|
|
|
@ -31,6 +31,17 @@ namespace llarp
|
|
|
|
|
return llarp::InitBuffer(buf, sz);
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
static uint32_t
|
|
|
|
|
ipchksum_pseudoIPv4(uint32_t src_ip_n, uint32_t dst_ip_n,
|
|
|
|
|
uint8_t proto, uint16_t innerlen)
|
|
|
|
|
{
|
|
|
|
|
#define IPCS(x) ((x & 0xFFFF) + (x >> 16))
|
|
|
|
|
uint32_t sum = (uint32_t)IPCS(src_ip_n) + (uint32_t)IPCS(dst_ip_n) +
|
|
|
|
|
(uint32_t)proto + (uint32_t)htons(innerlen);
|
|
|
|
|
#undef IPCS
|
|
|
|
|
return sum;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
static uint16_t
|
|
|
|
|
ipchksum(const byte_t *buf, size_t sz, uint32_t sum = 0)
|
|
|
|
|
{
|
|
|
|
@ -49,57 +60,111 @@ namespace llarp
|
|
|
|
|
return ~sum;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
static uint16_t
|
|
|
|
|
deltachksum(uint16_t old_sum,
|
|
|
|
|
uint32_t old_src_ip_n, uint32_t old_dst_ip_n,
|
|
|
|
|
uint32_t new_src_ip_n, uint32_t new_dst_ip_n)
|
|
|
|
|
{
|
|
|
|
|
#define IPCS(x) ((x & 0xFFFF) + (x >> 16))
|
|
|
|
|
uint32_t sum = ~old_sum
|
|
|
|
|
+ IPCS(new_src_ip_n) + IPCS(new_dst_ip_n)
|
|
|
|
|
- IPCS(old_src_ip_n) - IPCS(old_dst_ip_n);
|
|
|
|
|
#undef IPCS
|
|
|
|
|
while(sum >> 16)
|
|
|
|
|
sum = (sum & 0xffff) + (sum >> 16);
|
|
|
|
|
return ~sum;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
static std::map<
|
|
|
|
|
byte_t, std::function< void(const ip_header *, byte_t *, size_t) > >
|
|
|
|
|
protoCheckSummer = {
|
|
|
|
|
/// ICMP
|
|
|
|
|
{1,
|
|
|
|
|
[](const ip_header *hdr, byte_t *buf, size_t sz) {
|
|
|
|
|
auto len = hdr->ihl * 4;
|
|
|
|
|
uint16_t *check = (uint16_t *)buf + len + 2;
|
|
|
|
|
*check = 0;
|
|
|
|
|
*check = ipchksum(buf, sz);
|
|
|
|
|
}},
|
|
|
|
|
/// TCP
|
|
|
|
|
{6, [](const ip_header *hdr, byte_t *pkt, size_t sz) {
|
|
|
|
|
byte_t pktbuf[1500];
|
|
|
|
|
auto len = hdr->ihl * 4;
|
|
|
|
|
size_t pktsz = sz - len;
|
|
|
|
|
uint16_t *check = (uint16_t *)(pkt + len + 16);
|
|
|
|
|
*check = 0;
|
|
|
|
|
memcpy(pktbuf, &hdr->saddr, 4);
|
|
|
|
|
memcpy(pktbuf + 4, &hdr->daddr, 4);
|
|
|
|
|
pktbuf[8] = 0;
|
|
|
|
|
pktbuf[9] = 6;
|
|
|
|
|
// TODO: endian (?)
|
|
|
|
|
pktbuf[10] = (pktsz & 0xff00) >> 8;
|
|
|
|
|
pktbuf[11] = pktsz & 0x00ff;
|
|
|
|
|
memcpy(pktbuf + 12, pkt + len, pktsz);
|
|
|
|
|
*check = ipchksum(pktbuf, 12 + pktsz);
|
|
|
|
|
}}};
|
|
|
|
|
protoDstCheckSummer =
|
|
|
|
|
{
|
|
|
|
|
// is this even correct???
|
|
|
|
|
// {RFC3022} says that IPv4 hdr isn't included in ICMP checksum calc
|
|
|
|
|
// and that we don't need to modify it
|
|
|
|
|
#if 0
|
|
|
|
|
{
|
|
|
|
|
// ICMP
|
|
|
|
|
1,
|
|
|
|
|
[](const ip_header *hdr, byte_t *buf, size_t sz)
|
|
|
|
|
{
|
|
|
|
|
auto len = hdr->ihl * 4;
|
|
|
|
|
if(len + 2 + 2 > sz)
|
|
|
|
|
return;
|
|
|
|
|
uint16_t *check = (uint16_t *)(buf + len + 2);
|
|
|
|
|
|
|
|
|
|
*check = 0;
|
|
|
|
|
*check = ipchksum(buf, sz);
|
|
|
|
|
}
|
|
|
|
|
},
|
|
|
|
|
#endif
|
|
|
|
|
{
|
|
|
|
|
// TCP
|
|
|
|
|
6,
|
|
|
|
|
[](const ip_header *hdr, byte_t *pkt, size_t sz)
|
|
|
|
|
{
|
|
|
|
|
auto hlen = size_t(hdr->ihl * 4);
|
|
|
|
|
if(hlen + 16 + 2 > sz)
|
|
|
|
|
return;
|
|
|
|
|
|
|
|
|
|
uint16_t *check = (uint16_t *)(pkt + hlen + 16);
|
|
|
|
|
*check = deltachksum(*check, 0, 0, hdr->saddr, hdr->daddr);
|
|
|
|
|
}
|
|
|
|
|
},
|
|
|
|
|
};
|
|
|
|
|
void
|
|
|
|
|
IPv4Packet::UpdateChecksumsOnDst()
|
|
|
|
|
{
|
|
|
|
|
auto hdr = Header();
|
|
|
|
|
|
|
|
|
|
// IPv4 checksum
|
|
|
|
|
auto hdr = Header();
|
|
|
|
|
auto hlen = size_t(hdr->ihl * 4);
|
|
|
|
|
hdr->check = 0;
|
|
|
|
|
auto len = hdr->ihl * 4;
|
|
|
|
|
hdr->check = ipchksum(buf, len);
|
|
|
|
|
if(hlen <= sz)
|
|
|
|
|
hdr->check = ipchksum(buf, hlen);
|
|
|
|
|
|
|
|
|
|
// L4 checksum
|
|
|
|
|
auto proto = hdr->protocol;
|
|
|
|
|
auto itr = protoCheckSummer.find(proto);
|
|
|
|
|
if(itr != protoCheckSummer.end())
|
|
|
|
|
auto itr = protoDstCheckSummer.find(proto);
|
|
|
|
|
if(itr != protoDstCheckSummer.end())
|
|
|
|
|
{
|
|
|
|
|
itr->second(hdr, buf, sz);
|
|
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
static std::map<
|
|
|
|
|
byte_t, std::function< void(const ip_header *, byte_t *, size_t) > >
|
|
|
|
|
protoSrcCheckSummer =
|
|
|
|
|
{
|
|
|
|
|
{
|
|
|
|
|
// TCP
|
|
|
|
|
6,
|
|
|
|
|
[](const ip_header *hdr, byte_t *pkt, size_t sz)
|
|
|
|
|
{
|
|
|
|
|
auto hlen = size_t(hdr->ihl * 4);
|
|
|
|
|
if(hlen + 16 + 2 > sz)
|
|
|
|
|
return;
|
|
|
|
|
|
|
|
|
|
uint16_t *check = (uint16_t *)(pkt + hlen + 16);
|
|
|
|
|
*check = deltachksum(*check, hdr->saddr, hdr->daddr, 0, 0);
|
|
|
|
|
}
|
|
|
|
|
},
|
|
|
|
|
};
|
|
|
|
|
void
|
|
|
|
|
IPv4Packet::UpdateChecksumsOnSrc()
|
|
|
|
|
{
|
|
|
|
|
auto hdr = Header();
|
|
|
|
|
|
|
|
|
|
// L4
|
|
|
|
|
auto proto = hdr->protocol;
|
|
|
|
|
auto itr = protoSrcCheckSummer.find(proto);
|
|
|
|
|
if(itr != protoSrcCheckSummer.end())
|
|
|
|
|
{
|
|
|
|
|
itr->second(hdr, buf, sz);
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
// IPv4
|
|
|
|
|
Header()->check = 0;
|
|
|
|
|
hdr->check = 0;
|
|
|
|
|
}
|
|
|
|
|
} // namespace net
|
|
|
|
|
} // namespace llarp
|
|
|
|
|