312 lines
8.2 KiB
C
312 lines
8.2 KiB
C
/*
|
|
* Domain search option for DHCP (RFC 3397)
|
|
*
|
|
* Copyright (c) 2012 Klaus Stengel
|
|
*
|
|
* Permission is hereby granted, free of charge, to any person obtaining a copy
|
|
* of this software and associated documentation files (the "Software"), to deal
|
|
* in the Software without restriction, including without limitation the rights
|
|
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
|
|
* copies of the Software, and to permit persons to whom the Software is
|
|
* furnished to do so, subject to the following conditions:
|
|
*
|
|
* The above copyright notice and this permission notice shall be included in
|
|
* all copies or substantial portions of the Software.
|
|
*
|
|
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
|
|
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
|
|
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
|
|
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
|
|
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
|
|
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
|
|
* THE SOFTWARE.
|
|
*/
|
|
|
|
#include "qemu/osdep.h"
|
|
#include "slirp.h"
|
|
|
|
static const uint8_t RFC3397_OPT_DOMAIN_SEARCH = 119;
|
|
static const uint8_t MAX_OPT_LEN = 255;
|
|
static const uint8_t OPT_HEADER_LEN = 2;
|
|
static const uint8_t REFERENCE_LEN = 2;
|
|
|
|
struct compact_domain;
|
|
|
|
typedef struct compact_domain {
|
|
struct compact_domain *self;
|
|
struct compact_domain *refdom;
|
|
uint8_t *labels;
|
|
size_t len;
|
|
size_t common_octets;
|
|
} CompactDomain;
|
|
|
|
static size_t
|
|
domain_suffix_diffoff(const CompactDomain *a, const CompactDomain *b)
|
|
{
|
|
size_t la = a->len, lb = b->len;
|
|
uint8_t *da = a->labels + la, *db = b->labels + lb;
|
|
size_t i, lm = (la < lb) ? la : lb;
|
|
|
|
for (i = 0; i < lm; i++) {
|
|
da--; db--;
|
|
if (*da != *db) {
|
|
break;
|
|
}
|
|
}
|
|
return i;
|
|
}
|
|
|
|
static int domain_suffix_ord(const void *cva, const void *cvb)
|
|
{
|
|
const CompactDomain *a = cva, *b = cvb;
|
|
size_t la = a->len, lb = b->len;
|
|
size_t doff = domain_suffix_diffoff(a, b);
|
|
uint8_t ca = a->labels[la - doff];
|
|
uint8_t cb = b->labels[lb - doff];
|
|
|
|
if (ca < cb) {
|
|
return -1;
|
|
}
|
|
if (ca > cb) {
|
|
return 1;
|
|
}
|
|
if (la < lb) {
|
|
return -1;
|
|
}
|
|
if (la > lb) {
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static size_t domain_common_label(CompactDomain *a, CompactDomain *b)
|
|
{
|
|
size_t res, doff = domain_suffix_diffoff(a, b);
|
|
uint8_t *first_eq_pos = a->labels + (a->len - doff);
|
|
uint8_t *label = a->labels;
|
|
|
|
while (*label && label < first_eq_pos) {
|
|
label += *label + 1;
|
|
}
|
|
res = a->len - (label - a->labels);
|
|
/* only report if it can help to reduce the packet size */
|
|
return (res > REFERENCE_LEN) ? res : 0;
|
|
}
|
|
|
|
static void domain_fixup_order(CompactDomain *cd, size_t n)
|
|
{
|
|
size_t i;
|
|
|
|
for (i = 0; i < n; i++) {
|
|
CompactDomain *cur = cd + i, *next = cd[i].self;
|
|
|
|
while (!cur->common_octets) {
|
|
CompactDomain *tmp = next->self; /* backup target value */
|
|
|
|
next->self = cur;
|
|
cur->common_octets++;
|
|
|
|
cur = next;
|
|
next = tmp;
|
|
}
|
|
}
|
|
}
|
|
|
|
static void domain_mklabels(CompactDomain *cd, const char *input)
|
|
{
|
|
uint8_t *len_marker = cd->labels;
|
|
uint8_t *output = len_marker; /* pre-incremented */
|
|
const char *in = input;
|
|
char cur_chr;
|
|
size_t len = 0;
|
|
|
|
if (cd->len == 0) {
|
|
goto fail;
|
|
}
|
|
cd->len++;
|
|
|
|
do {
|
|
cur_chr = *in++;
|
|
if (cur_chr == '.' || cur_chr == '\0') {
|
|
len = output - len_marker;
|
|
if ((len == 0 && cur_chr == '.') || len >= 64) {
|
|
goto fail;
|
|
}
|
|
*len_marker = len;
|
|
|
|
output++;
|
|
len_marker = output;
|
|
} else {
|
|
output++;
|
|
*output = cur_chr;
|
|
}
|
|
} while (cur_chr != '\0');
|
|
|
|
/* ensure proper zero-termination */
|
|
if (len != 0) {
|
|
*len_marker = 0;
|
|
cd->len++;
|
|
}
|
|
return;
|
|
|
|
fail:
|
|
g_warning("failed to parse domain name '%s'\n", input);
|
|
cd->len = 0;
|
|
}
|
|
|
|
static void
|
|
domain_mkxrefs(CompactDomain *doms, CompactDomain *last, size_t depth)
|
|
{
|
|
CompactDomain *i = doms, *target = doms;
|
|
|
|
do {
|
|
if (i->labels < target->labels) {
|
|
target = i;
|
|
}
|
|
} while (i++ != last);
|
|
|
|
for (i = doms; i != last; i++) {
|
|
CompactDomain *group_last;
|
|
size_t next_depth;
|
|
|
|
if (i->common_octets == depth) {
|
|
continue;
|
|
}
|
|
|
|
next_depth = -1;
|
|
for (group_last = i; group_last != last; group_last++) {
|
|
size_t co = group_last->common_octets;
|
|
if (co <= depth) {
|
|
break;
|
|
}
|
|
if (co < next_depth) {
|
|
next_depth = co;
|
|
}
|
|
}
|
|
domain_mkxrefs(i, group_last, next_depth);
|
|
|
|
i = group_last;
|
|
if (i == last) {
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (depth == 0) {
|
|
return;
|
|
}
|
|
|
|
i = doms;
|
|
do {
|
|
if (i != target && i->refdom == NULL) {
|
|
i->refdom = target;
|
|
i->common_octets = depth;
|
|
}
|
|
} while (i++ != last);
|
|
}
|
|
|
|
static size_t domain_compactify(CompactDomain *domains, size_t n)
|
|
{
|
|
uint8_t *start = domains->self->labels, *outptr = start;
|
|
size_t i;
|
|
|
|
for (i = 0; i < n; i++) {
|
|
CompactDomain *cd = domains[i].self;
|
|
CompactDomain *rd = cd->refdom;
|
|
|
|
if (rd != NULL) {
|
|
size_t moff = (rd->labels - start)
|
|
+ (rd->len - cd->common_octets);
|
|
if (moff < 0x3FFFu) {
|
|
cd->len -= cd->common_octets - 2;
|
|
cd->labels[cd->len - 1] = moff & 0xFFu;
|
|
cd->labels[cd->len - 2] = 0xC0u | (moff >> 8);
|
|
}
|
|
}
|
|
|
|
if (cd->labels != outptr) {
|
|
memmove(outptr, cd->labels, cd->len);
|
|
cd->labels = outptr;
|
|
}
|
|
outptr += cd->len;
|
|
}
|
|
return outptr - start;
|
|
}
|
|
|
|
int translate_dnssearch(Slirp *s, const char **names)
|
|
{
|
|
size_t blocks, bsrc_start, bsrc_end, bdst_start;
|
|
size_t i, num_domains, memreq = 0;
|
|
uint8_t *result = NULL, *outptr;
|
|
CompactDomain *domains = NULL;
|
|
const char **nameptr = names;
|
|
|
|
while (*nameptr != NULL) {
|
|
nameptr++;
|
|
}
|
|
|
|
num_domains = nameptr - names;
|
|
if (num_domains == 0) {
|
|
return -2;
|
|
}
|
|
|
|
domains = g_malloc(num_domains * sizeof(*domains));
|
|
|
|
for (i = 0; i < num_domains; i++) {
|
|
size_t nlen = strlen(names[i]);
|
|
memreq += nlen + 2; /* 1 zero octet + 1 label length octet */
|
|
domains[i].self = domains + i;
|
|
domains[i].len = nlen;
|
|
domains[i].common_octets = 0;
|
|
domains[i].refdom = NULL;
|
|
}
|
|
|
|
/* reserve extra 2 header bytes for each 255 bytes of output */
|
|
memreq += DIV_ROUND_UP(memreq, MAX_OPT_LEN) * OPT_HEADER_LEN;
|
|
result = g_malloc(memreq * sizeof(*result));
|
|
|
|
outptr = result;
|
|
for (i = 0; i < num_domains; i++) {
|
|
domains[i].labels = outptr;
|
|
domain_mklabels(domains + i, names[i]);
|
|
outptr += domains[i].len;
|
|
}
|
|
|
|
if (outptr == result) {
|
|
g_free(domains);
|
|
g_free(result);
|
|
return -1;
|
|
}
|
|
|
|
qsort(domains, num_domains, sizeof(*domains), domain_suffix_ord);
|
|
domain_fixup_order(domains, num_domains);
|
|
|
|
for (i = 1; i < num_domains; i++) {
|
|
size_t cl = domain_common_label(domains + i - 1, domains + i);
|
|
domains[i - 1].common_octets = cl;
|
|
}
|
|
|
|
domain_mkxrefs(domains, domains + num_domains - 1, 0);
|
|
memreq = domain_compactify(domains, num_domains);
|
|
|
|
blocks = DIV_ROUND_UP(memreq, MAX_OPT_LEN);
|
|
bsrc_end = memreq;
|
|
bsrc_start = (blocks - 1) * MAX_OPT_LEN;
|
|
bdst_start = bsrc_start + blocks * OPT_HEADER_LEN;
|
|
memreq += blocks * OPT_HEADER_LEN;
|
|
|
|
while (blocks--) {
|
|
size_t len = bsrc_end - bsrc_start;
|
|
memmove(result + bdst_start, result + bsrc_start, len);
|
|
result[bdst_start - 2] = RFC3397_OPT_DOMAIN_SEARCH;
|
|
result[bdst_start - 1] = len;
|
|
bsrc_end = bsrc_start;
|
|
bsrc_start -= MAX_OPT_LEN;
|
|
bdst_start -= MAX_OPT_LEN + OPT_HEADER_LEN;
|
|
}
|
|
|
|
g_free(domains);
|
|
s->vdnssearch = result;
|
|
s->vdnssearch_len = memreq;
|
|
return 0;
|
|
}
|