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nfqws: ipfrag

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bol-van
2022-01-03 12:38:18 +03:00
parent 44175a5e2d
commit 690d458ec7
20 changed files with 340 additions and 88 deletions
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94
nfq/darkmagic.c
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@@ -307,6 +307,100 @@ bool prepare_udp_segment(
// split ipv4 packet into 2 fragments at data payload position frag_pos
bool ip_frag4(
const uint8_t *pkt, size_t pkt_size,
size_t frag_pos, uint32_t ident,
uint8_t *pkt1, size_t *pkt1_size,
uint8_t *pkt2, size_t *pkt2_size)
{
uint16_t hdrlen, payload_len;
// frag_pos must be 8-byte aligned
if (frag_pos & 7 || pkt_size < sizeof(struct ip)) return false;
payload_len = htons(((struct ip *)pkt)->ip_len);
hdrlen = ((struct ip *)pkt)->ip_hl<<2;
if (payload_len>pkt_size || hdrlen>pkt_size || hdrlen>payload_len) return false;
payload_len -= hdrlen;
if (frag_pos>=payload_len || *pkt1_size<(hdrlen+frag_pos) || *pkt2_size<(hdrlen+payload_len-frag_pos)) return false;
memcpy(pkt1, pkt, hdrlen+frag_pos);
((struct ip*)pkt1)->ip_off = htons(IP_MF);
((struct ip*)pkt1)->ip_len = htons(hdrlen+frag_pos);
if (ident!=(uint32_t)-1) ((struct ip*)pkt1)->ip_id = (uint16_t)ident;
*pkt1_size=hdrlen+frag_pos;
ip4_fix_checksum((struct ip *)pkt1);
memcpy(pkt2, pkt, hdrlen);
memcpy(pkt2+hdrlen, pkt+hdrlen+frag_pos, payload_len-frag_pos);
((struct ip*)pkt2)->ip_off = htons((uint16_t)frag_pos>>3 & IP_OFFMASK);
((struct ip*)pkt2)->ip_len = htons(hdrlen+payload_len-frag_pos);
if (ident!=(uint32_t)-1) ((struct ip*)pkt2)->ip_id = (uint16_t)ident;
*pkt2_size=hdrlen+payload_len-frag_pos;
ip4_fix_checksum((struct ip *)pkt2);
return true;
}
bool ip_frag6(
const uint8_t *pkt, size_t pkt_size,
size_t frag_pos, uint32_t ident,
uint8_t *pkt1, size_t *pkt1_size,
uint8_t *pkt2, size_t *pkt2_size)
{
uint16_t payload_len;
uint8_t proto;
struct ip6_frag *frag;
if (frag_pos & 7 || pkt_size < sizeof(struct ip6_hdr)) return false;
payload_len = htons(((struct ip6_hdr*)pkt)->ip6_ctlun.ip6_un1.ip6_un1_plen);
if ((sizeof(struct ip6_hdr)+payload_len)>pkt_size || frag_pos>=payload_len ||
*pkt1_size<(sizeof(struct ip6_hdr)+sizeof(struct ip6_frag)+frag_pos) ||
*pkt2_size<(sizeof(struct ip6_hdr)+sizeof(struct ip6_frag)+payload_len-frag_pos))
{
return false;
}
proto = ((struct ip6_hdr*)pkt)->ip6_ctlun.ip6_un1.ip6_un1_nxt;
memcpy(pkt1, pkt, sizeof(struct ip6_hdr));
((struct ip6_hdr*)pkt1)->ip6_ctlun.ip6_un1.ip6_un1_plen = htons(sizeof(struct ip6_frag)+frag_pos);
((struct ip6_hdr*)pkt1)->ip6_ctlun.ip6_un1.ip6_un1_nxt = IPPROTO_FRAGMENT;
frag = (struct ip6_frag*)(((struct ip6_hdr*)pkt1)+1);
frag->ip6f_nxt = proto;
frag->ip6f_reserved = 0;
frag->ip6f_offlg = IP6F_MORE_FRAG;
frag->ip6f_ident = ident;
memcpy(frag+1, pkt+sizeof(struct ip6_hdr), frag_pos);
*pkt1_size = sizeof(struct ip6_hdr)+sizeof(struct ip6_frag)+frag_pos;
memcpy(pkt2, pkt, sizeof(struct ip6_hdr));
((struct ip6_hdr*)pkt2)->ip6_ctlun.ip6_un1.ip6_un1_plen = htons(sizeof(struct ip6_frag)+payload_len-frag_pos);
((struct ip6_hdr*)pkt2)->ip6_ctlun.ip6_un1.ip6_un1_nxt = IPPROTO_FRAGMENT;
frag = (struct ip6_frag*)(((struct ip6_hdr*)pkt2)+1);
frag->ip6f_nxt = proto;
frag->ip6f_reserved = 0;
frag->ip6f_offlg = htons(frag_pos);
frag->ip6f_ident = ident;
memcpy(frag+1, pkt+sizeof(struct ip6_hdr)+frag_pos, payload_len-frag_pos);
*pkt2_size = sizeof(struct ip6_hdr)+sizeof(struct ip6_frag)+payload_len-frag_pos;
return true;
}
bool ip_frag(
const uint8_t *pkt, size_t pkt_size,
size_t frag_pos, uint32_t ident,
uint8_t *pkt1, size_t *pkt1_size,
uint8_t *pkt2, size_t *pkt2_size)
{
if (proto_check_ipv4(pkt,pkt_size))
return ip_frag4(pkt,pkt_size,frag_pos,ident,pkt1,pkt1_size,pkt2,pkt2_size);
else if (proto_check_ipv6(pkt,pkt_size))
return ip_frag6(pkt,pkt_size,frag_pos,ident,pkt1,pkt1_size,pkt2,pkt2_size);
else
return false;
}
void extract_ports(const struct tcphdr *tcphdr, const struct udphdr *udphdr, uint8_t *proto, uint16_t *sport, uint16_t *dport)
{
if (sport) *sport = htons(tcphdr ? tcphdr->th_sport : udphdr ? udphdr->uh_sport : 0);