new exit packet buffer format

docs/proto_v0.txt

@@ -745,6 +745,9 @@ transfer ip traffic
   X: "<list of ip packet buffers>",
 }
 
+an ip packet buffer is prefixed with a 64 bit big endian unsigned integer 
+denoting the sequence number for re-ordering followed by the ip packet itself.
+
 X is parsed as a alist of IP packet buffers.
 for each ip packet the source addresss is extracted and sent on the 
 appropriate network interface.

include/llarp/exit/endpoint.hpp

@@ -4,6 +4,7 @@
 #include <llarp/crypto.hpp>
 #include <llarp/router.h>
 #include <llarp/path.hpp>
+#include <llarp/ip.hpp>
 
 namespace llarp
 {
@@ -18,6 +19,8 @@ namespace llarp
     /// persistant exit state for 1 identity on the exit node
     struct Endpoint
     {
+      static constexpr size_t MaxUpstreamQueueSize = 256;
+
       Endpoint(const llarp::PubKey& remoteIdent,
                const llarp::PathID_t& beginPath, bool rewriteIP, huint32_t ip,
                llarp::handlers::ExitEndpoint* parent);
@@ -47,14 +50,14 @@ namespace llarp
       bool
       QueueInboundTraffic(llarp_buffer_t buff);
 
-      /// flush inbound traffic queue
+      /// flush inbound and outbound traffic queues
       bool
-      FlushInboundTraffic();
+      Flush();
 
-      /// send traffic to service node / internet
+      /// queue outbound traffic
       /// does ip rewrite here
       bool
-      SendOutboundTraffic(llarp_buffer_t buf);
+      QueueOutboundTraffic(llarp_buffer_t pkt, uint64_t counter);
 
       /// update local path id and cascade information to parent
       /// return true if success
@@ -106,6 +109,25 @@ namespace llarp
       using TieredQueue = std::map<uint8_t, InboundTrafficQueue_t>;
       // maps number of fragments the message will fit in to the queue for it
       TieredQueue m_DownstreamQueues;
+
+      struct UpstreamBuffer
+      {
+        UpstreamBuffer(const llarp::net::IPv4Packet & p, uint64_t c) : pkt(p), counter(c) 
+        {
+        }
+
+        llarp::net::IPv4Packet pkt;
+        uint64_t counter;
+
+        bool operator<(const UpstreamBuffer & other) const
+        {
+          return counter < other.counter;
+        }
+      };
+
+      using UpstreamQueue_t = std::priority_queue<UpstreamBuffer>;
+      UpstreamQueue_t m_UpstreamQueue;
+      uint64_t m_Counter;
     };
   }  // namespace exit
 }  // namespace llarp

include/llarp/exit/session.hpp

@@ -63,6 +63,7 @@ namespace llarp
       using UpstreamTrafficQueue_t = std::deque<llarp::routing::TransferTrafficMessage>;
       using TieredQueue_t = std::map<uint8_t, UpstreamTrafficQueue_t>;
       TieredQueue_t m_Upstream;
+      uint64_t m_Counter;
       llarp::SecretKey m_ExitIdentity;
     };
 

include/llarp/ip.hpp

@@ -88,6 +88,9 @@ namespace llarp
       llarp_buffer_t
       Buffer();
 
+      llarp_buffer_t
+      ConstBuffer() const;
+
       bool
       Load(llarp_buffer_t buf);
 

include/llarp/messages/transfer_traffic.hpp

@@ -26,7 +26,7 @@ namespace llarp
 
       /// append buffer to X
       bool
-      PutBuffer(llarp_buffer_t buf);
+      PutBuffer(llarp_buffer_t buf, uint64_t counter);
 
       bool
       BEncode(llarp_buffer_t* buf) const override;

include/llarp/path.hpp

@@ -290,7 +290,7 @@ namespace llarp
       using ExitUpdatedFunc = std::function< bool(Path*) >;
       using ExitClosedFunc  = std::function< bool(Path*) >;
       using ExitTrafficHandlerFunc =
-          std::function< bool(Path*, llarp_buffer_t) >;
+          std::function< bool(Path*, llarp_buffer_t, uint64_t) >;
       /// (path, backoff) backoff is 0 on success
       using ObtainedExitHandler = std::function< bool(Path*, llarp_time_t) >;
 

llarp/exit/endpoint.cpp

@@ -13,6 +13,7 @@ namespace llarp
         , m_CurrentPath(beginPath)
         , m_IP(ip)
         , m_RewriteSource(rewriteIP)
+        , m_Counter(0)
     {
       m_LastActive = parent->Now();
     }
@@ -76,22 +77,23 @@ namespace llarp
     }
 
     bool
-    Endpoint::SendOutboundTraffic(llarp_buffer_t buf)
+    Endpoint::QueueOutboundTraffic(llarp_buffer_t buf, uint64_t counter)
     {
+      // queue overflow
+      if(m_UpstreamQueue.size() > MaxUpstreamQueueSize)
+        return false;
+      
       llarp::net::IPv4Packet pkt;
       if(!pkt.Load(buf))
         return false;
+        
       huint32_t dst;
       if(m_RewriteSource)
         dst = m_Parent->GetIfAddr();
       else
         dst = pkt.dst();
       pkt.UpdateIPv4PacketOnDst(m_IP, dst);
-      if(!m_Parent->QueueOutboundTraffic(pkt.Buffer()))
-      {
-        llarp::LogError("failed to queue outbound traffic");
-        return false;
-      }
+      m_UpstreamQueue.emplace(pkt, counter);
       m_TxRate += buf.sz;
       m_LastActive = m_Parent->Now();
       return true;
@@ -116,21 +118,28 @@ namespace llarp
       if(queue.size() == 0)
       {
         queue.emplace_back();
-        return queue.back().PutBuffer(buf);
+        return queue.back().PutBuffer(buf, m_Counter++);
       }
       auto & msg = queue.back();
       if(msg.Size() + pktbuf.sz > llarp::routing::ExitPadSize)
       {
         queue.emplace_back();
-        return queue.back().PutBuffer(pktbuf);
+        return queue.back().PutBuffer(pktbuf, m_Counter++);
       }
       else
-        return msg.PutBuffer(pktbuf);
+        return msg.PutBuffer(pktbuf, m_Counter++);
     }
 
     bool 
-    Endpoint::FlushInboundTraffic()
+    Endpoint::Flush()
     {
+      // flush upstream queue
+      while(m_UpstreamQueue.size())
+      {
+        m_Parent->QueueOutboundTraffic(m_UpstreamQueue.top().pkt.ConstBuffer());
+        m_UpstreamQueue.pop();
+      }
+      // flush downstream queue
       auto path = GetCurrentPath();
       bool sent = path != nullptr;
       if(path)

llarp/exit/session.cpp

@@ -11,6 +11,7 @@ namespace llarp
         : llarp::path::Builder(r, r->dht, numpaths, hoplen)
         , m_ExitRouter(router)
         , m_WritePacket(writepkt)
+        , m_Counter(0)
     {
       r->crypto.identity_keygen(m_ExitIdentity);
     }
@@ -108,17 +109,17 @@ namespace llarp
       if(queue.size() == 0)
       {
         queue.emplace_back();
-        return queue.back().PutBuffer(buf);
+        return queue.back().PutBuffer(buf, m_Counter++);
       }
       auto & back = queue.back();
       // pack to nearest N
       if(back.Size() + buf.sz > N)
       {
          queue.emplace_back();
-         return queue.back().PutBuffer(buf);
+         return queue.back().PutBuffer(buf, m_Counter++);
       }
       else
-        return back.PutBuffer(buf);
+        return back.PutBuffer(buf, m_Counter++);
     }
 
     bool

llarp/exit/transfer_traffic.cpp

@@ -1,5 +1,6 @@
 #include <llarp/messages/transfer_traffic.hpp>
 #include <llarp/routing/handler.hpp>
+#include <llarp/endian.hpp>
 
 namespace llarp
 {
@@ -15,14 +16,17 @@ namespace llarp
     }
 
     bool
-    TransferTrafficMessage::PutBuffer(llarp_buffer_t buf)
+    TransferTrafficMessage::PutBuffer(llarp_buffer_t buf, uint64_t counter)
     {
       if(buf.sz > MaxExitMTU)
         return false;
-      X.emplace_back(buf.sz);
-      memcpy(X.back().data(), buf.base, buf.sz);
-      // 8 bytes encoding overhead
-      _size += buf.sz + 8;
+      X.emplace_back(buf.sz + 8);
+      byte_t * ptr = X.back().data();
+      htobe64buf(ptr, counter);
+      ptr += 8;
+      memcpy(ptr, buf.base, buf.sz);
+      // 8 bytes encoding overhead and 8 bytes counter
+      _size += buf.sz + 16;
       return true;
     }
 

llarp/handlers/exit.cpp

@@ -90,7 +90,7 @@ namespace llarp
       auto itr = m_ActiveExits.begin();
       while(itr != m_ActiveExits.end())
       {
-        if(!itr->second->FlushInboundTraffic())
+        if(!itr->second->Flush())
         {
           llarp::LogWarn("exit session with ", itr->first, " dropped packets");
         }

llarp/ip.cpp

@@ -23,6 +23,12 @@ namespace llarp
       return true;
     }
 
+    llarp_buffer_t
+    IPv4Packet::ConstBuffer() const 
+    {
+      return llarp::InitBuffer(buf, sz);
+    }
+
     llarp_buffer_t
     IPv4Packet::Buffer()
     {

llarp/path.cpp

@@ -6,6 +6,7 @@
 #include <llarp/messages/discard.hpp>
 #include "buffer.hpp"
 #include "router.hpp"
+#include <llarp/endian.hpp>
 
 namespace llarp
 {
@@ -801,7 +802,12 @@ namespace llarp
         return false;
       bool sent = msg->X.size() > 0;
       for(const auto & pkt : msg->X)
-        m_ExitTrafficHandler(this, pkt.Buffer());
+      {
+        if(pkt.size() <= 8)
+          return false;
+        uint64_t counter = bufbe64toh(pkt.data());
+        m_ExitTrafficHandler(this, llarp::InitBuffer(pkt.data() +8, pkt.size()-8), counter);
+      }
       return sent;
     }
 

llarp/transit_hop.cpp

@@ -3,6 +3,7 @@
 #include <llarp/messages/discard.hpp>
 #include "buffer.hpp"
 #include "router.hpp"
+#include <llarp/endian.hpp>
 
 namespace llarp
 {
@@ -259,7 +260,13 @@ namespace llarp
       {
         bool sent = true;
         for(const auto & pkt : msg->X)
-          sent &= endpoint->SendOutboundTraffic(pkt.Buffer());
+        {
+          // check short packet buffer
+          if(pkt.size() <= 8)
+            continue;
+          uint64_t counter = bufbe64toh(pkt.data());
+          sent &= endpoint->QueueOutboundTraffic(llarp::InitBuffer(pkt.data() + 8, pkt.size() - 8), counter);
+        }
         return sent;
       }
       else

test/traffic_transfer_unittest.cpp

@@ -12,7 +12,7 @@ TEST_F(TransferTrafficTest, TestPutBufferOverflow)
   TransferTrafficMessage msg;
   byte_t tmp[llarp::routing::MaxExitMTU * 2] = {0};
   auto buf = llarp::StackBuffer< decltype(tmp) >(tmp);
-  ASSERT_FALSE(msg.PutBuffer(buf));
+  ASSERT_FALSE(msg.PutBuffer(buf, 1));
 };
 
 TEST_F(TransferTrafficTest, TestPutBuffer)
@@ -20,5 +20,5 @@ TEST_F(TransferTrafficTest, TestPutBuffer)
   TransferTrafficMessage msg;
   byte_t tmp[llarp::routing::MaxExitMTU] = {0};
   auto buf = llarp::StackBuffer< decltype(tmp) >(tmp);
-  ASSERT_TRUE(msg.PutBuffer(buf));
+  ASSERT_TRUE(msg.PutBuffer(buf, 1));
 };