diff options
| -rw-r--r-- | src/dhcpv6.c | 25 |
1 files changed, 22 insertions, 3 deletions
diff --git a/src/dhcpv6.c b/src/dhcpv6.c index cc068a3..00628cd 100644 --- a/src/dhcpv6.c +++ b/src/dhcpv6.c @@ -397,10 +397,12 @@ static void handle_client_request(void *addr, void *data, size_t len, } search = {htons(DHCPV6_OPT_DNS_DOMAIN), htons(search_len)}; - struct __attribute__((packed)) { + struct __attribute__((packed)) dhcpv4o6_server { uint16_t type; uint16_t len; - } dhcpv4o6_server = {htons(DHCPV6_OPT_4O6_SERVER), 0}; + struct in6_addr addr; + } dhcpv4o6_server = {htons(DHCPV6_OPT_4O6_SERVER), htons(sizeof(struct in6_addr)), + IN6ADDR_ANY_INIT}; struct dhcpv6_cer_id cerid = { #ifdef EXT_CER_ID @@ -505,11 +507,28 @@ static void handle_client_request(void *addr, void *data, size_t len, } else if (otype == DHCPV6_OPT_ORO) { for (int i=0; i < olen/2; i++) { uint16_t option = ntohs(((uint16_t *)odata)[i]); + switch (option) { #ifdef DHCPV4_SUPPORT case DHCPV6_OPT_4O6_SERVER: - if (iface->dhcpv4) + if (iface->dhcpv4) { + /* According to RFC 7341, 7.2. DHCP 4o6 Server Address Option Format: + * This option may also carry no IPv6 addresses, which instructs the + * client to use the All_DHCP_Relay_Agents_and_Servers multicast address + * as the destination address. + * + * The ISC dhclient logs a missing IPv6 address as an error but seems to + * work anyway: + * dhcp4-o-dhcp6-server: expecting at least 16 bytes; got 0 + * + * Include the All_DHCP_Relay_Agents_and_Servers multicast address + * to make it explicit which address to use. */ + struct dhcpv4o6_server *server = iov[IOV_DHCPV4O6_SERVER].iov_base; + + inet_pton(AF_INET6, ALL_DHCPV6_RELAYS, &server->addr); + iov[IOV_DHCPV4O6_SERVER].iov_len = sizeof(dhcpv4o6_server); + } break; #endif /* DHCPV4_SUPPORT */ default: |