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package tcpstack
// import (
// // "encoding/binary"
// "fmt"
// // "syscall"
// "iptcp/pkg/ipstack"
// // ipv4header "github.com/brown-csci1680/iptcp-headers"
// // tcpheader "github.com/brown-csci1680/iptcp-headers"
// "github.com/google/netstack/tcpip/header"
// "github.com/pkg/errors"
// "iptcp/pkg/iptcp_utils"
// // "log"
// // "net"
// "net/netip"
// // "sync"
// // "time"
// "math/rand"
// "sync"
// "strings"
// )
// type ConnectionState string
// const (
// Established ConnectionState = "ESTABLISHED"
// Listening ConnectionState = "LISTENING"
// Closed ConnectionState = "CLOSED"
// SYNSENT ConnectionState = "SYNSENT"
// MAX_WINDOW_SIZE = 65535
// )
// // VTCPListener represents a listener socket (similar to Go’s net.TCPListener)
// type VTCPListener struct {
// LocalAddr string
// LocalPort uint16
// RemoteAddr string
// RemotePort uint16
// Socket int
// State ConnectionState
// }
// // // VTCPConn represents a “normal” socket for a TCP connection between two endpoints (similar to Go’s net.TCPConn)
// type VTCPConn struct {
// LocalAddr string
// LocalPort uint16
// RemoteAddr string
// RemotePort uint16
// Socket int
// State ConnectionState
// Buffer []byte
// }
// type SocketEntry struct {
// Socket int
// LocalIP string
// LocalPort uint16
// RemoteIP string
// RemotePort uint16
// State ConnectionState
// }
// // create a socket map to print the local and remote ip and port as well as the state of the socket
// var VHostSocketMaps = make(map[string]map[string]*SocketEntry)
// var mapMutex = &sync.Mutex{}
// var socketsMade = 0
// var myIP = ipstack.GetInterfaces()[0].IpPrefix.Addr()
// // Listen Sockets
// func VListen(port uint16) (*VTCPListener, error) {
// // get my ip address
// // myIP := ipstack.GetInterfaces()[0].IpPrefix.Addr()
// listener := &VTCPListener{
// Socket: socketsMade,
// State: Listening,
// LocalPort: port,
// LocalAddr: myIP.String(),
// }
// vhostMap, ok := VHostSocketMaps[myIP.String()]
// if !ok {
// vhostMap = make(map[string]*SocketEntry)
// VHostSocketMaps[fmt.Sprintf("%s:%d", "", port)] = vhostMap
// }
// // add the socket to the socket map
// mapMutex.Lock()
// vhostMap[fmt.Sprintf("%s:%d", "", port)] = &SocketEntry{
// Socket: socketsMade,
// LocalIP: "0.0.0.0",
// LocalPort: port,
// RemoteIP: "0.0.0.0",
// RemotePort: 0,
// State: Listening,
// }
// mapMutex.Unlock()
// socketsMade += 1
// return listener, nil
// }
// func (l *VTCPListener) VAccept() (*VTCPConn, error) {
// for {
// // wait for a SYN request
// // if there is a SYN request, create a new socket, send a SYN-ACK response, and return the socket
// myInterface := ipstack.GetInterfaces()[0]
// err := ipstack.RecvIP(myInterface, nil)
// if err != nil {
// return nil, err
// } else {
// break
// }
// }
// socketsMade += 1
// conn := &VTCPConn{
// }
// // add the socket to the socket map
// // mapMutex.Lock()
// return conn, nil
// // create a new socket
// // return the socket
// }
// func GetRandomPort() uint16 {
// const (
// minDynamicPort = 49152
// maxDynamicPort = 65535
// )
// return uint16(rand.Intn(maxDynamicPort - minDynamicPort) + minDynamicPort)
// }
// func VConnect(ip string, port uint16) (*VTCPConn, error) {
// // get my ip address
// // myIP := ipstack.GetInterfaces()[0].IpPrefix.Addr()
// // get random port
// portRand := GetRandomPort()
// // Create a new VTCPConn.
// conn := &VTCPConn{
// LocalAddr: myIP.String(),
// LocalPort: portRand,
// RemoteAddr: ip,
// RemotePort: port,
// Socket: socketsMade,
// State: SYNSENT,
// Buffer: []byte{},
// }
// // get the socket entry from the socket map in the given port
// vhostMap, ok := VHostSocketMaps[ip]
// if !ok {
// return nil, errors.New("socket not found")
// }
// socketEntry, ok := vhostMap[fmt.Sprintf("%s:%d", ip, port)]
// if !ok {
// return nil, errors.New("socket not found")
// }
// // if the socket is closed, return an error
// if socketEntry.State == Closed {
// return nil, errors.New("socket is closed")
// }
// // lookup neighbor
// neighbors := ipstack.GetNeighbors()[ipstack.GetInterfaces()[0].Name]
// var neighbor *ipstack.Neighbor
// for _, n := range neighbors {
// if n.VipAddr.String() == ip {
// neighbor = n
// }
// }
// // Send SYN request.
// if socketEntry.State == Listening {
// tcpHdr := &header.TCPFields{
// SrcPort: portRand,
// DstPort: port,
// SeqNum: 1,
// AckNum: 0,
// DataOffset: 20,
// Flags: header.TCPFlagSyn,
// WindowSize: MAX_WINDOW_SIZE,
// Checksum: 0,
// UrgentPointer: 0,
// }
// payload := []byte{}
// ipParsed, err := netip.ParseAddr(ip)
// if err != nil {
// return nil, err
// }
// checksum := iptcp_utils.ComputeTCPChecksum(tcpHdr, myIP, ipParsed, []byte{})
// tcpHdr.Checksum = checksum
// tcpHeaderBytes := make(header.TCP, iptcp_utils.TcpHeaderLen)
// tcpHeaderBytes.Encode(tcpHdr)
// ipPacketPayload := make([]byte, 0, len(tcpHeaderBytes)+len(payload))
// ipPacketPayload = append(ipPacketPayload, tcpHeaderBytes...)
// ipPacketPayload = append(ipPacketPayload, []byte(payload)...)
// _, err = ipstack.SendIP(&myIP, neighbor, 6, ipPacketPayload, ip, nil)
// if err != nil {
// return nil, err
// }
// }
// // wait for a SYN-ACK response in the socket buffer
// myIPinterface := ipstack.GetInterfaces()[0]
// for {
// err := ipstack.RecvIP(myIPinterface, nil)
// if err != nil {
// return nil, err
// } else {
// break
// }
// }
// return conn, nil
// }
// func SprintSockets() string {
// var socketStrings []string
// // for _, socket := range SocketMap {
// // socketStrings = append(socketStrings, fmt.Sprintf("%d\t%s\t%d\t%s\t%d\t%s", socket.Socket, socket.LocalIP, socket.LocalPort, socket.RemoteIP, socket.RemotePort, socket.State))
// // }
// // only print the sockets in the map with myIP as the key
// for _, socket := range VHostSocketMaps[myIP.String()] {
// socketStrings = append(socketStrings, fmt.Sprintf("%d\t%s\t%d\t%s\t%d\t%s", socket.Socket, socket.LocalIP, socket.LocalPort, socket.RemoteIP, socket.RemotePort, socket.State))
// }
// return strings.Join(socketStrings, "\t")
// }
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