rewrite txqueue sequencing logic to use per-packet sequence numbers

tcp/handler_test.go

@@ -1,6 +1,7 @@
 package tcp
 
 import (
+	"bytes"
 	"math/rand"
 	"testing"
 )
@@ -9,19 +10,59 @@ func TestHandler(t *testing.T) {
 	const mtu = 1500
 	const maxpackets = 3
 	rng := rand.New(rand.NewSource(0))
-	client, server := setupClientServer(t, rng, mtu, mtu, maxpackets, mtu, mtu, maxpackets)
+	client, server := newHandler(t, mtu, maxpackets), newHandler(t, mtu, maxpackets)
+	setupClientServer(t, rng, client, server)
 	var rawbuf [mtu]byte
 	establish(t, client, server, rawbuf[:])
+	sendDataFull(t, client, server, []byte("hello"), rawbuf[:])
 }
 
-func setupClientServer(t *testing.T, rng *rand.Rand, clientTxSize, clientRxSize, clientPackets, serverTxSize, serverRxSize, serverPackets int) (client, server *Handler) {
-	client = new(Handler)
-	server = new(Handler)
-	err := client.SetBuffers(make([]byte, clientTxSize), make([]byte, clientRxSize), clientPackets)
+func sendDataFull(t *testing.T, client, server *Handler, data, packetBuf []byte) {
+	n, err := client.Write(data)
+	if err != nil {
+		t.Fatal("client write:", err)
+	} else if n != len(data) {
+		t.Fatal("expected client to write full data packet")
+	}
+	n, err = client.Send(packetBuf)
+	if err != nil {
+		t.Fatal("client sending:", err)
+	} else if n < len(data)+sizeHeaderTCP {
+		t.Fatal("expected client to send full data packet", n, len(data)+sizeHeaderTCP)
+	}
+	err = server.Recv(packetBuf[:n])
+	if err != nil {
+		t.Fatal("server receiving:", err)
+	} else if server.Buffered() != len(data) {
+		t.Fatal("server did not receive full data packet", server.Buffered(), len(data))
+	}
+	clear(packetBuf)
+	n, err = server.Read(packetBuf)
+	if err != nil {
+		t.Fatal("server read:", err)
+	} else if n != len(data) {
+		t.Fatal("expected server to read full data packet")
+	} else if !bytes.Equal(packetBuf[:n], data) {
+		t.Fatal("server received unexpected data")
+	}
+}
+
+func newHandler(t *testing.T, mtu, mintaxpackets int) *Handler {
+	h := new(Handler)
+	err := h.SetBuffers(make([]byte, mtu), make([]byte, mtu), mintaxpackets)
 	if err != nil {
 		t.Fatal(err)
 	}
-	err = server.SetBuffers(make([]byte, serverTxSize), make([]byte, serverRxSize), serverPackets)
+	return h
+}
+
+func setupClientServer(t *testing.T, rng *rand.Rand, client, server *Handler) {
+	// Ensure buffer sizes are OK with reused buffers.
+	err := client.SetBuffers(nil, nil, 0)
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = server.SetBuffers(nil, nil, 0)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -39,21 +80,20 @@ func setupClientServer(t *testing.T, rng *rand.Rand, clientTxSize, clientRxSize,
 	if !server.AwaitingSynAck() {
 		t.Fatal("server in wrong state")
 	}
-	return client, server
 }
 
-func establish(t *testing.T, client, server *Handler, buf []byte) {
+func establish(t *testing.T, client, server *Handler, packetBuf []byte) {
 	if client.State() != StateClosed {
 		t.Fatal("client in wrong state")
 	} else if server.State() != StateListen {
 		t.Fatal("server in wrong state")
 	}
-	clear(buf)
+	clear(packetBuf)
 
 	// Commence 3-way handshake: client sends SYN, server sends SYN-ACK, client sends ACK.
 
 	// Client sends SYN.
-	n, err := client.Send(buf)
+	n, err := client.Send(packetBuf)
 	if err != nil {
 		t.Fatal("client sending:", err)
 	} else if n < sizeHeaderTCP {
@@ -61,15 +101,15 @@ func establish(t *testing.T, client, server *Handler, buf []byte) {
 	} else if client.State() != StateSynSent {
 		t.Fatal("client did not transition to SynSent state:", client.State().String())
 	}
-	err = server.Recv(buf[:n]) // Server receives SYN.
+	err = server.Recv(packetBuf[:n]) // Server receives SYN.
 	if err != nil {
 		t.Fatal(err)
 	} else if server.State() != StateSynRcvd {
 		t.Fatal("server did not transition to SynReceived state:", server.State().String())
 	}
-	clear(buf)
+	clear(packetBuf)
 	// Server sends SYNACK response to client's SYN.
-	n, err = server.Send(buf)
+	n, err = server.Send(packetBuf)
 	if err != nil {
 		t.Fatal("server sending:", err)
 	} else if n < sizeHeaderTCP {
@@ -77,15 +117,15 @@ func establish(t *testing.T, client, server *Handler, buf []byte) {
 	} else if server.State() != StateSynRcvd {
 		t.Fatal("server should remain in SynReceived state:", server.State().String())
 	}
-	err = client.Recv(buf[:n]) // Client receives SYNACK, is established but must send ACK.
+	err = client.Recv(packetBuf[:n]) // Client receives SYNACK, is established but must send ACK.
 	if err != nil {
 		t.Fatal(err)
 	} else if client.State() != StateEstablished {
 		t.Fatal("client did not transition to Established state:", client.State().String())
 	}
 
-	clear(buf)
-	n, err = client.Send(buf) // Client sends ACK.
+	clear(packetBuf)
+	n, err = client.Send(packetBuf) // Client sends ACK.
 	if err != nil {
 		t.Fatal("client sending ACK:", err)
 	} else if n < sizeHeaderTCP {
@@ -93,7 +133,7 @@ func establish(t *testing.T, client, server *Handler, buf []byte) {
 	} else if client.State() != StateEstablished {
 		t.Fatal("client should remain in Established state:", client.State().String())
 	}
-	err = server.Recv(buf[:n]) // Server receives ACK.
+	err = server.Recv(packetBuf[:n]) // Server receives ACK.
 	if err != nil {
 		t.Fatal(err)
 	} else if server.State() != StateEstablished {