slirp: Add domain-search option to slirp's DHCP server
This patch will allow the user to include the domain-search option in
replies from the built-in DHCP server. The domain suffixes can be
specified by adding dnssearch= entries to the "-net user" parameter.
[Jan: tiny style adjustments]
Signed-off-by: Klaus Stengel <Klaus.Stengel@asamnet.de>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
diff --git a/Makefile.objs b/Makefile.objs
index bb43d3c..2daa9dc 100644
--- a/Makefile.objs
+++ b/Makefile.objs
@@ -1,3 +1,3 @@
-common-obj-y = cksum.o if.o ip_icmp.o ip_input.o ip_output.o
+common-obj-y = cksum.o if.o ip_icmp.o ip_input.o ip_output.o dnssearch.o
common-obj-y += slirp.o mbuf.o misc.o sbuf.o socket.o tcp_input.o tcp_output.o
common-obj-y += tcp_subr.o tcp_timer.o udp.o bootp.o tftp.o arp_table.o
diff --git a/bootp.c b/bootp.c
index 5a2a027..8b057c1 100644
--- a/bootp.c
+++ b/bootp.c
@@ -292,6 +292,18 @@
memcpy(q, slirp->client_hostname, val);
q += val;
}
+
+ if (slirp->vdnssearch) {
+ size_t spaceleft = sizeof(rbp->bp_vend) - (q - rbp->bp_vend);
+ val = slirp->vdnssearch_len;
+ if (val + 1 > spaceleft) {
+ g_warning("DHCP packet size exceeded, "
+ "omitting domain-search option.");
+ } else {
+ memcpy(q, slirp->vdnssearch, val);
+ q += val;
+ }
+ }
} else {
static const char nak_msg[] = "requested address not available";
diff --git a/dnssearch.c b/dnssearch.c
new file mode 100644
index 0000000..522249e
--- /dev/null
+++ b/dnssearch.c
@@ -0,0 +1,314 @@
+/*
+ * 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;
+}
diff --git a/libslirp.h b/libslirp.h
index 8a47153..40a5568 100644
--- a/libslirp.h
+++ b/libslirp.h
@@ -12,7 +12,8 @@
struct in_addr vnetmask, struct in_addr vhost,
const char *vhostname, const char *tftp_path,
const char *bootfile, struct in_addr vdhcp_start,
- struct in_addr vnameserver, void *opaque);
+ struct in_addr vnameserver, const char **vdnssearch,
+ void *opaque);
void slirp_cleanup(Slirp *slirp);
void slirp_update_timeout(uint32_t *timeout);
diff --git a/slirp.c b/slirp.c
index fc2b75f..78e3983 100644
--- a/slirp.c
+++ b/slirp.c
@@ -202,7 +202,8 @@
struct in_addr vnetmask, struct in_addr vhost,
const char *vhostname, const char *tftp_path,
const char *bootfile, struct in_addr vdhcp_start,
- struct in_addr vnameserver, void *opaque)
+ struct in_addr vnameserver, const char **vdnssearch,
+ void *opaque)
{
Slirp *slirp = g_malloc0(sizeof(Slirp));
@@ -232,6 +233,10 @@
slirp->vdhcp_startaddr = vdhcp_start;
slirp->vnameserver_addr = vnameserver;
+ if (vdnssearch) {
+ translate_dnssearch(slirp, vdnssearch);
+ }
+
slirp->opaque = opaque;
register_savevm(NULL, "slirp", 0, 3, slirp_state_save, slirp_state_load,
@@ -251,6 +256,7 @@
ip_cleanup(slirp);
m_cleanup(slirp);
+ g_free(slirp->vdnssearch);
g_free(slirp->tftp_prefix);
g_free(slirp->bootp_filename);
g_free(slirp);
diff --git a/slirp.h b/slirp.h
index 26e327a..18d859d 100644
--- a/slirp.h
+++ b/slirp.h
@@ -235,6 +235,8 @@
/* bootp/dhcp states */
BOOTPClient bootp_clients[NB_BOOTP_CLIENTS];
char *bootp_filename;
+ size_t vdnssearch_len;
+ uint8_t *vdnssearch;
/* tcp states */
struct socket tcb;
@@ -294,6 +296,9 @@
#define SO_OPTIONS DO_KEEPALIVE
#define TCP_MAXIDLE (TCPTV_KEEPCNT * TCPTV_KEEPINTVL)
+/* dnssearch.c */
+int translate_dnssearch(Slirp *s, const char **names);
+
/* cksum.c */
int cksum(struct mbuf *m, int len);
