178 lines
6.0 KiB
C
178 lines
6.0 KiB
C
/*
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* mDNS registration handler. This file is part of Shairport.
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* Copyright (c) Paul Lietar 2013
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* Amendments and updates copyright (c) Mike Brady 2014 -- 2019
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* All rights reserved.
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*
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* Permission is hereby granted, free of charge, to any person
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* obtaining a copy of this software and associated documentation
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* files (the "Software"), to deal in the Software without
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* restriction, including without limitation the rights to use,
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* copy, modify, merge, publish, distribute, sublicense, and/or
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* sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
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* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
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* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
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* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
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* OTHER DEALINGS IN THE SOFTWARE.
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*/
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#include "common.h"
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#include "mdns.h"
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#include <errno.h>
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#include <fcntl.h>
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#include <stdio.h>
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#include <string.h>
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#include <unistd.h>
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int mdns_pid = 0;
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/*
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* Do a fork followed by a execvp, handling execvp errors correctly.
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* Return the pid of the new process upon success, or -1 if something failed.
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* Check errno for error details.
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*/
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static int fork_execvp(const char *file, char *const argv[]) {
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int execpipe[2];
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int response = -1;
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if (pipe(execpipe) >= 0) {
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if (fcntl(execpipe[1], F_SETFD, fcntl(execpipe[1], F_GETFD) | FD_CLOEXEC) < 0) {
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close(execpipe[0]);
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close(execpipe[1]);
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} else {
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int pid = fork();
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if (pid < 0) {
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close(execpipe[0]);
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close(execpipe[1]);
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} else if (pid == 0) { // Child
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close(execpipe[0]); // Close the read end
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execvp(file, argv);
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// If we reach this point then execve has failed.
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// Write erno's value into the pipe and exit.
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if (write(execpipe[1], &errno, sizeof(errno)) != sizeof(errno))
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debug(1,
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"Execve has failed and there was a further error writing an error message, duh.");
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die("mdns_external: execve has failed.");
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} else { // Parent
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close(execpipe[1]); // Close the write end
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int childErrno;
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// Block until child closes the pipe or sends errno.
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if (read(execpipe[0], &childErrno, sizeof(childErrno)) ==
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sizeof(childErrno)) { // We received errno
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errno = childErrno;
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} else {
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response = pid;
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}
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}
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}
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}
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return response;
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}
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static int mdns_external_avahi_register(char *ap1name, __attribute__((unused)) char *ap2name,
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__attribute__((unused)) int port,
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__attribute__((unused)) char **txt_records,
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__attribute__((unused)) char **secondary_txt_records) {
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char mdns_port[6];
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snprintf(mdns_port, sizeof(mdns_port), "%d", config.port);
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char *argvwithoutmetadata[] = {
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NULL, ap1name, config.regtype, mdns_port, MDNS_RECORD_WITHOUT_METADATA, NULL};
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#ifdef CONFIG_METADATA
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char *argvwithmetadata[] = {NULL, ap1name, config.regtype, mdns_port, MDNS_RECORD_WITH_METADATA,
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NULL};
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#endif
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char **argv;
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#ifdef CONFIG_METADATA
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if (config.metadata_enabled)
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argv = argvwithmetadata;
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else
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#endif
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argv = argvwithoutmetadata;
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argv[0] = "avahi-publish-service";
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int pid = fork_execvp(argv[0], argv);
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if (pid >= 0) {
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mdns_pid = pid;
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return 0;
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} else
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warn("Calling %s failed !", argv[0]);
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argv[0] = "mDNSPublish";
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pid = fork_execvp(argv[0], argv);
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if (pid >= 0) {
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mdns_pid = pid;
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return 0;
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} else
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warn("Calling %s failed !", argv[0]);
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// If we reach here, both execvp calls failed.
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return -1;
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}
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static int mdns_external_dns_sd_register(char *ap1name, __attribute__((unused)) char *ap2name,
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__attribute__((unused)) int port,
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__attribute__((unused)) char **txt_records,
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__attribute__((unused)) char **secondary_txt_records) {
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char mdns_port[6];
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snprintf(mdns_port, sizeof(mdns_port), "%d", config.port);
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char *argvwithoutmetadata[] = {
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NULL, ap1name, config.regtype, mdns_port, MDNS_RECORD_WITHOUT_METADATA, NULL};
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#ifdef CONFIG_METADATA
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char *argvwithmetadata[] = {NULL, ap1name, config.regtype, mdns_port, MDNS_RECORD_WITH_METADATA,
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NULL};
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#endif
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char **argv;
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#ifdef CONFIG_METADATA
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if (config.metadata_enabled)
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argv = argvwithmetadata;
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else
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#endif
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argv = argvwithoutmetadata;
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int pid = fork_execvp(argv[0], argv);
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if (pid >= 0) {
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mdns_pid = pid;
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return 0;
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} else
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warn("Calling %s failed !", argv[0]);
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return -1;
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}
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static void kill_mdns_child(void) {
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if (mdns_pid)
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kill(mdns_pid, SIGTERM);
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mdns_pid = 0;
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}
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mdns_backend mdns_external_avahi = {.name = "external-avahi",
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.mdns_register = mdns_external_avahi_register,
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.mdns_unregister = kill_mdns_child,
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.mdns_dacp_monitor_start = NULL,
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.mdns_dacp_monitor_set_id = NULL,
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.mdns_dacp_monitor_stop = NULL};
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mdns_backend mdns_external_dns_sd = {.name = "external-dns-sd",
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.mdns_register = mdns_external_dns_sd_register,
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.mdns_unregister = kill_mdns_child,
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.mdns_dacp_monitor_start = NULL,
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.mdns_dacp_monitor_set_id = NULL,
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.mdns_dacp_monitor_stop = NULL};
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