From ef291b45fd887b85fccbed1862606191cc94a443 Mon Sep 17 00:00:00 2001
From: sotech117 <michael_foiani@brown.edu>
Date: Thu, 9 Nov 2023 18:15:08 -0500
Subject: small fixed

---
 pkg/ipstack/ipstack.go |  34 +++++++++++++++++++++-------------
 vhost                  | Bin 3179481 -> 3191030 bytes
 vrouter                | Bin 3146532 -> 3183009 bytes
 3 files changed, 21 insertions(+), 13 deletions(-)

diff --git a/pkg/ipstack/ipstack.go b/pkg/ipstack/ipstack.go
index ba55869..cf2e9d9 100644
--- a/pkg/ipstack/ipstack.go
+++ b/pkg/ipstack/ipstack.go
@@ -1249,9 +1249,10 @@ type SocketKey struct {
 }
 
 type RecvBuffer struct {
-	recvNext uint32
-	lbr      uint32
-	buffer   []byte
+	recvNext   uint32
+	lbr        uint32
+	buffer     []byte
+	windowSize uint16
 }
 
 type SendBuffer struct {
@@ -1386,9 +1387,10 @@ func VConnect(ip string, port uint16) (*VTCPConn, error) {
 			buffer: make([]byte, MAX_WINDOW_SIZE),
 		},
 		RecvBuffer: &RecvBuffer{
-			recvNext: 0,
-			lbr:      0,
-			buffer:   make([]byte, MAX_WINDOW_SIZE),
+			recvNext:   0,
+			lbr:        0,
+			buffer:     make([]byte, MAX_WINDOW_SIZE),
+			windowSize: uint16(MAX_WINDOW_SIZE),
 		},
 	}
 
@@ -1507,21 +1509,25 @@ func (c *VTCPConn) VWrite(payload []byte) (int, error) {
 		return 0, errors.Errorf("error VWrite: payload is larger than the window size")
 	}
 
+	availableSendSpace := MAX_WINDOW_SIZE - c.SendBuffer.nxt - 1 - c.SendBuffer.lbw
+
 	// check if the payload is larger than the available window size
-	if len(payload) > int(MAX_WINDOW_SIZE-(c.SendBuffer.nxt-1-c.SendBuffer.lbw)) {
-		return 0, errors.Errorf("error VWrite: payload is larger than the available window size")
+	fmt.Println("space in send buffer", availableSendSpace, "recbuf next", c.RecvBuffer.recvNext, "lbr", c.RecvBuffer.lbr)
+	if len(payload) > int(availableSendSpace) {
+		return 0, errors.Errorf("error VWrite: payload is larger than the available space in send buffer")
 	}
 
+	// check if the payload is larger than the available window size
+	availableWindowSize := c.RecvBuffer.windowSize - uint16(c.RecvBuffer.recvNext-1-c.RecvBuffer.lbr)
 	// make the header
-	advertisedWindow := MAX_WINDOW_SIZE - (c.SendBuffer.nxt - 1 - c.SendBuffer.lbw)
 	tcpHdr := &header.TCPFields{
 		SrcPort:       c.LocalPort,
 		DstPort:       c.RemotePort,
-		SeqNum:        c.SendBuffer.nxt,
-		AckNum:        c.SendBuffer.una,
+		SeqNum:         c.SendBuffer.nxt,
+		AckNum:        startingSeqNum  c.SendBuffer.una,
 		DataOffset:    20,
 		Flags:         header.TCPFlagAck,
-		WindowSize:    uint16(advertisedWindow),
+		WindowSize:    availableWindowSize,
 		Checksum:      0,
 		UrgentPointer: 0,
 	}
@@ -1574,8 +1580,10 @@ func (c *VTCPConn) VRead(numBytesToRead int) (int, string, error) {
 		toReturn := string(socketEntry.Conn.RecvBuffer.buffer[c.RecvBuffer.lbr : c.RecvBuffer.lbr+diff])
 		// update the last byte read
 		c.RecvBuffer.lbr += diff
+		// increase the window size by bytes read
+		c.RecvBuffer.windowSize += uint16(diff)
 		// return the data
-		return numBytesToRead, toReturn, nil
+		return int(diff), toReturn, nil
 	}
 
 	return 0, "", nil
diff --git a/vhost b/vhost
index 82caaa7..0df683e 100755
Binary files a/vhost and b/vhost differ
diff --git a/vrouter b/vrouter
index e0eee04..3aefd02 100755
Binary files a/vrouter and b/vrouter differ
-- 
cgit v1.2.3-70-g09d2