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#include "proto.h"
#include "util.h"
enum {
Version = 0,
HdrLen = 0,
PktLen = 2,
Id = 4,
Proto = 9,
SrcIP = 12,
DestIP = 16,
};
void ipv4_parse(const uint8_t *buf, size_t len) {
uint8_t version, headerlen, proto;
uint16_t packetlen, id;
uint32_t dest, src;
version = buf[Version] >> 4;
if (version != 4) {
printf("bad IPv4 version %u\n", version);
return;
}
headerlen = (buf[HdrLen] & 0xf) * 4;
packetlen = nget16(buf + PktLen);
id = nget16(buf + Id);
proto = buf[Proto];
src = nget32(buf + SrcIP);
dest = nget32(buf + DestIP);
// TODO checksum
// TODO fragmentation
printf("headerlen %u, packetlen %u (real %u), id %u\n", headerlen, packetlen, len, id);
printf("from %x to %x\n", src, dest);
printf("id %u\n", id);
if (packetlen < headerlen) {
printf("headerlen too big\n");
return;
}
switch (proto) {
case 1:
printf("proto %u - icmp\n", proto);
icmp_parse(buf + headerlen, packetlen - headerlen);
break;
default:
printf("proto %u - unknown\n", proto);
break;
}
}
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