+
+struct icmp
+{
+ u_int8_t icmp_type; /* type of message, see below */
+ u_int8_t icmp_code; /* type sub code */
+ u_int16_t icmp_cksum; /* ones complement checksum of struct */
+ union
+ {
+ u_char ih_pptr; /* ICMP_PARAMPROB */
+ struct in_addr ih_gwaddr; /* gateway address */
+ struct ih_idseq /* echo datagram */
+ {
+ u_int16_t icd_id;
+ u_int16_t icd_seq;
+ } ih_idseq;
+ u_int32_t ih_void;
+
+ /* ICMP_UNREACH_NEEDFRAG -- Path MTU Discovery (RFC1191) */
+ struct ih_pmtu
+ {
+ u_int16_t ipm_void;
+ u_int16_t ipm_nextmtu;
+ } ih_pmtu;
+
+ struct ih_rtradv
+ {
+ u_int8_t irt_num_addrs;
+ u_int8_t irt_wpa;
+ u_int16_t irt_lifetime;
+ } ih_rtradv;
+ } icmp_hun;
+#define icmp_pptr icmp_hun.ih_pptr
+#define icmp_gwaddr icmp_hun.ih_gwaddr
+#define icmp_id icmp_hun.ih_idseq.icd_id
+#define icmp_seq icmp_hun.ih_idseq.icd_seq
+#define icmp_void icmp_hun.ih_void
+#define icmp_pmvoid icmp_hun.ih_pmtu.ipm_void
+#define icmp_nextmtu icmp_hun.ih_pmtu.ipm_nextmtu
+#define icmp_num_addrs icmp_hun.ih_rtradv.irt_num_addrs
+#define icmp_wpa icmp_hun.ih_rtradv.irt_wpa
+#define icmp_lifetime icmp_hun.ih_rtradv.irt_lifetime
+ union
+ {
+ struct
+ {
+ u_int32_t its_otime;
+ u_int32_t its_rtime;
+ u_int32_t its_ttime;
+ } id_ts;
+ struct
+ {
+ struct ip idi_ip;
+ /* options and then 64 bits of data */
+ } id_ip;
+ struct icmp_ra_addr id_radv;
+ u_int32_t id_mask;
+ u_int8_t id_data[1];
+ } icmp_dun;
+#define icmp_otime icmp_dun.id_ts.its_otime
+#define icmp_rtime icmp_dun.id_ts.its_rtime
+#define icmp_ttime icmp_dun.id_ts.its_ttime
+#define icmp_ip icmp_dun.id_ip.idi_ip
+#define icmp_radv icmp_dun.id_radv
+#define icmp_mask icmp_dun.id_mask
+#define icmp_data icmp_dun.id_data
+};
+#endif
+
+static const int DEFDATALEN = 56;
+static const int MAXIPLEN = 60;
+static const int MAXICMPLEN = 76;
+static const int MAXPACKET = 65468;