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xemu/slirp/ip6_icmp.c
Samuel Thibault a2f80fdfc6 slirp: Send RDNSS in RA only if host has an IPv6 DNS server 
Previously we would always send an RDNSS option in the RA, making the guest
try to resolve DNS through IPv6, even if the host does not actually have
and IPv6 DNS server available.

This makes the RDNSS option enabled only when an IPv6 DNS server is
available.

Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
2017-03-29 00:51:25 +02:00

442 lines
13 KiB
C
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/*
* Copyright (c) 2013
* Guillaume Subiron, Yann Bordenave, Serigne Modou Wagne.
*/
#include "qemu/osdep.h"
#include "slirp.h"
#include "ip6_icmp.h"
#include "qemu/timer.h"
#include "qemu/error-report.h"
#include "qemu/log.h"
#define NDP_Interval g_rand_int_range(slirp->grand, \
NDP_MinRtrAdvInterval, NDP_MaxRtrAdvInterval)
static void ra_timer_handler(void *opaque)
{
Slirp *slirp = opaque;
timer_mod(slirp->ra_timer,
qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) + NDP_Interval);
ndp_send_ra(slirp);
}
void icmp6_init(Slirp *slirp)
{
if (!slirp->in6_enabled) {
return;
}
slirp->ra_timer = timer_new_ms(QEMU_CLOCK_VIRTUAL, ra_timer_handler, slirp);
timer_mod(slirp->ra_timer,
qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) + NDP_Interval);
}
void icmp6_cleanup(Slirp *slirp)
{
if (!slirp->in6_enabled) {
return;
}
timer_del(slirp->ra_timer);
timer_free(slirp->ra_timer);
}
static void icmp6_send_echoreply(struct mbuf *m, Slirp *slirp, struct ip6 *ip,
struct icmp6 *icmp)
{
struct mbuf *t = m_get(slirp);
t->m_len = sizeof(struct ip6) + ntohs(ip->ip_pl);
memcpy(t->m_data, m->m_data, t->m_len);
/* IPv6 Packet */
struct ip6 *rip = mtod(t, struct ip6 *);
rip->ip_dst = ip->ip_src;
rip->ip_src = ip->ip_dst;
/* ICMPv6 packet */
t->m_data += sizeof(struct ip6);
struct icmp6 *ricmp = mtod(t, struct icmp6 *);
ricmp->icmp6_type = ICMP6_ECHO_REPLY;
ricmp->icmp6_cksum = 0;
/* Checksum */
t->m_data -= sizeof(struct ip6);
ricmp->icmp6_cksum = ip6_cksum(t);
ip6_output(NULL, t, 0);
}
void icmp6_send_error(struct mbuf *m, uint8_t type, uint8_t code)
{
Slirp *slirp = m->slirp;
struct mbuf *t;
struct ip6 *ip = mtod(m, struct ip6 *);
DEBUG_CALL("icmp6_send_error");
DEBUG_ARGS((dfd, " type = %d, code = %d\n", type, code));
if (IN6_IS_ADDR_MULTICAST(&ip->ip_src) ||
IN6_IS_ADDR_UNSPECIFIED(&ip->ip_src)) {
/* TODO icmp error? */
return;
}
t = m_get(slirp);
/* IPv6 packet */
struct ip6 *rip = mtod(t, struct ip6 *);
rip->ip_src = (struct in6_addr)LINKLOCAL_ADDR;
rip->ip_dst = ip->ip_src;
#if !defined(_WIN32) || (_WIN32_WINNT >= 0x0600)
char addrstr[INET6_ADDRSTRLEN];
inet_ntop(AF_INET6, &rip->ip_dst, addrstr, INET6_ADDRSTRLEN);
DEBUG_ARG("target = %s", addrstr);
#endif
rip->ip_nh = IPPROTO_ICMPV6;
const int error_data_len = MIN(m->m_len,
IF_MTU - (sizeof(struct ip6) + ICMP6_ERROR_MINLEN));
rip->ip_pl = htons(ICMP6_ERROR_MINLEN + error_data_len);
t->m_len = sizeof(struct ip6) + ntohs(rip->ip_pl);
/* ICMPv6 packet */
t->m_data += sizeof(struct ip6);
struct icmp6 *ricmp = mtod(t, struct icmp6 *);
ricmp->icmp6_type = type;
ricmp->icmp6_code = code;
ricmp->icmp6_cksum = 0;
switch (type) {
case ICMP6_UNREACH:
case ICMP6_TIMXCEED:
ricmp->icmp6_err.unused = 0;
break;
case ICMP6_TOOBIG:
ricmp->icmp6_err.mtu = htonl(IF_MTU);
break;
case ICMP6_PARAMPROB:
/* TODO: Handle this case */
break;
default:
g_assert_not_reached();
break;
}
t->m_data += ICMP6_ERROR_MINLEN;
memcpy(t->m_data, m->m_data, error_data_len);
/* Checksum */
t->m_data -= ICMP6_ERROR_MINLEN;
t->m_data -= sizeof(struct ip6);
ricmp->icmp6_cksum = ip6_cksum(t);
ip6_output(NULL, t, 0);
}
/*
* Send NDP Router Advertisement
*/
void ndp_send_ra(Slirp *slirp)
{
DEBUG_CALL("ndp_send_ra");
/* Build IPv6 packet */
struct mbuf *t = m_get(slirp);
struct ip6 *rip = mtod(t, struct ip6 *);
size_t pl_size = 0;
struct in6_addr addr;
uint32_t scope_id;
rip->ip_src = (struct in6_addr)LINKLOCAL_ADDR;
rip->ip_dst = (struct in6_addr)ALLNODES_MULTICAST;
rip->ip_nh = IPPROTO_ICMPV6;
/* Build ICMPv6 packet */
t->m_data += sizeof(struct ip6);
struct icmp6 *ricmp = mtod(t, struct icmp6 *);
ricmp->icmp6_type = ICMP6_NDP_RA;
ricmp->icmp6_code = 0;
ricmp->icmp6_cksum = 0;
/* NDP */
ricmp->icmp6_nra.chl = NDP_AdvCurHopLimit;
ricmp->icmp6_nra.M = NDP_AdvManagedFlag;
ricmp->icmp6_nra.O = NDP_AdvOtherConfigFlag;
ricmp->icmp6_nra.reserved = 0;
ricmp->icmp6_nra.lifetime = htons(NDP_AdvDefaultLifetime);
ricmp->icmp6_nra.reach_time = htonl(NDP_AdvReachableTime);
ricmp->icmp6_nra.retrans_time = htonl(NDP_AdvRetransTime);
t->m_data += ICMP6_NDP_RA_MINLEN;
pl_size += ICMP6_NDP_RA_MINLEN;
/* Source link-layer address (NDP option) */
struct ndpopt *opt = mtod(t, struct ndpopt *);
opt->ndpopt_type = NDPOPT_LINKLAYER_SOURCE;
opt->ndpopt_len = NDPOPT_LINKLAYER_LEN / 8;
in6_compute_ethaddr(rip->ip_src, opt->ndpopt_linklayer);
t->m_data += NDPOPT_LINKLAYER_LEN;
pl_size += NDPOPT_LINKLAYER_LEN;
/* Prefix information (NDP option) */
struct ndpopt *opt2 = mtod(t, struct ndpopt *);
opt2->ndpopt_type = NDPOPT_PREFIX_INFO;
opt2->ndpopt_len = NDPOPT_PREFIXINFO_LEN / 8;
opt2->ndpopt_prefixinfo.prefix_length = slirp->vprefix_len;
opt2->ndpopt_prefixinfo.L = 1;
opt2->ndpopt_prefixinfo.A = 1;
opt2->ndpopt_prefixinfo.reserved1 = 0;
opt2->ndpopt_prefixinfo.valid_lt = htonl(NDP_AdvValidLifetime);
opt2->ndpopt_prefixinfo.pref_lt = htonl(NDP_AdvPrefLifetime);
opt2->ndpopt_prefixinfo.reserved2 = 0;
opt2->ndpopt_prefixinfo.prefix = slirp->vprefix_addr6;
t->m_data += NDPOPT_PREFIXINFO_LEN;
pl_size += NDPOPT_PREFIXINFO_LEN;
/* Prefix information (NDP option) */
if (get_dns6_addr(&addr, &scope_id) >= 0) {
/* Host system does have an IPv6 DNS server, announce our proxy. */
struct ndpopt *opt3 = mtod(t, struct ndpopt *);
opt3->ndpopt_type = NDPOPT_RDNSS;
opt3->ndpopt_len = NDPOPT_RDNSS_LEN / 8;
opt3->ndpopt_rdnss.reserved = 0;
opt3->ndpopt_rdnss.lifetime = htonl(2 * NDP_MaxRtrAdvInterval);
opt3->ndpopt_rdnss.addr = slirp->vnameserver_addr6;
t->m_data += NDPOPT_RDNSS_LEN;
pl_size += NDPOPT_RDNSS_LEN;
}
rip->ip_pl = htons(pl_size);
t->m_data -= sizeof(struct ip6) + pl_size;
t->m_len = sizeof(struct ip6) + pl_size;
/* ICMPv6 Checksum */
ricmp->icmp6_cksum = ip6_cksum(t);
ip6_output(NULL, t, 0);
}
/*
* Send NDP Neighbor Solitication
*/
void ndp_send_ns(Slirp *slirp, struct in6_addr addr)
{
DEBUG_CALL("ndp_send_ns");
#if !defined(_WIN32) || (_WIN32_WINNT >= 0x0600)
char addrstr[INET6_ADDRSTRLEN];
inet_ntop(AF_INET6, &addr, addrstr, INET6_ADDRSTRLEN);
DEBUG_ARG("target = %s", addrstr);
#endif
/* Build IPv6 packet */
struct mbuf *t = m_get(slirp);
struct ip6 *rip = mtod(t, struct ip6 *);
rip->ip_src = slirp->vhost_addr6;
rip->ip_dst = (struct in6_addr)SOLICITED_NODE_PREFIX;
memcpy(&rip->ip_dst.s6_addr[13], &addr.s6_addr[13], 3);
rip->ip_nh = IPPROTO_ICMPV6;
rip->ip_pl = htons(ICMP6_NDP_NS_MINLEN + NDPOPT_LINKLAYER_LEN);
t->m_len = sizeof(struct ip6) + ntohs(rip->ip_pl);
/* Build ICMPv6 packet */
t->m_data += sizeof(struct ip6);
struct icmp6 *ricmp = mtod(t, struct icmp6 *);
ricmp->icmp6_type = ICMP6_NDP_NS;
ricmp->icmp6_code = 0;
ricmp->icmp6_cksum = 0;
/* NDP */
ricmp->icmp6_nns.reserved = 0;
ricmp->icmp6_nns.target = addr;
/* Build NDP option */
t->m_data += ICMP6_NDP_NS_MINLEN;
struct ndpopt *opt = mtod(t, struct ndpopt *);
opt->ndpopt_type = NDPOPT_LINKLAYER_SOURCE;
opt->ndpopt_len = NDPOPT_LINKLAYER_LEN / 8;
in6_compute_ethaddr(slirp->vhost_addr6, opt->ndpopt_linklayer);
/* ICMPv6 Checksum */
t->m_data -= ICMP6_NDP_NA_MINLEN;
t->m_data -= sizeof(struct ip6);
ricmp->icmp6_cksum = ip6_cksum(t);
ip6_output(NULL, t, 1);
}
/*
* Send NDP Neighbor Advertisement
*/
static void ndp_send_na(Slirp *slirp, struct ip6 *ip, struct icmp6 *icmp)
{
/* Build IPv6 packet */
struct mbuf *t = m_get(slirp);
struct ip6 *rip = mtod(t, struct ip6 *);
rip->ip_src = icmp->icmp6_nns.target;
if (IN6_IS_ADDR_UNSPECIFIED(&ip->ip_src)) {
rip->ip_dst = (struct in6_addr)ALLNODES_MULTICAST;
} else {
rip->ip_dst = ip->ip_src;
}
rip->ip_nh = IPPROTO_ICMPV6;
rip->ip_pl = htons(ICMP6_NDP_NA_MINLEN
+ NDPOPT_LINKLAYER_LEN);
t->m_len = sizeof(struct ip6) + ntohs(rip->ip_pl);
/* Build ICMPv6 packet */
t->m_data += sizeof(struct ip6);
struct icmp6 *ricmp = mtod(t, struct icmp6 *);
ricmp->icmp6_type = ICMP6_NDP_NA;
ricmp->icmp6_code = 0;
ricmp->icmp6_cksum = 0;
/* NDP */
ricmp->icmp6_nna.R = NDP_IsRouter;
ricmp->icmp6_nna.S = !IN6_IS_ADDR_MULTICAST(&rip->ip_dst);
ricmp->icmp6_nna.O = 1;
ricmp->icmp6_nna.reserved_hi = 0;
ricmp->icmp6_nna.reserved_lo = 0;
ricmp->icmp6_nna.target = icmp->icmp6_nns.target;
/* Build NDP option */
t->m_data += ICMP6_NDP_NA_MINLEN;
struct ndpopt *opt = mtod(t, struct ndpopt *);
opt->ndpopt_type = NDPOPT_LINKLAYER_TARGET;
opt->ndpopt_len = NDPOPT_LINKLAYER_LEN / 8;
in6_compute_ethaddr(ricmp->icmp6_nna.target,
opt->ndpopt_linklayer);
/* ICMPv6 Checksum */
t->m_data -= ICMP6_NDP_NA_MINLEN;
t->m_data -= sizeof(struct ip6);
ricmp->icmp6_cksum = ip6_cksum(t);
ip6_output(NULL, t, 0);
}
/*
* Process a NDP message
*/
static void ndp_input(struct mbuf *m, Slirp *slirp, struct ip6 *ip,
struct icmp6 *icmp)
{
m->m_len += ETH_HLEN;
m->m_data -= ETH_HLEN;
struct ethhdr *eth = mtod(m, struct ethhdr *);
m->m_len -= ETH_HLEN;
m->m_data += ETH_HLEN;
switch (icmp->icmp6_type) {
case ICMP6_NDP_RS:
DEBUG_CALL(" type = Router Solicitation");
if (ip->ip_hl == 255
&& icmp->icmp6_code == 0
&& ntohs(ip->ip_pl) >= ICMP6_NDP_RS_MINLEN) {
/* Gratuitous NDP */
ndp_table_add(slirp, ip->ip_src, eth->h_source);
ndp_send_ra(slirp);
}
break;
case ICMP6_NDP_RA:
DEBUG_CALL(" type = Router Advertisement");
qemu_log_mask(LOG_GUEST_ERROR,
"Warning: guest sent NDP RA, but shouldn't");
break;
case ICMP6_NDP_NS:
DEBUG_CALL(" type = Neighbor Solicitation");
if (ip->ip_hl == 255
&& icmp->icmp6_code == 0
&& !IN6_IS_ADDR_MULTICAST(&icmp->icmp6_nns.target)
&& ntohs(ip->ip_pl) >= ICMP6_NDP_NS_MINLEN
&& (!IN6_IS_ADDR_UNSPECIFIED(&ip->ip_src)
|| in6_solicitednode_multicast(&ip->ip_dst))) {
if (in6_equal_host(&icmp->icmp6_nns.target)) {
/* Gratuitous NDP */
ndp_table_add(slirp, ip->ip_src, eth->h_source);
ndp_send_na(slirp, ip, icmp);
}
}
break;
case ICMP6_NDP_NA:
DEBUG_CALL(" type = Neighbor Advertisement");
if (ip->ip_hl == 255
&& icmp->icmp6_code == 0
&& ntohs(ip->ip_pl) >= ICMP6_NDP_NA_MINLEN
&& !IN6_IS_ADDR_MULTICAST(&icmp->icmp6_nna.target)
&& (!IN6_IS_ADDR_MULTICAST(&ip->ip_dst)
|| icmp->icmp6_nna.S == 0)) {
ndp_table_add(slirp, ip->ip_src, eth->h_source);
}
break;
case ICMP6_NDP_REDIRECT:
DEBUG_CALL(" type = Redirect");
qemu_log_mask(LOG_GUEST_ERROR,
"Warning: guest sent NDP REDIRECT, but shouldn't");
break;
}
}
/*
* Process a received ICMPv6 message.
*/
void icmp6_input(struct mbuf *m)
{
struct icmp6 *icmp;
struct ip6 *ip = mtod(m, struct ip6 *);
Slirp *slirp = m->slirp;
int hlen = sizeof(struct ip6);
DEBUG_CALL("icmp6_input");
DEBUG_ARG("m = %lx", (long) m);
DEBUG_ARG("m_len = %d", m->m_len);
if (ntohs(ip->ip_pl) < ICMP6_MINLEN) {
goto end;
}
if (ip6_cksum(m)) {
goto end;
}
m->m_len -= hlen;
m->m_data += hlen;
icmp = mtod(m, struct icmp6 *);
m->m_len += hlen;
m->m_data -= hlen;
DEBUG_ARG("icmp6_type = %d", icmp->icmp6_type);
switch (icmp->icmp6_type) {
case ICMP6_ECHO_REQUEST:
if (in6_equal_host(&ip->ip_dst)) {
icmp6_send_echoreply(m, slirp, ip, icmp);
} else {
/* TODO */
error_report("external icmpv6 not supported yet");
}
break;
case ICMP6_NDP_RS:
case ICMP6_NDP_RA:
case ICMP6_NDP_NS:
case ICMP6_NDP_NA:
case ICMP6_NDP_REDIRECT:
ndp_input(m, slirp, ip, icmp);
break;
case ICMP6_UNREACH:
case ICMP6_TOOBIG:
case ICMP6_TIMXCEED:
case ICMP6_PARAMPROB:
/* XXX? report error? close socket? */
default:
break;
}
end:
m_free(m);
}
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