Thomas Huth | 7b14399 | 2016-06-28 12:48:31 +0200 | [diff] [blame] | 1 | /* |
| 2 | * SLIRP stateless DHCPv6 |
| 3 | * |
| 4 | * We only support stateless DHCPv6, e.g. for network booting. |
| 5 | * See RFC 3315, RFC 3736, RFC 3646 and RFC 5970 for details. |
| 6 | * |
| 7 | * Copyright 2016 Thomas Huth, Red Hat Inc. |
| 8 | * |
| 9 | * This program is free software; you can redistribute it and/or modify |
| 10 | * it under the terms of the GNU General Public License as published by |
| 11 | * the Free Software Foundation; either version 2 of the License, |
| 12 | * or (at your option) any later version. |
| 13 | * |
| 14 | * This program is distributed in the hope that it will be useful, |
| 15 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 16 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 17 | * GNU General Public License for more details. |
| 18 | * |
| 19 | * You should have received a copy of the GNU General Public License |
| 20 | * along with this program; if not, see <http://www.gnu.org/licenses/>. |
| 21 | */ |
| 22 | |
| 23 | #include "qemu/osdep.h" |
| 24 | #include "qemu/log.h" |
| 25 | #include "slirp.h" |
| 26 | #include "dhcpv6.h" |
| 27 | |
| 28 | /* DHCPv6 message types */ |
| 29 | #define MSGTYPE_REPLY 7 |
| 30 | #define MSGTYPE_INFO_REQUEST 11 |
| 31 | |
| 32 | /* DHCPv6 option types */ |
| 33 | #define OPTION_CLIENTID 1 |
| 34 | #define OPTION_IAADDR 5 |
| 35 | #define OPTION_ORO 6 |
| 36 | #define OPTION_DNS_SERVERS 23 |
| 37 | #define OPTION_BOOTFILE_URL 59 |
| 38 | |
| 39 | struct requested_infos { |
| 40 | uint8_t *client_id; |
| 41 | int client_id_len; |
| 42 | bool want_dns; |
| 43 | bool want_boot_url; |
| 44 | }; |
| 45 | |
| 46 | /** |
| 47 | * Analyze the info request message sent by the client to see what data it |
| 48 | * provided and what it wants to have. The information is gathered in the |
| 49 | * "requested_infos" struct. Note that client_id (if provided) points into |
| 50 | * the odata region, thus the caller must keep odata valid as long as it |
| 51 | * needs to access the requested_infos struct. |
| 52 | */ |
| 53 | static int dhcpv6_parse_info_request(uint8_t *odata, int olen, |
| 54 | struct requested_infos *ri) |
| 55 | { |
| 56 | int i, req_opt; |
| 57 | |
| 58 | while (olen > 4) { |
| 59 | /* Parse one option */ |
| 60 | int option = odata[0] << 8 | odata[1]; |
| 61 | int len = odata[2] << 8 | odata[3]; |
| 62 | |
| 63 | if (len + 4 > olen) { |
| 64 | qemu_log_mask(LOG_GUEST_ERROR, "Guest sent bad DHCPv6 packet!\n"); |
| 65 | return -E2BIG; |
| 66 | } |
| 67 | |
| 68 | switch (option) { |
| 69 | case OPTION_IAADDR: |
| 70 | /* According to RFC3315, we must discard requests with IA option */ |
| 71 | return -EINVAL; |
| 72 | case OPTION_CLIENTID: |
| 73 | if (len > 256) { |
| 74 | /* Avoid very long IDs which could cause problems later */ |
| 75 | return -E2BIG; |
| 76 | } |
| 77 | ri->client_id = odata + 4; |
| 78 | ri->client_id_len = len; |
| 79 | break; |
| 80 | case OPTION_ORO: /* Option request option */ |
| 81 | if (len & 1) { |
| 82 | return -EINVAL; |
| 83 | } |
| 84 | /* Check which options the client wants to have */ |
| 85 | for (i = 0; i < len; i += 2) { |
| 86 | req_opt = odata[4 + i] << 8 | odata[4 + i + 1]; |
| 87 | switch (req_opt) { |
| 88 | case OPTION_DNS_SERVERS: |
| 89 | ri->want_dns = true; |
| 90 | break; |
| 91 | case OPTION_BOOTFILE_URL: |
| 92 | ri->want_boot_url = true; |
| 93 | break; |
| 94 | default: |
| 95 | DEBUG_MISC((dfd, "dhcpv6: Unsupported option request %d\n", |
| 96 | req_opt)); |
| 97 | } |
| 98 | } |
| 99 | break; |
| 100 | default: |
| 101 | DEBUG_MISC((dfd, "dhcpv6 info req: Unsupported option %d, len=%d\n", |
| 102 | option, len)); |
| 103 | } |
| 104 | |
| 105 | odata += len + 4; |
| 106 | olen -= len + 4; |
| 107 | } |
| 108 | |
| 109 | return 0; |
| 110 | } |
| 111 | |
| 112 | |
| 113 | /** |
| 114 | * Handle information request messages |
| 115 | */ |
| 116 | static void dhcpv6_info_request(Slirp *slirp, struct sockaddr_in6 *srcsas, |
| 117 | uint32_t xid, uint8_t *odata, int olen) |
| 118 | { |
| 119 | struct requested_infos ri = { NULL }; |
| 120 | struct sockaddr_in6 sa6, da6; |
| 121 | struct mbuf *m; |
| 122 | uint8_t *resp; |
| 123 | |
| 124 | if (dhcpv6_parse_info_request(odata, olen, &ri) < 0) { |
| 125 | return; |
| 126 | } |
| 127 | |
| 128 | m = m_get(slirp); |
| 129 | if (!m) { |
| 130 | return; |
| 131 | } |
| 132 | memset(m->m_data, 0, m->m_size); |
| 133 | m->m_data += IF_MAXLINKHDR; |
| 134 | resp = (uint8_t *)m->m_data + sizeof(struct ip6) + sizeof(struct udphdr); |
| 135 | |
| 136 | /* Fill in response */ |
| 137 | *resp++ = MSGTYPE_REPLY; |
| 138 | *resp++ = (uint8_t)(xid >> 16); |
| 139 | *resp++ = (uint8_t)(xid >> 8); |
| 140 | *resp++ = (uint8_t)xid; |
| 141 | |
| 142 | if (ri.client_id) { |
| 143 | *resp++ = OPTION_CLIENTID >> 8; /* option-code high byte */ |
| 144 | *resp++ = OPTION_CLIENTID; /* option-code low byte */ |
| 145 | *resp++ = ri.client_id_len >> 8; /* option-len high byte */ |
| 146 | *resp++ = ri.client_id_len; /* option-len low byte */ |
| 147 | memcpy(resp, ri.client_id, ri.client_id_len); |
| 148 | resp += ri.client_id_len; |
| 149 | } |
| 150 | if (ri.want_dns) { |
| 151 | *resp++ = OPTION_DNS_SERVERS >> 8; /* option-code high byte */ |
| 152 | *resp++ = OPTION_DNS_SERVERS; /* option-code low byte */ |
| 153 | *resp++ = 0; /* option-len high byte */ |
| 154 | *resp++ = 16; /* option-len low byte */ |
| 155 | memcpy(resp, &slirp->vnameserver_addr6, 16); |
| 156 | resp += 16; |
| 157 | } |
| 158 | if (ri.want_boot_url) { |
| 159 | uint8_t *sa = slirp->vhost_addr6.s6_addr; |
| 160 | int slen, smaxlen; |
| 161 | |
| 162 | *resp++ = OPTION_BOOTFILE_URL >> 8; /* option-code high byte */ |
| 163 | *resp++ = OPTION_BOOTFILE_URL; /* option-code low byte */ |
| 164 | smaxlen = (uint8_t *)m->m_data + IF_MTU - (resp + 2); |
| 165 | slen = snprintf((char *)resp + 2, smaxlen, |
| 166 | "tftp://[%02x%02x:%02x%02x:%02x%02x:%02x%02x:" |
| 167 | "%02x%02x:%02x%02x:%02x%02x:%02x%02x]/%s", |
| 168 | sa[0], sa[1], sa[2], sa[3], sa[4], sa[5], sa[6], sa[7], |
| 169 | sa[8], sa[9], sa[10], sa[11], sa[12], sa[13], sa[14], |
| 170 | sa[15], slirp->bootp_filename); |
Yuval Shaia | 893dcdb | 2016-11-29 17:07:34 +0200 | [diff] [blame] | 171 | slen = MIN(slen, smaxlen); |
Thomas Huth | 7b14399 | 2016-06-28 12:48:31 +0200 | [diff] [blame] | 172 | *resp++ = slen >> 8; /* option-len high byte */ |
| 173 | *resp++ = slen; /* option-len low byte */ |
| 174 | resp += slen; |
| 175 | } |
| 176 | |
| 177 | sa6.sin6_addr = slirp->vhost_addr6; |
| 178 | sa6.sin6_port = DHCPV6_SERVER_PORT; |
| 179 | da6.sin6_addr = srcsas->sin6_addr; |
| 180 | da6.sin6_port = srcsas->sin6_port; |
| 181 | m->m_data += sizeof(struct ip6) + sizeof(struct udphdr); |
| 182 | m->m_len = resp - (uint8_t *)m->m_data; |
| 183 | udp6_output(NULL, m, &sa6, &da6); |
| 184 | } |
| 185 | |
| 186 | /** |
| 187 | * Handle DHCPv6 messages sent by the client |
| 188 | */ |
| 189 | void dhcpv6_input(struct sockaddr_in6 *srcsas, struct mbuf *m) |
| 190 | { |
| 191 | uint8_t *data = (uint8_t *)m->m_data + sizeof(struct udphdr); |
| 192 | int data_len = m->m_len - sizeof(struct udphdr); |
| 193 | uint32_t xid; |
| 194 | |
| 195 | if (data_len < 4) { |
| 196 | return; |
| 197 | } |
| 198 | |
| 199 | xid = ntohl(*(uint32_t *)data) & 0xffffff; |
| 200 | |
| 201 | switch (data[0]) { |
| 202 | case MSGTYPE_INFO_REQUEST: |
| 203 | dhcpv6_info_request(m->slirp, srcsas, xid, &data[4], data_len - 4); |
| 204 | break; |
| 205 | default: |
| 206 | DEBUG_MISC((dfd, "dhcpv6_input: Unsupported message type 0x%x\n", |
| 207 | data[0])); |
| 208 | } |
| 209 | } |