_setenv, optarg);
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if (r < 0)
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return log_oom();
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break;
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case ARG_FDNAME:
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if (!fdname_is_valid(optarg)) {
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log_error("File descriptor name %s is not valid, refusing.", optarg);
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return -EINVAL;
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}
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arg_fdname = optarg;
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break;
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case '?':
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return -EINVAL;
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default:
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assert_not_reached("Unhandled option");
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}
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if (optind == argc) {
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log_error("%s: command to execute is missing.",
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program_invocation_short_name);
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return -EINVAL;
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}
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arg_args = argv + optind;
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return 1 /* work to do */;
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}
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int main(int argc, char **argv, char **envp) {
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int r, n;
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int epoll_fd = -1;
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log_parse_environment();
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log_open();
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r = parse_argv(argc, argv);
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if (r <= 0)
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return r == 0 ? EXIT_SUCCESS : EXIT_FAILURE;
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r = install_chld_handler();
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if (r < 0)
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return EXIT_FAILURE;
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n = open_sockets(&epoll_fd, arg_accept);
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if (n < 0)
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return EXIT_FAILURE;
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if (n == 0) {
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log_error("No sockets to listen on specified or passed in.");
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return EXIT_FAILURE;
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}
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for (;;) {
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struct epoll_event event;
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r = epoll_wait(epoll_fd, &event, 1, -1);
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if (r < 0) {
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if (errno == EINTR)
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continue;
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log_error_errno(errno, "epoll_wait() failed: %m");
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return EXIT_FAILURE;
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}
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log_info("Communication attempt on fd %i.", event.data.fd);
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if (arg_accept) {
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r = do_accept(argv[optind], argv + optind, envp,
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event.data.fd);
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if (r < 0)
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return EXIT_FAILURE;
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} else
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break;
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}
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launch(argv[optind], argv + optind, envp, n);
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return EXIT_SUCCESS;
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}
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