bridge.c revision 5430f7f2bc7330f3088b894166bf3524a067e3d8
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
/***
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/>.
***/
#include <sys/socket.h>
#include <sys/un.h>
#include <sys/types.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <sys/epoll.h>
#include <stddef.h>
#include "log.h"
#include "util.h"
#include "socket-util.h"
#define BUFFER_SIZE (64*1024)
#define EXTRA_SIZE 16
static bool initial_nul = false;
static bool auth_over = false;
static void format_uid(char *buf, size_t l) {
char text[20 + 1]; /* enough space for a 64bit integer plus NUL */
unsigned j;
assert(l > 0);
snprintf(text, sizeof(text)-1, "%llu", (unsigned long long) geteuid());
text[sizeof(text)-1] = 0;
memset(buf, 0, l);
for (j = 0; text[j] && j*2+2 < l; j++) {
buf[j*2] = hexchar(text[j] >> 4);
buf[j*2+1] = hexchar(text[j] & 0xF);
}
buf[j*2] = 0;
}
static size_t patch_in_line(char *line, size_t l, size_t left) {
size_t r;
if (line[0] == 0 && !initial_nul) {
initial_nul = true;
line += 1;
l -= 1;
r = 1;
} else
r = 0;
if (l == 5 && strncmp(line, "BEGIN", 5) == 0) {
r += l;
auth_over = true;
} else if (l == 17 && strncmp(line, "NEGOTIATE_UNIX_FD", 17) == 0) {
memmove(line + 13, line + 17, left);
memcpy(line, "NEGOTIATE_NOP", 13);
r += 13;
} else if (l >= 14 && strncmp(line, "AUTH EXTERNAL ", 14) == 0) {
char uid[20*2 + 1];
size_t len;
format_uid(uid, sizeof(uid));
len = strlen(uid);
assert(len <= EXTRA_SIZE);
memmove(line + 14 + len, line + l, left);
memcpy(line + 14, uid, len);
r += 14 + len;
} else
r += l;
return r;
}
static size_t patch_in_buffer(char* in_buffer, size_t *in_buffer_full) {
size_t i, good = 0;
if (*in_buffer_full <= 0)
return *in_buffer_full;
/* If authentication is done, we don't touch anything anymore */
if (auth_over)
return *in_buffer_full;
if (*in_buffer_full < 2)
return 0;
for (i = 0; i <= *in_buffer_full - 2; i ++) {
/* Fully lines can be send on */
if (in_buffer[i] == '\r' && in_buffer[i+1] == '\n') {
if (i > good) {
size_t old_length, new_length;
old_length = i - good;
new_length = patch_in_line(in_buffer+good, old_length, *in_buffer_full - i);
*in_buffer_full = *in_buffer_full + new_length - old_length;
good += new_length + 2;
} else
good = i+2;
}
if (auth_over)
break;
}
return good;
}
int main(int argc, char *argv[]) {
int r = EXIT_FAILURE, fd = -1, ep = -1;
union sockaddr_union sa;
char in_buffer[BUFFER_SIZE+EXTRA_SIZE], out_buffer[BUFFER_SIZE+EXTRA_SIZE];
size_t in_buffer_full = 0, out_buffer_full = 0;
struct epoll_event stdin_ev, stdout_ev, fd_ev;
bool stdin_readable = false, stdout_writable = false, fd_readable = false, fd_writable = false;
bool stdin_rhup = false, stdout_whup = false, fd_rhup = false, fd_whup = false;
if (argc > 1) {
log_error("This program takes no argument.");
return EXIT_FAILURE;
}
log_set_target(LOG_TARGET_JOURNAL_OR_KMSG);
log_parse_environment();
log_open();
if ((fd = socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0)) < 0) {
log_error("Failed to create socket: %s", strerror(errno));
goto finish;
}
zero(sa);
sa.un.sun_family = AF_UNIX;
strncpy(sa.un.sun_path, "/run/dbus/system_bus_socket", sizeof(sa.un.sun_path));
if (connect(fd, &sa.sa, offsetof(struct sockaddr_un, sun_path) + strlen(sa.un.sun_path)) < 0) {
log_error("Failed to connect: %m");
goto finish;
}
fd_nonblock(STDIN_FILENO, 1);
fd_nonblock(STDOUT_FILENO, 1);
if ((ep = epoll_create1(EPOLL_CLOEXEC)) < 0) {
log_error("Failed to create epoll: %m");
goto finish;
}
zero(stdin_ev);
stdin_ev.events = EPOLLIN|EPOLLET;
stdin_ev.data.fd = STDIN_FILENO;
zero(stdout_ev);
stdout_ev.events = EPOLLOUT|EPOLLET;
stdout_ev.data.fd = STDOUT_FILENO;
zero(fd_ev);
fd_ev.events = EPOLLIN|EPOLLOUT|EPOLLET;
fd_ev.data.fd = fd;
if (epoll_ctl(ep, EPOLL_CTL_ADD, STDIN_FILENO, &stdin_ev) < 0 ||
epoll_ctl(ep, EPOLL_CTL_ADD, STDOUT_FILENO, &stdout_ev) < 0 ||
epoll_ctl(ep, EPOLL_CTL_ADD, fd, &fd_ev) < 0) {
log_error("Failed to regiser fds in epoll: %m");
goto finish;
}
do {
struct epoll_event ev[16];
ssize_t k;
int i, nfds;
if ((nfds = epoll_wait(ep, ev, ELEMENTSOF(ev), -1)) < 0) {
if (errno == EINTR || errno == EAGAIN)
continue;
log_error("epoll_wait(): %m");
goto finish;
}
assert(nfds >= 1);
for (i = 0; i < nfds; i++) {
if (ev[i].data.fd == STDIN_FILENO) {
if (!stdin_rhup && (ev[i].events & (EPOLLHUP|EPOLLIN)))
stdin_readable = true;
} else if (ev[i].data.fd == STDOUT_FILENO) {
if (ev[i].events & EPOLLHUP) {
stdout_writable = false;
stdout_whup = true;
}
if (!stdout_whup && (ev[i].events & EPOLLOUT))
stdout_writable = true;
} else if (ev[i].data.fd == fd) {
if (ev[i].events & EPOLLHUP) {
fd_writable = false;
fd_whup = true;
}
if (!fd_rhup && (ev[i].events & (EPOLLHUP|EPOLLIN)))
fd_readable = true;
if (!fd_whup && (ev[i].events & EPOLLOUT))
fd_writable = true;
}
}
while ((stdin_readable && in_buffer_full <= 0) ||
(fd_writable && patch_in_buffer(in_buffer, &in_buffer_full) > 0) ||
(fd_readable && out_buffer_full <= 0) ||
(stdout_writable && out_buffer_full > 0)) {
size_t in_buffer_good = 0;
if (stdin_readable && in_buffer_full < BUFFER_SIZE) {
if ((k = read(STDIN_FILENO, in_buffer + in_buffer_full, BUFFER_SIZE - in_buffer_full)) < 0) {
if (errno == EAGAIN)
stdin_readable = false;
else if (errno == EPIPE || errno == ECONNRESET)
k = 0;
else {
log_error("read(): %m");
goto finish;
}
} else
in_buffer_full += (size_t) k;
if (k == 0) {
stdin_rhup = true;
stdin_readable = false;
shutdown(STDIN_FILENO, SHUT_RD);
close_nointr_nofail(STDIN_FILENO);
}
}
in_buffer_good = patch_in_buffer(in_buffer, &in_buffer_full);
if (fd_writable && in_buffer_good > 0) {
if ((k = write(fd, in_buffer, in_buffer_good)) < 0) {
if (errno == EAGAIN)
fd_writable = false;
else if (errno == EPIPE || errno == ECONNRESET) {
fd_whup = true;
fd_writable = false;
shutdown(fd, SHUT_WR);
} else {
log_error("write(): %m");
goto finish;
}
} else {
assert(in_buffer_full >= (size_t) k);
memmove(in_buffer, in_buffer + k, in_buffer_full - k);
in_buffer_full -= k;
}
}
if (fd_readable && out_buffer_full < BUFFER_SIZE) {
if ((k = read(fd, out_buffer + out_buffer_full, BUFFER_SIZE - out_buffer_full)) < 0) {
if (errno == EAGAIN)
fd_readable = false;
else if (errno == EPIPE || errno == ECONNRESET)
k = 0;
else {
log_error("read(): %m");
goto finish;
}
} else
out_buffer_full += (size_t) k;
if (k == 0) {
fd_rhup = true;
fd_readable = false;
shutdown(fd, SHUT_RD);
}
}
if (stdout_writable && out_buffer_full > 0) {
if ((k = write(STDOUT_FILENO, out_buffer, out_buffer_full)) < 0) {
if (errno == EAGAIN)
stdout_writable = false;
else if (errno == EPIPE || errno == ECONNRESET) {
stdout_whup = true;
stdout_writable = false;
shutdown(STDOUT_FILENO, SHUT_WR);
close_nointr(STDOUT_FILENO);
} else {
log_error("write(): %m");
goto finish;
}
} else {
assert(out_buffer_full >= (size_t) k);
memmove(out_buffer, out_buffer + k, out_buffer_full - k);
out_buffer_full -= k;
}
}
}
if (stdin_rhup && in_buffer_full <= 0 && !fd_whup) {
fd_whup = true;
fd_writable = false;
shutdown(fd, SHUT_WR);
}
if (fd_rhup && out_buffer_full <= 0 && !stdout_whup) {
stdout_whup = true;
stdout_writable = false;
shutdown(STDOUT_FILENO, SHUT_WR);
close_nointr(STDOUT_FILENO);
}
} while (!stdout_whup || !fd_whup);
r = EXIT_SUCCESS;
finish:
if (fd >= 0)
close_nointr_nofail(fd);
if (ep >= 0)
close_nointr_nofail(ep);
return r;
}