diff options
Diffstat (limited to 'usr.sbin/pkg/dns_utils.c')
| -rw-r--r-- | usr.sbin/pkg/dns_utils.c | 222 |
1 files changed, 222 insertions, 0 deletions
diff --git a/usr.sbin/pkg/dns_utils.c b/usr.sbin/pkg/dns_utils.c new file mode 100644 index 0000000..a3c3a7e --- /dev/null +++ b/usr.sbin/pkg/dns_utils.c @@ -0,0 +1,222 @@ +/*- + * Copyright (c) 2012-2013 Baptiste Daroussin <bapt@FreeBSD.org> + * All rights reserved. + * + * 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, + * without modification, immediately at the beginning of the file. + * 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. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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 <sys/cdefs.h> +__FBSDID("$FreeBSD$"); + +#include <stdlib.h> +#include <string.h> +#include <netinet/in.h> +#include <resolv.h> + +#include "dns_utils.h" + +typedef union { + HEADER hdr; + unsigned char buf[1024]; +} dns_query; + +static int +srv_priority_cmp(const void *a, const void *b) +{ + const struct dns_srvinfo *da, *db; + unsigned int r, l; + + da = *(struct dns_srvinfo * const *)a; + db = *(struct dns_srvinfo * const *)b; + + l = da->priority; + r = db->priority; + + return ((l > r) - (l < r)); +} + +static int +srv_final_cmp(const void *a, const void *b) +{ + const struct dns_srvinfo *da, *db; + unsigned int r, l, wr, wl; + int res; + + da = *(struct dns_srvinfo * const *)a; + db = *(struct dns_srvinfo * const *)b; + + l = da->priority; + r = db->priority; + + res = ((l > r) - (l < r)); + + if (res == 0) { + wl = da->finalweight; + wr = db->finalweight; + res = ((wr > wl) - (wr < wl)); + } + + return (res); +} + +static void +compute_weight(struct dns_srvinfo **d, int first, int last) +{ + int i, j, totalweight; + int *chosen; + + totalweight = 0; + + for (i = 0; i <= last; i++) + totalweight += d[i]->weight; + + if (totalweight == 0) + return; + + chosen = malloc(sizeof(int) * (last - first + 1)); + + for (i = 0; i <= last; i++) { + for (;;) { + chosen[i] = random() % (d[i]->weight * 100 / totalweight); + for (j = 0; j < i; j++) { + if (chosen[i] == chosen[j]) + break; + } + if (j == i) { + d[i]->finalweight = chosen[i]; + break; + } + } + } + + free(chosen); +} + +struct dns_srvinfo * +dns_getsrvinfo(const char *zone) +{ + struct dns_srvinfo **res, *first; + unsigned char *end, *p; + char host[MAXHOSTNAMELEN]; + dns_query q; + int len, qdcount, ancount, n, i, f, l; + unsigned int type, class, ttl, priority, weight, port; + + if ((len = res_query(zone, C_IN, T_SRV, q.buf, sizeof(q.buf))) == -1 || + len < (int)sizeof(HEADER)) + return (NULL); + + qdcount = ntohs(q.hdr.qdcount); + ancount = ntohs(q.hdr.ancount); + + end = q.buf + len; + p = q.buf + sizeof(HEADER); + + while(qdcount > 0 && p < end) { + qdcount--; + if((len = dn_expand(q.buf, end, p, host, MAXHOSTNAMELEN)) < 0) + return (NULL); + p += len + NS_QFIXEDSZ; + } + + res = calloc(ancount, sizeof(struct dns_srvinfo *)); + if (res == NULL) + return (NULL); + + n = 0; + while (ancount > 0 && p < end) { + ancount--; + len = dn_expand(q.buf, end, p, host, MAXHOSTNAMELEN); + if (len < 0) { + for (i = 0; i < n; i++) + free(res[i]); + free(res); + return NULL; + } + + p += len; + + NS_GET16(type, p); + NS_GET16(class, p); + NS_GET32(ttl, p); + NS_GET16(len, p); + + if (type != T_SRV) { + p += len; + continue; + } + + NS_GET16(priority, p); + NS_GET16(weight, p); + NS_GET16(port, p); + + len = dn_expand(q.buf, end, p, host, MAXHOSTNAMELEN); + if (len < 0) { + for (i = 0; i < n; i++) + free(res[i]); + free(res); + return (NULL); + } + + res[n] = malloc(sizeof(struct dns_srvinfo)); + if (res[n] == NULL) { + for (i = 0; i < n; i++) + free(res[i]); + free(res); + return (NULL); + } + res[n]->type = type; + res[n]->class = class; + res[n]->ttl = ttl; + res[n]->priority = priority; + res[n]->weight = weight; + res[n]->port = port; + res[n]->next = NULL; + strlcpy(res[n]->host, host, MAXHOSTNAMELEN); + + p += len; + n++; + } + + qsort(res, n, sizeof(res[0]), srv_priority_cmp); + + priority = f = l = 0; + for (i = 0; i < n; i++) { + if (res[i]->priority != priority) { + if (f != l) + compute_weight(res, f, l); + f = i; + priority = res[i]->priority; + } + l = i; + } + + qsort(res, n, sizeof(res[0]), srv_final_cmp); + + for (i = 0; i < n - 1; i++) + res[i]->next = res[i + 1]; + + first = res[0]; + free(res); + + return (first); +} |
