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#include <llarp/link/utp.hpp>
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#include "router.hpp"
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#include <llarp/messages/link_intro.hpp>
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#include <llarp/buffer.hpp>
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#include <llarp/endian.h>
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#include <utp.h>
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#include <cassert>
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namespace llarp
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{
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namespace utp
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{
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constexpr size_t FragmentBufferSize = 1088;
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constexpr size_t FragmentHashSize = 32;
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constexpr size_t FragmentNonceSize = 24;
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constexpr size_t FragmentOverheadSize =
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FragmentHashSize + FragmentNonceSize;
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constexpr size_t FragmentBodySize =
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FragmentBufferSize - FragmentOverheadSize;
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typedef llarp::AlignedBuffer< FragmentBufferSize > FragmentBuffer;
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struct LinkLayer;
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struct BaseSession : public ILinkSession
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{
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RouterContact remoteRC;
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utp_socket* sock;
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LinkLayer* parent;
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bool gotLIM;
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PubKey remoteTransportPubKey;
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Addr remoteAddr;
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SharedSecret sessionKey;
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llarp_time_t lastActive;
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const static llarp_time_t sessionTimeout = 10 * 1000;
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std::queue< FragmentBuffer > sendq;
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FragmentBuffer recvBuf;
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size_t recvBufOffset;
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std::vector< byte_t > recvMsg;
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void
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Alive()
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{
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lastActive = llarp_time_now_ms();
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}
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/// base
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BaseSession(llarp_router* r);
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/// outbound
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BaseSession(llarp_router* r, utp_socket* s, const RouterContact& rc,
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const AddressInfo& addr);
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/// inbound
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BaseSession(llarp_router* r, utp_socket* s, const Addr& remote);
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enum State
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{
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eInitial,
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eConnecting,
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eLinkEstablished, // when utp connection is established
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eCryptoHandshake, // crypto handshake initiated
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eSessionReady, // session is ready
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eClose // utp connection is closed
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};
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llarp_router*
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Router();
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State state;
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void
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OnLinkEstablished(LinkLayer* p)
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{
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parent = p;
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EnterState(eLinkEstablished);
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llarp::LogDebug("link established with ", remoteAddr);
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Alive();
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}
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void
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EnterState(State st);
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BaseSession();
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virtual ~BaseSession();
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void
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PumpWrite()
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{
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// TODO: use utp_writev
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while(sendq.size())
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{
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auto& front = sendq.front();
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write_ll(front.data(), front.size());
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sendq.pop();
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}
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}
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void
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write_ll(void* buf, size_t sz)
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{
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if(sock == nullptr)
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{
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llarp::LogWarn("write_ll failed: no socket");
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return;
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}
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llarp::LogDebug("utp_write ", sz, " bytes to ", remoteAddr);
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ssize_t wrote = utp_write(sock, buf, sz);
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if(wrote < 0)
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{
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llarp::LogWarn("utp_write returned ", wrote);
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}
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llarp::LogDebug("utp_write wrote ", wrote, " bytes to ", remoteAddr);
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}
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bool
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VerifyThenDecrypt(FragmentBuffer& buf);
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void
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EncryptThenHash(FragmentBuffer& buf, const byte_t* ptr, uint32_t sz,
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bool isLastFragment);
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bool
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QueueWriteBuffers(llarp_buffer_t buf)
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{
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llarp::LogDebug("write ", buf.sz, " bytes to ", remoteAddr);
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if(state != eSessionReady)
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{
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llarp::LogWarn("failed to send ", buf.sz,
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" bytes on non ready session state=", state);
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return false;
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}
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size_t sz = buf.sz;
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while(sz)
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{
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uint32_t s =
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std::min((FragmentBodySize - (llarp_randint() % 128)), sz);
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sendq.emplace();
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EncryptThenHash(sendq.back(), buf.cur, s, ((sz - s) == 0));
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buf.cur += s;
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sz -= s;
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}
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return true;
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}
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void
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Connect()
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{
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utp_connect(sock, remoteAddr, remoteAddr.SockLen());
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EnterState(eConnecting);
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}
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void
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OutboundLinkEstablished(LinkLayer* p)
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{
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OnLinkEstablished(p);
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KeyExchangeNonce nonce;
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nonce.Randomize();
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SendHandshake(nonce, sock);
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gotLIM = true;
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EnterState(eCryptoHandshake);
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auto router = Router();
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if(DoKeyExchange(sock, router->crypto.dh_client, nonce,
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remoteTransportPubKey, router->encryption))
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{
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EnterState(eSessionReady);
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}
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}
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// send our RC to the remote
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void
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SendHandshake(const KeyExchangeNonce& n, utp_socket* s)
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{
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auto buf = InitBuffer(recvBuf.data(), recvBuf.size());
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// fastforward buffer for handshake to fit before
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buf.cur += sizeof(uint32_t) * 2;
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byte_t* begin = buf.cur;
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LinkIntroMessage msg;
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msg.rc = Router()->rc;
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msg.N = n;
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if(!msg.BEncode(&buf))
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{
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llarp::LogError("failed to encode our RC for handshake");
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Close(s);
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return;
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}
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uint32_t sz = buf.cur - begin;
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llarp::LogDebug("handshake is of size ", sz, " bytes");
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// write handshake header
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buf.cur = buf.base;
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llarp_buffer_put_uint32(&buf, LLARP_PROTO_VERSION);
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llarp_buffer_put_uint32(&buf, sz);
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// send it
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write_ll(recvBuf.data(), sz + (sizeof(uint32_t) * 2));
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sock = s;
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}
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bool
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DoKeyExchange(utp_socket* s, llarp_transport_dh_func dh,
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const KeyExchangeNonce& n, const PubKey& other,
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const SecretKey& secret)
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{
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sock = s;
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if(!dh(sessionKey, other, secret, n))
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{
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llarp::LogError("key exchange with ", other, " failed");
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Close(sock);
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return false;
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}
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return true;
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}
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void
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TickImpl(llarp_time_t now)
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{
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}
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bool
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SendKeepAlive()
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{
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return true;
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}
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void
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SendClose()
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{
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if(sock)
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Close(sock);
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}
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void
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Close(utp_socket* s)
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{
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if(state != eClose)
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{
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utp_shutdown(s, SHUT_RDWR);
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utp_close(s);
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utp_set_userdata(s, nullptr);
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}
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EnterState(eClose);
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sock = nullptr;
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}
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void
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RecvHandshake(const void* buf, size_t bufsz, LinkLayer* p, utp_socket* s);
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bool
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Recv(const void* buf, size_t sz)
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{
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Alive();
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const byte_t* ptr = (const byte_t*)buf;
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llarp::LogDebug("utp read ", sz, " from ", remoteAddr);
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while(sz + recvBufOffset > FragmentBufferSize)
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{
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memcpy(recvBuf.data() + recvBufOffset, ptr, FragmentBufferSize);
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sz -= FragmentBufferSize;
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ptr += FragmentBufferSize;
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VerifyThenDecrypt(recvBuf);
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recvBufOffset = 0;
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}
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memcpy(recvBuf.data() + recvBufOffset, ptr, sz);
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if(sz + recvBufOffset <= FragmentBufferSize)
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{
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recvBufOffset = 0;
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VerifyThenDecrypt(recvBuf);
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}
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else
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recvBufOffset += sz;
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return true;
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}
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bool
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IsTimedOut(llarp_time_t now) const
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{
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if(now < lastActive)
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return false;
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return lastActive - now > sessionTimeout;
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}
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const PubKey&
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RemotePubKey() const
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{
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return remoteRC.pubkey;
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}
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const Addr&
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GetRemoteEndpoint() const
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{
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return remoteAddr;
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}
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void
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MarkEstablished();
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}; // namespace utp
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struct LinkLayer : public ILinkLayer
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{
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utp_context* _utp_ctx = nullptr;
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llarp_router* router = nullptr;
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static uint64
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OnRead(utp_callback_arguments* arg);
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static uint64
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SendTo(utp_callback_arguments* arg)
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{
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LinkLayer* l =
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static_cast< LinkLayer* >(utp_context_get_userdata(arg->context));
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llarp_ev_udp_sendto(&l->m_udp, arg->address, arg->buf, arg->len);
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return 0;
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}
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static uint64
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OnStateChange(utp_callback_arguments*);
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static uint64
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OnAccept(utp_callback_arguments*);
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LinkLayer(llarp_router* r) : ILinkLayer()
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{
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router = r;
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_utp_ctx = utp_init(2);
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utp_context_set_userdata(_utp_ctx, this);
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utp_set_callback(_utp_ctx, UTP_SENDTO, &LinkLayer::SendTo);
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utp_set_callback(_utp_ctx, UTP_ON_ACCEPT, &LinkLayer::OnAccept);
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utp_set_callback(_utp_ctx, UTP_ON_STATE_CHANGE,
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&LinkLayer::OnStateChange);
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utp_set_callback(_utp_ctx, UTP_ON_READ, &LinkLayer::OnRead);
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utp_context_set_option(_utp_ctx, UTP_LOG_NORMAL, 1);
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utp_context_set_option(_utp_ctx, UTP_LOG_MTU, 1);
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utp_context_set_option(_utp_ctx, UTP_LOG_DEBUG, 1);
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}
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~LinkLayer()
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{
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utp_destroy(_utp_ctx);
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}
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uint16_t
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Rank() const
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{
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return 1;
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}
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void
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RecvFrom(const Addr& from, const void* buf, size_t sz)
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{
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utp_process_udp(_utp_ctx, (const byte_t*)buf, sz, from, from.SockLen());
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}
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void
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Pump()
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{
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utp_check_timeouts(_utp_ctx);
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utp_issue_deferred_acks(_utp_ctx);
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ILinkLayer::Pump();
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}
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void
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Stop()
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{
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}
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llarp_router*
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GetRouter();
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bool
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KeyGen(SecretKey& k)
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{
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router->crypto.encryption_keygen(k);
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return true;
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}
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ILinkSession*
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NewOutboundSession(const RouterContact& rc, const AddressInfo& addr);
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utp_socket*
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NewSocket()
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{
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return utp_create_socket(_utp_ctx);
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}
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const char*
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Name() const
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{
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return "utp";
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}
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};
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std::unique_ptr< ILinkLayer >
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NewServer(llarp_router* r)
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{
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return std::unique_ptr< LinkLayer >(new LinkLayer(r));
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}
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BaseSession::BaseSession(llarp_router* r)
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{
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recvBufOffset = 0;
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TimedOut = [&](llarp_time_t now) -> bool {
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return this->IsTimedOut(now);
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};
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GetPubKey = std::bind(&BaseSession::RemotePubKey, this);
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lastActive = llarp_time_now_ms();
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Pump = [&]() { PumpWrite(); };
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Tick = std::bind(&BaseSession::TickImpl, this, std::placeholders::_1);
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SendMessageBuffer = [&](llarp_buffer_t buf) -> bool {
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return this->QueueWriteBuffers(buf);
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};
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IsEstablished = [&]() { return this->state == eSessionReady; };
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HandleLinkIntroMessage = [](const LinkIntroMessage*) -> bool {
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return false;
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};
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|
}
|
|
|
|
|
|
|
|
BaseSession::BaseSession(llarp_router* r, utp_socket* s,
|
|
|
|
const RouterContact& rc, const AddressInfo& addr)
|
|
|
|
: BaseSession(r)
|
|
|
|
{
|
|
|
|
remoteRC.Clear();
|
|
|
|
remoteTransportPubKey = addr.pubkey;
|
|
|
|
remoteRC = rc;
|
|
|
|
sock = s;
|
|
|
|
assert(utp_set_userdata(sock, this) == this);
|
|
|
|
assert(s == sock);
|
|
|
|
remoteAddr = addr;
|
|
|
|
Start = std::bind(&BaseSession::Connect, this);
|
|
|
|
}
|
|
|
|
|
|
|
|
BaseSession::BaseSession(llarp_router* r, utp_socket* s, const Addr& addr)
|
|
|
|
: BaseSession(r)
|
|
|
|
{
|
|
|
|
remoteRC.Clear();
|
|
|
|
sock = s;
|
|
|
|
assert(s == sock);
|
|
|
|
assert(utp_set_userdata(sock, this) == this);
|
|
|
|
remoteAddr = addr;
|
|
|
|
Start = []() {};
|
|
|
|
}
|
|
|
|
|
|
|
|
llarp_router*
|
|
|
|
BaseSession::Router()
|
|
|
|
{
|
|
|
|
return parent->router;
|
|
|
|
}
|
|
|
|
|
|
|
|
BaseSession::~BaseSession()
|
|
|
|
{
|
|
|
|
if(sock)
|
|
|
|
{
|
|
|
|
utp_close(sock);
|
|
|
|
utp_set_userdata(sock, nullptr);
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
ILinkSession*
|
|
|
|
LinkLayer::NewOutboundSession(const RouterContact& rc,
|
|
|
|
const AddressInfo& addr)
|
|
|
|
{
|
|
|
|
return new BaseSession(router, utp_create_socket(_utp_ctx), rc, addr);
|
|
|
|
}
|
|
|
|
|
|
|
|
uint64
|
|
|
|
LinkLayer::OnRead(utp_callback_arguments* arg)
|
|
|
|
{
|
|
|
|
BaseSession* self =
|
|
|
|
static_cast< BaseSession* >(utp_get_userdata(arg->socket));
|
|
|
|
if(self)
|
|
|
|
{
|
|
|
|
if(self->state == BaseSession::eClose)
|
|
|
|
{
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
else if(self->state == BaseSession::eSessionReady)
|
|
|
|
self->Recv(arg->buf, arg->len);
|
|
|
|
else if(self->state == BaseSession::eLinkEstablished)
|
|
|
|
{
|
|
|
|
LinkLayer* parent =
|
|
|
|
static_cast< LinkLayer* >(utp_context_get_userdata(arg->context));
|
|
|
|
self->RecvHandshake(arg->buf, arg->len, parent, arg->socket);
|
|
|
|
}
|
|
|
|
utp_read_drained(arg->socket);
|
|
|
|
}
|
|
|
|
else
|
|
|
|
{
|
|
|
|
llarp::LogWarn("utp_socket got data with no underlying session");
|
|
|
|
}
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
uint64
|
|
|
|
LinkLayer::OnStateChange(utp_callback_arguments* arg)
|
|
|
|
{
|
|
|
|
LinkLayer* l =
|
|
|
|
static_cast< LinkLayer* >(utp_context_get_userdata(arg->context));
|
|
|
|
BaseSession* session =
|
|
|
|
static_cast< BaseSession* >(utp_get_userdata(arg->socket));
|
|
|
|
if(session)
|
|
|
|
{
|
|
|
|
if(arg->state == UTP_STATE_CONNECT)
|
|
|
|
{
|
|
|
|
if(session->state == BaseSession::eClose)
|
|
|
|
{
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
session->OutboundLinkEstablished(l);
|
|
|
|
}
|
|
|
|
else if(arg->state == UTP_STATE_EOF)
|
|
|
|
{
|
|
|
|
session->SendClose();
|
|
|
|
}
|
|
|
|
}
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
uint64
|
|
|
|
LinkLayer::OnAccept(utp_callback_arguments* arg)
|
|
|
|
{
|
|
|
|
LinkLayer* self =
|
|
|
|
static_cast< LinkLayer* >(utp_context_get_userdata(arg->context));
|
|
|
|
Addr remote(*arg->address);
|
|
|
|
llarp::LogDebug("utp accepted from ", remote);
|
|
|
|
if(self->HasSessionVia(remote))
|
|
|
|
{
|
|
|
|
// TODO should we do this?
|
|
|
|
llarp::LogWarn(
|
|
|
|
"utp socket closed because we already have a session "
|
|
|
|
"via ",
|
|
|
|
remote);
|
|
|
|
utp_close(arg->socket);
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
BaseSession* session = new BaseSession(self->router, arg->socket, remote);
|
|
|
|
self->PutSession(remote, session);
|
|
|
|
session->OnLinkEstablished(self);
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
void
|
|
|
|
BaseSession::EncryptThenHash(FragmentBuffer& buf, const byte_t* ptr,
|
|
|
|
uint32_t sz, bool isLastFragment)
|
|
|
|
|
|
|
|
{
|
|
|
|
llarp::LogDebug("encrypt then hash ", sz, " bytes");
|
|
|
|
buf.Randomize();
|
|
|
|
const byte_t* nonce = buf.data() + FragmentHashSize;
|
|
|
|
byte_t* body = buf.data() + FragmentOverheadSize;
|
|
|
|
byte_t* base = body;
|
|
|
|
if(isLastFragment)
|
|
|
|
htobe32buf(body, 0);
|
|
|
|
body += sizeof(uint32_t);
|
|
|
|
htobe32buf(body, sz);
|
|
|
|
body += sizeof(uint32_t);
|
|
|
|
memcpy(body, ptr, sz);
|
|
|
|
auto payload = InitBuffer(base, FragmentBodySize);
|
|
|
|
parent->router->crypto.xchacha20(payload, sessionKey, nonce);
|
|
|
|
parent->router->crypto.hmac(buf, payload, sessionKey);
|
|
|
|
}
|
|
|
|
|
|
|
|
void
|
|
|
|
BaseSession::EnterState(State st)
|
|
|
|
{
|
|
|
|
Alive();
|
|
|
|
state = st;
|
|
|
|
if(st == eSessionReady)
|
|
|
|
{
|
|
|
|
parent->MapAddr(this->remoteAddr, remoteRC.pubkey);
|
|
|
|
Router()->HandleLinkSessionEstablished(remoteRC);
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
bool
|
|
|
|
BaseSession::VerifyThenDecrypt(FragmentBuffer& buf)
|
|
|
|
{
|
|
|
|
ShortHash digest;
|
|
|
|
if(!Router()->crypto.hmac(
|
|
|
|
digest,
|
|
|
|
InitBuffer(buf.data() + FragmentHashSize,
|
|
|
|
FragmentBufferSize - FragmentHashSize),
|
|
|
|
sessionKey))
|
|
|
|
{
|
|
|
|
llarp::LogError("keyed hash failed");
|
|
|
|
return false;
|
|
|
|
}
|
|
|
|
if(digest != ShortHash(buf.data()))
|
|
|
|
{
|
|
|
|
llarp::LogError("Message Integrity Failed");
|
|
|
|
return false;
|
|
|
|
}
|
|
|
|
AlignedBuffer< FragmentNonceSize > nonce(buf.data() + FragmentHashSize);
|
|
|
|
|
|
|
|
auto body = InitBuffer(buf.data() + FragmentOverheadSize,
|
|
|
|
FragmentBufferSize - FragmentOverheadSize);
|
|
|
|
|
|
|
|
Router()->crypto.xchacha20(body, sessionKey, nonce);
|
|
|
|
|
|
|
|
uint32_t upper, lower;
|
|
|
|
if(!(llarp_buffer_read_uint32(&body, &upper)
|
|
|
|
&& llarp_buffer_read_uint32(&body, &lower)))
|
|
|
|
return false;
|
|
|
|
bool fragmentEnd = upper == 0;
|
|
|
|
if(recvMsg.size() + lower > MAX_LINK_MSG_SIZE)
|
|
|
|
{
|
|
|
|
llarp::LogError("Fragment too big: ", lower, " bytes");
|
|
|
|
return false;
|
|
|
|
}
|
|
|
|
size_t newsz = recvMsg.size() + lower;
|
|
|
|
recvMsg.reserve(newsz);
|
|
|
|
byte_t* ptr = recvMsg.data() + (newsz - lower);
|
|
|
|
memcpy(ptr, body.cur, lower);
|
|
|
|
if(fragmentEnd)
|
|
|
|
{
|
|
|
|
// got a message
|
|
|
|
auto mbuf = Buffer(recvMsg);
|
|
|
|
auto result = Router()->HandleRecvLinkMessageBuffer(this, mbuf);
|
|
|
|
recvMsg.clear();
|
|
|
|
recvMsg.shrink_to_fit();
|
|
|
|
return result;
|
|
|
|
}
|
|
|
|
return true;
|
|
|
|
}
|
|
|
|
|
|
|
|
void
|
|
|
|
BaseSession::RecvHandshake(const void* buf, size_t bufsz, LinkLayer* p,
|
|
|
|
utp_socket* s)
|
|
|
|
{
|
|
|
|
Alive();
|
|
|
|
size_t sz = bufsz;
|
|
|
|
parent = p;
|
|
|
|
sock = s;
|
|
|
|
if(parent->HasSessionVia(remoteAddr))
|
|
|
|
{
|
|
|
|
llarp::LogDebug("already have session via ", remoteAddr,
|
|
|
|
" so closing before processing handshake");
|
|
|
|
Close(sock);
|
|
|
|
return;
|
|
|
|
}
|
|
|
|
|
|
|
|
llarp::LogDebug("recv handshake ", sz, " from ", remoteAddr);
|
|
|
|
if(recvBuf.size() < sz)
|
|
|
|
{
|
|
|
|
llarp::LogDebug("handshake too big from ", remoteAddr);
|
|
|
|
Close(sock);
|
|
|
|
return;
|
|
|
|
}
|
|
|
|
if(sz <= 8)
|
|
|
|
{
|
|
|
|
llarp::LogDebug("handshake too small from ", remoteAddr);
|
|
|
|
Close(sock);
|
|
|
|
return;
|
|
|
|
}
|
|
|
|
memcpy(recvBuf.data(), buf, sz);
|
|
|
|
|
|
|
|
// process handshake header
|
|
|
|
uint8_t* ptr = recvBuf.data();
|
|
|
|
uint32_t version = bufbe32toh(ptr);
|
|
|
|
if(version != LLARP_PROTO_VERSION)
|
|
|
|
{
|
|
|
|
llarp::LogWarn("protocol version missmatch ", version,
|
|
|
|
" != ", LLARP_PROTO_VERSION);
|
|
|
|
Close(sock);
|
|
|
|
return;
|
|
|
|
}
|
|
|
|
ptr += sizeof(uint32_t);
|
|
|
|
sz -= sizeof(uint32_t);
|
|
|
|
uint32_t limsz = bufbe32toh(ptr);
|
|
|
|
ptr += sizeof(uint32_t);
|
|
|
|
sz -= sizeof(uint32_t);
|
|
|
|
if(limsz > sz)
|
|
|
|
{
|
|
|
|
// not enough data
|
|
|
|
// TODO: don't bail here, continue reading
|
|
|
|
llarp::LogDebug("not enough data for handshake, want ", limsz,
|
|
|
|
" bytes but got ", sz);
|
|
|
|
Close(sock);
|
|
|
|
return;
|
|
|
|
}
|
|
|
|
llarp::LogInfo("read LIM from ", remoteAddr);
|
|
|
|
|
|
|
|
// process LIM
|
|
|
|
auto mbuf = InitBuffer(ptr, limsz);
|
|
|
|
LinkIntroMessage msg(this);
|
|
|
|
if(!msg.BDecode(&mbuf))
|
|
|
|
{
|
|
|
|
llarp::LogError("Failed to parse LIM from ", remoteAddr);
|
|
|
|
llarp::DumpBuffer(mbuf);
|
|
|
|
Close(sock);
|
|
|
|
return;
|
|
|
|
}
|
|
|
|
if(!msg.HandleMessage(Router()))
|
|
|
|
{
|
|
|
|
llarp::LogError("failed to verify signature of rc");
|
|
|
|
return;
|
|
|
|
}
|
|
|
|
if(!DoKeyExchange(sock, Router()->crypto.dh_server, msg.N, msg.rc.enckey,
|
|
|
|
parent->TransportSecretKey()))
|
|
|
|
return;
|
|
|
|
remoteRC = msg.rc;
|
|
|
|
gotLIM = true;
|
|
|
|
llarp::LogInfo("we got a new session from ", GetPubKey());
|
|
|
|
EnterState(eSessionReady);
|
|
|
|
}
|
|
|
|
|
|
|
|
} // namespace utp
|
|
|
|
|
|
|
|
} // namespace llarp
|