/* * Copyright (c) 2008-2014, Simon Schubert <2@0x2c.org>. * Copyright (c) 2008 The DragonFly Project. All rights reserved. * * This code is derived from software contributed to The DragonFly Project * by Simon Schubert <2@0x2c.org>. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in * the documentation and/or other materials provided with the * distribution. * 3. Neither the name of The DragonFly Project nor the names of its * contributors may be used to endorse or promote products derived * from this software without specific, prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #include #include #include #include #include #include #include #include #include #include "dma.h" static int sort_pref(const void *a, const void *b) { const struct mx_hostentry *ha = a, *hb = b; int v; /* sort increasing by preference primarily */ v = ha->pref - hb->pref; if (v != 0) return (v); /* sort PF_INET6 before PF_INET */ v = - (ha->ai.ai_family - hb->ai.ai_family); return (v); } static int add_host(int pref, const char *host, int port, struct mx_hostentry **he, size_t *ps) { struct addrinfo hints, *res, *res0 = NULL; char servname[10]; struct mx_hostentry *p; const int count_inc = 10; int err; memset(&hints, 0, sizeof(hints)); hints.ai_family = PF_UNSPEC; hints.ai_socktype = SOCK_STREAM; hints.ai_protocol = IPPROTO_TCP; snprintf(servname, sizeof(servname), "%d", port); err = getaddrinfo(host, servname, &hints, &res0); if (err) return (err == EAI_AGAIN ? 1 : -1); for (res = res0; res != NULL; res = res->ai_next) { if (*ps + 1 >= roundup(*ps, count_inc)) { size_t newsz = roundup(*ps + 2, count_inc); *he = reallocf(*he, newsz * sizeof(**he)); if (*he == NULL) goto out; } p = &(*he)[*ps]; strlcpy(p->host, host, sizeof(p->host)); p->pref = pref; p->ai = *res; p->ai.ai_addr = NULL; bcopy(res->ai_addr, &p->sa, p->ai.ai_addrlen); getnameinfo((struct sockaddr *)&p->sa, p->ai.ai_addrlen, p->addr, sizeof(p->addr), NULL, 0, NI_NUMERICHOST); (*ps)++; } freeaddrinfo(res0); return (0); out: if (res0 != NULL) freeaddrinfo(res0); return (1); } int dns_get_mx_list(const char *host, int port, struct mx_hostentry **he, int no_mx) { char outname[MAXDNAME]; ns_msg msg; ns_rr rr; const char *searchhost; const unsigned char *cp; unsigned char *ans; struct mx_hostentry *hosts = NULL; size_t nhosts = 0; size_t anssz; int pref; int cname_recurse; int have_mx = 0; int err; int i; res_init(); searchhost = host; cname_recurse = 0; anssz = 65536; ans = malloc(anssz); if (ans == NULL) return (1); if (no_mx) goto out; repeat: err = res_search(searchhost, ns_c_in, ns_t_mx, ans, anssz); if (err < 0) { switch (h_errno) { case NO_DATA: /* * Host exists, but no MX (or CNAME) entry. * Not an error, use host name instead. */ goto out; case TRY_AGAIN: /* transient error */ goto transerr; case NO_RECOVERY: case HOST_NOT_FOUND: default: errno = ENOENT; goto err; } } if (!ns_initparse(ans, anssz, &msg)) goto transerr; switch (ns_msg_getflag(msg, ns_f_rcode)) { case ns_r_noerror: break; case ns_r_nxdomain: goto err; default: goto transerr; } for (i = 0; i < ns_msg_count(msg, ns_s_an); i++) { if (ns_parserr(&msg, ns_s_an, i, &rr)) goto transerr; cp = ns_rr_rdata(rr); switch (ns_rr_type(rr)) { case ns_t_mx: have_mx = 1; pref = ns_get16(cp); cp += 2; err = ns_name_uncompress(ns_msg_base(msg), ns_msg_end(msg), cp, outname, sizeof(outname)); if (err < 0) goto transerr; err = add_host(pref, outname, port, &hosts, &nhosts); if (err == -1) goto err; break; case ns_t_cname: err = ns_name_uncompress(ns_msg_base(msg), ns_msg_end(msg), cp, outname, sizeof(outname)); if (err < 0) goto transerr; /* Prevent a CNAME loop */ if (cname_recurse++ > 10) goto err; searchhost = outname; goto repeat; default: break; } } out: err = 0; if (0) { transerr: if (nhosts == 0) err = 1; } if (0) { err: err = -1; } free(ans); if (err == 0) { if (!have_mx) { /* * If we didn't find any MX, use the hostname instead. */ err = add_host(0, host, port, &hosts, &nhosts); } else if (nhosts == 0) { /* * We did get MX, but couldn't resolve any of them * due to transient errors. */ err = 1; } } if (nhosts > 0) { qsort(hosts, nhosts, sizeof(*hosts), sort_pref); /* terminate list */ *hosts[nhosts].host = 0; } else { if (hosts != NULL) free(hosts); hosts = NULL; } *he = hosts; return (err); free(ans); if (hosts != NULL) free(hosts); return (err); } #if defined(TESTING) int main(int argc, char **argv) { struct mx_hostentry *he, *p; int err; err = dns_get_mx_list(argv[1], 53, &he, 0); if (err) return (err); for (p = he; *p->host != 0; p++) { printf("%d\t%s\t%s\n", p->pref, p->host, p->addr); } return (0); } #endif