1 /* $OpenBSD: ypldap_dns.c,v 1.16 2023/07/18 13:06:33 claudio Exp $ */ 2 3 /* 4 * Copyright (c) 2003-2008 Henning Brauer <henning@openbsd.org> 5 * 6 * Permission to use, copy, modify, and distribute this software for any 7 * purpose with or without fee is hereby granted, provided that the above 8 * copyright notice and this permission notice appear in all copies. 9 * 10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 14 * WHATSOEVER RESULTING FROM LOSS OF MIND, USE, DATA OR PROFITS, WHETHER 15 * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING 16 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 17 */ 18 19 #include <sys/types.h> 20 #include <sys/socket.h> 21 #include <sys/stat.h> 22 #include <sys/time.h> 23 #include <sys/tree.h> 24 #include <sys/queue.h> 25 26 #include <netinet/in.h> 27 28 #include <netdb.h> 29 #include <pwd.h> 30 #include <errno.h> 31 #include <event.h> 32 #include <resolv.h> 33 #include <poll.h> 34 #include <signal.h> 35 #include <stdlib.h> 36 #include <string.h> 37 #include <unistd.h> 38 #include <limits.h> 39 40 #include "ypldap.h" 41 #include "log.h" 42 43 volatile sig_atomic_t quit_dns = 0; 44 struct imsgev *iev_dns; 45 46 void dns_dispatch_imsg(int, short, void *); 47 void dns_sig_handler(int, short, void *); 48 void dns_shutdown(void); 49 int host_dns(const char *, struct ypldap_addr_list *); 50 51 void 52 dns_sig_handler(int sig, short event, void *p) 53 { 54 switch (sig) { 55 case SIGINT: 56 case SIGTERM: 57 dns_shutdown(); 58 break; 59 case SIGHUP: 60 /* ignore */ 61 break; 62 default: 63 fatalx("unexpected signal"); 64 } 65 } 66 67 void 68 dns_shutdown(void) 69 { 70 log_info("dns engine exiting"); 71 _exit(0); 72 } 73 74 pid_t 75 ypldap_dns(int pipe_ntp[2], struct passwd *pw) 76 { 77 pid_t pid; 78 struct event ev_sigint; 79 struct event ev_sigterm; 80 struct event ev_sighup; 81 struct env env; 82 83 switch (pid = fork()) { 84 case -1: 85 fatal("cannot fork"); 86 break; 87 case 0: 88 break; 89 default: 90 return (pid); 91 } 92 93 setproctitle("dns engine"); 94 close(pipe_ntp[0]); 95 96 if (setgroups(1, &pw->pw_gid) || 97 setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) || 98 setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid)) 99 fatal("can't drop privileges"); 100 endservent(); 101 102 if (pledge("stdio dns", NULL) == -1) 103 fatal("pledge"); 104 105 event_init(); 106 signal_set(&ev_sigint, SIGINT, dns_sig_handler, NULL); 107 signal_set(&ev_sigterm, SIGTERM, dns_sig_handler, NULL); 108 signal_set(&ev_sighup, SIGHUP, dns_sig_handler, NULL); 109 signal_add(&ev_sigint, NULL); 110 signal_add(&ev_sigterm, NULL); 111 signal_add(&ev_sighup, NULL); 112 113 if ((env.sc_iev = calloc(1, sizeof(*env.sc_iev))) == NULL) 114 fatal(NULL); 115 116 env.sc_iev->events = EV_READ; 117 env.sc_iev->data = &env; 118 imsg_init(&env.sc_iev->ibuf, pipe_ntp[1]); 119 env.sc_iev->handler = dns_dispatch_imsg; 120 event_set(&env.sc_iev->ev, env.sc_iev->ibuf.fd, env.sc_iev->events, 121 env.sc_iev->handler, &env); 122 event_add(&env.sc_iev->ev, NULL); 123 124 event_dispatch(); 125 dns_shutdown(); 126 127 return (0); 128 } 129 130 void 131 dns_dispatch_imsg(int fd, short events, void *p) 132 { 133 struct imsg imsg; 134 int n, cnt; 135 char *name; 136 struct ypldap_addr_list hn = TAILQ_HEAD_INITIALIZER(hn); 137 struct ypldap_addr *h; 138 struct ibuf *buf; 139 struct env *env = p; 140 struct imsgev *iev = env->sc_iev; 141 struct imsgbuf *ibuf = &iev->ibuf; 142 int shut = 0; 143 size_t len; 144 145 if ((events & (EV_READ | EV_WRITE)) == 0) 146 fatalx("unknown event"); 147 148 if (events & EV_READ) { 149 if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN) 150 fatal("imsg_read error"); 151 if (n == 0) 152 shut = 1; 153 } 154 if (events & EV_WRITE) { 155 if ((n = msgbuf_write(&ibuf->w)) == -1 && errno != EAGAIN) 156 fatal("msgbuf_write"); 157 if (n == 0) 158 shut = 1; 159 goto done; 160 } 161 162 for (;;) { 163 if ((n = imsg_get(ibuf, &imsg)) == -1) 164 fatal("client_dispatch_imsg: imsg_get error"); 165 if (n == 0) 166 break; 167 168 switch (imsg.hdr.type) { 169 case IMSG_HOST_DNS: 170 name = imsg.data; 171 if (imsg.hdr.len < 1 + IMSG_HEADER_SIZE) 172 fatalx("invalid IMSG_HOST_DNS received"); 173 len = imsg.hdr.len - 1 - IMSG_HEADER_SIZE; 174 if (name[len] != '\0' || 175 strlen(name) != len) 176 fatalx("invalid IMSG_HOST_DNS received"); 177 if ((cnt = host_dns(name, &hn)) == -1) 178 break; 179 buf = imsg_create(ibuf, IMSG_HOST_DNS, 180 imsg.hdr.peerid, 0, 181 cnt * sizeof(struct sockaddr_storage)); 182 if (buf == NULL) 183 break; 184 if (cnt > 0) { 185 while (!TAILQ_EMPTY(&hn)) { 186 h = TAILQ_FIRST(&hn); 187 TAILQ_REMOVE(&hn, h, next); 188 imsg_add(buf, &h->ss, sizeof(h->ss)); 189 free(h); 190 } 191 } 192 193 imsg_close(ibuf, buf); 194 break; 195 default: 196 break; 197 } 198 imsg_free(&imsg); 199 } 200 201 done: 202 if (!shut) 203 imsg_event_add(iev); 204 else { 205 /* this pipe is dead, so remove the event handler */ 206 event_del(&iev->ev); 207 event_loopexit(NULL); 208 } 209 } 210 211 int 212 host_dns(const char *s, struct ypldap_addr_list *hn) 213 { 214 struct addrinfo hints, *res0, *res; 215 int error, cnt = 0; 216 struct sockaddr_in *sa_in; 217 struct sockaddr_in6 *sa_in6; 218 struct ypldap_addr *h; 219 220 memset(&hints, 0, sizeof(hints)); 221 hints.ai_family = PF_UNSPEC; 222 hints.ai_socktype = SOCK_DGRAM; /* DUMMY */ 223 error = getaddrinfo(s, NULL, &hints, &res0); 224 if (error != 0) { 225 log_warnx("could not resolve \"%s\": %s", s, 226 gai_strerror(error)); 227 if (error == EAI_AGAIN || error == EAI_NODATA || 228 error == EAI_NONAME) 229 return (0); 230 return (-1); 231 } 232 233 for (res = res0; res && cnt < MAX_SERVERS_DNS; res = res->ai_next) { 234 if (res->ai_family != AF_INET && 235 res->ai_family != AF_INET6) 236 continue; 237 if ((h = calloc(1, sizeof(struct ypldap_addr))) == NULL) 238 fatal(NULL); 239 h->ss.ss_family = res->ai_family; 240 if (res->ai_family == AF_INET) { 241 sa_in = (struct sockaddr_in *)&h->ss; 242 sa_in->sin_len = sizeof(struct sockaddr_in); 243 sa_in->sin_addr.s_addr = ((struct sockaddr_in *) 244 res->ai_addr)->sin_addr.s_addr; 245 } else { 246 sa_in6 = (struct sockaddr_in6 *)&h->ss; 247 sa_in6->sin6_len = sizeof(struct sockaddr_in6); 248 memcpy(&sa_in6->sin6_addr, &((struct sockaddr_in6 *) 249 res->ai_addr)->sin6_addr, sizeof(struct in6_addr)); 250 } 251 252 TAILQ_INSERT_HEAD(hn, h, next); 253 cnt++; 254 } 255 freeaddrinfo(res0); 256 return (cnt); 257 } 258