diff options
Diffstat (limited to 'release-0.6.9/avahi-core/dns.c')
| -rw-r--r-- | release-0.6.9/avahi-core/dns.c | 838 |
1 files changed, 838 insertions, 0 deletions
diff --git a/release-0.6.9/avahi-core/dns.c b/release-0.6.9/avahi-core/dns.c new file mode 100644 index 0000000..66b0bdf --- /dev/null +++ b/release-0.6.9/avahi-core/dns.c @@ -0,0 +1,838 @@ +/* $Id$ */ + +/*** + This file is part of avahi. + + avahi is free software; you can redistribute it and/or modify it + under the terms of the GNU Lesser General Public License as + published by the Free Software Foundation; either version 2.1 of the + License, or (at your option) any later version. + + avahi is distributed in the hope that it will be useful, but WITHOUT + ANY WARRANTY; without even the implied warranty of MERCHANTABILITY + or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General + Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with avahi; if not, write to the Free Software + Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 + USA. +***/ + +#ifdef HAVE_CONFIG_H +#include <config.h> +#endif + +#include <stdlib.h> +#include <string.h> +#include <stdio.h> +#include <assert.h> + +#include <netinet/in.h> + +#include <avahi-common/defs.h> +#include <avahi-common/domain.h> +#include <avahi-common/malloc.h> + +#include "dns.h" +#include "log.h" + +AvahiDnsPacket* avahi_dns_packet_new(unsigned mtu) { + AvahiDnsPacket *p; + size_t max_size; + + if (mtu <= 0) + max_size = AVAHI_DNS_PACKET_SIZE_MAX; + else if (mtu >= AVAHI_DNS_PACKET_EXTRA_SIZE) + max_size = mtu - AVAHI_DNS_PACKET_EXTRA_SIZE; + else + max_size = 0; + + if (max_size < AVAHI_DNS_PACKET_HEADER_SIZE) + max_size = AVAHI_DNS_PACKET_HEADER_SIZE; + + if (!(p = avahi_malloc(sizeof(AvahiDnsPacket) + max_size))) + return p; + + p->size = p->rindex = AVAHI_DNS_PACKET_HEADER_SIZE; + p->max_size = max_size; + p->name_table = NULL; + p->data = NULL; + + memset(AVAHI_DNS_PACKET_DATA(p), 0, p->size); + return p; +} + +AvahiDnsPacket* avahi_dns_packet_new_query(unsigned mtu) { + AvahiDnsPacket *p; + + if (!(p = avahi_dns_packet_new(mtu))) + return NULL; + + avahi_dns_packet_set_field(p, AVAHI_DNS_FIELD_FLAGS, AVAHI_DNS_FLAGS(0, 0, 0, 0, 0, 0, 0, 0, 0, 0)); + return p; +} + +AvahiDnsPacket* avahi_dns_packet_new_response(unsigned mtu, int aa) { + AvahiDnsPacket *p; + + if (!(p = avahi_dns_packet_new(mtu))) + return NULL; + + avahi_dns_packet_set_field(p, AVAHI_DNS_FIELD_FLAGS, AVAHI_DNS_FLAGS(1, 0, aa, 0, 0, 0, 0, 0, 0, 0)); + return p; +} + +AvahiDnsPacket* avahi_dns_packet_new_reply(AvahiDnsPacket* p, unsigned mtu, int copy_queries, int aa) { + AvahiDnsPacket *r; + assert(p); + + if (!(r = avahi_dns_packet_new_response(mtu, aa))) + return NULL; + + if (copy_queries) { + unsigned saved_rindex; + uint32_t n; + + saved_rindex = p->rindex; + p->rindex = AVAHI_DNS_PACKET_HEADER_SIZE; + + for (n = avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_QDCOUNT); n > 0; n--) { + AvahiKey *k; + int unicast_response; + + if ((k = avahi_dns_packet_consume_key(p, &unicast_response))) { + avahi_dns_packet_append_key(r, k, unicast_response); + avahi_key_unref(k); + } + } + + p->rindex = saved_rindex; + + avahi_dns_packet_set_field(r, AVAHI_DNS_FIELD_QDCOUNT, avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_QDCOUNT)); + } + + avahi_dns_packet_set_field(r, AVAHI_DNS_FIELD_ID, avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_ID)); + + avahi_dns_packet_set_field(r, AVAHI_DNS_FIELD_FLAGS, + (avahi_dns_packet_get_field(r, AVAHI_DNS_FIELD_FLAGS) & ~AVAHI_DNS_FLAG_OPCODE) | + (avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_FLAGS) & AVAHI_DNS_FLAG_OPCODE)); + + return r; +} + + +void avahi_dns_packet_free(AvahiDnsPacket *p) { + assert(p); + + if (p->name_table) + avahi_hashmap_free(p->name_table); + + avahi_free(p); +} + +void avahi_dns_packet_set_field(AvahiDnsPacket *p, unsigned idx, uint16_t v) { + assert(p); + assert(idx < AVAHI_DNS_PACKET_HEADER_SIZE); + + ((uint16_t*) AVAHI_DNS_PACKET_DATA(p))[idx] = htons(v); +} + +uint16_t avahi_dns_packet_get_field(AvahiDnsPacket *p, unsigned idx) { + assert(p); + assert(idx < AVAHI_DNS_PACKET_HEADER_SIZE); + + return ntohs(((uint16_t*) AVAHI_DNS_PACKET_DATA(p))[idx]); +} + +void avahi_dns_packet_inc_field(AvahiDnsPacket *p, unsigned idx) { + assert(p); + assert(idx < AVAHI_DNS_PACKET_HEADER_SIZE); + + avahi_dns_packet_set_field(p, idx, avahi_dns_packet_get_field(p, idx) + 1); +} + +uint8_t* avahi_dns_packet_append_name(AvahiDnsPacket *p, const char *name) { + uint8_t *d, *saved_ptr = NULL; + size_t saved_size; + + assert(p); + assert(name); + + saved_size = p->size; + saved_ptr = avahi_dns_packet_extend(p, 0); + + while (*name) { + uint8_t* prev; + const char *pname; + char label[64], *u; + + /* Check whether we can compress this name. */ + + if (p->name_table && (prev = avahi_hashmap_lookup(p->name_table, name))) { + unsigned idx; + + assert(prev >= AVAHI_DNS_PACKET_DATA(p)); + idx = (unsigned) (prev - AVAHI_DNS_PACKET_DATA(p)); + + assert(idx < p->size); + + if (idx < 0x4000) { + uint8_t *t; + if (!(t = (uint8_t*) avahi_dns_packet_extend(p, sizeof(uint16_t)))) + return NULL; + + t[0] = (uint8_t) ((0xC000 | idx) >> 8); + t[1] = (uint8_t) idx; + return saved_ptr; + } + } + + pname = name; + + if (!(avahi_unescape_label(&name, label, sizeof(label)))) + goto fail; + + if (!(d = avahi_dns_packet_append_string(p, label))) + goto fail; + + if (!p->name_table) + /* This works only for normalized domain names */ + p->name_table = avahi_hashmap_new(avahi_string_hash, avahi_string_equal, avahi_free, NULL); + + if (!(u = avahi_strdup(pname))) + avahi_log_error("avahi_strdup() failed."); + else + avahi_hashmap_insert(p->name_table, u, d); + } + + if (!(d = avahi_dns_packet_extend(p, 1))) + goto fail; + + *d = 0; + + return saved_ptr; + +fail: + p->size = saved_size; + return NULL; +} + +uint8_t* avahi_dns_packet_append_uint16(AvahiDnsPacket *p, uint16_t v) { + uint8_t *d; + assert(p); + + if (!(d = avahi_dns_packet_extend(p, sizeof(uint16_t)))) + return NULL; + + d[0] = (uint8_t) (v >> 8); + d[1] = (uint8_t) v; + return d; +} + +uint8_t *avahi_dns_packet_append_uint32(AvahiDnsPacket *p, uint32_t v) { + uint8_t *d; + assert(p); + + if (!(d = avahi_dns_packet_extend(p, sizeof(uint32_t)))) + return NULL; + + d[0] = (uint8_t) (v >> 24); + d[1] = (uint8_t) (v >> 16); + d[2] = (uint8_t) (v >> 8); + d[3] = (uint8_t) v; + + return d; +} + +uint8_t *avahi_dns_packet_append_bytes(AvahiDnsPacket *p, const void *b, size_t l) { + uint8_t* d; + + assert(p); + assert(b); + assert(l); + + if (!(d = avahi_dns_packet_extend(p, l))) + return NULL; + + memcpy(d, b, l); + return d; +} + +uint8_t* avahi_dns_packet_append_string(AvahiDnsPacket *p, const char *s) { + uint8_t* d; + size_t k; + + assert(p); + assert(s); + + if ((k = strlen(s)) >= 255) + k = 255; + + if (!(d = avahi_dns_packet_extend(p, k+1))) + return NULL; + + *d = (uint8_t) k; + memcpy(d+1, s, k); + + return d; +} + +uint8_t *avahi_dns_packet_extend(AvahiDnsPacket *p, size_t l) { + uint8_t *d; + + assert(p); + + if (p->size+l > p->max_size) + return NULL; + + d = AVAHI_DNS_PACKET_DATA(p) + p->size; + p->size += l; + + return d; +} + +int avahi_dns_packet_check_valid(AvahiDnsPacket *p) { + uint16_t flags; + assert(p); + + if (p->size < AVAHI_DNS_PACKET_HEADER_SIZE) + return -1; + + flags = avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_FLAGS); + + if (flags & AVAHI_DNS_FLAG_OPCODE) + return -1; + + return 0; +} + +int avahi_dns_packet_check_valid_multicast(AvahiDnsPacket *p) { + uint16_t flags; + assert(p); + + if (avahi_dns_packet_check_valid(p) < 0) + return -1; + + flags = avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_FLAGS); + + if (flags & AVAHI_DNS_FLAG_RCODE) + return -1; + + return 0; +} + + +int avahi_dns_packet_is_query(AvahiDnsPacket *p) { + assert(p); + + return !(avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_FLAGS) & AVAHI_DNS_FLAG_QR); +} + +static int consume_labels(AvahiDnsPacket *p, unsigned idx, char *ret_name, size_t l) { + int ret = 0; + int compressed = 0; + int first_label = 1; + assert(p && ret_name && l); + + for (;;) { + uint8_t n; + + if (idx+1 > p->size) + return -1; + + n = AVAHI_DNS_PACKET_DATA(p)[idx]; + + if (!n) { + idx++; + if (!compressed) + ret++; + + if (l < 1) + return -1; + *ret_name = 0; + + return ret; + + } else if (n <= 63) { + /* Uncompressed label */ + idx++; + if (!compressed) + ret++; + + if (idx + n > p->size) + return -1; + + if ((size_t) n + 1 > l) + return -1; + + if (!first_label) { + *(ret_name++) = '.'; + l--; + } else + first_label = 0; + + if (!(avahi_escape_label((char*) AVAHI_DNS_PACKET_DATA(p) + idx, n, &ret_name, &l))) + return -1; + + idx += n; + + if (!compressed) + ret += n; + } else if ((n & 0xC0) == 0xC0) { + /* Compressed label */ + + if (idx+2 > p->size) + return -1; + + idx = ((unsigned) (AVAHI_DNS_PACKET_DATA(p)[idx] & ~0xC0)) << 8 | AVAHI_DNS_PACKET_DATA(p)[idx+1]; + + if (!compressed) + ret += 2; + + compressed = 1; + } else + return -1; + } +} + +int avahi_dns_packet_consume_name(AvahiDnsPacket *p, char *ret_name, size_t l) { + int r; + + if ((r = consume_labels(p, p->rindex, ret_name, l)) < 0) + return -1; + + p->rindex += r; + return 0; +} + +int avahi_dns_packet_consume_uint16(AvahiDnsPacket *p, uint16_t *ret_v) { + uint8_t *d; + + assert(p); + assert(ret_v); + + if (p->rindex + sizeof(uint16_t) > p->size) + return -1; + + d = (uint8_t*) (AVAHI_DNS_PACKET_DATA(p) + p->rindex); + *ret_v = (d[0] << 8) | d[1]; + p->rindex += sizeof(uint16_t); + + return 0; +} + +int avahi_dns_packet_consume_uint32(AvahiDnsPacket *p, uint32_t *ret_v) { + uint8_t* d; + + assert(p); + assert(ret_v); + + if (p->rindex + sizeof(uint32_t) > p->size) + return -1; + + d = (uint8_t*) (AVAHI_DNS_PACKET_DATA(p) + p->rindex); + *ret_v = (d[0] << 24) | (d[1] << 16) | (d[2] << 8) | d[3]; + p->rindex += sizeof(uint32_t); + + return 0; +} + +int avahi_dns_packet_consume_bytes(AvahiDnsPacket *p, void * ret_data, size_t l) { + assert(p); + assert(ret_data); + assert(l > 0); + + if (p->rindex + l > p->size) + return -1; + + memcpy(ret_data, AVAHI_DNS_PACKET_DATA(p) + p->rindex, l); + p->rindex += l; + + return 0; +} + +int avahi_dns_packet_consume_string(AvahiDnsPacket *p, char *ret_string, size_t l) { + size_t k; + + assert(p); + assert(ret_string); + assert(l > 0); + + if (p->rindex >= p->size) + return -1; + + k = AVAHI_DNS_PACKET_DATA(p)[p->rindex]; + + if (p->rindex+1+k > p->size) + return -1; + + if (l > k+1) + l = k+1; + + memcpy(ret_string, AVAHI_DNS_PACKET_DATA(p)+p->rindex+1, l-1); + ret_string[l-1] = 0; + + p->rindex += 1+k; + + return 0; +} + +const void* avahi_dns_packet_get_rptr(AvahiDnsPacket *p) { + assert(p); + + if (p->rindex > p->size) + return NULL; + + return AVAHI_DNS_PACKET_DATA(p) + p->rindex; +} + +int avahi_dns_packet_skip(AvahiDnsPacket *p, size_t length) { + assert(p); + + if (p->rindex + length > p->size) + return -1; + + p->rindex += length; + return 0; +} + +static int parse_rdata(AvahiDnsPacket *p, AvahiRecord *r, uint16_t rdlength) { + char buf[AVAHI_DOMAIN_NAME_MAX]; + const void* start; + + assert(p); + assert(r); + + start = avahi_dns_packet_get_rptr(p); + + switch (r->key->type) { + case AVAHI_DNS_TYPE_PTR: + case AVAHI_DNS_TYPE_CNAME: + case AVAHI_DNS_TYPE_NS: + + if (avahi_dns_packet_consume_name(p, buf, sizeof(buf)) < 0) + return -1; + + r->data.ptr.name = avahi_strdup(buf); + break; + + + case AVAHI_DNS_TYPE_SRV: + + if (avahi_dns_packet_consume_uint16(p, &r->data.srv.priority) < 0 || + avahi_dns_packet_consume_uint16(p, &r->data.srv.weight) < 0 || + avahi_dns_packet_consume_uint16(p, &r->data.srv.port) < 0 || + avahi_dns_packet_consume_name(p, buf, sizeof(buf)) < 0) + return -1; + + r->data.srv.name = avahi_strdup(buf); + break; + + case AVAHI_DNS_TYPE_HINFO: + + if (avahi_dns_packet_consume_string(p, buf, sizeof(buf)) < 0) + return -1; + + r->data.hinfo.cpu = avahi_strdup(buf); + + if (avahi_dns_packet_consume_string(p, buf, sizeof(buf)) < 0) + return -1; + + r->data.hinfo.os = avahi_strdup(buf); + break; + + case AVAHI_DNS_TYPE_TXT: + + if (rdlength > 0) { + if (avahi_string_list_parse(avahi_dns_packet_get_rptr(p), rdlength, &r->data.txt.string_list) < 0) + return -1; + + if (avahi_dns_packet_skip(p, rdlength) < 0) + return -1; + } else + r->data.txt.string_list = NULL; + + break; + + case AVAHI_DNS_TYPE_A: + +/* avahi_log_debug("A"); */ + + if (avahi_dns_packet_consume_bytes(p, &r->data.a.address, sizeof(AvahiIPv4Address)) < 0) + return -1; + + break; + + case AVAHI_DNS_TYPE_AAAA: + +/* avahi_log_debug("aaaa"); */ + + if (avahi_dns_packet_consume_bytes(p, &r->data.aaaa.address, sizeof(AvahiIPv6Address)) < 0) + return -1; + + break; + + default: + +/* avahi_log_debug("generic"); */ + + if (rdlength > 0) { + + r->data.generic.data = avahi_memdup(avahi_dns_packet_get_rptr(p), rdlength); + + if (avahi_dns_packet_skip(p, rdlength) < 0) + return -1; + } + + break; + } + + /* Check if we read enough data */ + if ((const uint8_t*) avahi_dns_packet_get_rptr(p) - (const uint8_t*) start != rdlength) + return -1; + + return 0; +} + +AvahiRecord* avahi_dns_packet_consume_record(AvahiDnsPacket *p, int *ret_cache_flush) { + char name[AVAHI_DOMAIN_NAME_MAX]; + uint16_t type, class; + uint32_t ttl; + uint16_t rdlength; + AvahiRecord *r = NULL; + + assert(p); + + if (avahi_dns_packet_consume_name(p, name, sizeof(name)) < 0 || + avahi_dns_packet_consume_uint16(p, &type) < 0 || + avahi_dns_packet_consume_uint16(p, &class) < 0 || + avahi_dns_packet_consume_uint32(p, &ttl) < 0 || + avahi_dns_packet_consume_uint16(p, &rdlength) < 0 || + p->rindex + rdlength > p->size) + goto fail; + + if (ret_cache_flush) + *ret_cache_flush = !!(class & AVAHI_DNS_CACHE_FLUSH); + class &= ~AVAHI_DNS_CACHE_FLUSH; + + if (!(r = avahi_record_new_full(name, class, type, ttl))) + goto fail; + + if (parse_rdata(p, r, rdlength) < 0) + goto fail; + + return r; + +fail: + if (r) + avahi_record_unref(r); + + return NULL; +} + +AvahiKey* avahi_dns_packet_consume_key(AvahiDnsPacket *p, int *ret_unicast_response) { + char name[256]; + uint16_t type, class; + + assert(p); + + if (avahi_dns_packet_consume_name(p, name, sizeof(name)) < 0 || + avahi_dns_packet_consume_uint16(p, &type) < 0 || + avahi_dns_packet_consume_uint16(p, &class) < 0) + return NULL; + + if (ret_unicast_response) + *ret_unicast_response = !!(class & AVAHI_DNS_UNICAST_RESPONSE); + + class &= ~AVAHI_DNS_UNICAST_RESPONSE; + + return avahi_key_new(name, class, type); +} + +uint8_t* avahi_dns_packet_append_key(AvahiDnsPacket *p, AvahiKey *k, int unicast_response) { + uint8_t *t; + size_t size; + + assert(p); + assert(k); + + size = p->size; + + if (!(t = avahi_dns_packet_append_name(p, k->name)) || + !avahi_dns_packet_append_uint16(p, k->type) || + !avahi_dns_packet_append_uint16(p, k->clazz | (unicast_response ? AVAHI_DNS_UNICAST_RESPONSE : 0))) { + p->size = size; + return NULL; + } + + return t; +} + +static int append_rdata(AvahiDnsPacket *p, AvahiRecord *r) { + assert(p); + assert(r); + + switch (r->key->type) { + + case AVAHI_DNS_TYPE_PTR: + case AVAHI_DNS_TYPE_CNAME: + case AVAHI_DNS_TYPE_NS: + + if (!(avahi_dns_packet_append_name(p, r->data.ptr.name))) + return -1; + + break; + + case AVAHI_DNS_TYPE_SRV: + + if (!avahi_dns_packet_append_uint16(p, r->data.srv.priority) || + !avahi_dns_packet_append_uint16(p, r->data.srv.weight) || + !avahi_dns_packet_append_uint16(p, r->data.srv.port) || + !avahi_dns_packet_append_name(p, r->data.srv.name)) + return -1; + + break; + + case AVAHI_DNS_TYPE_HINFO: + if (!avahi_dns_packet_append_string(p, r->data.hinfo.cpu) || + !avahi_dns_packet_append_string(p, r->data.hinfo.os)) + return -1; + + break; + + case AVAHI_DNS_TYPE_TXT: { + + uint8_t *data; + size_t n; + + n = avahi_string_list_serialize(r->data.txt.string_list, NULL, 0); + + if (!(data = avahi_dns_packet_extend(p, n))) + return -1; + + avahi_string_list_serialize(r->data.txt.string_list, data, n); + break; + } + + + case AVAHI_DNS_TYPE_A: + + if (!avahi_dns_packet_append_bytes(p, &r->data.a.address, sizeof(r->data.a.address))) + return -1; + + break; + + case AVAHI_DNS_TYPE_AAAA: + + if (!avahi_dns_packet_append_bytes(p, &r->data.aaaa.address, sizeof(r->data.aaaa.address))) + return -1; + + break; + + default: + + if (r->data.generic.size) + if (avahi_dns_packet_append_bytes(p, r->data.generic.data, r->data.generic.size)) + return -1; + + break; + } + + return 0; +} + + +uint8_t* avahi_dns_packet_append_record(AvahiDnsPacket *p, AvahiRecord *r, int cache_flush, unsigned max_ttl) { + uint8_t *t, *l, *start; + size_t size; + + assert(p); + assert(r); + + size = p->size; + + if (!(t = avahi_dns_packet_append_name(p, r->key->name)) || + !avahi_dns_packet_append_uint16(p, r->key->type) || + !avahi_dns_packet_append_uint16(p, cache_flush ? (r->key->clazz | AVAHI_DNS_CACHE_FLUSH) : (r->key->clazz &~ AVAHI_DNS_CACHE_FLUSH)) || + !avahi_dns_packet_append_uint32(p, (max_ttl && r->ttl > max_ttl) ? max_ttl : r->ttl) || + !(l = avahi_dns_packet_append_uint16(p, 0))) + goto fail; + + start = avahi_dns_packet_extend(p, 0); + + if (append_rdata(p, r) < 0) + goto fail; + + size = avahi_dns_packet_extend(p, 0) - start; + assert(size <= 0xFFFF); + +/* avahi_log_debug("appended %u", size); */ + + l[0] = (uint8_t) ((uint16_t) size >> 8); + l[1] = (uint8_t) ((uint16_t) size); + + return t; + + +fail: + p->size = size; + return NULL; +} + +int avahi_dns_packet_is_empty(AvahiDnsPacket *p) { + assert(p); + + return p->size <= AVAHI_DNS_PACKET_HEADER_SIZE; +} + +size_t avahi_dns_packet_space(AvahiDnsPacket *p) { + assert(p); + + assert(p->size <= p->max_size); + + return p->max_size - p->size; +} + +int avahi_rdata_parse(AvahiRecord *record, const void* rdata, size_t size) { + int ret; + AvahiDnsPacket p; + + assert(record); + assert(rdata); + + p.data = (void*) rdata; + p.max_size = p.size = size; + p.rindex = 0; + p.name_table = NULL; + + ret = parse_rdata(&p, record, size); + + assert(!p.name_table); + + return ret; +} + +size_t avahi_rdata_serialize(AvahiRecord *record, void *rdata, size_t max_size) { + int ret; + AvahiDnsPacket p; + + assert(record); + assert(rdata); + assert(max_size > 0); + + p.data = (void*) rdata; + p.max_size = max_size; + p.size = p.rindex = 0; + p.name_table = NULL; + + ret = append_rdata(&p, record); + + if (p.name_table) + avahi_hashmap_free(p.name_table); + + if (ret < 0) + return (size_t) -1; + + return p.size; +} |