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https://code.semirocket.science/wrapsix
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Completed enhanced ICMP support
This commit is contained in:
Michal Zima
parent
7a7651674c
commit
b61eec5bc8
488
src/icmp.c
488
src/icmp.c
@ -36,6 +36,10 @@
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int sub_icmp4_error(unsigned char *payload, unsigned short payload_size,
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unsigned char *packet, unsigned short *packet_len,
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struct s_icmp **icmp, struct s_nat **connection);
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int sub_icmp6_error(struct s_ethernet *eth6,
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unsigned char *payload, unsigned short payload_size,
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unsigned char *packet, unsigned short *packet_len,
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struct s_icmp **icmp, struct s_nat **connection);
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/**
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* Processing of incoming ICMPv4 packets. Directly sends translated ICMPv6
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@ -61,6 +65,8 @@ int icmp_ipv4(struct s_ethernet *eth4, struct s_ipv4 *ip4,
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struct s_nat *connection;
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unsigned short orig_checksum;
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unsigned char packet[MTU + sizeof(struct s_ethernet)];
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unsigned short new_len = sizeof(struct s_ethernet) +
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sizeof(struct s_ipv6);
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struct s_icmp_echo *echo;
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struct s_ethernet *eth6;
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@ -69,8 +75,6 @@ int icmp_ipv4(struct s_ethernet *eth4, struct s_ipv4 *ip4,
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/* for error messages */
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struct s_ipv4 *eip4;
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struct s_ipv6 *eip6;
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unsigned short new_len = sizeof(struct s_ethernet) +
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sizeof(struct s_ipv6);
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/* sanity check */
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if (payload_size < sizeof(struct s_icmp) + 4) {
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@ -132,7 +136,7 @@ int icmp_ipv4(struct s_ethernet *eth4, struct s_ipv4 *ip4,
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if (icmp->code <= 13 || icmp->code == 15) {
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if (sub_icmp4_error(icmp_data + 4,
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payload_size - sizeof(struct s_icmp) - 4,
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&packet[0], &new_len, &icmp, &connection)) {
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packet, &new_len, &icmp, &connection)) {
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/* something went wrong */
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return 1;
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}
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@ -221,7 +225,7 @@ int icmp_ipv4(struct s_ethernet *eth4, struct s_ipv4 *ip4,
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case ICMPV4_TIME_EXCEEDED:
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if (sub_icmp4_error(icmp_data + 4,
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payload_size - sizeof(struct s_icmp) - 4,
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&packet[0], &new_len, &icmp, &connection)) {
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packet, &new_len, &icmp, &connection)) {
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/* something went wrong */
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return 1;
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}
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@ -239,7 +243,7 @@ int icmp_ipv4(struct s_ethernet *eth4, struct s_ipv4 *ip4,
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(((unsigned char *) icmp) +
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sizeof(struct s_icmp));
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icmp_extra_c = (unsigned char *) icmp_extra;
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switch ((int) icmp_extra_c) {
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switch (*icmp_extra_c) {
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case 0:
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case 1:
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break;
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@ -283,7 +287,7 @@ int icmp_ipv4(struct s_ethernet *eth4, struct s_ipv4 *ip4,
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/* translate body of the packet */
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if (sub_icmp4_error(icmp_data + 4,
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payload_size - sizeof(struct s_icmp) - 4,
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&packet[0], &new_len, &icmp, &connection)) {
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packet, &new_len, &icmp, &connection)) {
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/* something went wrong */
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return 1;
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}
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@ -301,7 +305,7 @@ int icmp_ipv4(struct s_ethernet *eth4, struct s_ipv4 *ip4,
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return 0;
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}
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eth6 = (struct s_ethernet *) &packet[0];
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eth6 = (struct s_ethernet *) packet;
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ip6 = (struct s_ipv6 *) &packet[sizeof(struct s_ethernet)];
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/* build ethernet header */
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@ -328,7 +332,7 @@ int icmp_ipv4(struct s_ethernet *eth4, struct s_ipv4 *ip4,
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(unsigned char *) icmp);
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/* send translated packet */
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transmit_raw(&packet[0], new_len);
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transmit_raw(packet, new_len);
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return 0;
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}
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@ -346,14 +350,28 @@ int icmp_ipv4(struct s_ethernet *eth4, struct s_ipv4 *ip4,
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*/
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int icmp_ipv6(struct s_ethernet *eth6, struct s_ipv6 *ip6, char *payload)
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{
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struct s_icmp *icmp;
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unsigned char *icmp_data;
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struct s_nat *connection;
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unsigned short orig_checksum;
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unsigned char *packet;
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struct s_icmp *icmp;
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unsigned int *icmp_extra;
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unsigned short *icmp_extra_s;
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unsigned char *icmp_extra_c;
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unsigned char *icmp_data;
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struct s_nat *connection;
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unsigned short orig_checksum;
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unsigned short payload_size;
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unsigned char packet[PACKET_BUFFER - sizeof(struct s_ethernet)];
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unsigned short new_len = sizeof(struct s_ipv4);
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struct s_icmp_echo *echo;
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struct s_ipv4 *ip4;
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struct s_ipv6 *eip6;
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payload_size = ntohs(ip6->len);
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/* sanity check */
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if (payload_size < sizeof(struct s_icmp) + 4) {
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log_debug("Too short ICMPv6 packet");
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return 1;
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}
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icmp = (struct s_icmp *) payload;
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icmp_data = (unsigned char *) (payload + sizeof(struct s_icmp));
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@ -362,7 +380,7 @@ int icmp_ipv6(struct s_ethernet *eth6, struct s_ipv6 *ip6, char *payload)
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orig_checksum = icmp->checksum;
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icmp->checksum = 0;
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icmp->checksum = checksum_ipv6(ip6->ip_src, ip6->ip_dest,
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htons(ip6->len), IPPROTO_ICMPV6,
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payload_size, IPPROTO_ICMPV6,
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(unsigned char *) icmp);
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if (icmp->checksum != orig_checksum) {
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@ -376,8 +394,7 @@ int icmp_ipv6(struct s_ethernet *eth6, struct s_ipv6 *ip6, char *payload)
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case ICMPV6_ECHO_REQUEST:
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echo = (struct s_icmp_echo *) icmp_data;
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connection = nat_out(nat6_icmp, nat4_icmp,
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eth6->src,
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connection = nat_out(nat6_icmp, nat4_icmp, eth6->src,
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ip6->ip_src, ip6->ip_dest,
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echo->id, 0, 1);
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@ -401,35 +418,196 @@ int icmp_ipv6(struct s_ethernet *eth6, struct s_ipv6 *ip6, char *payload)
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/* override information in original ICMP header */
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icmp->type = ICMPV4_ECHO_REQUEST;
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/* copy the payload data */
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/* IPv6 node can handle too big packets itself */
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if (payload_size < 1500 - sizeof(struct s_ipv4)) {
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memcpy(&packet[new_len], payload, payload_size);
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icmp = (struct s_icmp *) &packet[new_len];
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new_len += payload_size;
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} else {
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memcpy(&packet[new_len], payload, 1500 -
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sizeof(struct s_ipv4));
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icmp = (struct s_icmp *) &packet[new_len];
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new_len += 1500 - sizeof(struct s_ipv4);
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}
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break;
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case ICMPV6_ECHO_REPLY:
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/* this is pretty non-sense situation */
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return 1;
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case ICMPV6_NDP_NS:
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/* sanity check */
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if (payload_size < sizeof(struct s_icmp) +
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sizeof(struct s_icmp_ndp_ns)) {
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log_debug("Too short NDP NS");
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return 1;
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}
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return icmp_ndp(eth6, ip6,
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(struct s_icmp_ndp_ns *) icmp_data);
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case ICMPV6_DST_UNREACHABLE:
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/* translate type */
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icmp->type = ICMPV4_DST_UNREACHABLE;
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/* translate code */
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if (icmp->code == 0 ||
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icmp->code == 3 ||
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icmp->code == 2) {
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icmp->code = 1;
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} else if (icmp->code == 1) {
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icmp->code = 10;
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} else if (icmp->code == 4) {
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icmp->code = 3;
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} else {
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/* silently drop */
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return 0;
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}
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/* translate body of the packet */
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if (sub_icmp6_error(eth6, icmp_data + 4,
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payload_size - sizeof(struct s_icmp) - 4,
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packet, &new_len, &icmp, &connection)) {
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/* something went wrong */
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return 1;
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}
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/* new packet is almost finished, yay! */
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break;
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case ICMPV6_TIME_EXCEEDED:
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/* translate type; code doesn't change */
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icmp->type = ICMPV4_TIME_EXCEEDED;
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/* translate body of the packet */
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if (sub_icmp6_error(eth6, icmp_data + 4,
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payload_size - sizeof(struct s_icmp) - 4,
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packet, &new_len, &icmp, &connection)) {
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/* something went wrong */
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return 1;
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}
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/* new packet is almost finished, yay! */
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break;
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case ICMPV6_PARAM_PROBLEM:
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if (icmp->code == 0) {
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/* update type; code remains unchanged */
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icmp->type = ICMPV4_PARAM_PROBLEM;
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/* update the extra field */
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icmp_extra = (unsigned int *)
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(((unsigned char *) icmp) +
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sizeof(struct s_icmp));
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icmp_extra_c = (unsigned char *) icmp_extra;
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switch (*icmp_extra) {
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case 0:
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case 1:
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break;
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case 4:
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case 5:
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*icmp_extra_c = 2;
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break;
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case 6:
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*icmp_extra_c = 9;
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break;
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case 7:
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*icmp_extra_c = 8;
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break;
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default:
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/* 8-23 */
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if (*icmp_extra_c >= 8 &&
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*icmp_extra_c <= 23) {
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*icmp_extra_c = 12;
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/* 24-39 */
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} else if (*icmp_extra_c > 23 &&
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*icmp_extra_c <= 39) {
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*icmp_extra_c = 16;
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} else {
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/* silently drop */
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return 0;
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}
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}
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} else if (icmp->code == 1) {
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/* update type&code */
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icmp->type = ICMPV4_DST_UNREACHABLE;
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icmp->code = 2;
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} else {
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/* silently drop */
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return 0;
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}
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/* translate body of the packet */
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if (sub_icmp6_error(eth6, icmp_data + 4,
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payload_size - sizeof(struct s_icmp) - 4,
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packet, &new_len, &icmp, &connection)) {
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/* something went wrong */
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return 1;
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}
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/* new packet is almost finished, yay! */
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break;
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/* this shouldn't happen! it would mean MTU is set badly */
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case ICMPV6_PKT_TOO_BIG:
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log_warn("ICMPv6 'Packet too big' received. Your MTU "
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"setting is too high!");
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/* sanity check */
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if (payload_size < sizeof(struct s_icmp) + 4 +
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sizeof(struct s_ipv6)) {
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log_debug("Too short ICMPv6 packet 6");
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return 1;
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}
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eip6 = (struct s_ipv6 *) (icmp_data + 4);
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/* translate type&code */
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icmp->type = ICMPV4_DST_UNREACHABLE;
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icmp->code = 4;
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icmp_extra = (unsigned int *)
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(((unsigned char *) icmp) +
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sizeof(struct s_icmp));
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icmp_extra_s = (unsigned short *)
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(((unsigned char *) icmp) +
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sizeof(struct s_icmp) + 2);
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if (eip6->next_header != IPPROTO_FRAGMENT) {
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*icmp_extra_s = htons(ntohl(*icmp_extra) - 20);
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} else {
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/* D(IPv4, IPv6) - fragment header = 20 - 8 */
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*icmp_extra_s = htons(ntohl(*icmp_extra) - 12);
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}
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/* translate body of the packet */
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if (sub_icmp6_error(eth6, icmp_data + 4,
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payload_size - sizeof(struct s_icmp) - 4,
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packet, &new_len, &icmp, &connection)) {
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/* something went wrong */
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return 1;
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}
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/* new packet is almost finished, yay! */
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break;
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default:
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log_debug("ICMPv6 Type: unknown [%d/0x%x]",
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icmp->type, icmp->type);
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return 1;
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/* silently drop */
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return 0;
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}
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/* allocate memory for translated packet */
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if ((packet = (unsigned char *) malloc(sizeof(struct s_ipv4) +
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htons(ip6->len))) == NULL) {
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log_error("Lack of free memory");
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return 1;
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}
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ip4 = (struct s_ipv4 *) packet;
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/* build IPv4 packet */
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ip4->ver_hdrlen = 0x45; /* ver 4, header length 20 B */
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ip4->tos = ((ip6->ver & 0x0f) << 4) |
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((ip6->traffic_class & 0xf0) >> 4);
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ip4->len = htons(sizeof(struct s_ipv4) + htons(ip6->len));
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ip4->len = htons(new_len);
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ip4->id = 0x0;
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ip4->flags_offset = htons(IPV4_FLAG_DONT_FRAGMENT);
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ip4->ttl = ip6->hop_limit;
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@ -439,21 +617,16 @@ int icmp_ipv6(struct s_ethernet *eth6, struct s_ipv6 *ip6, char *payload)
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/* compute ICMP checksum */
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icmp->checksum = 0x0;
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icmp->checksum = checksum((unsigned char *) icmp, htons(ip6->len));
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/* copy the payload data (with new checksum) */
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memcpy(packet + sizeof(struct s_ipv4), payload, htons(ip6->len));
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icmp->checksum = checksum((unsigned char *) icmp, new_len -
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sizeof(struct s_ipv4));
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/* compute IPv4 checksum */
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ip4->checksum = checksum_ipv4(ip4->ip_src, ip4->ip_dest,
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htons(ip4->len), IPPROTO_ICMP,
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new_len, IPPROTO_ICMP,
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(unsigned char *) icmp);
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/* send translated packet */
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transmit_ipv4(&ip4->ip_dest, packet, htons(ip4->len));
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/* clean-up */
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free(packet);
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transmit_ipv4(&ip4->ip_dest, packet, new_len);
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return 0;
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}
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@ -645,6 +818,7 @@ int icmp6_error(struct s_mac_addr mac_dest, struct s_ipv6_addr ip_dest,
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struct s_icmp *icmp;
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/* 4 = unused space after ICMP header */
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/* 1280 -- because RFC on ICMPv6 says so */
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unsigned short payload_size = length > 1280 - sizeof(struct s_ipv6) -
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sizeof(struct s_icmp) - 4 ?
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1280 - sizeof(struct s_ipv6) - sizeof(struct s_icmp) - 4 :
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@ -747,11 +921,11 @@ int sub_icmp4_error(unsigned char *payload, unsigned short payload_size,
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eip4_hlen = (eip4->ver_hdrlen & 0x0f) * 4;
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/* sanity check */
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/* 4 B -> L4 addrs */
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if (payload_size < eip4_hlen + 4) {
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log_debug("Too short ICMPv4 packet 3");
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return 1;
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}
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/* 4 B -> L4 addrs */
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payload_size -= eip4_hlen;
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payload += eip4_hlen;
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@ -768,7 +942,7 @@ int sub_icmp4_error(unsigned char *payload, unsigned short payload_size,
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case IPPROTO_TCP:
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etcp = (struct s_tcp *) payload;
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*connection = nat_in(nat4_tcp, eip4->ip_dest,
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etcp->port_dest, etcp->port_src);
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etcp->port_dest, etcp->port_src);
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if (*connection == NULL) {
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log_debug("Incoming TCP error connection "
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@ -784,7 +958,7 @@ int sub_icmp4_error(unsigned char *payload, unsigned short payload_size,
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case IPPROTO_UDP:
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eudp = (struct s_udp *) payload;
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*connection = nat_in(nat4_udp, eip4->ip_dest,
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eudp->port_dest, eudp->port_src);
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eudp->port_dest, eudp->port_src);
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if (*connection == NULL) {
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log_debug("Incoming UDP error connection "
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@ -820,7 +994,7 @@ int sub_icmp4_error(unsigned char *payload, unsigned short payload_size,
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sizeof(struct s_icmp));
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*connection = nat_in(nat4_icmp, eip4->ip_dest, 0,
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echo->id);
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echo->id);
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if (*connection == NULL) {
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log_debug("Incoming ICMP error connection "
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@ -860,14 +1034,23 @@ int sub_icmp4_error(unsigned char *payload, unsigned short payload_size,
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*packet_len += sizeof(struct s_icmp) + 4 + sizeof(struct s_ipv6);
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/* was the IPv4 packet fragmented? */
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if ((eip4->flags_offset & htons(0x1fff)) != 0x0000) {
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/* original length of error packet,
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* but without IP header, but with
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* fragment header(!) */
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if (ntohs(eip4->flags_offset) & 0x1fff) {
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eip6_frag = (struct s_ipv6_fragment *) &packet[*packet_len];
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if (ntohs(eip4->flags_offset) & IPV4_FLAG_MORE_FRAGMENTS) {
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eip6_frag->offset_flag = htons(((ntohs(eip4->
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flags_offset) & 0x1fff) << 3) |
|
||||
IPV6_FLAG_MORE_FRAGMENTS);
|
||||
} else {
|
||||
eip6_frag->offset_flag = htons((ntohs(eip4->
|
||||
flags_offset) & 0x1fff) << 3);
|
||||
}
|
||||
|
||||
/* original length of error packet, but without IP header,
|
||||
* but with fragment header(!) */
|
||||
eip6->len = htons(ntohs(eip4->len) - eip4_hlen +
|
||||
sizeof(struct s_ipv6_fragment));
|
||||
|
||||
eip6_frag = (struct s_ipv6_fragment *) &packet[*packet_len];
|
||||
eip6_frag->next_header = eip6->next_header;
|
||||
eip6->next_header = IPPROTO_FRAGMENT;
|
||||
eip6_frag->id = htonl(ntohs(eip4->id));
|
||||
@ -880,8 +1063,9 @@ int sub_icmp4_error(unsigned char *payload, unsigned short payload_size,
|
||||
/* copy payload, aligned to MTU */
|
||||
/* we can afford to use full MTU instead of just 1280 B as admin
|
||||
* warrants this to us */
|
||||
if (payload_size > (unsigned int) MTU - *packet_len) {
|
||||
memcpy(&packet[*packet_len], payload, MTU - *packet_len);
|
||||
if (payload_size > MTU + sizeof(struct s_ethernet) - *packet_len) {
|
||||
memcpy(&packet[*packet_len], payload,
|
||||
MTU + sizeof(struct s_ethernet) - *packet_len);
|
||||
*packet_len = MTU;
|
||||
} else {
|
||||
memcpy(&packet[*packet_len], payload, payload_size);
|
||||
@ -890,3 +1074,207 @@ int sub_icmp4_error(unsigned char *payload, unsigned short payload_size,
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
/**
|
||||
* Helper function for translating inner packet in ICMPv6 error.
|
||||
*
|
||||
* @param eth6 Ethernet header of incoming packet
|
||||
* @param payload Original inner packet data
|
||||
* @param payload_size Length of original data
|
||||
* @param packet Space for translated packet data
|
||||
* @param packet_len Length of translated data
|
||||
* @param icmp Outer ICMP header
|
||||
* @param connection NAT connection for inner packet
|
||||
*
|
||||
* @return 0 for success
|
||||
* @return 1 for failure
|
||||
*/
|
||||
int sub_icmp6_error(struct s_ethernet *eth6,
|
||||
unsigned char *payload, unsigned short payload_size,
|
||||
unsigned char *packet, unsigned short *packet_len,
|
||||
struct s_icmp **icmp, struct s_nat **connection)
|
||||
{
|
||||
struct s_ipv4 *eip4;
|
||||
struct s_ipv6 *eip6;
|
||||
struct s_ipv6_fragment *eip6_frag;
|
||||
struct s_tcp *etcp;
|
||||
struct s_udp *eudp;
|
||||
struct s_icmp *eicmp;
|
||||
struct s_icmp_echo *echo;
|
||||
|
||||
unsigned char skip_l4 = 0;
|
||||
|
||||
/* sanity check */
|
||||
if (payload_size < sizeof(struct s_ipv6)) {
|
||||
log_debug("Too short ICMPv6 packet 2");
|
||||
return 1;
|
||||
}
|
||||
|
||||
eip6 = (struct s_ipv6 *) payload;
|
||||
payload += sizeof(struct s_ipv6);
|
||||
payload_size -= sizeof(struct s_ipv6);
|
||||
|
||||
/* define new inner IPv4 header */
|
||||
/* new_len+4+4+20=48 < 576 */
|
||||
eip4 = (struct s_ipv4 *) &packet[*packet_len + sizeof(struct s_icmp) +
|
||||
4];
|
||||
/* we'll need this right now */
|
||||
ipv6_to_ipv4(&eip6->ip_src, &eip4->ip_src);
|
||||
|
||||
/* handle fragmented inner packets */
|
||||
if (eip6->next_header == IPPROTO_FRAGMENT) {
|
||||
/* sanity check */
|
||||
if (payload_size < sizeof(struct s_ipv6_fragment)) {
|
||||
log_debug("Too short ICMPv6 packet 4");
|
||||
return 1;
|
||||
}
|
||||
|
||||
eip6_frag = (struct s_ipv6_fragment *) payload;
|
||||
|
||||
eip4->id = htons(ntohl(eip6_frag->id));
|
||||
if (ntohs(eip6_frag->offset_flag) & 0xfff8) {
|
||||
skip_l4 = 1;
|
||||
}
|
||||
if (ntohs(eip6_frag->offset_flag) & IPV6_FLAG_MORE_FRAGMENTS) {
|
||||
eip4->flags_offset = htons(((ntohs(eip6_frag->
|
||||
offset_flag) & 0xfff8) >> 3) |
|
||||
IPV4_FLAG_MORE_FRAGMENTS);
|
||||
} else {
|
||||
eip4->flags_offset = htons((ntohs(eip6_frag->
|
||||
offset_flag) & 0xfff8) >> 3);
|
||||
}
|
||||
eip6->next_header = eip6_frag->next_header;
|
||||
|
||||
payload += sizeof(struct s_ipv6_fragment);
|
||||
payload_size -= sizeof(struct s_ipv6_fragment);
|
||||
} else {
|
||||
/* sanity check */
|
||||
/* 4 B -> L4 addrs */
|
||||
if (payload_size < 4) {
|
||||
log_debug("Too short ICMPv6 packet 5");
|
||||
return 1;
|
||||
}
|
||||
|
||||
eip4->id = 0x0;
|
||||
eip4->flags_offset = htons(IPV4_FLAG_DONT_FRAGMENT);
|
||||
}
|
||||
|
||||
/* look for the original connection */
|
||||
if (skip_l4 == 0) {
|
||||
switch (eip6->next_header) {
|
||||
case IPPROTO_TCP:
|
||||
etcp = (struct s_tcp *) payload;
|
||||
*connection = nat_out(nat6_tcp, nat4_tcp,
|
||||
eth6->src, eip6->ip_dest, eip6->ip_src,
|
||||
etcp->port_dest, etcp->port_src, 0);
|
||||
|
||||
if (*connection == NULL) {
|
||||
log_debug("Outgoing TCP error "
|
||||
"connection wasn't found in "
|
||||
"NAT");
|
||||
return 1;
|
||||
}
|
||||
|
||||
/* fix port for remote client */
|
||||
etcp->port_dest = (*connection)->ipv4_port_src;
|
||||
|
||||
break;
|
||||
|
||||
case IPPROTO_UDP:
|
||||
eudp = (struct s_udp *) payload;
|
||||
*connection = nat_out(nat6_udp, nat4_udp,
|
||||
eth6->src, eip6->ip_dest, eip6->ip_src,
|
||||
eudp->port_dest, eudp->port_src, 0);
|
||||
|
||||
if (*connection == NULL) {
|
||||
log_debug("Outgoing UDP error "
|
||||
"connection wasn't found in "
|
||||
"NAT");
|
||||
return 1;
|
||||
}
|
||||
|
||||
/* fix port for remote client */
|
||||
eudp->port_dest = (*connection)->ipv4_port_src;
|
||||
|
||||
break;
|
||||
|
||||
case IPPROTO_ICMP:
|
||||
eicmp = (struct s_icmp *) payload;
|
||||
|
||||
/* we translate only echo replies so handle
|
||||
* only them here too */
|
||||
if (eicmp->type != ICMPV6_ECHO_REPLY) {
|
||||
log_debug("Unknown ICMP type within "
|
||||
"ICMP error");
|
||||
return 1;
|
||||
}
|
||||
|
||||
/* else: */
|
||||
|
||||
/* sanity check */
|
||||
if (payload_size < sizeof(struct s_icmp) +
|
||||
sizeof(struct s_icmp_echo)) {
|
||||
log_debug("Too short ICMPv6 packet 3");
|
||||
return 1;
|
||||
}
|
||||
|
||||
echo = (struct s_icmp_echo *) (payload +
|
||||
sizeof(struct s_icmp));
|
||||
|
||||
*connection = nat_out(nat6_icmp, nat4_icmp,
|
||||
eth6->src, eip6->ip_dest, eip6->ip_src,
|
||||
echo->id, 0, 0);
|
||||
|
||||
if (*connection == NULL) {
|
||||
log_debug("Incoming ICMP error "
|
||||
"connection wasn't found in "
|
||||
"NAT");
|
||||
return 1;
|
||||
}
|
||||
|
||||
/* fix port for remote client */
|
||||
echo->id = (*connection)->ipv4_port_src;
|
||||
|
||||
/* adjust ICMP type */
|
||||
eicmp->type = ICMPV4_ECHO_REPLY;
|
||||
|
||||
break;
|
||||
|
||||
default:
|
||||
/* anything else surely wasn't translated */
|
||||
return 1;
|
||||
}
|
||||
}
|
||||
|
||||
/* copy ICMP header to new packet */
|
||||
memcpy(&packet[*packet_len], *icmp, sizeof(struct s_icmp) + 4);
|
||||
*icmp = (struct s_icmp *) &packet[*packet_len];
|
||||
|
||||
/* complete inner IPv4 header */
|
||||
eip4->ver_hdrlen = 0x45; /* ver 4, header length 20 B */
|
||||
eip4->tos = ((eip6->ver & 0x0f) << 4) |
|
||||
((eip6->traffic_class & 0xf0) >> 4);
|
||||
eip4->len = htons(sizeof(struct s_ipv4) + ntohs(eip6->len));
|
||||
eip4->ttl = eip6->hop_limit;
|
||||
eip4->ip_src = wrapsix_ipv4_addr;
|
||||
if (eip6->next_header != IPPROTO_ICMPV6) {
|
||||
eip4->proto = eip6->next_header;
|
||||
} else {
|
||||
eip4->proto = IPPROTO_ICMP;
|
||||
}
|
||||
|
||||
/* packet_len == sizeof(IPv4) */
|
||||
*packet_len += sizeof(struct s_icmp) + 4 + sizeof(struct s_ipv4);
|
||||
|
||||
/* copy payload */
|
||||
/* let's use 576 as an IPv4 MTU */
|
||||
if (payload_size > 576 - *packet_len) {
|
||||
memcpy(&packet[*packet_len], payload, 576 - *packet_len);
|
||||
*packet_len = 576;
|
||||
} else {
|
||||
memcpy(&packet[*packet_len], payload, payload_size);
|
||||
*packet_len += payload_size;
|
||||
}
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
Loading…
Reference in New Issue
Block a user