+static_always_inline void
+cnat_translation_icmp4_echo (ip4_header_t * ip4, icmp46_header_t * icmp,
+ ip4_address_t new_addr[VLIB_N_DIR],
+ u16 new_port[VLIB_N_DIR])
+{
+ ip_csum_t sum;
+ u16 old_port;
+ cnat_echo_header_t *echo = (cnat_echo_header_t *) (icmp + 1);
+
+ cnat_ip4_translate_l3 (ip4, new_addr);
+ old_port = echo->identifier;
+ echo->identifier = new_port[VLIB_RX];
+
+ sum = icmp->checksum;
+ sum = ip_csum_update (sum, old_port, new_port[VLIB_RX],
+ ip4_header_t /* cheat */ ,
+ length /* changed member */ );
+
+ icmp->checksum = ip_csum_fold (sum);
+}
+
+static_always_inline void
+cnat_translation_icmp4_error (ip4_header_t * outer_ip4,
+ icmp46_header_t * icmp,
+ ip4_address_t outer_new_addr[VLIB_N_DIR],
+ u16 outer_new_port[VLIB_N_DIR],
+ u8 snat_outer_ip)
+{
+ ip4_address_t new_addr[VLIB_N_DIR];
+ ip4_address_t old_addr[VLIB_N_DIR];
+ u16 new_port[VLIB_N_DIR];
+ u16 old_port[VLIB_N_DIR];
+ ip_csum_t sum, old_ip_sum, inner_l4_sum, inner_l4_old_sum;
+
+ ip4_header_t *ip4 = (ip4_header_t *) (icmp + 2);
+ udp_header_t *udp = (udp_header_t *) (ip4 + 1);
+ tcp_header_t *tcp = (tcp_header_t *) udp;
+
+ /* Swap inner ports */
+ new_addr[VLIB_TX] = outer_new_addr[VLIB_RX];
+ new_addr[VLIB_RX] = outer_new_addr[VLIB_TX];
+ new_port[VLIB_TX] = outer_new_port[VLIB_RX];
+ new_port[VLIB_RX] = outer_new_port[VLIB_TX];
+
+ old_addr[VLIB_TX] = ip4->dst_address;
+ old_addr[VLIB_RX] = ip4->src_address;
+ old_port[VLIB_RX] = udp->src_port;
+ old_port[VLIB_TX] = udp->dst_port;
+
+ sum = icmp->checksum;
+ old_ip_sum = ip4->checksum;
+
+ /* translate outer ip. */
+ if (!snat_outer_ip)
+ outer_new_addr[VLIB_RX] = outer_ip4->src_address;
+ cnat_ip4_translate_l3 (outer_ip4, outer_new_addr);
+
+ if (ip4->protocol == IP_PROTOCOL_TCP)
+ {
+ inner_l4_old_sum = inner_l4_sum = tcp->checksum;
+ cnat_ip4_translate_l4 (ip4, udp, &inner_l4_sum, new_addr, new_port);
+ tcp->checksum = ip_csum_fold (inner_l4_sum);
+ }
+ else if (ip4->protocol == IP_PROTOCOL_UDP)
+ {
+ inner_l4_old_sum = inner_l4_sum = udp->checksum;
+ cnat_ip4_translate_l4 (ip4, udp, &inner_l4_sum, new_addr, new_port);
+ udp->checksum = ip_csum_fold (inner_l4_sum);
+ }
+ else
+ return;
+
+ /* UDP/TCP checksum changed */
+ sum = ip_csum_update (sum, inner_l4_old_sum, inner_l4_sum,
+ ip4_header_t, checksum);
+
+ /* UDP/TCP Ports changed */
+ if (old_port[VLIB_TX] && new_port[VLIB_TX])
+ sum = ip_csum_update (sum, old_port[VLIB_TX], new_port[VLIB_TX],
+ ip4_header_t /* cheat */ ,
+ length /* changed member */ );
+
+ if (old_port[VLIB_RX] && new_port[VLIB_RX])
+ sum = ip_csum_update (sum, old_port[VLIB_RX], new_port[VLIB_RX],
+ ip4_header_t /* cheat */ ,
+ length /* changed member */ );
+
+
+ cnat_ip4_translate_l3 (ip4, new_addr);
+ ip_csum_t new_ip_sum = ip4->checksum;
+ /* IP checksum changed */
+ sum = ip_csum_update (sum, old_ip_sum, new_ip_sum, ip4_header_t, checksum);
+
+ /* IP src/dst addr changed */
+ if (new_addr[VLIB_TX].as_u32)
+ sum =
+ ip_csum_update (sum, old_addr[VLIB_TX].as_u32, new_addr[VLIB_TX].as_u32,
+ ip4_header_t, dst_address);
+
+ if (new_addr[VLIB_RX].as_u32)
+ sum =
+ ip_csum_update (sum, old_addr[VLIB_RX].as_u32, new_addr[VLIB_RX].as_u32,
+ ip4_header_t, src_address);
+
+ icmp->checksum = ip_csum_fold (sum);
+}
+