1 /* $OpenBSD: ypldap_dns.c,v 1.13 2017/04/17 16:37:39 otto 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 #include <arpa/nameser.h> 28 29 #include <netdb.h> 30 #include <pwd.h> 31 #include <errno.h> 32 #include <event.h> 33 #include <resolv.h> 34 #include <poll.h> 35 #include <signal.h> 36 #include <stdlib.h> 37 #include <string.h> 38 #include <unistd.h> 39 #include <limits.h> 40 41 #include "ypldap.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 default: 60 fatalx("unexpected signal"); 61 } 62 } 63 64 void 65 dns_shutdown(void) 66 { 67 log_info("dns engine exiting"); 68 _exit(0); 69 } 70 71 pid_t 72 ypldap_dns(int pipe_ntp[2], struct passwd *pw) 73 { 74 pid_t pid; 75 struct event ev_sigint; 76 struct event ev_sigterm; 77 struct event ev_sighup; 78 struct env env; 79 80 switch (pid = fork()) { 81 case -1: 82 fatal("cannot fork"); 83 break; 84 case 0: 85 break; 86 default: 87 return (pid); 88 } 89 90 setproctitle("dns engine"); 91 close(pipe_ntp[0]); 92 93 if (setgroups(1, &pw->pw_gid) || 94 setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) || 95 setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid)) 96 fatal("can't drop privileges"); 97 endservent(); 98 99 if (pledge("stdio dns", NULL) == -1) 100 fatal("pledge"); 101 102 event_init(); 103 signal_set(&ev_sigint, SIGINT, dns_sig_handler, NULL); 104 signal_set(&ev_sigterm, SIGTERM, dns_sig_handler, NULL); 105 signal_set(&ev_sighup, SIGHUP, dns_sig_handler, NULL); 106 signal_add(&ev_sigint, NULL); 107 signal_add(&ev_sigterm, NULL); 108 signal_add(&ev_sighup, NULL); 109 110 if ((env.sc_iev = calloc(1, sizeof(*env.sc_iev))) == NULL) 111 fatal(NULL); 112 113 env.sc_iev->events = EV_READ; 114 env.sc_iev->data = &env; 115 imsg_init(&env.sc_iev->ibuf, pipe_ntp[1]); 116 env.sc_iev->handler = dns_dispatch_imsg; 117 event_set(&env.sc_iev->ev, env.sc_iev->ibuf.fd, env.sc_iev->events, 118 env.sc_iev->handler, &env); 119 event_add(&env.sc_iev->ev, NULL); 120 121 event_dispatch(); 122 dns_shutdown(); 123 124 return (0); 125 } 126 127 void 128 dns_dispatch_imsg(int fd, short events, void *p) 129 { 130 struct imsg imsg; 131 int n, cnt; 132 char *name; 133 struct ypldap_addr_list hn = TAILQ_HEAD_INITIALIZER(hn); 134 struct ypldap_addr *h; 135 struct ibuf *buf; 136 struct env *env = p; 137 struct imsgev *iev = env->sc_iev; 138 struct imsgbuf *ibuf = &iev->ibuf; 139 int shut = 0; 140 size_t len; 141 142 if ((events & (EV_READ | EV_WRITE)) == 0) 143 fatalx("unknown event"); 144 145 if (events & EV_READ) { 146 if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN) 147 fatal("imsg_read error"); 148 if (n == 0) 149 shut = 1; 150 } 151 if (events & EV_WRITE) { 152 if ((n = msgbuf_write(&ibuf->w)) == -1 && errno != EAGAIN) 153 fatal("msgbuf_write"); 154 if (n == 0) 155 shut = 1; 156 goto done; 157 } 158 159 for (;;) { 160 if ((n = imsg_get(ibuf, &imsg)) == -1) 161 fatal("client_dispatch_imsg: imsg_get error"); 162 if (n == 0) 163 break; 164 165 switch (imsg.hdr.type) { 166 case IMSG_HOST_DNS: 167 name = imsg.data; 168 if (imsg.hdr.len < 1 + IMSG_HEADER_SIZE) 169 fatalx("invalid IMSG_HOST_DNS received"); 170 len = imsg.hdr.len - 1 - IMSG_HEADER_SIZE; 171 if (name[len] != '\0' || 172 strlen(name) != len) 173 fatalx("invalid IMSG_HOST_DNS received"); 174 if ((cnt = host_dns(name, &hn)) == -1) 175 break; 176 buf = imsg_create(ibuf, IMSG_HOST_DNS, 177 imsg.hdr.peerid, 0, 178 cnt * sizeof(struct sockaddr_storage)); 179 if (buf == NULL) 180 break; 181 if (cnt > 0) { 182 while (!TAILQ_EMPTY(&hn)) { 183 h = TAILQ_FIRST(&hn); 184 TAILQ_REMOVE(&hn, h, next); 185 imsg_add(buf, &h->ss, sizeof(h->ss)); 186 free(h); 187 } 188 } 189 190 imsg_close(ibuf, buf); 191 break; 192 default: 193 break; 194 } 195 imsg_free(&imsg); 196 } 197 198 done: 199 if (!shut) 200 imsg_event_add(iev); 201 else { 202 /* this pipe is dead, so remove the event handler */ 203 event_del(&iev->ev); 204 event_loopexit(NULL); 205 } 206 } 207 208 int 209 host_dns(const char *s, struct ypldap_addr_list *hn) 210 { 211 struct addrinfo hints, *res0, *res; 212 int error, cnt = 0; 213 struct sockaddr_in *sa_in; 214 struct sockaddr_in6 *sa_in6; 215 struct ypldap_addr *h; 216 217 memset(&hints, 0, sizeof(hints)); 218 hints.ai_family = PF_UNSPEC; 219 hints.ai_socktype = SOCK_DGRAM; /* DUMMY */ 220 error = getaddrinfo(s, NULL, &hints, &res0); 221 if (error == EAI_AGAIN || error == EAI_NODATA || error == EAI_NONAME) 222 return (0); 223 if (error) { 224 log_warnx("could not parse \"%s\": %s", s, 225 gai_strerror(error)); 226 return (-1); 227 } 228 229 for (res = res0; res && cnt < MAX_SERVERS_DNS; res = res->ai_next) { 230 if (res->ai_family != AF_INET && 231 res->ai_family != AF_INET6) 232 continue; 233 if ((h = calloc(1, sizeof(struct ypldap_addr))) == NULL) 234 fatal(NULL); 235 h->ss.ss_family = res->ai_family; 236 if (res->ai_family == AF_INET) { 237 sa_in = (struct sockaddr_in *)&h->ss; 238 sa_in->sin_len = sizeof(struct sockaddr_in); 239 sa_in->sin_addr.s_addr = ((struct sockaddr_in *) 240 res->ai_addr)->sin_addr.s_addr; 241 } else { 242 sa_in6 = (struct sockaddr_in6 *)&h->ss; 243 sa_in6->sin6_len = sizeof(struct sockaddr_in6); 244 memcpy(&sa_in6->sin6_addr, &((struct sockaddr_in6 *) 245 res->ai_addr)->sin6_addr, sizeof(struct in6_addr)); 246 } 247 248 TAILQ_INSERT_HEAD(hn, h, next); 249 cnt++; 250 } 251 freeaddrinfo(res0); 252 return (cnt); 253 } 254