#include #include #include #include "llarp/buffer.hpp" #include "mem.hpp" #ifndef _WIN32 #include #endif #include #include namespace llarp { namespace net { bool IPv4Packet::Load(llarp_buffer_t pkt) { sz = std::min(pkt.sz, sizeof(buf)); memcpy(buf, pkt.base, sz); return true; } llarp_buffer_t IPv4Packet::Buffer() { 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) ((uint32_t)(x & 0xFFFF) + (uint32_t)(x >> 16)) uint32_t sum = IPCS(src_ip_n) + 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) { while(sz > 1) { sum += *(const uint16_t *)buf; sz -= sizeof(uint16_t); buf += sizeof(uint16_t); } if(sz > 0) sum += *(const byte_t *)buf; while(sum >> 16) sum = (sum & 0xffff) + (sum >> 16); 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 ADDIPCS(x) ((uint32_t)(x & 0xFFFF) + (uint32_t)(x >> 16)) #define SUBIPCS(x) ((uint32_t)((~x) & 0xFFFF) + (uint32_t)((~x) >> 16)) uint32_t sum = ~old_sum + ADDIPCS(new_src_ip_n) + ADDIPCS(new_dst_ip_n) + SUBIPCS(old_src_ip_n) + SUBIPCS(old_dst_ip_n); #undef ADDIPCS #undef SUBIPCS 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) > > 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); 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 hlen = size_t(hdr->ihl * 4); hdr->check = 0; hdr->check = ipchksum(buf, hlen); // L4 checksum auto proto = hdr->protocol; 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); 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 hdr->check = 0; } } // namespace net } // namespace llarp