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net/ip: cleanup

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pull/686/head
cathugger 5 years ago
parent de51ef23bf
commit 891f5d156c
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GPG Key ID: 9BADDA2DAF6F01A8
1 changed files with 87 additions and 143 deletions
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230
llarp/net/ip.cpp
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@ -20,12 +20,12 @@ namespace llarp
{
#if __BYTE_ORDER == __BIG_ENDIAN
return huint128_t{addr.s6_addr32[0]}
| (huint128_t{addr.s6_addr32[1]} << 32)
| (huint128_t{addr.s6_addr32[1]} << 32)
| (huint128_t{addr.s6_addr32[2]} << 64)
| (huint128_t{addr.s6_addr32[3]} << 96);
#else
return huint128_t{ntohl(addr.s6_addr32[3])}
| (huint128_t{ntohl(addr.s6_addr32[2])} << 32)
| (huint128_t{ntohl(addr.s6_addr32[2])} << 32)
| (huint128_t{ntohl(addr.s6_addr32[1])} << 64)
| (huint128_t{ntohl(addr.s6_addr32[0])} << 96);
#endif
@ -102,26 +102,6 @@ namespace llarp
return huint32_t{ntohl(Header()->daddr)};
}
void
IPPacket::UpdateV6Address(huint128_t src, huint128_t dst)
{
if(sz <= 40)
return;
auto hdr = HeaderV6();
auto oldSrc = hdr->srcaddr;
auto oldDst = hdr->dstaddr;
hdr->srcaddr = HUIntToIn6(src);
hdr->dstaddr = HUIntToIn6(dst);
const size_t ihs = 40;
auto pld = buf + ihs;
auto psz = sz - ihs;
switch(hdr->proto)
{
//tcp
case 6:
return;
}
}
#if 0
static uint32_t
@ -161,84 +141,16 @@ namespace llarp
}
#endif
static nuint16_t
deltaIPv4Checksum(nuint16_t old_sum, nuint32_t old_src_ip,
nuint32_t old_dst_ip, nuint32_t new_src_ip,
nuint32_t new_dst_ip)
{
#define ADDIPCS(x) ((uint32_t)(x.n & 0xFFff) + (uint32_t)(x.n >> 16))
#define SUBIPCS(x) ((uint32_t)((~x.n) & 0xFFff) + (uint32_t)((~x.n) >> 16))
uint32_t sum = uint32_t(old_sum.n) + ADDIPCS(old_src_ip)
+ ADDIPCS(old_dst_ip) + SUBIPCS(new_src_ip) + SUBIPCS(new_dst_ip);
#undef ADDIPCS
#undef SUBIPCS
// only need to do it 2 times to be sure
// proof: 0xFFff + 0xFFff = 0x1FFfe -> 0xFFff
sum = (sum & 0xFFff) + (sum >> 16);
sum += sum >> 16;
return nuint16_t{uint16_t(sum & 0xFFff)};
}
static void
checksumDstIPv4TCP(byte_t *pld, ABSL_ATTRIBUTE_UNUSED size_t psz,
size_t fragoff, size_t chksumoff, nuint32_t oSrcIP,
nuint32_t oDstIP, nuint32_t nSrcIP, nuint32_t nDstIP)
{
if(fragoff > chksumoff)
return;
auto check = (nuint16_t *)(pld + chksumoff - fragoff);
*check = deltaIPv4Checksum(*check, oSrcIP, oDstIP, nSrcIP, nDstIP);
// usually, TCP checksum field cannot be 0xFFff,
// because one's complement addition cannot result in 0x0000,
// and there's inversion in the end;
// emulate that.
if(check->n == 0xFFff)
check->n = 0x0000;
}
static void
checksumDstIPv4UDP(byte_t *pld, ABSL_ATTRIBUTE_UNUSED size_t psz,
size_t fragoff, nuint32_t oSrcIP, nuint32_t oDstIP,
nuint32_t nSrcIP, nuint32_t nDstIP)
{
if(fragoff > 6)
return;
auto check = (nuint16_t *)(pld + 6);
if(check->n == 0x0000)
return; // 0 is used to indicate "no checksum", don't change
*check = deltaIPv4Checksum(*check, oSrcIP, oDstIP, nSrcIP, nDstIP);
// 0 is used to indicate "no checksum"
// 0xFFff and 0 are equivalent in one's complement math
// 0xFFff + 1 = 0x10000 -> 0x0001 (same as 0 + 1)
// infact it's impossible to get 0 with such addition,
// when starting from non-0 value.
// inside deltachksum we don't invert so it's safe to skip check there
// if(check->n == 0x0000)
// check->n = 0xFFff;
}
void
IPPacket::UpdateV4Address(huint32_t newSrcIP, huint32_t newDstIP)
IPPacket::UpdateIPv4Address(nuint32_t nSrcIP, nuint32_t nDstIP)
{
llarp::LogDebug("set src=", newSrcIP, " dst=", newDstIP);
auto hdr = Header();
auto oSrcIP = nuint32_t{hdr->saddr};
auto oDstIP = nuint32_t{hdr->daddr};
auto nSrcIP = xhtonl(newSrcIP);
auto nDstIP = xhtonl(newDstIP);
// IPv4 checksum
auto v4chk = (nuint16_t *)&(hdr->check);
*v4chk = deltaIPv4Checksum(*v4chk, oSrcIP, oDstIP, nSrcIP, nDstIP);
// L4 checksum
auto ihs = size_t(hdr->ihl * 4);
@ -267,23 +179,98 @@ namespace llarp
}
}
// IPv4 checksum
auto v4chk = (nuint16_t *)&(hdr->check);
*v4chk = deltaIPv4Checksum(*v4chk, oSrcIP, oDstIP, nSrcIP, nDstIP);
// write new IP addresses
hdr->saddr = nSrcIP.n;
hdr->daddr = nDstIP.n;
}
#define ADD32CS(x) ((uint32_t)(x & 0xFFff) + (uint32_t)(x >> 16))
#define SUB32CS(x) ((uint32_t)((~x) & 0xFFff) + (uint32_t)((~x) >> 16))
static nuint16_t
deltaIPv4Checksum(nuint16_t old_sum, nuint32_t old_src_ip,
nuint32_t old_dst_ip, nuint32_t new_src_ip,
nuint32_t new_dst_ip)
{
uint32_t sum = uint32_t(old_sum.n) +
ADD32CS(old_src_ip.n) + ADD32CS(old_dst_ip.n) +
SUB32CS(new_src_ip.n) + SUB32CS(new_dst_ip.n);
// only need to do it 2 times to be sure
// proof: 0xFFff + 0xFFff = 0x1FFfe -> 0xFFff
sum = (sum & 0xFFff) + (sum >> 16);
sum += sum >> 16;
return nuint16_t{uint16_t(sum & 0xFFff)};
}
static nuint16_t
deltaIPv6Checksum(nuint16_t old_sum,
const uint32 old_src_ip[4], const uint32 old_dst_ip[4],
const uint32 new_src_ip[4], const uint32 new_dst_ip[4])
{
/* we don't actually care in what way integers are arranged in memory internally */
/* as long as uint16 pairs are swapped in correct direction, result will be correct (assuming there are no gaps in structure) */
/* we represent 128bit stuff there as 4 32bit ints, that should be more or less correct */
/* we could do 64bit ints too but then we couldn't reuse 32bit macros and that'd suck for 32bit cpus */
#define ADDN128CS(x) (ADD32CS(x[0]) + ADD32CS(x[1]) + ADD32CS(x[2]) + ADD32CS(x[3]))
#define SUBN128CS(x) (SUB32CS(x[0]) + SUB32CS(x[1]) + SUB32CS(x[2]) + SUB32CS(x[3]))
uint32_t sum = uint32_t(old_sum) +
ADDN128CS(old_src_ip) + ADDN128CS(old_dst_ip) +
SUBN128CS(new_src_ip) + SUBN128CS(new_dst_ip);
#undef ADDN128CS
#undef SUBN128CS
// only need to do it 2 times to be sure
// proof: 0xFFff + 0xFFff = 0x1FFfe -> 0xFFff
sum = (sum & 0xFFff) + (sum >> 16);
sum += sum >> 16;
return nuint16_t{uint16_t(sum & 0xFFff)};
}
#undef ADD32CS
#undef SUB32CS
void
IPPacket::UpdateIPv6Address(huint128_t src, huint128_t dst)
{
if(sz <= 40)
return;
auto hdr = HeaderV6();
auto oldSrc = hdr->srcaddr;
auto oldDst = hdr->dstaddr;
hdr->srcaddr = HUIntToIn6(src);
hdr->dstaddr = HUIntToIn6(dst);
const size_t ihs = 40;
auto pld = buf + ihs;
auto psz = sz - ihs;
switch(hdr->proto)
{
//tcp
case 6:
return;
}
}
static void
checksumSrcIPv4TCP(byte_t *pld, ABSL_ATTRIBUTE_UNUSED size_t psz,
deltaChecksumIPv4TCP(byte_t *pld, ABSL_ATTRIBUTE_UNUSED size_t psz,
size_t fragoff, size_t chksumoff, nuint32_t oSrcIP,
nuint32_t oDstIP)
nuint32_t oDstIP, nuint32_t nSrcIP, nuint32_t nDstIP)
{
if(fragoff > chksumoff)
return;
auto check = (nuint16_t *)(pld + chksumoff - fragoff);
*check =
deltaIPv4Checksum(*check, oSrcIP, oDstIP, nuint32_t{0}, nuint32_t{0});
*check = deltaIPv4Checksum(*check, oSrcIP, oDstIP, nSrcIP, nDstIP);
// usually, TCP checksum field cannot be 0xFFff,
// because one's complement addition cannot result in 0x0000,
// and there's inversion in the end;
@ -293,8 +280,9 @@ namespace llarp
}
static void
checksumSrcIPv4UDP(byte_t *pld, ABSL_ATTRIBUTE_UNUSED size_t psz,
size_t fragoff, nuint32_t oSrcIP, nuint32_t oDstIP)
deltaChecksumIPv4UDP(byte_t *pld, ABSL_ATTRIBUTE_UNUSED size_t psz,
size_t fragoff, nuint32_t oSrcIP, nuint32_t oDstIP,
nuint32_t nSrcIP, nuint32_t nDstIP)
{
if(fragoff > 6)
return;
@ -303,8 +291,7 @@ namespace llarp
if(check->n == 0x0000)
return; // 0 is used to indicate "no checksum", don't change
*check =
deltaIPv4Checksum(*check, oSrcIP, oDstIP, nuint32_t{0}, nuint32_t{0});
*check = deltaIPv4Checksum(*check, oSrcIP, oDstIP, nSrcIP, nDstIP);
// 0 is used to indicate "no checksum"
// 0xFFff and 0 are equivalent in one's complement math
// 0xFFff + 1 = 0x10000 -> 0x0001 (same as 0 + 1)
@ -314,48 +301,5 @@ namespace llarp
// if(check->n == 0x0000)
// check->n = 0xFFff;
}
/*
void
IPacket::UpdateIPv4PacketOnSrc()
{
auto hdr = Header();
auto oSrcIP = nuint32_t{hdr->saddr};
auto oDstIP = nuint32_t{hdr->daddr};
// L4
auto ihs = size_t(hdr->ihl * 4);
if(ihs <= sz)
{
auto pld = buf + ihs;
auto psz = sz - ihs;
auto fragoff = size_t((ntohs(hdr->frag_off) & 0x1Fff) * 8);
switch(hdr->protocol)
{
case 6: // TCP
checksumSrcIPv4TCP(pld, psz, fragoff, 16, oSrcIP, oDstIP);
break;
case 17: // UDP
case 136: // UDP-Lite
checksumSrcIPv4UDP(pld, psz, fragoff, oSrcIP, oDstIP);
break;
case 33: // DCCP
checksumSrcIPv4TCP(pld, psz, fragoff, 6, oSrcIP, oDstIP);
break;
}
}
// IPv4
auto v4chk = (nuint16_t *)&(hdr->check);
*v4chk =
deltaIPv4Checksum(*v4chk, oSrcIP, oDstIP, nuint32_t{0}, nuint32_t{0});
// clear addresses
hdr->saddr = 0;
hdr->daddr = 0;
}
*/
} // namespace net
} // namespace llarp

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