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bol-van
650
nfq/darkmagic.c
Normal file
650
nfq/darkmagic.c
Normal file
@@ -0,0 +1,650 @@
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||||
#define _GNU_SOURCE
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#include "darkmagic.h"
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <arpa/inet.h>
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#include <sys/param.h>
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#include <errno.h>
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#include "helpers.h"
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uint32_t net32_add(uint32_t netorder_value, uint32_t cpuorder_increment)
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{
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return htonl(ntohl(netorder_value)+cpuorder_increment);
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}
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uint8_t *tcp_find_option(struct tcphdr *tcp, uint8_t kind)
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{
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uint8_t *t = (uint8_t*)(tcp+1);
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uint8_t *end = (uint8_t*)tcp + (tcp->th_off<<2);
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while(t<end)
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{
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switch(*t)
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{
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case 0: // end
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return NULL;
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case 1: // noop
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t++;
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break;
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default: // kind,len,data
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if ((t+1)>=end || t[1]<2 || (t+t[1])>end)
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return NULL;
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if (*t==kind)
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return t;
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t+=t[1];
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break;
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}
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}
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return NULL;
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}
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uint32_t *tcp_find_timestamps(struct tcphdr *tcp)
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{
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uint8_t *t = tcp_find_option(tcp,8);
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return (t && t[1]==10) ? (uint32_t*)(t+2) : NULL;
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}
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static void fill_tcphdr(struct tcphdr *tcp, uint8_t tcp_flags, uint32_t seq, uint32_t ack_seq, uint8_t fooling, uint16_t nsport, uint16_t ndport, uint16_t nwsize, uint32_t *timestamps)
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{
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char *tcpopt = (char*)(tcp+1);
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uint8_t t=0;
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memset(tcp,0,sizeof(*tcp));
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tcp->th_sport = nsport;
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tcp->th_dport = ndport;
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if (fooling & TCP_FOOL_BADSEQ)
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{
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tcp->th_seq = net32_add(seq,0x80000000);
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tcp->th_ack = net32_add(ack_seq,0x80000000);
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}
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else
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{
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tcp->th_seq = seq;
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tcp->th_ack = ack_seq;
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}
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tcp->th_off = 5;
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*((uint8_t*)tcp+13)= tcp_flags;
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tcp->th_win = nwsize;
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if (fooling & TCP_FOOL_MD5SIG)
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{
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tcpopt[0] = 19; // kind
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tcpopt[1] = 18; // len
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*(uint32_t*)(tcpopt+2)=random();
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*(uint32_t*)(tcpopt+6)=random();
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*(uint32_t*)(tcpopt+10)=random();
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*(uint32_t*)(tcpopt+14)=random();
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t=18;
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}
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if (timestamps || (fooling & TCP_FOOL_TS))
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{
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tcpopt[t] = 8; // kind
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tcpopt[t+1] = 10; // len
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// forge only TSecr if orig timestamp is present
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*(uint32_t*)(tcpopt+t+2) = timestamps ? timestamps[0] : -1;
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*(uint32_t*)(tcpopt+t+6) = (timestamps && !(fooling & TCP_FOOL_TS)) ? timestamps[1] : -1;
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t+=10;
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}
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while (t&3) tcpopt[t++]=1; // noop
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tcp->th_off += t>>2;
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}
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static uint16_t tcpopt_len(uint8_t fooling, uint32_t *timestamps)
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{
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uint16_t t=0;
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if (fooling & TCP_FOOL_MD5SIG) t=18;
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if ((fooling & TCP_FOOL_TS) || timestamps) t+=10;
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return (t+3)&~3;
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}
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||||
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static int rawsend_sock4=-1, rawsend_sock6=-1;
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static void rawsend_clean_sock(int *sock)
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||||
{
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||||
if (sock && *sock!=-1)
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||||
{
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close(*sock);
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*sock=-1;
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||||
}
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}
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void rawsend_cleanup()
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{
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||||
rawsend_clean_sock(&rawsend_sock4);
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rawsend_clean_sock(&rawsend_sock6);
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}
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||||
static int *rawsend_family_sock(sa_family_t family)
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||||
{
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||||
switch(family)
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||||
{
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case AF_INET: return &rawsend_sock4;
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||||
case AF_INET6: return &rawsend_sock6;
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default: return NULL;
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||||
}
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}
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#ifdef BSD
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static int rawsend_socket_divert(sa_family_t family)
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{
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||||
// HACK HACK HACK HACK HACK HACK HACK HACK
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// FreeBSD doesnt allow IP_HDRINCL for IPV6
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// OpenBSD doesnt allow rawsending tcp frames
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// we either have to go to the link layer (its hard, possible problems arise, compat testing, ...) or use some HACKING
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// from my point of view disabling direct ability to send ip frames is not security. its SHIT
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||||
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int fd = socket(family, SOCK_RAW, IPPROTO_DIVERT);
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if (!set_socket_buffers(fd,4096,RAW_SNDBUF))
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{
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close(fd);
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return -1;
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}
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return fd;
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}
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static int rawsend_sendto_divert(sa_family_t family, int sock, const void *buf, size_t len)
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{
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struct sockaddr_storage sa;
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socklen_t slen;
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memset(&sa,0,sizeof(sa));
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sa.ss_family = family;
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switch(family)
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{
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case AF_INET:
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slen = sizeof(struct sockaddr_in);
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break;
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case AF_INET6:
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slen = sizeof(struct sockaddr_in6);
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break;
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default:
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return -1;
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}
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return sendto(sock, buf, len, 0, (struct sockaddr*)&sa, slen);
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}
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#endif
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static int rawsend_socket_raw(int domain, int proto)
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{
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int fd = socket(domain, SOCK_RAW, proto);
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if (fd!=-1)
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{
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#ifdef __linux__
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||||
int s=RAW_SNDBUF/2;
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int r=2048;
|
||||
#else
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int s=RAW_SNDBUF;
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int r=4096;
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#endif
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if (!set_socket_buffers(fd,r,s))
|
||||
{
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close(fd);
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return -1;
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||||
}
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}
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return fd;
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}
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static int rawsend_socket(sa_family_t family,uint32_t fwmark)
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||||
{
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int yes=1;
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int *sock = rawsend_family_sock(family);
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if (!sock) return -1;
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||||
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if (*sock==-1)
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||||
{
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int yes=1,pri=6;
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//printf("rawsend_socket: family %d",family);
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#ifdef __FreeBSD__
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// IPPROTO_RAW with ipv6 in FreeBSD always returns EACCES on sendto.
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// must use IPPROTO_TCP for ipv6. IPPROTO_RAW works for ipv4
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// divert sockets are always v4 but accept both v4 and v6
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*sock = (family==AF_INET) ? rawsend_socket_raw(family, IPPROTO_TCP) : rawsend_socket_divert(AF_INET);
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#elif defined(__OpenBSD__) || defined (__APPLE__)
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// OpenBSD does not allow sending TCP frames through raw sockets
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// I dont know about macos. They have dropped ipfw in recent versions and their PF does not support divert-packet
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*sock = rawsend_socket_divert(family);
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#else
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*sock = rawsend_socket_raw(family, IPPROTO_RAW);
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#endif
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if (*sock==-1)
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{
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perror("rawsend: socket()");
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return -1;
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}
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#ifdef BSD
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#if !(defined(__OpenBSD__) || defined (__APPLE__))
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// HDRINCL not supported for ipv6 in any BSD
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if (family==AF_INET && setsockopt(*sock,IPPROTO_IP,IP_HDRINCL,&yes,sizeof(yes)) == -1)
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{
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perror("rawsend: setsockopt(IP_HDRINCL)");
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goto exiterr;
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}
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#endif
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#ifdef SO_USER_COOKIE
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if (setsockopt(*sock, SOL_SOCKET, SO_USER_COOKIE, &fwmark, sizeof(fwmark)) == -1)
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{
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perror("rawsend: setsockopt(SO_MARK)");
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goto exiterr;
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}
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#endif
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#endif
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#ifdef __linux__
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if (setsockopt(*sock, SOL_SOCKET, SO_MARK, &fwmark, sizeof(fwmark)) == -1)
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{
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perror("rawsend: setsockopt(SO_MARK)");
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goto exiterr;
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}
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if (setsockopt(*sock, SOL_SOCKET, SO_PRIORITY, &pri, sizeof(pri)) == -1)
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{
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perror("rawsend: setsockopt(SO_PRIORITY)");
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goto exiterr;
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}
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#endif
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}
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return *sock;
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exiterr:
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rawsend_clean_sock(sock);
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return -1;
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}
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bool rawsend_preinit(uint32_t fwmark)
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{
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return rawsend_socket(AF_INET,fwmark)!=-1 && rawsend_socket(AF_INET6,fwmark)!=-1;
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}
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bool rawsend(const struct sockaddr* dst,uint32_t fwmark,const void *data,size_t len)
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{
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int sock=rawsend_socket(dst->sa_family,fwmark);
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if (sock==-1) return false;
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int salen = dst->sa_family == AF_INET ? sizeof(struct sockaddr_in) : sizeof(struct sockaddr_in6);
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struct sockaddr_storage dst2;
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memcpy(&dst2,dst,salen);
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if (dst->sa_family==AF_INET6)
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((struct sockaddr_in6 *)&dst2)->sin6_port = 0; // or will be EINVAL in linux
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#ifdef BSD
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||||
/*
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// this works only for local connections and not working for transit : cant spoof source addr
|
||||
if (len>=sizeof(struct ip6_hdr))
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||||
{
|
||||
// BSD ipv6 raw socks are limited. cannot pass the whole packet with ip6 header.
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||||
struct sockaddr_storage sa_src;
|
||||
int v;
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||||
extract_endpoints(NULL,(struct ip6_hdr *)data,NULL, &sa_src, NULL);
|
||||
v = ((struct ip6_hdr *)data)->ip6_ctlun.ip6_un1.ip6_un1_hlim;
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||||
if (setsockopt(sock, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &v, sizeof(v)) == -1)
|
||||
perror("rawsend: setsockopt(IPV6_HOPLIMIT)");
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||||
// the only way to control source address is bind. make it equal to ip6_hdr
|
||||
if (bind(sock, (struct sockaddr*)&sa_src, salen) < 0)
|
||||
perror("rawsend bind: ");
|
||||
//printf("BSD v6 RAWSEND "); print_sockaddr((struct sockaddr*)&sa_src); printf(" -> "); print_sockaddr((struct sockaddr*)&dst2); printf("\n");
|
||||
proto_skip_ipv6((uint8_t**)&data, &len, NULL);
|
||||
}
|
||||
*/
|
||||
|
||||
#if !(defined(__OpenBSD__) || defined (__APPLE__))
|
||||
// OpenBSD doesnt allow rawsending tcp frames. always use divert socket
|
||||
if (dst->sa_family==AF_INET6)
|
||||
#endif
|
||||
{
|
||||
ssize_t bytes = rawsend_sendto_divert(dst->sa_family,sock,data,len);
|
||||
if (bytes==-1)
|
||||
{
|
||||
perror("rawsend: sendto_divert");
|
||||
return false;
|
||||
}
|
||||
return true;
|
||||
}
|
||||
#endif
|
||||
|
||||
#if defined(__FreeBSD__) && __FreeBSD__<=10
|
||||
// old FreeBSD requires some fields in the host byte order
|
||||
if (dst->sa_family==AF_INET && len>=sizeof(struct ip))
|
||||
{
|
||||
((struct ip*)data)->ip_len = htons(((struct ip*)data)->ip_len);
|
||||
((struct ip*)data)->ip_off = htons(((struct ip*)data)->ip_off);
|
||||
}
|
||||
#endif
|
||||
// normal raw socket sendto
|
||||
ssize_t bytes = sendto(sock, data, len, 0, (struct sockaddr*)&dst2, salen);
|
||||
#if defined(__FreeBSD) && __FreeBSD__<=10
|
||||
// restore byte order
|
||||
if (dst->sa_family==AF_INET && len>=sizeof(struct ip))
|
||||
{
|
||||
((struct ip*)data)->ip_len = htons(((struct ip*)data)->ip_len);
|
||||
((struct ip*)data)->ip_off = htons(((struct ip*)data)->ip_off);
|
||||
}
|
||||
#endif
|
||||
if (bytes==-1)
|
||||
{
|
||||
perror("rawsend: sendto");
|
||||
return false;
|
||||
}
|
||||
return true;
|
||||
}
|
||||
bool prepare_tcp_segment4(
|
||||
const struct sockaddr_in *src, const struct sockaddr_in *dst,
|
||||
uint8_t tcp_flags,
|
||||
uint32_t seq, uint32_t ack_seq,
|
||||
uint16_t wsize,
|
||||
uint32_t *timestamps,
|
||||
uint8_t ttl,
|
||||
uint8_t fooling,
|
||||
const void *data, uint16_t len,
|
||||
uint8_t *buf, size_t *buflen)
|
||||
{
|
||||
uint16_t tcpoptlen = tcpopt_len(fooling,timestamps);
|
||||
uint16_t pktlen = sizeof(struct ip) + sizeof(struct tcphdr) + tcpoptlen + len;
|
||||
if (pktlen>*buflen)
|
||||
{
|
||||
fprintf(stderr,"prepare_tcp_segment : packet len cannot exceed %zu\n",*buflen);
|
||||
return false;
|
||||
}
|
||||
|
||||
struct ip *ip = (struct ip*) buf;
|
||||
struct tcphdr *tcp = (struct tcphdr*) (ip+1);
|
||||
|
||||
ip->ip_off = 0;
|
||||
ip->ip_v = 4;
|
||||
ip->ip_hl = 5;
|
||||
ip->ip_len = htons(pktlen);
|
||||
ip->ip_id = 0;
|
||||
ip->ip_ttl = ttl;
|
||||
ip->ip_p = IPPROTO_TCP;
|
||||
ip->ip_src = src->sin_addr;
|
||||
ip->ip_dst = dst->sin_addr;
|
||||
|
||||
fill_tcphdr(tcp,tcp_flags,seq,ack_seq,fooling,src->sin_port,dst->sin_port,wsize,timestamps);
|
||||
|
||||
memcpy((char*)tcp+sizeof(struct tcphdr)+tcpoptlen,data,len);
|
||||
tcp4_fix_checksum(tcp,sizeof(struct tcphdr)+tcpoptlen+len,&ip->ip_src,&ip->ip_dst);
|
||||
if (fooling & TCP_FOOL_BADSUM) tcp->th_sum^=0xBEAF;
|
||||
|
||||
*buflen = pktlen;
|
||||
return true;
|
||||
}
|
||||
|
||||
|
||||
bool prepare_tcp_segment6(
|
||||
const struct sockaddr_in6 *src, const struct sockaddr_in6 *dst,
|
||||
uint8_t tcp_flags,
|
||||
uint32_t seq, uint32_t ack_seq,
|
||||
uint16_t wsize,
|
||||
uint32_t *timestamps,
|
||||
uint8_t ttl,
|
||||
uint8_t fooling,
|
||||
const void *data, uint16_t len,
|
||||
uint8_t *buf, size_t *buflen)
|
||||
{
|
||||
uint16_t tcpoptlen = tcpopt_len(fooling,timestamps);
|
||||
uint16_t payloadlen = sizeof(struct tcphdr) + tcpoptlen + len;
|
||||
uint16_t pktlen = sizeof(struct ip6_hdr) + payloadlen;
|
||||
if (pktlen>*buflen)
|
||||
{
|
||||
fprintf(stderr,"prepare_tcp_segment : packet len cannot exceed %zu\n",*buflen);
|
||||
return false;
|
||||
}
|
||||
|
||||
struct ip6_hdr *ip6 = (struct ip6_hdr*) buf;
|
||||
struct tcphdr *tcp = (struct tcphdr*) (ip6+1);
|
||||
|
||||
ip6->ip6_ctlun.ip6_un1.ip6_un1_flow = htonl(0x60000000);
|
||||
ip6->ip6_ctlun.ip6_un1.ip6_un1_plen = htons(payloadlen);
|
||||
ip6->ip6_ctlun.ip6_un1.ip6_un1_nxt = IPPROTO_TCP;
|
||||
ip6->ip6_ctlun.ip6_un1.ip6_un1_hlim = ttl;
|
||||
ip6->ip6_src = src->sin6_addr;
|
||||
ip6->ip6_dst = dst->sin6_addr;
|
||||
|
||||
fill_tcphdr(tcp,tcp_flags,seq,ack_seq,fooling,src->sin6_port,dst->sin6_port,wsize,timestamps);
|
||||
|
||||
memcpy((char*)tcp+sizeof(struct tcphdr)+tcpoptlen,data,len);
|
||||
tcp6_fix_checksum(tcp,sizeof(struct tcphdr)+tcpoptlen+len,&ip6->ip6_src,&ip6->ip6_dst);
|
||||
if (fooling & TCP_FOOL_BADSUM) tcp->th_sum^=0xBEAF;
|
||||
|
||||
*buflen = pktlen;
|
||||
return true;
|
||||
}
|
||||
|
||||
bool prepare_tcp_segment(
|
||||
const struct sockaddr *src, const struct sockaddr *dst,
|
||||
uint8_t tcp_flags,
|
||||
uint32_t seq, uint32_t ack_seq,
|
||||
uint16_t wsize,
|
||||
uint32_t *timestamps,
|
||||
uint8_t ttl,
|
||||
uint8_t fooling,
|
||||
const void *data, uint16_t len,
|
||||
uint8_t *buf, size_t *buflen)
|
||||
{
|
||||
return (src->sa_family==AF_INET && dst->sa_family==AF_INET) ?
|
||||
prepare_tcp_segment4((struct sockaddr_in *)src,(struct sockaddr_in *)dst,tcp_flags,seq,ack_seq,wsize,timestamps,ttl,fooling,data,len,buf,buflen) :
|
||||
(src->sa_family==AF_INET6 && dst->sa_family==AF_INET6) ?
|
||||
prepare_tcp_segment6((struct sockaddr_in6 *)src,(struct sockaddr_in6 *)dst,tcp_flags,seq,ack_seq,wsize,timestamps,ttl,fooling,data,len,buf,buflen) :
|
||||
false;
|
||||
}
|
||||
|
||||
|
||||
void extract_endpoints(const struct ip *ip,const struct ip6_hdr *ip6hdr,const struct tcphdr *tcphdr, struct sockaddr_storage *src, struct sockaddr_storage *dst)
|
||||
{
|
||||
if (ip)
|
||||
{
|
||||
struct sockaddr_in *si;
|
||||
|
||||
if (dst)
|
||||
{
|
||||
si = (struct sockaddr_in*)dst;
|
||||
si->sin_family = AF_INET;
|
||||
si->sin_port = tcphdr ? tcphdr->th_dport : 0;
|
||||
si->sin_addr = ip->ip_dst;
|
||||
}
|
||||
|
||||
if (src)
|
||||
{
|
||||
si = (struct sockaddr_in*)src;
|
||||
si->sin_family = AF_INET;
|
||||
si->sin_port = tcphdr ? tcphdr->th_sport : 0;
|
||||
si->sin_addr = ip->ip_src;
|
||||
}
|
||||
}
|
||||
else if (ip6hdr)
|
||||
{
|
||||
struct sockaddr_in6 *si;
|
||||
|
||||
if (dst)
|
||||
{
|
||||
si = (struct sockaddr_in6*)dst;
|
||||
si->sin6_family = AF_INET6;
|
||||
si->sin6_port = tcphdr ? tcphdr->th_dport : 0;
|
||||
si->sin6_addr = ip6hdr->ip6_dst;
|
||||
si->sin6_flowinfo = 0;
|
||||
si->sin6_scope_id = 0;
|
||||
}
|
||||
|
||||
if (src)
|
||||
{
|
||||
si = (struct sockaddr_in6*)src;
|
||||
si->sin6_family = AF_INET6;
|
||||
si->sin6_port = tcphdr ? tcphdr->th_sport : 0;
|
||||
si->sin6_addr = ip6hdr->ip6_src;
|
||||
si->sin6_flowinfo = 0;
|
||||
si->sin6_scope_id = 0;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
static const char *proto_name(uint8_t proto)
|
||||
{
|
||||
switch(proto)
|
||||
{
|
||||
case IPPROTO_TCP:
|
||||
return "tcp";
|
||||
case IPPROTO_UDP:
|
||||
return "udp";
|
||||
case IPPROTO_ICMP:
|
||||
return "icmp";
|
||||
case IPPROTO_IGMP:
|
||||
return "igmp";
|
||||
case IPPROTO_ESP:
|
||||
return "esp";
|
||||
case IPPROTO_AH:
|
||||
return "ah";
|
||||
case IPPROTO_IPV6:
|
||||
return "6in4";
|
||||
#ifdef IPPROTO_SCTP
|
||||
case IPPROTO_SCTP:
|
||||
return "sctp";
|
||||
#endif
|
||||
default:
|
||||
return NULL;
|
||||
}
|
||||
}
|
||||
static void str_proto_name(char *s, size_t s_len, uint8_t proto)
|
||||
{
|
||||
const char *name = proto_name(proto);
|
||||
if (name)
|
||||
snprintf(s,s_len,"%s",name);
|
||||
else
|
||||
snprintf(s,s_len,"%u",proto);
|
||||
}
|
||||
|
||||
static void str_srcdst_ip(char *s, size_t s_len, const void *saddr,const void *daddr)
|
||||
{
|
||||
char s_ip[16],d_ip[16];
|
||||
*s_ip=*d_ip=0;
|
||||
inet_ntop(AF_INET, saddr, s_ip, sizeof(s_ip));
|
||||
inet_ntop(AF_INET, daddr, d_ip, sizeof(d_ip));
|
||||
snprintf(s,s_len,"%s => %s",s_ip,d_ip);
|
||||
}
|
||||
static void str_ip(char *s, size_t s_len, const struct ip *ip)
|
||||
{
|
||||
char ss[64],s_proto[16];
|
||||
str_srcdst_ip(ss,sizeof(ss),&ip->ip_src,&ip->ip_dst);
|
||||
str_proto_name(s_proto,sizeof(s_proto),ip->ip_p);
|
||||
snprintf(s,s_len,"%s proto=%s",ss,s_proto);
|
||||
}
|
||||
void print_ip(const struct ip *ip)
|
||||
{
|
||||
char s[64];
|
||||
str_ip(s,sizeof(s),ip);
|
||||
printf("%s",s);
|
||||
}
|
||||
static void str_srcdst_ip6(char *s, size_t s_len, const void *saddr,const void *daddr)
|
||||
{
|
||||
char s_ip[40],d_ip[40];
|
||||
*s_ip=*d_ip=0;
|
||||
inet_ntop(AF_INET6, saddr, s_ip, sizeof(s_ip));
|
||||
inet_ntop(AF_INET6, daddr, d_ip, sizeof(d_ip));
|
||||
snprintf(s,s_len,"%s => %s",s_ip,d_ip);
|
||||
}
|
||||
static void str_ip6hdr(char *s, size_t s_len, const struct ip6_hdr *ip6hdr, uint8_t proto)
|
||||
{
|
||||
char ss[128],s_proto[16];
|
||||
str_srcdst_ip6(ss,sizeof(ss),&ip6hdr->ip6_src,&ip6hdr->ip6_dst);
|
||||
str_proto_name(s_proto,sizeof(s_proto),proto);
|
||||
snprintf(s,s_len,"%s proto=%s",ss,s_proto);
|
||||
}
|
||||
void print_ip6hdr(const struct ip6_hdr *ip6hdr, uint8_t proto)
|
||||
{
|
||||
char s[128];
|
||||
str_ip6hdr(s,sizeof(s),ip6hdr,proto);
|
||||
printf("%s",s);
|
||||
}
|
||||
|
||||
static void str_tcphdr(char *s, size_t s_len, const struct tcphdr *tcphdr)
|
||||
{
|
||||
char flags[7],*f=flags;
|
||||
if (tcphdr->th_flags & TH_SYN) *f++='S';
|
||||
if (tcphdr->th_flags & TH_ACK) *f++='A';
|
||||
if (tcphdr->th_flags & TH_RST) *f++='R';
|
||||
if (tcphdr->th_flags & TH_FIN) *f++='F';
|
||||
if (tcphdr->th_flags & TH_PUSH) *f++='P';
|
||||
if (tcphdr->th_flags & TH_URG) *f++='U';
|
||||
*f=0;
|
||||
snprintf(s,s_len,"sport=%u dport=%u flags=%s seq=%u ack_seq=%u",htons(tcphdr->th_sport),htons(tcphdr->th_dport),flags,htonl(tcphdr->th_seq),htonl(tcphdr->th_ack));
|
||||
}
|
||||
void print_tcphdr(const struct tcphdr *tcphdr)
|
||||
{
|
||||
char s[80];
|
||||
str_tcphdr(s,sizeof(s),tcphdr);
|
||||
printf("%s",s);
|
||||
}
|
||||
|
||||
|
||||
|
||||
|
||||
bool proto_check_ipv4(uint8_t *data, size_t len)
|
||||
{
|
||||
return len >= 20 && (data[0] & 0xF0) == 0x40 &&
|
||||
len >= ((data[0] & 0x0F) << 2);
|
||||
}
|
||||
// move to transport protocol
|
||||
void proto_skip_ipv4(uint8_t **data, size_t *len)
|
||||
{
|
||||
size_t l;
|
||||
|
||||
l = (**data & 0x0F) << 2;
|
||||
*data += l;
|
||||
*len -= l;
|
||||
}
|
||||
bool proto_check_tcp(uint8_t *data, size_t len)
|
||||
{
|
||||
return len >= 20 && len >= ((data[12] & 0xF0) >> 2);
|
||||
}
|
||||
void proto_skip_tcp(uint8_t **data, size_t *len)
|
||||
{
|
||||
size_t l;
|
||||
l = ((*data)[12] & 0xF0) >> 2;
|
||||
*data += l;
|
||||
*len -= l;
|
||||
}
|
||||
|
||||
bool proto_check_ipv6(uint8_t *data, size_t len)
|
||||
{
|
||||
return len >= 40 && (data[0] & 0xF0) == 0x60 &&
|
||||
(len - 40) >= htons(*(uint16_t*)(data + 4)); // payload length
|
||||
}
|
||||
// move to transport protocol
|
||||
// proto_type = 0 => error
|
||||
void proto_skip_ipv6(uint8_t **data, size_t *len, uint8_t *proto_type)
|
||||
{
|
||||
size_t hdrlen;
|
||||
uint8_t HeaderType;
|
||||
|
||||
if (proto_type) *proto_type = 0; // put error in advance
|
||||
|
||||
HeaderType = (*data)[6]; // NextHeader field
|
||||
*data += 40; *len -= 40; // skip ipv6 base header
|
||||
while (*len > 0) // need at least one byte for NextHeader field
|
||||
{
|
||||
switch (HeaderType)
|
||||
{
|
||||
case 0: // Hop-by-Hop Options
|
||||
case 43: // routing
|
||||
case 51: // authentication
|
||||
case 60: // Destination Options
|
||||
case 135: // mobility
|
||||
case 139: // Host Identity Protocol Version v2
|
||||
case 140: // Shim6
|
||||
if (*len < 2) return; // error
|
||||
hdrlen = 8 + ((*data)[1] << 3);
|
||||
break;
|
||||
case 44: // fragment. length fixed to 8, hdrlen field defined as reserved
|
||||
hdrlen = 8;
|
||||
break;
|
||||
case 59: // no next header
|
||||
return; // error
|
||||
default:
|
||||
// we found some meaningful payload. it can be tcp, udp, icmp or some another exotic shit
|
||||
if (proto_type) *proto_type = HeaderType;
|
||||
return;
|
||||
}
|
||||
if (*len < hdrlen) return; // error
|
||||
HeaderType = **data;
|
||||
// advance to the next header location
|
||||
*len -= hdrlen;
|
||||
*data += hdrlen;
|
||||
}
|
||||
// we have garbage
|
||||
}
|
||||
|
||||
bool tcp_synack_segment(const struct tcphdr *tcphdr)
|
||||
{
|
||||
/* check for set bits in TCP hdr */
|
||||
return ((tcphdr->th_flags & (TH_URG|TH_ACK|TH_PUSH|TH_RST|TH_SYN|TH_FIN)) == (TH_ACK|TH_SYN));
|
||||
}
|
||||
Reference in New Issue
Block a user