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// SPDX-License-Identifier: GPL-2.0-or-later
// SPDX-FileCopyrightText: 2020-2021 Alyssa Ross <hi@alyssa.is>
#define _GNU_SOURCE
#include <errno.h>
#include <inttypes.h>
#include <poll.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdnoreturn.h>
#include <sys/wait.h>
#include <sysexits.h>
#include <unistd.h>
#include "env.h"
#include "log.h"
#include "vsock.h"
noreturn static void ex_usage(void)
{
if (verbosity)
fprintf(stderr, "Usage: %s [ -1 ] [ -q | -Q | -v ] prog...\n",
program_invocation_short_name);
exit(EX_USAGE);
}
int main(int argc, char *argv[])
{
bool notify = false;
int opt;
pid_t child;
uint32_t lcid, lport, rcid, rport;
struct pollfd poll_fd =
{ .fd = STDIN_FILENO, .events = POLLIN, .revents = 0 };
while ((opt = getopt(argc, argv, "+1qQv")) != -1) {
switch (opt) {
case '1':
notify = true;
break;
case 'q':
case 'Q':
case 'v':
set_verbosity(opt);
break;
default:
ex_usage();
}
}
// Check that there is something for us to exec into.
if (optind > argc - 1)
ex_usage();
// Find out the CID and port of the socket.
if (vsock_get_cid_and_port(STDIN_FILENO, &lcid, &lport)) {
if (errno == ENOTSOCK || errno == EPROTOTYPE)
die(EX_USAGE, "stdin is not an AF_VSOCK socket");
diee(EX_OSERR, "getsockname");
}
// Notify the user of our port and indicate readiness.
if (notify) {
printf("%" PRIu32 "\n", lport);
fclose(stdout);
}
// Set our CID and port as environment variables so `prog' can
// know them.
setenvf("VSOCKLOCALCID", 1, "%" PRIu32, lcid);
setenvf("VSOCKLOCALPORT", 1, "%" PRIu32, lport);
ilog("listening as %" PRIu32 " on port %" PRIu32, lcid, lport);
// Wait for a connection.
while (poll(&poll_fd, 1, -1) != -1) {
// On Linux, conn will be blocking. On other
// platforms, this may not be the case. If other
// platforms are to be supported, we'd probably want
// to set O_NONBLOCK here.
int conn = vsock_accept(STDIN_FILENO, &rcid, &rport);
if (conn == -1)
diee(EX_OSERR, "accept");
// Set the client's CID and port as environment
// variables so `prog' can know them.
setenvf("VSOCKREMOTECID", 1, "%" PRIu32, rcid);
setenvf("VSOCKREMOTEPORT", 1, "%" PRIu32, rport);
ilog("connection from %" PRIu32 " port %" PRIu32, rcid, rport);
switch (child = fork()) {
case -1: diee(EX_OSERR, "fork");
case 0:
// Set up the connection socket on prog's
// stdin and stdout. This has the happy side
// effect of closing the listening socket in
// the child, since it's also on stdin.
if (dup2(conn, STDIN_FILENO) == -1)
diee(EX_OSERR, "dup2");
if (dup2(conn, STDOUT_FILENO) == -1)
diee(EX_OSERR, "dup2");
if (conn != STDIN_FILENO && conn != STDOUT_FILENO)
close(conn);
// exec into `prog'.
execvp(argv[optind], &argv[optind]);
diee(EX_OSERR, "exec");
}
if (waitpid(child, NULL, 0) == -1)
diee(EX_OSERR, "waitpid");
close(conn);
}
diee(EX_OSERR, "poll");
}
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