How can I kill a Websocket connection? - websocket

Question

How can I kill a Websocket connection? I'm not talking about closing the connection on either end but interrupting it "in the middle". I need to test some application logic that must happen on a reconnect (which is handled through SocketIO).
And no, unplugging the network cable doesn't count because I can't really automate that in a unit test :-) Besides, I wish to kill only one specific connection and not all of them.

Answer 1

It is painful, but it is possible. You can find an explanation here. The code is as follows:
using System;
using System.Collections;
using System.Runtime.InteropServices;
/// <summary>
/// This is a class for disconnecting TCP connections.
/// You can get a list of all connections and close by a connection, localIP,
/// remoteIP, localPort and remotePort.
/// </summary>
public class Disconnecter {
//Enumeration of the states
public enum State{
All=0,
Closed=1,
Listen=2,
Syn_Sent=3,
Syn_Rcvd=4,
Established=5,
Fin_Wait1=6,
Fin_Wait2=7,
Close_Wait=8,
Closing=9,
Last_Ack=10,
Time_Wait=11,
Delete_TCB=12
}
//Connection info
private struct MIB_TCPROW{
public int dwState;
public int dwLocalAddr;
public int dwLocalPort;
public int dwRemoteAddr;
public int dwRemotePort;
}
//API to get list of connections
[DllImport("iphlpapi.dll")]
private static extern int GetTcpTable(IntPtr pTcpTable,ref int pdwSize,bool bOrder);
//API to change status of connection
[DllImport("iphlpapi.dll")]
//private static extern int SetTcpEntry(MIB_TCPROW tcprow);
private static extern int SetTcpEntry(IntPtr pTcprow);
//Convert 16-bit value from network to host byte order
[DllImport("wsock32.dll")]
private static extern int ntohs(int netshort);
//Convert 16-bit value back again
[DllImport("wsock32.dll")]
private static extern int htons(int netshort);
//Close all connection to the remote IP
public static void CloseRemoteIP(string IP){
MIB_TCPROW[] rows = getTcpTable();
for(int i=0; i<rows.Length; i++){
if(rows[i].dwRemoteAddr==IPStringToInt(IP)){
rows[i].dwState = (int) State.Delete_TCB;
IntPtr ptr = GetPtrToNewObject(rows[i]);
int ret = SetTcpEntry(ptr);
}
}
}
//Close all connections at current local IP
public static void CloseLocalIP(string IP){
MIB_TCPROW[] rows = getTcpTable();
for(int i=0; i<rows.Length; i++){
if(rows[i].dwLocalAddr==IPStringToInt(IP)){
rows[i].dwState = (int) State.Delete_TCB;
IntPtr ptr = GetPtrToNewObject(rows[i]);
int ret = SetTcpEntry(ptr);
}
}
}
//Closes all connections to the remote port
public static void CloseRemotePort(int port){
MIB_TCPROW[] rows = getTcpTable();
for(int i=0; i<rows.Length; i++){
if(port==ntohs(rows[i].dwRemotePort)){
rows[i].dwState = (int) State.Delete_TCB;
IntPtr ptr = GetPtrToNewObject(rows[i]);
int ret = SetTcpEntry(ptr);
}
}
}
//Closes all connections to the local port
public static void CloseLocalPort(int port){
MIB_TCPROW[] rows = getTcpTable();
for(int i=0; i<rows.Length; i++){
if(port==ntohs(rows[i].dwLocalPort)){
rows[i].dwState = (int) State.Delete_TCB;
IntPtr ptr = GetPtrToNewObject(rows[i]);
int ret = SetTcpEntry(ptr);
}
}
}
//Close a connection by returning the connectionstring
public static void CloseConnection(string connectionstring){
try{
//Split the string to its subparts
string[] parts = connectionstring.Split('-');
if(parts.Length!=4) throw new Exception("Invalid connectionstring - use the one provided by Connections.");
string[] loc = parts[0].Split(':');
string[] rem = parts[1].Split(':');
string[] locaddr = loc[0].Split('.');
string[] remaddr = rem[0].Split('.');
//Fill structure with data
MIB_TCPROW row = new MIB_TCPROW();
row.dwState = 12;
byte[] bLocAddr = new byte[]{byte.Parse(locaddr[0]),byte.Parse(locaddr[1]),byte.Parse(locaddr[2]),byte.Parse(locaddr[3])};
byte[] bRemAddr = new byte[]{byte.Parse(remaddr[0]),byte.Parse(remaddr[1]),byte.Parse(remaddr[2]),byte.Parse(remaddr[3])};
row.dwLocalAddr = BitConverter.ToInt32(bLocAddr,0);
row.dwRemoteAddr = BitConverter.ToInt32(bRemAddr,0);
row.dwLocalPort = htons(int.Parse(loc[1]));
row.dwRemotePort = htons(int.Parse(rem[1]));
//Make copy of the structure into memory and use the pointer to call SetTcpEntry
IntPtr ptr = GetPtrToNewObject(row);
int ret = SetTcpEntry(ptr);
if(ret==-1) throw new Exception("Unsuccessful");
if(ret==65) throw new Exception("User has no sufficient privilege to execute this API successfully");
if(ret==87) throw new Exception("Specified port is not in state to be closed down");
if(ret!=0) throw new Exception("Unknown error ("+ret+")");
}catch(Exception ex){
throw new Exception("CloseConnection failed ("+connectionstring+")! ["+ex.GetType().ToString()+","+ex.Message+"]");
}
}
//Gets all connections
public static string[] Connections(){
return Connections(State.All);
}
//Gets a connection list of connections with a defined state
public static string[] Connections(State state){
MIB_TCPROW[] rows = getTcpTable();
ArrayList arr = new ArrayList();
foreach(MIB_TCPROW row in rows){
if(state == State.All || state == (State)row.dwState){
string localaddress = IPIntToString(row.dwLocalAddr) +":"+ ntohs(row.dwLocalPort);
string remoteaddress = IPIntToString(row.dwRemoteAddr) + ":" + ntohs(row.dwRemotePort);
arr.Add(localaddress + "-" + remoteaddress + "-" + ((State)row.dwState).ToString() + "-" + row.dwState);
}
}
return (string[])arr.ToArray(typeof(System.String));
}
//The function that fills the MIB_TCPROW array with connectioninfos
private static MIB_TCPROW[] getTcpTable(){
IntPtr buffer = IntPtr.Zero; bool allocated=false;
try{
int iBytes=0;
GetTcpTable(IntPtr.Zero, ref iBytes, false); //Getting size of return data
buffer=Marshal.AllocCoTaskMem(iBytes); //allocating the datasize
allocated=true;
GetTcpTable(buffer, ref iBytes, false); //Run it again to fill the memory with the data
int structCount=Marshal.ReadInt32(buffer); // Get the number of structures
IntPtr buffSubPointer = buffer; //Making a pointer that will point into the buffer
buffSubPointer = (IntPtr)((int)buffer + 4); //Move to the first data (ignoring dwNumEntries from the original MIB_TCPTABLE struct)
MIB_TCPROW[] tcpRows = new MIB_TCPROW[structCount]; //Declaring the array
//Get the struct size
MIB_TCPROW tmp = new MIB_TCPROW();
int sizeOfTCPROW = Marshal.SizeOf(tmp);
//Fill the array 1 by 1
for(int i=0; i<structCount; i++){
tcpRows[i] = (MIB_TCPROW)Marshal.PtrToStructure(buffSubPointer, typeof(MIB_TCPROW)); //copy struct data
buffSubPointer = (IntPtr)((int)buffSubPointer + sizeOfTCPROW ); //move to next structdata
}
return tcpRows;
}catch(Exception ex){
throw new Exception("getTcpTable failed! ["+ex.GetType().ToString()+","+ex.Message+"]");
}finally{
if(allocated) Marshal.FreeCoTaskMem(buffer); //Free the allocated memory
}
}
private static IntPtr GetPtrToNewObject(object obj){
IntPtr ptr = Marshal.AllocCoTaskMem(Marshal.SizeOf(obj));
Marshal.StructureToPtr(obj,ptr,false);
return ptr;
}
//Convert an IP string to the INT value
private static int IPStringToInt(string IP){
if(IP.IndexOf(".")<0) throw new Exception("Invalid IP address");
string[] addr = IP.Split('.');
if(addr.Length!=4) throw new Exception("Invalid IP address");
byte[] bytes = new byte[]{byte.Parse(addr[0]),byte.Parse(addr[1]),byte.Parse(addr[2]),byte.Parse(addr[3])};
return BitConverter.ToInt32(bytes,0);
}
//Convert an IP integer to IP string
private static string IPIntToString(int IP){
byte[] addr = System.BitConverter.GetBytes(IP);
return addr[0] +"."+addr[1] +"."+addr[2] +"."+addr[3];
}
}

Answer 2

Is the WebSocket connection running within a browser? If so, could you get hold of the WebSocket object reference using JavaScript and call websocketInstance.close();? This seems a bit easier than doing it at a lower OS level.
You could then use something like the Selenium .NET driver to control the browser instance and execute the JavaScript that closes the WebSocket connection. Other similar libraries are available to do this sort of thing too.