129aaa961SBaptiste Daroussin /*- 235e07a7aSBaptiste Daroussin * Copyright (c) 2012-2013 Baptiste Daroussin <bapt@FreeBSD.org> 329aaa961SBaptiste Daroussin * All rights reserved. 429aaa961SBaptiste Daroussin * 529aaa961SBaptiste Daroussin * Redistribution and use in source and binary forms, with or without 629aaa961SBaptiste Daroussin * modification, are permitted provided that the following conditions 729aaa961SBaptiste Daroussin * are met: 829aaa961SBaptiste Daroussin * 1. Redistributions of source code must retain the above copyright 929aaa961SBaptiste Daroussin * notice, this list of conditions and the following disclaimer, 1029aaa961SBaptiste Daroussin * without modification, immediately at the beginning of the file. 1129aaa961SBaptiste Daroussin * 2. Redistributions in binary form must reproduce the above copyright 1229aaa961SBaptiste Daroussin * notice, this list of conditions and the following disclaimer in the 1329aaa961SBaptiste Daroussin * documentation and/or other materials provided with the distribution. 1429aaa961SBaptiste Daroussin * 1529aaa961SBaptiste Daroussin * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 1629aaa961SBaptiste Daroussin * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 1729aaa961SBaptiste Daroussin * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 1829aaa961SBaptiste Daroussin * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 1929aaa961SBaptiste Daroussin * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 2029aaa961SBaptiste Daroussin * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 2129aaa961SBaptiste Daroussin * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 2229aaa961SBaptiste Daroussin * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 2329aaa961SBaptiste Daroussin * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 2429aaa961SBaptiste Daroussin * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 2529aaa961SBaptiste Daroussin */ 2629aaa961SBaptiste Daroussin 2729aaa961SBaptiste Daroussin #include <sys/cdefs.h> 2829aaa961SBaptiste Daroussin __FBSDID("$FreeBSD$"); 2929aaa961SBaptiste Daroussin 3029aaa961SBaptiste Daroussin #include <stdlib.h> 3129aaa961SBaptiste Daroussin #include <string.h> 3229aaa961SBaptiste Daroussin #include <netinet/in.h> 3329aaa961SBaptiste Daroussin #include <resolv.h> 3429aaa961SBaptiste Daroussin 3529aaa961SBaptiste Daroussin #include "dns_utils.h" 3629aaa961SBaptiste Daroussin 3729aaa961SBaptiste Daroussin typedef union { 3829aaa961SBaptiste Daroussin HEADER hdr; 3929aaa961SBaptiste Daroussin unsigned char buf[1024]; 4029aaa961SBaptiste Daroussin } dns_query; 4129aaa961SBaptiste Daroussin 4235e07a7aSBaptiste Daroussin static int 4335e07a7aSBaptiste Daroussin srv_priority_cmp(const void *a, const void *b) 4435e07a7aSBaptiste Daroussin { 45959bd879SBaptiste Daroussin const struct dns_srvinfo *da, *db; 4635e07a7aSBaptiste Daroussin unsigned int r, l; 4735e07a7aSBaptiste Daroussin 48959bd879SBaptiste Daroussin da = *(struct dns_srvinfo * const *)a; 49959bd879SBaptiste Daroussin db = *(struct dns_srvinfo * const *)b; 5035e07a7aSBaptiste Daroussin 5135e07a7aSBaptiste Daroussin l = da->priority; 5235e07a7aSBaptiste Daroussin r = db->priority; 5335e07a7aSBaptiste Daroussin 5435e07a7aSBaptiste Daroussin return ((l > r) - (l < r)); 5535e07a7aSBaptiste Daroussin } 5635e07a7aSBaptiste Daroussin 5735e07a7aSBaptiste Daroussin static int 5835e07a7aSBaptiste Daroussin srv_final_cmp(const void *a, const void *b) 5935e07a7aSBaptiste Daroussin { 60959bd879SBaptiste Daroussin const struct dns_srvinfo *da, *db; 6135e07a7aSBaptiste Daroussin unsigned int r, l, wr, wl; 6235e07a7aSBaptiste Daroussin int res; 6335e07a7aSBaptiste Daroussin 64959bd879SBaptiste Daroussin da = *(struct dns_srvinfo * const *)a; 65959bd879SBaptiste Daroussin db = *(struct dns_srvinfo * const *)b; 6635e07a7aSBaptiste Daroussin 6735e07a7aSBaptiste Daroussin l = da->priority; 6835e07a7aSBaptiste Daroussin r = db->priority; 6935e07a7aSBaptiste Daroussin 7035e07a7aSBaptiste Daroussin res = ((l > r) - (l < r)); 7135e07a7aSBaptiste Daroussin 7235e07a7aSBaptiste Daroussin if (res == 0) { 7335e07a7aSBaptiste Daroussin wl = da->finalweight; 7435e07a7aSBaptiste Daroussin wr = db->finalweight; 7535e07a7aSBaptiste Daroussin res = ((wr > wl) - (wr < wl)); 7635e07a7aSBaptiste Daroussin } 7735e07a7aSBaptiste Daroussin 7835e07a7aSBaptiste Daroussin return (res); 7935e07a7aSBaptiste Daroussin } 8035e07a7aSBaptiste Daroussin 8135e07a7aSBaptiste Daroussin static void 8235e07a7aSBaptiste Daroussin compute_weight(struct dns_srvinfo **d, int first, int last) 8335e07a7aSBaptiste Daroussin { 8435e07a7aSBaptiste Daroussin int i, j, totalweight; 8535e07a7aSBaptiste Daroussin int *chosen; 8635e07a7aSBaptiste Daroussin 8735e07a7aSBaptiste Daroussin totalweight = 0; 8835e07a7aSBaptiste Daroussin 8935e07a7aSBaptiste Daroussin for (i = 0; i <= last; i++) 9035e07a7aSBaptiste Daroussin totalweight += d[i]->weight; 9135e07a7aSBaptiste Daroussin 9235e07a7aSBaptiste Daroussin if (totalweight == 0) 9335e07a7aSBaptiste Daroussin return; 9435e07a7aSBaptiste Daroussin 95f595a30bSXin LI chosen = malloc(sizeof(int) * (last - first + 1)); 96f595a30bSXin LI 9735e07a7aSBaptiste Daroussin for (i = 0; i <= last; i++) { 9835e07a7aSBaptiste Daroussin for (;;) { 9935e07a7aSBaptiste Daroussin chosen[i] = random() % (d[i]->weight * 100 / totalweight); 10035e07a7aSBaptiste Daroussin for (j = 0; j < i; j++) { 10135e07a7aSBaptiste Daroussin if (chosen[i] == chosen[j]) 10235e07a7aSBaptiste Daroussin break; 10335e07a7aSBaptiste Daroussin } 10435e07a7aSBaptiste Daroussin if (j == i) { 10535e07a7aSBaptiste Daroussin d[i]->finalweight = chosen[i]; 10635e07a7aSBaptiste Daroussin break; 10735e07a7aSBaptiste Daroussin } 10835e07a7aSBaptiste Daroussin } 10935e07a7aSBaptiste Daroussin } 11035e07a7aSBaptiste Daroussin 11135e07a7aSBaptiste Daroussin free(chosen); 11235e07a7aSBaptiste Daroussin } 11335e07a7aSBaptiste Daroussin 11429aaa961SBaptiste Daroussin struct dns_srvinfo * 11529aaa961SBaptiste Daroussin dns_getsrvinfo(const char *zone) 11629aaa961SBaptiste Daroussin { 11729aaa961SBaptiste Daroussin struct dns_srvinfo **res, *first; 11829aaa961SBaptiste Daroussin unsigned char *end, *p; 11929aaa961SBaptiste Daroussin char host[MAXHOSTNAMELEN]; 12029aaa961SBaptiste Daroussin dns_query q; 12135e07a7aSBaptiste Daroussin int len, qdcount, ancount, n, i, f, l; 12229aaa961SBaptiste Daroussin unsigned int type, class, ttl, priority, weight, port; 12329aaa961SBaptiste Daroussin 12429aaa961SBaptiste Daroussin if ((len = res_query(zone, C_IN, T_SRV, q.buf, sizeof(q.buf))) == -1 || 12529aaa961SBaptiste Daroussin len < (int)sizeof(HEADER)) 12629aaa961SBaptiste Daroussin return (NULL); 12729aaa961SBaptiste Daroussin 12829aaa961SBaptiste Daroussin qdcount = ntohs(q.hdr.qdcount); 12929aaa961SBaptiste Daroussin ancount = ntohs(q.hdr.ancount); 13029aaa961SBaptiste Daroussin 13129aaa961SBaptiste Daroussin end = q.buf + len; 13229aaa961SBaptiste Daroussin p = q.buf + sizeof(HEADER); 13329aaa961SBaptiste Daroussin 13429aaa961SBaptiste Daroussin while(qdcount > 0 && p < end) { 13529aaa961SBaptiste Daroussin qdcount--; 13629aaa961SBaptiste Daroussin if((len = dn_expand(q.buf, end, p, host, MAXHOSTNAMELEN)) < 0) 13729aaa961SBaptiste Daroussin return (NULL); 13829aaa961SBaptiste Daroussin p += len + NS_QFIXEDSZ; 13929aaa961SBaptiste Daroussin } 14029aaa961SBaptiste Daroussin 1418ad6d917SBaptiste Daroussin res = calloc(ancount, sizeof(struct dns_srvinfo *)); 14229aaa961SBaptiste Daroussin if (res == NULL) 14329aaa961SBaptiste Daroussin return (NULL); 14429aaa961SBaptiste Daroussin 14529aaa961SBaptiste Daroussin n = 0; 14629aaa961SBaptiste Daroussin while (ancount > 0 && p < end) { 14729aaa961SBaptiste Daroussin ancount--; 14829aaa961SBaptiste Daroussin len = dn_expand(q.buf, end, p, host, MAXHOSTNAMELEN); 14929aaa961SBaptiste Daroussin if (len < 0) { 15029aaa961SBaptiste Daroussin for (i = 0; i < n; i++) 15129aaa961SBaptiste Daroussin free(res[i]); 15229aaa961SBaptiste Daroussin free(res); 15329aaa961SBaptiste Daroussin return NULL; 15429aaa961SBaptiste Daroussin } 15529aaa961SBaptiste Daroussin 15629aaa961SBaptiste Daroussin p += len; 15729aaa961SBaptiste Daroussin 15829aaa961SBaptiste Daroussin NS_GET16(type, p); 15929aaa961SBaptiste Daroussin NS_GET16(class, p); 16029aaa961SBaptiste Daroussin NS_GET32(ttl, p); 16129aaa961SBaptiste Daroussin NS_GET16(len, p); 16229aaa961SBaptiste Daroussin 16329aaa961SBaptiste Daroussin if (type != T_SRV) { 16429aaa961SBaptiste Daroussin p += len; 16529aaa961SBaptiste Daroussin continue; 16629aaa961SBaptiste Daroussin } 16729aaa961SBaptiste Daroussin 16829aaa961SBaptiste Daroussin NS_GET16(priority, p); 16929aaa961SBaptiste Daroussin NS_GET16(weight, p); 17029aaa961SBaptiste Daroussin NS_GET16(port, p); 17129aaa961SBaptiste Daroussin 17229aaa961SBaptiste Daroussin len = dn_expand(q.buf, end, p, host, MAXHOSTNAMELEN); 17329aaa961SBaptiste Daroussin if (len < 0) { 17429aaa961SBaptiste Daroussin for (i = 0; i < n; i++) 17529aaa961SBaptiste Daroussin free(res[i]); 17629aaa961SBaptiste Daroussin free(res); 17729aaa961SBaptiste Daroussin return (NULL); 17829aaa961SBaptiste Daroussin } 17929aaa961SBaptiste Daroussin 18029aaa961SBaptiste Daroussin res[n] = malloc(sizeof(struct dns_srvinfo)); 18129aaa961SBaptiste Daroussin if (res[n] == NULL) { 18229aaa961SBaptiste Daroussin for (i = 0; i < n; i++) 18329aaa961SBaptiste Daroussin free(res[i]); 18429aaa961SBaptiste Daroussin free(res); 18529aaa961SBaptiste Daroussin return (NULL); 18629aaa961SBaptiste Daroussin } 18729aaa961SBaptiste Daroussin res[n]->type = type; 18829aaa961SBaptiste Daroussin res[n]->class = class; 18929aaa961SBaptiste Daroussin res[n]->ttl = ttl; 19029aaa961SBaptiste Daroussin res[n]->priority = priority; 19129aaa961SBaptiste Daroussin res[n]->weight = weight; 19229aaa961SBaptiste Daroussin res[n]->port = port; 19329aaa961SBaptiste Daroussin res[n]->next = NULL; 19429aaa961SBaptiste Daroussin strlcpy(res[n]->host, host, MAXHOSTNAMELEN); 19529aaa961SBaptiste Daroussin 19629aaa961SBaptiste Daroussin p += len; 19729aaa961SBaptiste Daroussin n++; 19829aaa961SBaptiste Daroussin } 19929aaa961SBaptiste Daroussin 20035e07a7aSBaptiste Daroussin qsort(res, n, sizeof(res[0]), srv_priority_cmp); 20135e07a7aSBaptiste Daroussin 20235e07a7aSBaptiste Daroussin priority = f = l = 0; 20335e07a7aSBaptiste Daroussin for (i = 0; i < n; i++) { 20435e07a7aSBaptiste Daroussin if (res[i]->priority != priority) { 20535e07a7aSBaptiste Daroussin if (f != l) 20635e07a7aSBaptiste Daroussin compute_weight(res, f, l); 20735e07a7aSBaptiste Daroussin f = i; 20835e07a7aSBaptiste Daroussin priority = res[i]->priority; 20935e07a7aSBaptiste Daroussin } 21035e07a7aSBaptiste Daroussin l = i; 21135e07a7aSBaptiste Daroussin } 21235e07a7aSBaptiste Daroussin 21335e07a7aSBaptiste Daroussin qsort(res, n, sizeof(res[0]), srv_final_cmp); 21435e07a7aSBaptiste Daroussin 21529aaa961SBaptiste Daroussin for (i = 0; i < n - 1; i++) 21629aaa961SBaptiste Daroussin res[i]->next = res[i + 1]; 21729aaa961SBaptiste Daroussin 21829aaa961SBaptiste Daroussin first = res[0]; 21929aaa961SBaptiste Daroussin free(res); 22029aaa961SBaptiste Daroussin 22129aaa961SBaptiste Daroussin return (first); 22229aaa961SBaptiste Daroussin } 223