make tun write correct number of bytes

try doing correct ip checksum and for upper layers that need it too

supported right now are icmp, tcp, and udp. more will come later
probably.

llarp/handlers/tun.cpp

@@ -209,14 +209,15 @@ namespace llarp
       uint32_t usIP   = m_OurIP;
       auto buf        = llarp::Buffer(msg->payload);
       net::IPv4Packet pkt;
-      memcpy(pkt.buf, buf.base, std::min(buf.sz, sizeof(pkt.buf)));
+      pkt.sz = std::min(buf.sz, sizeof(pkt.buf));
+      memcpy(pkt.buf, buf.base, pkt.sz);
       pkt.src(themIP);
       pkt.dst(usIP);
       pkt.UpdateChecksum();
       llarp::LogInfo(Name(), " handle data message ", msg->payload.size(),
                      " bytes from ", inet_ntoa({htonl(themIP)}));
-
       llarp_ev_tun_async_write(&tunif, pkt.buf, pkt.sz);
+
       /*
       if(!m_NetworkToUserPktQueue.EmplaceIf(
              [buf, themIP, usIP](net::IPv4Packet &pkt) -> bool {

llarp/ip.cpp

@@ -3,6 +3,8 @@
 #include <llarp/ip.hpp>
 #include "llarp/buffer.hpp"
 #include "mem.hpp"
+#include <netinet/in.h>
+#include <map>
 
 namespace llarp
 {
@@ -26,29 +28,44 @@ namespace llarp
       return llarp::InitBuffer(buf, sz);
     }
 
-    void
-    IPv4Packet::UpdateChecksum()
-    {
-      auto hdr   = Header();
-      hdr->check = 0;
+    /// bytes offset to checksum relative to end of ip header for each protocol
+    static std::map< byte_t, uint16_t > protoChecksumOffsets = {
+        {IPPROTO_TCP, 16}, {IPPROTO_ICMP, 2}, {IPPROTO_UDP, 6}};
 
-      size_t count = hdr->ihl;
+    static uint16_t
+    ipchksum(const byte_t *buf, size_t sz)
+    {
       uint32_t sum = 0;
-      byte_t *addr = buf;
-
-      while(count > 1)
+      while(sz > 1)
       {
-        sum += *(uint16_t *)addr;
-        count -= sizeof(uint16_t);
-        addr += sizeof(uint16_t);
+        sum += *(const uint16_t *)buf;
+        sz -= sizeof(uint16_t);
+        buf += sizeof(uint16_t);
       }
-      if(count > 0)
-        sum += *(byte_t *)addr;
+      if(sz > 0)
+        sum += *(const byte_t *)buf;
 
       while(sum >> 16)
         sum = (sum & 0xffff) + (sum >> 16);
 
-      hdr->check = ~sum;
+      return ~sum;
+    }
+
+    void
+    IPv4Packet::UpdateChecksum()
+    {
+      auto hdr   = Header();
+      hdr->check = 0;
+      auto len   = hdr->ihl * 4;
+      hdr->check = ipchksum(buf, len);
+
+      auto itr = protoChecksumOffsets.find(hdr->protocol);
+      if(itr != protoChecksumOffsets.end())
+      {
+        uint16_t *check = (uint16_t *)(buf + len + itr->second);
+        *check          = 0;
+        *check          = ipchksum(buf, sz);
+      }
     }
 
   }  // namespace net

llarp/service/endpoint.cpp

@@ -820,7 +820,7 @@ namespace llarp
     Endpoint::OutboundContext::OnIntroSetUpdate(const Address& addr,
                                                 const IntroSet* i)
     {
-      if(i && addr == i->A.Addr() && currentIntroSet.OtherIsNewer(*i))
+      if(i)
       {
         currentIntroSet = *i;
         ShiftIntroduction();
@@ -837,8 +837,9 @@ namespace llarp
         auto itr = m_AddressToService.find(remote);
         if(itr != m_AddressToService.end())
         {
-          ProtocolFrame f;
-          path::Path* p = nullptr;
+          routing::PathTransferMessage transfer;
+          ProtocolFrame& f = transfer.T;
+          path::Path* p    = nullptr;
           std::set< ConvoTag > tags;
           if(!GetConvoTagsForService(itr->second, tags))
           {
@@ -869,18 +870,20 @@ namespace llarp
             return false;
           }
           ProtocolMessage m(f.T);
-          m.PutBuffer(data);
           m.proto      = t;
           m.introReply = p->intro;
           m.sender     = m_Identity.pub;
+          m.PutBuffer(data);
           f.N.Randomize();
+          f.S = GetSeqNoForConvo(f.T);
           f.C.Zero();
+          transfer.Y.Randomize();
+          transfer.P = intro.pathID;
           if(!f.EncryptAndSign(&Router()->crypto, m, K, m_Identity))
           {
             llarp::LogError("failed to encrypt and sign");
             return false;
           }
-          routing::PathTransferMessage transfer(f, intro.pathID);
           return p->SendRoutingMessage(&transfer, Router());
         }
       }

llarp/service/protocol.cpp

@@ -248,7 +248,7 @@ namespace llarp
         if(!self->frame->Verify(crypto, self->msg->sender))
         {
           llarp::LogError("intro frame has invalid signature Z=",
-                          self->frame->Z, " from ", self->msg->sender);
+                          self->frame->Z, " from ", self->msg->sender.Addr());
           delete self->msg;
           delete self;
           return;