| 1 | /* -*- indent-tabs-mode: nil; -*- */
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| 2 | /**
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| 3 | * Simple stateless DHCPv6 (RFC 3736) server.
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| 4 | */
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| 5 | #include "winutils.h"
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| 6 | #include "dhcp6.h"
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| 7 | #include "proxy.h"
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| 8 |
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| 9 | #include <string.h>
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| 10 |
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| 11 | #include "lwip/opt.h"
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| 12 | #include "lwip/mld6.h"
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| 13 | #include "lwip/udp.h"
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| 14 |
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| 15 |
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| 16 | static void dhcp6ds_recv(void *, struct udp_pcb *, struct pbuf *, ip6_addr_t *, u16_t);
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| 17 |
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| 18 |
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| 19 | /* ff02::1:2 - "All_DHCP_Relay_Agents_and_Servers" link-scoped multicast */
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| 20 | static /* const */ ip6_addr_t all_dhcp_relays_and_servers = {
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| 21 | { PP_HTONL(0xff020000UL), 0, 0, PP_HTONL(0x00010002UL) }
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| 22 | };
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| 23 |
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| 24 | /* ff05::1:3 - "All_DHCP_Servers" site-scoped multicast */
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| 25 | static /* const */ ip6_addr_t all_dhcp_servers = {
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| 26 | { PP_HTONL(0xff050000UL), 0, 0, PP_HTONL(0x00010003UL) }
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| 27 | };
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| 28 |
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| 29 |
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| 30 | static struct udp_pcb *dhcp6ds_pcb;
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| 31 |
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| 32 | /* prebuilt Server ID option */
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| 33 | #define DUID_LL_LEN (/* duid type */ 2 + /* hw type */ 2 + /* ether addr */ 6)
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| 34 | static u8_t dhcp6ds_serverid[/* opt */ 2 + /* optlen */ 2 + DUID_LL_LEN];
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| 35 |
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| 36 | /* prebuilt DNS Servers option */
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| 37 | static u8_t dhcp6ds_dns[/* opt */ 2 + /* optlen */ 2 + /* IPv6 addr */ 16];
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| 38 |
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| 39 |
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| 40 | /**
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| 41 | * Initialize DHCP6 server.
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| 42 | *
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| 43 | * Join DHCP6 multicast groups.
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| 44 | * Create and bind server pcb.
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| 45 | * Prebuild fixed parts of reply.
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| 46 | */
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| 47 | err_t
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| 48 | dhcp6ds_init(struct netif *proxy_netif)
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| 49 | {
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| 50 | ip6_addr_t *pxaddr, *pxaddr_nonlocal;
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| 51 | int i;
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| 52 | err_t error;
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| 53 |
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| 54 | LWIP_ASSERT1(proxy_netif != NULL);
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| 55 | LWIP_ASSERT1(proxy_netif->hwaddr_len == 6); /* ethernet */
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| 56 |
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| 57 | pxaddr = netif_ip6_addr(proxy_netif, 0); /* link local */
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| 58 |
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| 59 | /*
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| 60 | * XXX: TODO: This is a leftover from testing with IPv6 mapped
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| 61 | * loopback with a special IPv6->IPv4 mapping hack in pxudp.c
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| 62 | */
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| 63 | /* advertise ourself as DNS resolver - will be proxied to host */
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| 64 | pxaddr_nonlocal = NULL;
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| 65 | for (i = 1; i < LWIP_IPV6_NUM_ADDRESSES; ++i) {
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| 66 | if (ip6_addr_ispreferred(netif_ip6_addr_state(proxy_netif, i))
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| 67 | && !ip6_addr_islinklocal(netif_ip6_addr(proxy_netif, i)))
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| 68 | {
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| 69 | pxaddr_nonlocal = netif_ip6_addr(proxy_netif, i);
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| 70 | break;
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| 71 | }
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| 72 | }
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| 73 | LWIP_ASSERT1(pxaddr_nonlocal != NULL); /* must be configured on the netif */
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| 74 |
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| 75 |
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| 76 | error = mld6_joingroup(pxaddr, &all_dhcp_relays_and_servers);
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| 77 | if (error != ERR_OK) {
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| 78 | DPRINTF0(("%s: failed to join All_DHCP_Relay_Agents_and_Servers: %s\n",
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| 79 | __func__, proxy_lwip_strerr(error)));
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| 80 | goto err;
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| 81 | }
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| 82 |
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| 83 | error = mld6_joingroup(pxaddr, &all_dhcp_servers);
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| 84 | if (error != ERR_OK) {
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| 85 | DPRINTF0(("%s: failed to join All_DHCP_Servers: %s\n",
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| 86 | __func__, proxy_lwip_strerr(error)));
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| 87 | goto err1;
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| 88 | }
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| 89 |
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| 90 |
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| 91 | dhcp6ds_pcb = udp_new_ip6();
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| 92 | if (dhcp6ds_pcb == NULL) {
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| 93 | DPRINTF0(("%s: failed to allocate PCB\n", __func__));
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| 94 | error = ERR_MEM;
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| 95 | goto err2;
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| 96 | }
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| 97 |
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| 98 | udp_recv_ip6(dhcp6ds_pcb, dhcp6ds_recv, NULL);
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| 99 |
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| 100 | error = udp_bind_ip6(dhcp6ds_pcb, pxaddr, DHCP6_SERVER_PORT);
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| 101 | if (error != ERR_OK) {
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| 102 | DPRINTF0(("%s: failed to bind PCB\n", __func__));
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| 103 | goto err3;
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| 104 | }
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| 105 |
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| 106 |
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| 107 | #define OPT_SET(buf, off, c) do { \
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| 108 | u16_t _s = PP_HTONS(c); \
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| 109 | memcpy(&(buf)[off], &_s, sizeof(u16_t)); \
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| 110 | } while (0)
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| 111 |
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| 112 | #define SERVERID_SET(off, c) OPT_SET(dhcp6ds_serverid, (off), (c))
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| 113 | #define DNSSRV_SET(off, c) OPT_SET(dhcp6ds_dns, (off), (c))
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| 114 |
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| 115 | SERVERID_SET(0, DHCP6_OPTION_SERVERID);
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| 116 | SERVERID_SET(2, DUID_LL_LEN);
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| 117 | SERVERID_SET(4, DHCP6_DUID_LL);
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| 118 | SERVERID_SET(6, ARES_HRD_ETHERNET);
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| 119 | memcpy(&dhcp6ds_serverid[8], proxy_netif->hwaddr, 6);
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| 120 |
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| 121 | DNSSRV_SET(0, DHCP6_OPTION_DNS_SERVERS);
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| 122 | DNSSRV_SET(2, 16); /* one IPv6 address */
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| 123 | /*
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| 124 | * XXX: TODO: This is a leftover from testing with IPv6 mapped
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| 125 | * loopback with a special IPv6->IPv4 mapping hack in pxudp.c
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| 126 | */
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| 127 | memcpy(&dhcp6ds_dns[4], pxaddr_nonlocal, sizeof(ip6_addr_t));
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| 128 |
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| 129 | #undef SERVERID_SET
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| 130 | #undef DNSSRV_SET
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| 131 |
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| 132 | return ERR_OK;
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| 133 |
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| 134 |
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| 135 | err3:
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| 136 | udp_remove(dhcp6ds_pcb);
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| 137 | dhcp6ds_pcb = NULL;
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| 138 | err2:
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| 139 | mld6_leavegroup(pxaddr, &all_dhcp_servers);
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| 140 | err1:
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| 141 | mld6_leavegroup(pxaddr, &all_dhcp_relays_and_servers);
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| 142 | err:
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| 143 | return error;
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| 144 | }
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| 145 |
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| 146 |
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| 147 | static u8_t dhcp6ds_reply_buf[1024];
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| 148 |
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| 149 | static void
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| 150 | dhcp6ds_recv(void *arg, struct udp_pcb *pcb, struct pbuf *p,
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| 151 | ip6_addr_t *addr, u16_t port)
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| 152 | {
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| 153 | u8_t msg_header[4];
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| 154 | unsigned int msg_type, msg_tid;
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| 155 | int copied;
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| 156 | size_t roff;
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| 157 | struct pbuf *q;
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| 158 | err_t error;
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| 159 |
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| 160 | LWIP_UNUSED_ARG(arg);
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| 161 | LWIP_ASSERT1(p != NULL);
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| 162 |
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| 163 | copied = pbuf_copy_partial(p, msg_header, sizeof(msg_header), 0);
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| 164 | if (copied != sizeof(msg_header)) {
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| 165 | DPRINTF(("%s: message header truncated\n", __func__));
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| 166 | pbuf_free(p);
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| 167 | return;
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| 168 | }
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| 169 | pbuf_header(p, -(s16_t)sizeof(msg_header));
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| 170 |
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| 171 | msg_type = msg_header[0];
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| 172 | msg_tid = (msg_header[1] << 16) | (msg_header[2] << 8) | msg_header[3];
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| 173 | DPRINTF(("%s: type %u, tid 0x%6x\n", __func__, msg_type, msg_tid));
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| 174 | if (msg_type != DHCP6_INFORMATION_REQUEST) { /* TODO:? RELAY_FORW */
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| 175 | pbuf_free(p);
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| 176 | return;
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| 177 | }
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| 178 |
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| 179 | roff = 0;
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| 180 |
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| 181 | msg_header[0] = DHCP6_REPLY;
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| 182 | memcpy(dhcp6ds_reply_buf + roff, msg_header, sizeof(msg_header));
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| 183 | roff += sizeof(msg_header);
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| 184 |
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| 185 |
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| 186 | /* loop over options */
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| 187 | while (p->tot_len > 0) {
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| 188 | u16_t opt, optlen;
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| 189 |
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| 190 | /* fetch option code */
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| 191 | copied = pbuf_copy_partial(p, &opt, sizeof(opt), 0);
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| 192 | if (copied != sizeof(opt)) {
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| 193 | DPRINTF(("%s: option header truncated\n", __func__));
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| 194 | pbuf_free(p);
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| 195 | return;
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| 196 | }
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| 197 | pbuf_header(p, -(s16_t)sizeof(opt));
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| 198 | opt = ntohs(opt);
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| 199 |
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| 200 | /* fetch option length */
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| 201 | copied = pbuf_copy_partial(p, &optlen, sizeof(optlen), 0);
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| 202 | if (copied != sizeof(optlen)) {
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| 203 | DPRINTF(("%s: option %u length truncated\n", __func__, opt));
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| 204 | pbuf_free(p);
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| 205 | return;
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| 206 | }
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| 207 | pbuf_header(p, -(s16_t)sizeof(optlen));
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| 208 | optlen = ntohs(optlen);
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| 209 |
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| 210 | /* enough data? */
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| 211 | if (optlen > p->tot_len) {
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| 212 | DPRINTF(("%s: option %u truncated: expect %u, got %u\n",
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| 213 | __func__, opt, optlen, p->tot_len));
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| 214 | pbuf_free(p);
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| 215 | return;
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| 216 | }
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| 217 |
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| 218 | DPRINTF2(("%s: option %u length %u\n", __func__, opt, optlen));
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| 219 |
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| 220 | if (opt == DHCP6_OPTION_CLIENTID) {
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| 221 | u16_t s;
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| 222 |
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| 223 | /* "A DUID can be no more than 128 octets long (not
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| 224 | including the type code)." */
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| 225 | if (optlen > 130) {
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| 226 | DPRINTF(("%s: client DUID too long: %u\n", __func__, optlen));
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| 227 | pbuf_free(p);
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| 228 | return;
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| 229 | }
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| 230 |
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| 231 | s = PP_HTONS(DHCP6_OPTION_CLIENTID);
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| 232 | memcpy(dhcp6ds_reply_buf + roff, &s, sizeof(s));
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| 233 | roff += sizeof(s);
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| 234 |
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| 235 | s = ntohs(optlen);
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| 236 | memcpy(dhcp6ds_reply_buf + roff, &s, sizeof(s));
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| 237 | roff += sizeof(s);
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| 238 |
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| 239 | pbuf_copy_partial(p, dhcp6ds_reply_buf + roff, optlen, 0);
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| 240 | roff += optlen;
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| 241 | }
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| 242 | else if (opt == DHCP6_OPTION_ORO) {
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| 243 | u16_t *opts;
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| 244 | int i, nopts;
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| 245 |
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| 246 | if (optlen % 2 != 0) {
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| 247 | DPRINTF2(("%s: Option Request of odd length\n", __func__));
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| 248 | goto bad_oro;
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| 249 | }
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| 250 | nopts = optlen / 2;
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| 251 |
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| 252 | opts = (u16_t *)malloc(optlen);
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| 253 | if (opts == NULL) {
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| 254 | DPRINTF2(("%s: failed to allocate space for Option Request\n",
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| 255 | __func__));
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| 256 | goto bad_oro;
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| 257 | }
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| 258 |
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| 259 | pbuf_copy_partial(p, opts, optlen, 0);
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| 260 | for (i = 0; i < nopts; ++i) {
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| 261 | opt = ntohs(opts[i]);
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| 262 | DPRINTF2(("> request option %u\n", opt));
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| 263 | };
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| 264 | free(opts);
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| 265 |
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| 266 | bad_oro: /* empty */;
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| 267 | }
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| 268 |
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| 269 | pbuf_header(p, -optlen); /* go to next option */
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| 270 | }
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| 271 | pbuf_free(p); /* done */
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| 272 |
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| 273 |
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| 274 | memcpy(dhcp6ds_reply_buf + roff, dhcp6ds_serverid, sizeof(dhcp6ds_serverid));
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| 275 | roff += sizeof(dhcp6ds_serverid);
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| 276 |
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| 277 | memcpy(dhcp6ds_reply_buf + roff, dhcp6ds_dns, sizeof(dhcp6ds_dns));
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| 278 | roff += sizeof(dhcp6ds_dns);
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| 279 |
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| 280 | q = pbuf_alloc(PBUF_RAW, roff, PBUF_RAM);
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| 281 | if (q == NULL) {
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| 282 | DPRINTF(("%s: pbuf_alloc(%d) failed\n", __func__, (int)roff));
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| 283 | return;
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| 284 | }
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| 285 |
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| 286 | error = pbuf_take(q, dhcp6ds_reply_buf, roff);
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| 287 | if (error != ERR_OK) {
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| 288 | DPRINTF(("%s: pbuf_take(%d) failed: %s\n",
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| 289 | __func__, (int)roff, proxy_lwip_strerr(error)));
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| 290 | pbuf_free(q);
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| 291 | return;
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| 292 | }
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| 293 |
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| 294 | error = udp_sendto_ip6(pcb, q, addr, port);
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| 295 | if (error != ERR_OK) {
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| 296 | DPRINTF(("%s: udp_sendto failed: %s\n",
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| 297 | __func__, proxy_lwip_strerr(error)));
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| 298 | }
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| 299 |
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| 300 | pbuf_free(q);
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| 301 | }
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