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/*
* SLIRP stateless DHCPv6
*
* We only support stateless DHCPv6, e.g. for network booting.
* See RFC 3315, RFC 3736, RFC 3646 and RFC 5970 for details.
*
* Copyright 2016 Thomas Huth, Red Hat Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License,
* or (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
#include "qemu/osdep.h"
#include "qemu/log.h"
#include "slirp.h"
#include "dhcpv6.h"
/* DHCPv6 message types */
#define MSGTYPE_REPLY 7
#define MSGTYPE_INFO_REQUEST 11
/* DHCPv6 option types */
#define OPTION_CLIENTID 1
#define OPTION_IAADDR 5
#define OPTION_ORO 6
#define OPTION_DNS_SERVERS 23
#define OPTION_BOOTFILE_URL 59
struct requested_infos {
uint8_t *client_id;
int client_id_len;
bool want_dns;
bool want_boot_url;
};
/**
* Analyze the info request message sent by the client to see what data it
* provided and what it wants to have. The information is gathered in the
* "requested_infos" struct. Note that client_id (if provided) points into
* the odata region, thus the caller must keep odata valid as long as it
* needs to access the requested_infos struct.
*/
static int dhcpv6_parse_info_request(uint8_t *odata, int olen,
struct requested_infos *ri)
{
int i, req_opt;
while (olen > 4) {
/* Parse one option */
int option = odata[0] << 8 | odata[1];
int len = odata[2] << 8 | odata[3];
if (len + 4 > olen) {
qemu_log_mask(LOG_GUEST_ERROR, "Guest sent bad DHCPv6 packet!\n");
return -E2BIG;
}
switch (option) {
case OPTION_IAADDR:
/* According to RFC3315, we must discard requests with IA option */
return -EINVAL;
case OPTION_CLIENTID:
if (len > 256) {
/* Avoid very long IDs which could cause problems later */
return -E2BIG;
}
ri->client_id = odata + 4;
ri->client_id_len = len;
break;
case OPTION_ORO: /* Option request option */
if (len & 1) {
return -EINVAL;
}
/* Check which options the client wants to have */
for (i = 0; i < len; i += 2) {
req_opt = odata[4 + i] << 8 | odata[4 + i + 1];
switch (req_opt) {
case OPTION_DNS_SERVERS:
ri->want_dns = true;
break;
case OPTION_BOOTFILE_URL:
ri->want_boot_url = true;
break;
default:
DEBUG_MISC("dhcpv6: Unsupported option request %d\n",
req_opt);
}
}
break;
default:
DEBUG_MISC("dhcpv6 info req: Unsupported option %d, len=%d\n",
option, len);
}
odata += len + 4;
olen -= len + 4;
}
return 0;
}
/**
* Handle information request messages
*/
static void dhcpv6_info_request(Slirp *slirp, struct sockaddr_in6 *srcsas,
uint32_t xid, uint8_t *odata, int olen)
{
struct requested_infos ri = { NULL };
struct sockaddr_in6 sa6, da6;
struct mbuf *m;
uint8_t *resp;
if (dhcpv6_parse_info_request(odata, olen, &ri) < 0) {
return;
}
m = m_get(slirp);
if (!m) {
return;
}
memset(m->m_data, 0, m->m_size);
m->m_data += IF_MAXLINKHDR;
resp = (uint8_t *)m->m_data + sizeof(struct ip6) + sizeof(struct udphdr);
/* Fill in response */
*resp++ = MSGTYPE_REPLY;
*resp++ = (uint8_t)(xid >> 16);
*resp++ = (uint8_t)(xid >> 8);
*resp++ = (uint8_t)xid;
if (ri.client_id) {
*resp++ = OPTION_CLIENTID >> 8; /* option-code high byte */
*resp++ = OPTION_CLIENTID; /* option-code low byte */
*resp++ = ri.client_id_len >> 8; /* option-len high byte */
*resp++ = ri.client_id_len; /* option-len low byte */
memcpy(resp, ri.client_id, ri.client_id_len);
resp += ri.client_id_len;
}
if (ri.want_dns) {
*resp++ = OPTION_DNS_SERVERS >> 8; /* option-code high byte */
*resp++ = OPTION_DNS_SERVERS; /* option-code low byte */
*resp++ = 0; /* option-len high byte */
*resp++ = 16; /* option-len low byte */
memcpy(resp, &slirp->vnameserver_addr6, 16);
resp += 16;
}
if (ri.want_boot_url) {
uint8_t *sa = slirp->vhost_addr6.s6_addr;
int slen, smaxlen;
*resp++ = OPTION_BOOTFILE_URL >> 8; /* option-code high byte */
*resp++ = OPTION_BOOTFILE_URL; /* option-code low byte */
smaxlen = (uint8_t *)m->m_data + IF_MTU - (resp + 2);
slen = snprintf((char *)resp + 2, smaxlen,
"tftp://[%02x%02x:%02x%02x:%02x%02x:%02x%02x:"
"%02x%02x:%02x%02x:%02x%02x:%02x%02x]/%s",
sa[0], sa[1], sa[2], sa[3], sa[4], sa[5], sa[6], sa[7],
sa[8], sa[9], sa[10], sa[11], sa[12], sa[13], sa[14],
sa[15], slirp->bootp_filename);
slen = MIN(slen, smaxlen);
*resp++ = slen >> 8; /* option-len high byte */
*resp++ = slen; /* option-len low byte */
resp += slen;
}
sa6.sin6_addr = slirp->vhost_addr6;
sa6.sin6_port = DHCPV6_SERVER_PORT;
da6.sin6_addr = srcsas->sin6_addr;
da6.sin6_port = srcsas->sin6_port;
m->m_data += sizeof(struct ip6) + sizeof(struct udphdr);
m->m_len = resp - (uint8_t *)m->m_data;
udp6_output(NULL, m, &sa6, &da6);
}
/**
* Handle DHCPv6 messages sent by the client
*/
void dhcpv6_input(struct sockaddr_in6 *srcsas, struct mbuf *m)
{
uint8_t *data = (uint8_t *)m->m_data + sizeof(struct udphdr);
int data_len = m->m_len - sizeof(struct udphdr);
uint32_t xid;
if (data_len < 4) {
return;
}
xid = ntohl(*(uint32_t *)data) & 0xffffff;
switch (data[0]) {
case MSGTYPE_INFO_REQUEST:
dhcpv6_info_request(m->slirp, srcsas, xid, &data[4], data_len - 4);
break;
default:
DEBUG_MISC("dhcpv6_input: Unsupported message type 0x%x\n", data[0]);
}
}
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