mirror of
https://github.com/oxen-io/lokinet.git
synced 2024-11-17 15:25:35 +00:00
441 lines
13 KiB
C++
441 lines
13 KiB
C++
#include <net/ip.hpp>
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#include <util/buffer.hpp>
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#include <util/endian.hpp>
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#include <util/mem.hpp>
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#ifndef _WIN32
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#include <netinet/in.h>
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#endif
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#include <algorithm>
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#include <map>
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namespace llarp
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{
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namespace net
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{
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inline static uint32_t *
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in6_uint32_ptr(in6_addr &addr)
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{
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return (uint32_t *)addr.s6_addr;
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}
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inline static const uint32_t *
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in6_uint32_ptr(const in6_addr &addr)
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{
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return (uint32_t *)addr.s6_addr;
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}
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huint128_t
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IPPacket::In6ToHUInt(in6_addr addr)
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{
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uint32_t *ptr = in6_uint32_ptr(addr);
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return huint128_t{ntohl(ptr[3])} | (huint128_t{ntohl(ptr[2])} << 32)
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}
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in6_addr
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IPPacket::HUIntToIn6(huint128_t x)
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{
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in6_addr addr;
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auto i = ntoh128(x.h);
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memcpy(&addr, &i, 16);
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return addr;
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}
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huint128_t
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IPPacket::ExpandV4(huint32_t i)
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{
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huint128_t ff = {0xff};
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huint128_t expanded{i.h};
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return (ff << 40) | (ff << 32) | expanded;
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}
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huint32_t
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IPPacket::TruncateV6(huint128_t i)
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{
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huint32_t ret = {0};
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ret.h = (uint32_t)(i.h & (0x00000000ffffffffUL));
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return ret;
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}
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huint128_t
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IPPacket::srcv6() const
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{
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if(IsV6())
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return In6ToHUInt(HeaderV6()->srcaddr);
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return ExpandV4(srcv4());
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}
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huint128_t
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IPPacket::dstv6() const
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{
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if(IsV6())
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return In6ToHUInt(HeaderV6()->dstaddr);
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return ExpandV4(dstv4());
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}
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bool
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IPPacket::Load(const llarp_buffer_t &pkt)
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{
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if(pkt.sz > sizeof(buf) or pkt.sz == 0)
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return false;
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sz = pkt.sz;
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std::copy_n(pkt.base, sz, buf);
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return true;
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}
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ManagedBuffer
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IPPacket::ConstBuffer() const
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{
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const byte_t *ptr = buf;
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llarp_buffer_t b(ptr, sz);
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return ManagedBuffer(b);
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}
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ManagedBuffer
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IPPacket::Buffer()
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{
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byte_t *ptr = buf;
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llarp_buffer_t b(ptr, sz);
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return ManagedBuffer(b);
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}
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huint32_t
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IPPacket::srcv4() const
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{
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return huint32_t{ntohl(Header()->saddr)};
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}
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huint32_t
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IPPacket::dstv4() const
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{
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return huint32_t{ntohl(Header()->daddr)};
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}
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#if 0
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static uint32_t
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ipchksum_pseudoIPv4(nuint32_t src_ip, nuint32_t dst_ip, uint8_t proto,
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uint16_t innerlen)
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{
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#define IPCS(x) ((uint32_t)(x & 0xFFff) + (uint32_t)(x >> 16))
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uint32_t sum = IPCS(src_ip.n) + IPCS(dst_ip.n) + (uint32_t)proto
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+ (uint32_t)htons(innerlen);
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#undef IPCS
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return sum;
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}
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static uint16_t
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ipchksum(const byte_t *buf, size_t sz, uint32_t sum = 0)
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{
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while(sz > 1)
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{
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sum += *(const uint16_t *)buf;
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sz -= sizeof(uint16_t);
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buf += sizeof(uint16_t);
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}
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if(sz != 0)
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{
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uint16_t x = 0;
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*(byte_t *)&x = *(const byte_t *)buf;
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sum += x;
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}
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// only need to do it 2 times to be sure
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// proof: 0xFFff + 0xFFff = 0x1FFfe -> 0xFFff
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sum = (sum & 0xFFff) + (sum >> 16);
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sum += sum >> 16;
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return uint16_t((~sum) & 0xFFff);
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}
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#endif
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#define ADD32CS(x) ((uint32_t)(x & 0xFFff) + (uint32_t)(x >> 16))
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#define SUB32CS(x) ((uint32_t)((~x) & 0xFFff) + (uint32_t)((~x) >> 16))
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static nuint16_t
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deltaIPv4Checksum(nuint16_t old_sum, nuint32_t old_src_ip,
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nuint32_t old_dst_ip, nuint32_t new_src_ip,
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nuint32_t new_dst_ip)
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{
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uint32_t sum = uint32_t(old_sum.n) + ADD32CS(old_src_ip.n)
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+ ADD32CS(old_dst_ip.n) + SUB32CS(new_src_ip.n)
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+ SUB32CS(new_dst_ip.n);
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// only need to do it 2 times to be sure
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// proof: 0xFFff + 0xFFff = 0x1FFfe -> 0xFFff
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sum = (sum & 0xFFff) + (sum >> 16);
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sum += sum >> 16;
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return nuint16_t{uint16_t(sum & 0xFFff)};
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}
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static nuint16_t
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deltaIPv6Checksum(nuint16_t old_sum, const uint32_t old_src_ip[4],
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const uint32_t old_dst_ip[4],
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const uint32_t new_src_ip[4],
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const uint32_t new_dst_ip[4])
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{
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/* we don't actually care in what way integers are arranged in memory
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* internally */
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/* as long as uint16 pairs are swapped in correct direction, result will
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* be correct (assuming there are no gaps in structure) */
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/* we represent 128bit stuff there as 4 32bit ints, that should be more or
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* less correct */
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/* we could do 64bit ints too but then we couldn't reuse 32bit macros and
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* that'd suck for 32bit cpus */
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#define ADDN128CS(x) \
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(ADD32CS(x[0]) + ADD32CS(x[1]) + ADD32CS(x[2]) + ADD32CS(x[3]))
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#define SUBN128CS(x) \
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(SUB32CS(x[0]) + SUB32CS(x[1]) + SUB32CS(x[2]) + SUB32CS(x[3]))
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uint32_t sum = uint32_t(old_sum.n) + ADDN128CS(old_src_ip)
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+ ADDN128CS(old_dst_ip) + SUBN128CS(new_src_ip)
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+ SUBN128CS(new_dst_ip);
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#undef ADDN128CS
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#undef SUBN128CS
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// only need to do it 2 times to be sure
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// proof: 0xFFff + 0xFFff = 0x1FFfe -> 0xFFff
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sum = (sum & 0xFFff) + (sum >> 16);
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sum += sum >> 16;
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return nuint16_t{uint16_t(sum & 0xFFff)};
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}
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#undef ADD32CS
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#undef SUB32CS
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static void
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deltaChecksumIPv4TCP(byte_t *pld, size_t psz, size_t fragoff,
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size_t chksumoff, nuint32_t oSrcIP, nuint32_t oDstIP,
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nuint32_t nSrcIP, nuint32_t nDstIP)
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{
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if(fragoff > chksumoff || psz < chksumoff - fragoff + 2)
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return;
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auto check = (nuint16_t *)(pld + chksumoff - fragoff);
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*check = deltaIPv4Checksum(*check, oSrcIP, oDstIP, nSrcIP, nDstIP);
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// usually, TCP checksum field cannot be 0xFFff,
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// because one's complement addition cannot result in 0x0000,
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// and there's inversion in the end;
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// emulate that.
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if(check->n == 0xFFff)
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check->n = 0x0000;
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}
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static void
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deltaChecksumIPv6TCP(byte_t *pld, size_t psz, size_t fragoff,
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size_t chksumoff, const uint32_t oSrcIP[4],
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const uint32_t oDstIP[4], const uint32_t nSrcIP[4],
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const uint32_t nDstIP[4])
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{
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if(fragoff > chksumoff || psz < chksumoff - fragoff + 2)
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return;
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auto check = (nuint16_t *)(pld + chksumoff - fragoff);
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*check = deltaIPv6Checksum(*check, oSrcIP, oDstIP, nSrcIP, nDstIP);
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// usually, TCP checksum field cannot be 0xFFff,
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// because one's complement addition cannot result in 0x0000,
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// and there's inversion in the end;
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// emulate that.
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if(check->n == 0xFFff)
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check->n = 0x0000;
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}
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static void
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deltaChecksumIPv4UDP(byte_t *pld, size_t psz, size_t fragoff,
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nuint32_t oSrcIP, nuint32_t oDstIP, nuint32_t nSrcIP,
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nuint32_t nDstIP)
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{
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if(fragoff > 6 || psz < 6 + 2)
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return;
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auto check = (nuint16_t *)(pld + 6);
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if(check->n == 0x0000)
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return; // 0 is used to indicate "no checksum", don't change
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*check = deltaIPv4Checksum(*check, oSrcIP, oDstIP, nSrcIP, nDstIP);
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// 0 is used to indicate "no checksum"
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// 0xFFff and 0 are equivalent in one's complement math
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// 0xFFff + 1 = 0x10000 -> 0x0001 (same as 0 + 1)
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// infact it's impossible to get 0 with such addition,
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// when starting from non-0 value.
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// inside deltachksum we don't invert so it's safe to skip check there
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// if(check->n == 0x0000)
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// check->n = 0xFFff;
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}
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static void
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deltaChecksumIPv6UDP(byte_t *pld, size_t psz, size_t fragoff,
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const uint32_t oSrcIP[4], const uint32_t oDstIP[4],
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const uint32_t nSrcIP[4], const uint32_t nDstIP[4])
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{
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if(fragoff > 6 || psz < 6 + 2)
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return;
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auto check = (nuint16_t *)(pld + 6);
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// 0 is used to indicate "no checksum", don't change
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// even tho this shouldn't happen for IPv6, handle it properly
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// we actually should drop/log 0-checksum packets per spec
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// but that should be done at upper level than this function
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// it's better to do correct thing there regardless
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// XXX or maybe we should change this function to be able to return error?
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// either way that's not a priority
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if(check->n == 0x0000)
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return;
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*check = deltaIPv6Checksum(*check, oSrcIP, oDstIP, nSrcIP, nDstIP);
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// 0 is used to indicate "no checksum"
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// 0xFFff and 0 are equivalent in one's complement math
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// 0xFFff + 1 = 0x10000 -> 0x0001 (same as 0 + 1)
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// infact it's impossible to get 0 with such addition,
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// when starting from non-0 value.
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// inside deltachksum we don't invert so it's safe to skip check there
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// if(check->n == 0x0000)
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// check->n = 0xFFff;
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}
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void
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IPPacket::UpdateIPv4Address(nuint32_t nSrcIP, nuint32_t nDstIP)
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{
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llarp::LogDebug("set src=", nSrcIP, " dst=", nDstIP);
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auto hdr = Header();
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auto oSrcIP = nuint32_t{hdr->saddr};
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auto oDstIP = nuint32_t{hdr->daddr};
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// L4 checksum
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auto ihs = size_t(hdr->ihl * 4);
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if(ihs <= sz)
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{
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auto pld = buf + ihs;
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auto psz = sz - ihs;
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auto fragoff = size_t((ntohs(hdr->frag_off) & 0x1Fff) * 8);
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switch(hdr->protocol)
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{
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case 6: // TCP
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deltaChecksumIPv4TCP(pld, psz, fragoff, 16, oSrcIP, oDstIP, nSrcIP,
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nDstIP);
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break;
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case 17: // UDP
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case 136: // UDP-Lite - same checksum place, same 0->0xFFff condition
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deltaChecksumIPv4UDP(pld, psz, fragoff, oSrcIP, oDstIP, nSrcIP,
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nDstIP);
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break;
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case 33: // DCCP
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deltaChecksumIPv4TCP(pld, psz, fragoff, 6, oSrcIP, oDstIP, nSrcIP,
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nDstIP);
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break;
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}
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}
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// IPv4 checksum
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auto v4chk = (nuint16_t *)&(hdr->check);
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*v4chk = deltaIPv4Checksum(*v4chk, oSrcIP, oDstIP, nSrcIP, nDstIP);
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// write new IP addresses
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hdr->saddr = nSrcIP.n;
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hdr->daddr = nDstIP.n;
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}
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void
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IPPacket::UpdateIPv6Address(huint128_t src, huint128_t dst)
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{
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const size_t ihs = 4 + 4 + 16 + 16;
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// XXX should've been checked at upper level?
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if(sz <= ihs)
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return;
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auto hdr = HeaderV6();
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const auto oldSrcIP = hdr->srcaddr;
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const auto oldDstIP = hdr->dstaddr;
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const uint32_t *oSrcIP = in6_uint32_ptr(oldSrcIP);
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const uint32_t *oDstIP = in6_uint32_ptr(oldDstIP);
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// IPv6 address
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hdr->srcaddr = HUIntToIn6(src);
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hdr->dstaddr = HUIntToIn6(dst);
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const uint32_t *nSrcIP = in6_uint32_ptr(hdr->srcaddr);
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const uint32_t *nDstIP = in6_uint32_ptr(hdr->dstaddr);
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// TODO IPv6 header options
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auto pld = buf + ihs;
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auto psz = sz - ihs;
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size_t fragoff = 0;
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auto nextproto = hdr->proto;
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for(;;)
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{
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switch(nextproto)
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{
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case 0: // Hop-by-Hop Options
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case 43: // Routing Header
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case 60: // Destination Options
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{
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nextproto = pld[0];
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auto addlen = (size_t(pld[1]) + 1) * 8;
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if(psz < addlen)
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return;
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pld += addlen;
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psz -= addlen;
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break;
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}
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case 44: // Fragment Header
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/*
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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| Next Header | Reserved | Fragment Offset |Res|M|
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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| Identification |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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*/
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nextproto = pld[0];
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fragoff = (uint16_t(pld[2]) << 8) | (uint16_t(pld[3]) & 0xFC);
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if(psz < 8)
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return;
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pld += 8;
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psz -= 8;
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// jump straight to payload processing
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if(fragoff != 0)
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goto endprotohdrs;
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break;
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default:
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goto endprotohdrs;
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}
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}
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endprotohdrs:
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switch(nextproto)
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{
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case 6: // TCP
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deltaChecksumIPv6TCP(pld, psz, fragoff, 16, oSrcIP, oDstIP, nSrcIP,
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nDstIP);
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break;
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case 17: // UDP
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case 136: // UDP-Lite - same checksum place, same 0->0xFFff condition
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deltaChecksumIPv6UDP(pld, psz, fragoff, oSrcIP, oDstIP, nSrcIP,
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nDstIP);
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break;
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case 33: // DCCP
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deltaChecksumIPv6TCP(pld, psz, fragoff, 6, oSrcIP, oDstIP, nSrcIP,
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nDstIP);
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break;
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}
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}
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} // namespace net
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} // namespace llarp
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