mirror of
https://code.semirocket.science/wrapsix
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Base of enhanced ICMP support
Translated ICMPv4 packets are statically allocated ICMPv4 sanitizes size of payload Fix of an overflow
This commit is contained in:
Michal Zima
parent
f7a03e8240
commit
d1a25aee7f
385
src/icmp.c
385
src/icmp.c
@ -27,7 +27,9 @@
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#include "linkedlist.h"
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#include "log.h"
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#include "nat.h"
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#include "tcp.h"
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#include "transmitter.h"
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#include "udp.h"
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#include "wrapper.h"
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/**
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@ -46,16 +48,34 @@
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int icmp_ipv4(struct s_ethernet *eth4, struct s_ipv4 *ip4,
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char *payload, unsigned short payload_size)
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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_data;
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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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struct s_icmp_echo *echo;
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struct s_ethernet *eth6;
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struct s_ipv6 *ip6;
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/* for error messages */
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unsigned short payload_size_left, new_len;
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struct s_ipv4 *eip4;
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struct s_ipv6 *eip6;
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struct s_tcp *etcp;
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struct s_udp *eudp;
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struct s_icmp *eicmp;
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unsigned short eip4_hlen;
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struct s_ipv6_fragment *eip6_frag;
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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 ICMPv4 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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@ -71,11 +91,9 @@ int icmp_ipv4(struct s_ethernet *eth4, struct s_ipv4 *ip4,
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}
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switch (icmp->type) {
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case ICMPV4_ECHO_REQUEST:
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/* this is pretty non-sense situation */
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return 1;
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case ICMPV4_ECHO_REPLY:
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/* this option is already sanitized */
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echo = (struct s_icmp_echo *) icmp_data;
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connection = nat_in(nat4_icmp, ip4->ip_src,
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@ -94,23 +112,309 @@ int icmp_ipv4(struct s_ethernet *eth4, struct s_ipv4 *ip4,
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/* override information in original ICMP header */
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icmp->type = ICMPV6_ECHO_REPLY;
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new_len = sizeof(struct s_ethernet) +
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sizeof(struct s_ipv6);
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/* copy the payload data */
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payload_size_left = payload_size >
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MTU - sizeof(struct s_ipv6) ?
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MTU - sizeof(struct s_ipv6) : payload_size;
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memcpy(&packet[new_len], payload, payload_size_left);
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icmp = (struct s_icmp *) &packet[new_len];
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new_len += payload_size_left;
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break;
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case ICMPV4_DST_UNREACHABLE:
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if (icmp->code <= 13 || icmp->code == 15) {
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/* sanity check */
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payload_size_left = payload_size -
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sizeof(struct s_icmp) - 4;
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if (payload_size_left < 1) {
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log_debug("Too short ICMPv4 packet 2");
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return 1;
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}
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/* skip unused space */
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icmp_data += 4;
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/* parse IPv4 header */
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eip4 = (struct s_ipv4 *) icmp_data;
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/* # of 4 byte words */
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eip4_hlen = (eip4->ver_hdrlen & 0x0f) * 4;
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/* sanity check */
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if (payload_size_left < 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_left -= eip4_hlen + 4;
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icmp_data += eip4_hlen;
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new_len = sizeof(struct s_ethernet) +
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sizeof(struct s_ipv6);
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/* define new inner IPv6 header */
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/* new_len+4+4+40=102 < 1280 */
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eip6 = (struct s_ipv6 *) &packet[new_len +
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sizeof(struct s_icmp) + 4];
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/* we'll need this right now */
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ipv4_to_ipv6(&eip4->ip_dest, &eip6->ip_dest);
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/* look for the original connection */
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switch (eip4->proto) {
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case IPPROTO_TCP:
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etcp = (struct s_tcp *)
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icmp_data;
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connection = nat_in(nat4_tcp,
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eip4->ip_dest,
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etcp->port_dest,
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etcp->port_src);
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if (connection == NULL) {
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log_debug("Incoming "
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"TCP error "
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"connection "
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"wasn't found "
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"in NAT");
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return 1;
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}
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/* fix port for local client */
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etcp->port_src = connection->
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ipv6_port_src;
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break;
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case IPPROTO_UDP:
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eudp = (struct s_udp *)
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icmp_data;
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connection = nat_in(nat4_udp,
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eip4->ip_dest,
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eudp->port_dest,
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eudp->port_src);
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if (connection == NULL) {
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log_debug("Incoming "
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"UDP error "
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"connection "
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"wasn't found "
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"in NAT");
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return 1;
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}
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/* fix port for local client */
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eudp->port_src = connection->
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ipv6_port_src;
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break;
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case IPPROTO_ICMP:
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eicmp = (struct s_icmp *)
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icmp_data;
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/* we translate only echo
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* requests so handle only them
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* here too */
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if (eicmp->type !=
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ICMPV4_ECHO_REQUEST) {
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log_debug("Unknown ICMP"
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" type within "
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"ICMP error");
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return 1;
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}
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/* else: */
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/* sanity check */
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if (payload_size_left < 4) {
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log_debug("Too short "
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"ICMPv4 packet "
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"4");
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return 1;
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}
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echo = (struct s_icmp_echo *)
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(icmp_data +
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sizeof(struct s_icmp));
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connection = nat_in(nat4_icmp,
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eip4->ip_dest, 0,
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echo->id);
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if (connection == NULL) {
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log_debug("Incoming "
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"ICMP error "
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"connection "
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"wasn't found "
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"in NAT");
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return 1;
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}
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/* fix port for local client */
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echo->id = connection->
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ipv6_port_src;
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/* adjust ICMP type */
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eicmp->type =
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ICMPV6_ECHO_REQUEST;
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break;
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default:
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/* we don't know where to send
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* it */
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return 1;
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}
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/* copy ICMP header to new packet */
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memcpy(&packet[new_len], icmp,
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sizeof(struct s_icmp) + 4);
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icmp = (struct s_icmp *) &packet[new_len];
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new_len += sizeof(struct s_icmp) + 4;
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/* complete inner IPv6 header */
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eip6->ver = 0x60 | (eip4->tos >> 4);
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eip6->traffic_class = eip4->tos << 4;
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eip6->flow_label = 0x0;
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eip6->hop_limit = eip4->ttl;
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if (eip4->proto != IPPROTO_ICMP) {
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eip6->next_header = eip4->proto;
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} else {
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eip6->next_header = IPPROTO_ICMPV6;
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}
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eip6->ip_src = connection->ipv6;
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new_len += sizeof(struct s_ipv6);
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/* was the IPv4 packet fragmented? */
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if ((eip4->flags_offset & htons(0x1fff)) !=
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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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eip6->len = htons(ntohs(eip4->len) -
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eip4_hlen +
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sizeof(struct s_ipv6_fragment));
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eip6_frag = (struct s_ipv6_fragment *)
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&packet[new_len];
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eip6_frag->next_header =
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eip6->next_header;
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eip6->next_header = IPPROTO_FRAGMENT;
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eip6_frag->id = htonl(ntohs(eip4->id));
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new_len +=
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sizeof(struct s_ipv6_fragment);
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} else {
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eip6->len = htons(ntohs(eip4->len) -
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eip4_hlen);
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}
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/* translate ICMP type&code */
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if (icmp->code == 2) {
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icmp->type = ICMPV6_PARAM_PROBLEM;
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icmp->code = 1;
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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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if (eip6->next_header ==
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IPPROTO_FRAGMENT) {
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/* field next_header in FragH */
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*icmp_extra = htonl(40);
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} else {
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/* field next_header in IPv6 */
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*icmp_extra = htonl(6);
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}
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} else if (icmp->code == 4) {
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icmp->type = ICMPV6_PKT_TOO_BIG;
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icmp->code = 0;
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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 (ntohs(*icmp_extra_s) < 68) {
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*icmp_extra = htonl(
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*icmp_extra_s + 20 <
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MTU ? (unsigned int)
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*icmp_extra_s + 20 :
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MTU);
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} else {
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/* RFC1191 */
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/* NOTE: >= would cause infinite
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* loop */
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/* 1492+ don't have to be
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* checked -- the biggest packet
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* we can send there is 1480 */
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if (ntohs(eip4->len) >
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1006) {
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*icmp_extra =
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htonl(1006);
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} else if (ntohs(eip4->len) >
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508) {
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*icmp_extra =
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htonl(508);
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} else if (ntohs(eip4->len) >
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296) {
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*icmp_extra =
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htonl(296);
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} else {
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*icmp_extra = htonl(68);
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}
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}
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} else if (icmp->code == 3) {
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icmp->type = ICMPV6_DST_UNREACHABLE;
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icmp->code = 4;
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} else if (icmp->code == 9 ||
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icmp->code == 10 ||
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icmp->code == 13 ||
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icmp->code == 15) {
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icmp->type = ICMPV6_DST_UNREACHABLE;
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icmp->code = 1;
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} else {
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icmp->type = ICMPV6_DST_UNREACHABLE;
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icmp->code = 0;
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}
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/* copy payload, aligned to MTU */
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/* we can afford to use full MTU instead of
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* just 1280 B as admin warrants this to us */
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if (payload_size - sizeof(struct s_icmp) - 4 -
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eip4_hlen > (unsigned int) MTU - new_len) {
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memcpy(&packet[new_len], icmp_data,
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MTU - new_len);
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new_len = MTU;
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} else {
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memcpy(&packet[new_len], icmp_data,
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payload_size -
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sizeof(struct s_icmp) - 4 -
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eip4_hlen);
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new_len += payload_size -
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sizeof(struct s_icmp) - 4 -
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eip4_hlen;
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}
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/* new packet is almost finished, yay! */
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break;
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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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default:
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log_debug("ICMPv4 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_ethernet) +
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sizeof(struct s_ipv6) +
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payload_size)) == 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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eth6 = (struct s_ethernet *) packet;
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ip6 = (struct s_ipv6 *) (packet + sizeof(struct s_ethernet));
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eth6 = (struct s_ethernet *) &packet[0];
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ip6 = (struct s_ipv6 *) &packet[sizeof(struct s_ethernet)];
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/* build ethernet header */
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eth6->dest = connection->mac;
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@ -121,27 +425,21 @@ int icmp_ipv4(struct s_ethernet *eth4, struct s_ipv4 *ip4,
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ip6->ver = 0x60 | (ip4->tos >> 4);
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ip6->traffic_class = ip4->tos << 4;
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ip6->flow_label = 0x0;
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ip6->len = htons(payload_size);
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ip6->len = htons(new_len - sizeof(struct s_ethernet) - sizeof(struct s_ipv6));
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ip6->next_header = IPPROTO_ICMPV6;
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ip6->hop_limit = ip4->ttl;
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ipv4_to_ipv6(&ip4->ip_src, &ip6->ip_src);
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ip6->ip_dest = connection->ipv6;
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/* compute ICMP checksum */
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/* compute ICMP checksum; this is already in new packet */
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icmp->checksum = 0x0;
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icmp->checksum = checksum_ipv6(ip6->ip_src, ip6->ip_dest, payload_size,
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IPPROTO_ICMPV6, (unsigned char *) icmp);
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/* copy the payload data (with new checksum) */
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memcpy(packet + sizeof(struct s_ethernet) + sizeof(struct s_ipv6),
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payload, payload_size);
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icmp->checksum = checksum_ipv6(ip6->ip_src, ip6->ip_dest, new_len -
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sizeof(struct s_ethernet) -
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sizeof(struct s_ipv6), IPPROTO_ICMPV6,
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(unsigned char *) icmp);
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/* send translated packet */
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transmit_raw(packet, sizeof(struct s_ethernet) + sizeof(struct s_ipv6) +
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payload_size);
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/* clean-up */
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free(packet);
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transmit_raw(&packet[0], new_len);
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return 0;
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}
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@ -370,6 +668,7 @@ int icmp4_error(struct s_ipv4_addr ip_dest, unsigned char type,
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unsigned char code, unsigned char *data, unsigned short length)
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{
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unsigned char *packet, *payload;
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unsigned int *unused;
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struct s_ipv4 *ip4;
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struct s_icmp *icmp;
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@ -385,9 +684,11 @@ int icmp4_error(struct s_ipv4_addr ip_dest, unsigned char type,
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return 1;
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}
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ip4 = (struct s_ipv4 *) packet;
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icmp = (struct s_icmp *) (packet + sizeof(struct s_ipv4));
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payload = (unsigned char *) (packet + sizeof(struct s_ipv4) +
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ip4 = (struct s_ipv4 *) packet;
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icmp = (struct s_icmp *) (packet + sizeof(struct s_ipv4));
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unused = (unsigned int *) (packet + sizeof(struct s_ipv4) +
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sizeof(struct s_icmp));
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payload = (unsigned char *) (packet + sizeof(struct s_ipv4) +
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sizeof(struct s_icmp) + 4);
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/* build IPv4 packet */
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@ -407,6 +708,9 @@ int icmp4_error(struct s_ipv4_addr ip_dest, unsigned char type,
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icmp->code = code;
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icmp->checksum = 0x0;
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/* set unused area to zero */
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*unused = 0x0;
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/* copy the payload data */
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memcpy(payload, data, payload_size);
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@ -446,6 +750,7 @@ int icmp6_error(struct s_mac_addr mac_dest, struct s_ipv6_addr ip_dest,
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unsigned short length)
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{
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unsigned char *packet, *payload;
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unsigned int *unused;
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struct s_ethernet *eth;
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struct s_ipv6 *ip6;
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struct s_icmp *icmp;
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@ -467,6 +772,9 @@ int icmp6_error(struct s_mac_addr mac_dest, struct s_ipv6_addr ip_dest,
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ip6 = (struct s_ipv6 *) (packet + sizeof(struct s_ethernet));
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icmp = (struct s_icmp *) (packet + sizeof(struct s_ethernet) +
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sizeof(struct s_ipv6));
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unused = (unsigned int *) (packet + sizeof(struct s_ethernet) +
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sizeof(struct s_ipv6) +
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sizeof(struct s_icmp));
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payload = (unsigned char *) (packet + sizeof(struct s_ethernet) +
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sizeof(struct s_ipv6) +
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sizeof(struct s_icmp) + 4);
|
||||
@ -489,6 +797,9 @@ int icmp6_error(struct s_mac_addr mac_dest, struct s_ipv6_addr ip_dest,
|
||||
icmp->code = code;
|
||||
icmp->checksum = 0x0;
|
||||
|
||||
/* set unused area to zero */
|
||||
*unused = 0x0;
|
||||
|
||||
/* copy the payload data */
|
||||
memcpy(payload, data, payload_size);
|
||||
|
||||
|
||||
@ -25,7 +25,9 @@
|
||||
/* ICMP types */
|
||||
#define ICMPV4_ECHO_REPLY 0x0
|
||||
#define ICMPV4_ECHO_REQUEST 0x8
|
||||
#define ICMPV4_DST_UNREACHABLE 0x3
|
||||
#define ICMPV4_TIME_EXCEEDED 0xb
|
||||
#define ICMPV4_PARAM_PROBLEM 0xc
|
||||
|
||||
/* ICMPv6 types */
|
||||
#define ICMPV6_DST_UNREACHABLE 0x1
|
||||
|
||||
Loading…
Reference in New Issue
Block a user