1 /* $OpenBSD: talkd.c,v 1.26 2019/06/28 13:32:53 deraadt Exp $ */ 2 3 /* 4 * Copyright (c) 1983 Regents of the University of California. 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of the University nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 /* 33 * The top level of the daemon, the format is heavily borrowed 34 * from rwhod.c. Basically: find out who and where you are; 35 * disconnect all descriptors and ttys, and then endless 36 * loop on waiting for and processing requests 37 */ 38 #include <sys/socket.h> 39 #include <protocols/talkd.h> 40 41 #include <errno.h> 42 #include <limits.h> 43 #include <paths.h> 44 #include <signal.h> 45 #include <stdio.h> 46 #include <stdlib.h> 47 #include <string.h> 48 #include <syslog.h> 49 #include <unistd.h> 50 51 #include "talkd.h" 52 53 int debug = 0; 54 void timeout(int); 55 long lastmsgtime; 56 57 char hostname[HOST_NAME_MAX+1]; 58 59 #define TIMEOUT 30 60 #define MAXIDLE 120 61 62 int 63 main(int argc, char *argv[]) 64 { 65 if (getuid() != 0) { 66 fprintf(stderr, "%s: getuid: not super-user\n", argv[0]); 67 exit(1); 68 } 69 openlog("talkd", LOG_PID, LOG_DAEMON); 70 if (gethostname(hostname, sizeof(hostname)) == -1) { 71 syslog(LOG_ERR, "gethostname: %m"); 72 _exit(1); 73 } 74 if (chdir(_PATH_DEV) == -1) { 75 syslog(LOG_ERR, "chdir: %s: %m", _PATH_DEV); 76 _exit(1); 77 } 78 if (argc > 1 && strcmp(argv[1], "-d") == 0) 79 debug = 1; 80 init_table(); 81 signal(SIGALRM, timeout); 82 alarm(TIMEOUT); 83 84 if (pledge("stdio rpath wpath cpath inet dns", NULL) == -1) { 85 syslog(LOG_ERR, "pledge: %m"); 86 _exit(1); 87 } 88 89 for (;;) { 90 CTL_RESPONSE response; 91 socklen_t len = sizeof(response.addr); 92 CTL_MSG request; 93 int cc; 94 struct sockaddr ctl_addr; 95 96 memset(&response, 0, sizeof(response)); 97 cc = recvfrom(STDIN_FILENO, (char *)&request, 98 sizeof(request), 0, (struct sockaddr *)&response.addr, 99 &len); 100 if (cc != sizeof(request)) { 101 if (cc == -1 && errno != EINTR) 102 syslog(LOG_WARNING, "recvfrom: %m"); 103 continue; 104 } 105 106 /* Force NUL termination */ 107 request.l_name[sizeof(request.l_name) - 1] = '\0'; 108 request.r_name[sizeof(request.r_name) - 1] = '\0'; 109 request.r_tty[sizeof(request.r_tty) - 1] = '\0'; 110 111 memcpy(&ctl_addr, &request.ctl_addr, sizeof(ctl_addr)); 112 ctl_addr.sa_family = ntohs(request.ctl_addr.sa_family); 113 ctl_addr.sa_len = sizeof(ctl_addr); 114 if (ctl_addr.sa_family != AF_INET) 115 continue; 116 117 lastmsgtime = time(0); 118 process_request(&request, &response); 119 /* can block here, is this what I want? */ 120 cc = sendto(STDOUT_FILENO, (char *)&response, 121 sizeof(response), 0, &ctl_addr, sizeof(ctl_addr)); 122 if (cc != sizeof(response)) 123 syslog(LOG_WARNING, "sendto: %m"); 124 } 125 } 126 127 void 128 timeout(int signo) 129 { 130 int save_errno = errno; 131 132 if (time(0) - lastmsgtime >= MAXIDLE) 133 _exit(0); 134 alarm(TIMEOUT); 135 errno = save_errno; 136 } 137