--- /dev/null
+/*
+ * 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 <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+#include <glib.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 += ((memreq + MAX_OPT_LEN - 1) / 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 = (memreq + MAX_OPT_LEN - 1) / 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;
+}
Code Review / kvmfornfv.git / blobdiff