+/*
+ * Translate IPv4 UDP/TCP packet to IPv6.
+ */
+always_inline int
+map_ip4_to_ip6_tcp_udp (vlib_buffer_t * p, ip4_mapt_pseudo_header_t * pheader)
+{
+ map_main_t *mm = &map_main;
+ ip4_header_t *ip4;
+ ip6_header_t *ip6;
+ ip_csum_t csum;
+ u16 *checksum;
+ ip6_frag_hdr_t *frag;
+ u32 frag_id;
+ ip4_address_t old_src, old_dst;
+
+ ip4 = vlib_buffer_get_current (p);
+
+ if (ip4->protocol == IP_PROTOCOL_UDP)
+ {
+ udp_header_t *udp = ip4_next_header (ip4);
+ checksum = &udp->checksum;
+
+ /*
+ * UDP checksum is optional over IPv4 but mandatory for IPv6 We
+ * do not check udp->length sanity but use our safe computed
+ * value instead
+ */
+ if (PREDICT_FALSE (!*checksum))
+ {
+ u16 udp_len = clib_host_to_net_u16 (ip4->length) - sizeof (*ip4);
+ csum = ip_incremental_checksum (0, udp, udp_len);
+ csum = ip_csum_with_carry (csum, clib_host_to_net_u16 (udp_len));
+ csum =
+ ip_csum_with_carry (csum, clib_host_to_net_u16 (IP_PROTOCOL_UDP));
+ csum = ip_csum_with_carry (csum, *((u64 *) (&ip4->src_address)));
+ *checksum = ~ip_csum_fold (csum);
+ }
+ }
+ else
+ {
+ tcp_header_t *tcp = ip4_next_header (ip4);
+ if (mm->tcp_mss > 0)
+ {
+ csum = tcp->checksum;
+ map_mss_clamping (tcp, &csum, mm->tcp_mss);
+ tcp->checksum = ip_csum_fold (csum);
+ }
+ checksum = &tcp->checksum;
+ }
+
+ old_src.as_u32 = ip4->src_address.as_u32;
+ old_dst.as_u32 = ip4->dst_address.as_u32;
+
+ /* Deal with fragmented packets */
+ if (PREDICT_FALSE (ip4->flags_and_fragment_offset &
+ clib_host_to_net_u16 (IP4_HEADER_FLAG_MORE_FRAGMENTS)))
+ {
+ ip6 =
+ (ip6_header_t *) u8_ptr_add (ip4,
+ sizeof (*ip4) - sizeof (*ip6) -
+ sizeof (*frag));
+ frag =
+ (ip6_frag_hdr_t *) u8_ptr_add (ip4, sizeof (*ip4) - sizeof (*frag));
+ frag_id = frag_id_4to6 (ip4->fragment_id);
+ vlib_buffer_advance (p, sizeof (*ip4) - sizeof (*ip6) - sizeof (*frag));
+ }
+ else
+ {
+ ip6 = (ip6_header_t *) (((u8 *) ip4) + sizeof (*ip4) - sizeof (*ip6));
+ vlib_buffer_advance (p, sizeof (*ip4) - sizeof (*ip6));
+ frag = NULL;
+ }
+
+ ip6->ip_version_traffic_class_and_flow_label =
+ clib_host_to_net_u32 ((6 << 28) + (ip4->tos << 20));
+ ip6->payload_length = u16_net_add (ip4->length, -sizeof (*ip4));
+ ip6->hop_limit = ip4->ttl;
+ ip6->protocol = ip4->protocol;
+ if (PREDICT_FALSE (frag != NULL))
+ {
+ frag->next_hdr = ip6->protocol;
+ frag->identification = frag_id;
+ frag->rsv = 0;
+ frag->fragment_offset_and_more = ip6_frag_hdr_offset_and_more (0, 1);
+ ip6->protocol = IP_PROTOCOL_IPV6_FRAGMENTATION;
+ ip6->payload_length = u16_net_add (ip6->payload_length, sizeof (*frag));
+ }
+
+ ip6->dst_address.as_u64[0] = pheader->daddr.as_u64[0];
+ ip6->dst_address.as_u64[1] = pheader->daddr.as_u64[1];
+ ip6->src_address.as_u64[0] = pheader->saddr.as_u64[0];
+ ip6->src_address.as_u64[1] = pheader->saddr.as_u64[1];
+
+ csum = ip_csum_sub_even (*checksum, old_src.as_u32);
+ csum = ip_csum_sub_even (csum, old_dst.as_u32);
+ csum = ip_csum_add_even (csum, ip6->src_address.as_u64[0]);
+ csum = ip_csum_add_even (csum, ip6->src_address.as_u64[1]);
+ csum = ip_csum_add_even (csum, ip6->dst_address.as_u64[0]);
+ csum = ip_csum_add_even (csum, ip6->dst_address.as_u64[1]);
+ *checksum = ip_csum_fold (csum);
+
+ return 0;
+}
+