/* * Copyright (c) 2017 Cisco and/or its affiliates. * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at: * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ /** * @file * @brief IPv6 to IPv4 translation */ #ifndef __included_ip6_to_ip4_h__ #define __included_ip6_to_ip4_h__ #include <vnet/ip/ip.h> /** * IPv6 to IPv4 set call back function type */ typedef int (*ip6_to_ip4_icmp_set_fn_t) (ip6_header_t * ip6, ip4_header_t * ip4, void *ctx); typedef int (*ip6_to_ip4_tcp_udp_set_fn_t) (vlib_buffer_t * b, ip6_header_t * ip6, ip4_header_t * ip4, void *ctx); /* *INDENT-OFF* */ static u8 icmp6_to_icmp_updater_pointer_table[] = { 0, 1, ~0, ~0, 2, 2, 9, 8, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24 }; /* *INDENT-ON* */ #define frag_id_6to4(id) ((id) ^ ((id) >> 16)) /** * @brief Parse some useful information from IPv6 header. * * @param vm vlib main * @param b vlib buffer * @param ip6 IPv6 header. * @param buff_len Buffer length. * @param l4_protocol L4 protocol number. * @param l4_offset L4 header offset. * @param frag_hdr_offset Fragment header offset if present, 0 otherwise. * * @returns 0 on success, non-zero value otherwise. */ static_always_inline int ip6_parse (vlib_main_t * vm, vlib_buffer_t * b, const ip6_header_t * ip6, u32 buff_len, u8 * l4_protocol, u16 * l4_offset, u16 * frag_hdr_offset) { ip6_ext_header_t *last_hdr, *frag_hdr; u32 length; if (ip6_walk_ext_hdr (vm, b, ip6, IP_PROTOCOL_IPV6_FRAGMENTATION, &length, &frag_hdr, &last_hdr)) { return -1; } if (length > 0) { if (frag_hdr) { *frag_hdr_offset = (u8 *) frag_hdr - (u8 *) ip6; } else { *frag_hdr_offset = 0; } *l4_protocol = last_hdr->next_hdr; } else { *frag_hdr_offset = 0; *l4_protocol = ip6->protocol; } *l4_offset = sizeof (*ip6) + length; return (buff_len < (*l4_offset + 4)) || (clib_net_to_host_u16 (ip6->payload_length) < (*l4_offset + 4 - sizeof (*ip6))); } /** * @brief Get L4 information like port number or ICMP id from IPv6 packet. * * @param ip6 IPv6 header. * @param buffer_len Buffer length. * @param ip_protocol L4 protocol * @param src_port L4 src port or icmp id * @param dst_post L4 dst port or icmp id * @param icmp_type_or_tcp_flags ICMP type or TCP flags, if applicable * @param tcp_ack_number TCP ack number, if applicable * @param tcp_seq_number TCP seq number, if applicable * * @returns 1 on success, 0 otherwise. */ always_inline u16 ip6_get_port (vlib_main_t * vm, vlib_buffer_t * b, ip6_header_t * ip6, u16 buffer_len, u8 * ip_protocol, u16 * src_port, u16 * dst_port, u8 * icmp_type_or_tcp_flags, u32 * tcp_ack_number, u32 * tcp_seq_number) { u8 l4_protocol; u16 l4_offset; u16 frag_offset; u8 *l4; if (ip6_parse (vm, b, ip6, buffer_len, &l4_protocol, &l4_offset, &frag_offset)) return 0; if (frag_offset && ip6_frag_hdr_offset (((ip6_frag_hdr_t *) u8_ptr_add (ip6, frag_offset)))) return 0; //Can't deal with non-first fragment for now if (ip_protocol) { *ip_protocol = l4_protocol; } l4 = u8_ptr_add (ip6, l4_offset); if (l4_protocol == IP_PROTOCOL_TCP || l4_protocol == IP_PROTOCOL_UDP) { if (src_port) *src_port = ((udp_header_t *) (l4))->src_port; if (dst_port) *dst_port = ((udp_header_t *) (l4))->dst_port; if (icmp_type_or_tcp_flags && l4_protocol == IP_PROTOCOL_TCP) *icmp_type_or_tcp_flags = ((tcp_header_t *) (l4))->flags; if (tcp_ack_number && l4_protocol == IP_PROTOCOL_TCP) *tcp_ack_number = ((tcp_header_t *) (l4))->ack_number; if (tcp_seq_number && l4_protocol == IP_PROTOCOL_TCP) *tcp_seq_number = ((tcp_header_t *) (l4))->seq_number; } else if (l4_protocol == IP_PROTOCOL_ICMP6) { icmp46_header_t *icmp = (icmp46_header_t *) (l4); if (icmp_type_or_tcp_flags) *icmp_type_or_tcp_flags = ((icmp46_header_t *) (l4))->type; if (icmp->type == ICMP6_echo_request) { if (src_port) *src_port = ((u16 *) (icmp))[2]; if (dst_port) *dst_port = ((u16 *) (icmp))[2]; } else if (icmp->type == ICMP6_echo_reply) { if (src_port) *src_port = ((u16 *) (icmp))[2]; if (dst_port) *dst_port = ((u16 *) (icmp))[2]; } else if (clib_net_to_host_u16 (ip6->payload_length) >= 64) { u16 ip6_pay_len; ip6_header_t *inner_ip6; u8 inner_l4_protocol; u16 inner_l4_offset; u16 inner_frag_offset; u8 *inner_l4; ip6_pay_len = clib_net_to_host_u16 (ip6->payload_length); inner_ip6 = (ip6_header_t *) u8_ptr_add (icmp, 8); if (ip6_parse (vm, b, inner_ip6, ip6_pay_len - 8, &inner_l4_protocol, &inner_l4_offset, &inner_frag_offset)) return 0; if (inner_frag_offset && ip6_frag_hdr_offset (((ip6_frag_hdr_t *) u8_ptr_add (inner_ip6, inner_frag_offset)))) return 0; inner_l4 = u8_ptr_add (inner_ip6, inner_l4_offset); if (inner_l4_protocol == IP_PROTOCOL_TCP || inner_l4_protocol == IP_PROTOCOL_UDP) { if (src_port) *src_port = ((udp_header_t *) (inner_l4))->dst_port; if (dst_port) *dst_port = ((udp_header_t *) (inner_l4))->src_port; } else if (inner_l4_protocol == IP_PROTOCOL_ICMP6) { icmp46_header_t *inner_icmp = (icmp46_header_t *) (inner_l4); if (inner_icmp->type == ICMP6_echo_request) { if (src_port) *src_port = ((u16 *) (inner_icmp))[2]; if (dst_port) *dst_port = ((u16 *) (inner_icmp))[2]; } else if (inner_icmp->type == ICMP6_echo_reply) { if (src_port) *src_port = ((u16 *) (inner_icmp))[2]; if (dst_port) *dst_port = ((u16 *) (inner_icmp))[2]; } } } } return 1; } /** * @brief Convert type and code value from ICMP6 to ICMP4. * * @param icmp ICMP header. * @param inner_ip6 Inner IPv6 header if present, 0 otherwise. * * @returns 0 on success, non-zero value otherwise. */ static_always_inline int icmp6_to_icmp_header (icmp46_header_t * icmp, ip6_header_t ** inner_ip6) { *inner_ip6 = NULL; switch (icmp->type) { case ICMP6_echo_request: icmp->type = ICMP4_echo_request; break; case ICMP6_echo_reply: icmp->type = ICMP4_echo_reply; break; case ICMP6_destination_unreachable: *inner_ip6 = (ip6_header_t *) u8_ptr_add (icmp, 8); switch (icmp->code) { case ICMP6_destination_unreachable_no_route_to_destination: //0 case ICMP6_destination_unreachable_beyond_scope_of_source_address: //2 case ICMP6_destination_unreachable_address_unreachable: //3 icmp->type = ICMP4_destination_unreachable; icmp->code = ICMP4_destination_unreachable_destination_unreachable_host; break; case ICMP6_destination_unreachable_destination_administratively_prohibited: //1 icmp->type = ICMP4_destination_unreachable; icmp->code = ICMP4_destination_unreachable_communication_administratively_prohibited; break; case ICMP6_destination_unreachable_port_unreachable: icmp->type = ICMP4_destination_unreachable; icmp->code = ICMP4_destination_unreachable_port_unreachable; break; default: return -1; } break; case ICMP6_packet_too_big: *inner_ip6 = (ip6_header_t *) u8_ptr_add (icmp, 8); icmp->type = ICMP4_destination_unreachable; icmp->code = 4; { u32 advertised_mtu = clib_net_to_host_u32 (*((u32 *) (icmp + 1))); advertised_mtu -= 20; //FIXME: = minimum(advertised MTU-20, MTU_of_IPv4_nexthop, (MTU_of_IPv6_nexthop)-20) ((u16 *) (icmp))[3] = clib_host_to_net_u16 (advertised_mtu); } break; case ICMP6_time_exceeded: *inner_ip6 = (ip6_header_t *) u8_ptr_add (icmp, 8); icmp->type = ICMP4_time_exceeded; break; case ICMP6_parameter_problem: *inner_ip6 = (ip6_header_t *) u8_ptr_add (icmp, 8); switch (icmp->code) { case ICMP6_parameter_problem_erroneous_header_field: icmp->type = ICMP4_parameter_problem; icmp->code = ICMP4_parameter_problem_pointer_indicates_error; u32 pointer = clib_net_to_host_u32 (*((u32 *) (icmp + 1))); if (pointer >= 40) return -1; ((u8 *) (icmp + 1))[0] = icmp6_to_icmp_updater_pointer_table[pointer]; break; case ICMP6_parameter_problem_unrecognized_next_header: icmp->type = ICMP4_destination_unreachable; icmp->code = ICMP4_destination_unreachable_port_unreachable; break; case ICMP6_parameter_problem_unrecognized_option: default: return -1; } break; default: return -1; break; } return 0; } /** * @brief Translate TOS value from IPv6 to IPv4. * * @param ip_version_traffic_class_and_flow_label in network byte order * * @returns IPv4 TOS value. */ static_always_inline u8 ip6_translate_tos (u32 ip_version_traffic_class_and_flow_label) { return (clib_net_to_host_u32 (ip_version_traffic_class_and_flow_label) & 0x0ff00000) >> 20; } /** * @brief Translate ICMP6 packet to ICMP4. * * @param p Buffer to translate. * @param fn The function to translate outer header. * @param ctx A context passed in the outer header translate function. * @param inner_fn The function to translate inner header. * @param inner_ctx A context passed in the inner header translate function. * * @returns 0 on success, non-zero value otherwise. */ always_inline int icmp6_to_icmp (vlib_main_t * vm, vlib_buffer_t * p, ip6_to_ip4_icmp_set_fn_t fn, void *ctx, ip6_to_ip4_icmp_set_fn_t inner_fn, void *inner_ctx) { ip6_header_t *ip6, *inner_ip6; ip4_header_t *ip4, *inner_ip4; u32 ip6_pay_len; icmp46_header_t *icmp; ip_csum_t csum; int rv; ip6_address_t old_src, old_dst; ip6 = vlib_buffer_get_current (p); ip6_pay_len = clib_net_to_host_u16 (ip6->payload_length); icmp = (icmp46_header_t *) (ip6 + 1); ASSERT (ip6_pay_len + sizeof (*ip6) <= p->current_length); //No extensions headers allowed here if (ip6->protocol != IP_PROTOCOL_ICMP6) return -1; //There are no fragmented ICMP messages, so no extension header for now if (icmp6_to_icmp_header (icmp, &inner_ip6)) return -1; if (inner_ip6) { u16 *inner_L4_checksum, inner_l4_offset, inner_frag_offset, inner_frag_id; u8 *inner_l4, inner_protocol; //We have two headers to translate // FROM // [ IPv6 ]<- ext ->[IC][ IPv6 ]<- ext ->[L4 header ... // Handled cases: // [ IPv6 ][IC][ IPv6 ][L4 header ... // [ IPv6 ][IC][ IPv6 ][Fr][L4 header ... // TO // [ IPv4][IC][ IPv4][L4 header ... if (ip6_parse (vm, p, inner_ip6, ip6_pay_len - 8, &inner_protocol, &inner_l4_offset, &inner_frag_offset)) return -1; inner_l4 = u8_ptr_add (inner_ip6, inner_l4_offset); inner_ip4 = (ip4_header_t *) u8_ptr_add (inner_l4, -sizeof (*inner_ip4)); if (inner_frag_offset) { ip6_frag_hdr_t *inner_frag = (ip6_frag_hdr_t *) u8_ptr_add (inner_ip6, inner_frag_offset); inner_frag_id = frag_id_6to4 (inner_frag->identification); } else { inner_frag_id = 0; } //Do the translation of the inner packet if (inner_protocol == IP_PROTOCOL_TCP) { inner_L4_checksum = (u16 *) u8_ptr_add (inner_l4, 16); } else if (inner_protocol == IP_PROTOCOL_UDP) { inner_L4_checksum = (u16 *) u8_ptr_add (inner_l4, 6); } else if (inner_protocol == IP_PROTOCOL_ICMP6) { icmp46_header_t *inner_icmp = (icmp46_header_t *) inner_l4; //It cannot be of a different type as ip6_icmp_to_icmp6_in_place succeeded inner_icmp->type = (inner_icmp->type == ICMP6_echo_request) ? ICMP4_echo_request : ICMP4_echo_reply; inner_protocol = IP_PROTOCOL_ICMP; //Will be copied to ip6 later inner_L4_checksum = &inner_icmp->checksum; } else { return -1; } old_src.as_u64[0] = inner_ip6->src_address.as_u64[0]; old_src.as_u64[1] = inner_ip6->src_address.as_u64[1]; old_dst.as_u64[0] = inner_ip6->dst_address.as_u64[0]; old_dst.as_u64[1] = inner_ip6->dst_address.as_u64[1]; if ((rv = inner_fn (inner_ip6, inner_ip4, inner_ctx)) != 0) return rv; inner_ip4->ip_version_and_header_length = IP4_VERSION_AND_HEADER_LENGTH_NO_OPTIONS; inner_ip4->tos = ip6_translate_tos (inner_ip6->ip_version_traffic_class_and_flow_label); inner_ip4->length = u16_net_add (inner_ip6->payload_length, sizeof (*ip4) + sizeof (*ip6) - inner_l4_offset); inner_ip4->fragment_id = inner_frag_id; inner_ip4->flags_and_fragment_offset = clib_host_to_net_u16 (IP4_HEADER_FLAG_MORE_FRAGMENTS); inner_ip4->ttl = inner_ip6->hop_limit; inner_ip4->protocol = inner_protocol; inner_ip4->checksum = ip4_header_checksum (inner_ip4); if (inner_ip4->protocol == IP_PROTOCOL_ICMP) { //Recompute ICMP checksum icmp46_header_t *inner_icmp = (icmp46_header_t *) inner_l4; inner_icmp->checksum = 0; csum = ip_incremental_checksum (0, inner_icmp, clib_net_to_host_u16 (inner_ip4->length) - sizeof (*inner_ip4)); inner_icmp->checksum = ~ip_csum_fold (csum); } else { //Update to new pseudo-header csum = *inner_L4_checksum; csum = ip_csum_sub_even (csum, old_src.as_u64[0]); csum = ip_csum_sub_even (csum, old_src.as_u64[1]); csum = ip_csum_sub_even (csum, old_dst.as_u64[0]); csum = ip_csum_sub_even (csum, old_dst.as_u64[1]); csum = ip_csum_add_even (csum, inner_ip4->src_address.as_u32); csum = ip_csum_add_even (csum, inner_ip4->dst_address.as_u32); *inner_L4_checksum = ip_csum_fold (csum); } //Move up icmp header ip4 = (ip4_header_t *) u8_ptr_add (inner_l4, -2 * sizeof (*ip4) - 8); clib_memcpy_fast (u8_ptr_add (inner_l4, -sizeof (*ip4) - 8), icmp, 8); icmp = (icmp46_header_t *) u8_ptr_add (inner_l4, -sizeof (*ip4) - 8); } else { //Only one header to translate ip4 = (ip4_header_t *) u8_ptr_add (ip6, sizeof (*ip6) - sizeof (*ip4)); } vlib_buffer_advance (p, (u32) (((u8 *) ip4) - ((u8 *) ip6))); if ((rv = fn (ip6, ip4, ctx)) != 0) return rv; ip4->ip_version_and_header_length = IP4_VERSION_AND_HEADER_LENGTH_NO_OPTIONS; ip4->tos = ip6_translate_tos (ip6->ip_version_traffic_class_and_flow_label); ip4->fragment_id = 0; ip4->flags_and_fragment_offset = 0; ip4->ttl = ip6->hop_limit; ip4->protocol = IP_PROTOCOL_ICMP; //TODO fix the length depending on offset length ip4->length = u16_net_add (ip6->payload_length, (inner_ip6 == NULL) ? sizeof (*ip4) : (2 * sizeof (*ip4) - sizeof (*ip6))); ip4->checksum = ip4_header_checksum (ip4); //Recompute ICMP checksum icmp->checksum = 0; csum = ip_incremental_checksum (0, icmp, clib_net_to_host_u16 (ip4->length) - sizeof (*ip4)); icmp->checksum = ~ip_csum_fold (csum); return 0; } #endif /* __included_ip6_to_ip4_h__ */ /* * fd.io coding-style-patch-verification: ON * * Local Variables: * eval: (c-set-style "gnu") * End: */