How to find out which port uses a process? - delphi

Question

I would like to know how I can find out which ports a program / process uses. I want to know the used ports from one process and write then in a label.
Is there a unit or function that is available?

Answer 1

You can use the GetExtendedTcpTable function passing the TCP_TABLE_OWNER_PID_ALL TableClass value , this will return a MIB_TCPTABLE_OWNER_PID structure which is an array to the MIB_TCPROW_OWNER_PID record , this structure contains the port number (dwLocalPort) and the PID (dwOwningPid) of the process, you can resolve the name of the PID using the CreateToolhelp32Snapshot function.
Sample
{$APPTYPE CONSOLE}
uses
WinSock,
TlHelp32,
Classes,
Windows,
SysUtils;
const
ANY_SIZE = 1;
iphlpapi = 'iphlpapi.dll';
TCP_TABLE_OWNER_PID_ALL = 5;
type
TCP_TABLE_CLASS = Integer;
PMibTcpRowOwnerPid = ^TMibTcpRowOwnerPid;
TMibTcpRowOwnerPid = packed record
dwState : DWORD;
dwLocalAddr : DWORD;
dwLocalPort : DWORD;
dwRemoteAddr: DWORD;
dwRemotePort: DWORD;
dwOwningPid : DWORD;
end;
PMIB_TCPTABLE_OWNER_PID = ^MIB_TCPTABLE_OWNER_PID;
MIB_TCPTABLE_OWNER_PID = packed record
dwNumEntries: DWORD;
table: Array [0..ANY_SIZE - 1] of TMibTcpRowOwnerPid;
end;
var
GetExtendedTcpTable:function (pTcpTable: Pointer; dwSize: PDWORD; bOrder: BOOL; lAf: ULONG; TableClass: TCP_TABLE_CLASS; Reserved: ULONG): DWord; stdcall;
function GetPIDName(hSnapShot: THandle; PID: DWORD): string;
var
ProcInfo: TProcessEntry32;
begin
ProcInfo.dwSize := SizeOf(ProcInfo);
if not Process32First(hSnapShot, ProcInfo) then
Result := 'Unknow'
else
repeat
if ProcInfo.th32ProcessID = PID then
Result := ProcInfo.szExeFile;
until not Process32Next(hSnapShot, ProcInfo);
end;
procedure ShowTCPPortsUsed(const AppName : string);
var
Error : DWORD;
TableSize : DWORD;
i : integer;
pTcpTable : PMIB_TCPTABLE_OWNER_PID;
SnapShot : THandle;
LAppName : string;
LPorts : TStrings;
begin
LPorts:=TStringList.Create;
try
TableSize := 0;
//Get the size o the tcp table
Error := GetExtendedTcpTable(nil, #TableSize, False, AF_INET, TCP_TABLE_OWNER_PID_ALL, 0);
if Error <> ERROR_INSUFFICIENT_BUFFER then exit;
GetMem(pTcpTable, TableSize);
try
SnapShot := CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0);
try
//get the tcp table data
if GetExtendedTcpTable(pTcpTable, #TableSize, TRUE, AF_INET, TCP_TABLE_OWNER_PID_ALL, 0) = NO_ERROR then
for i := 0 to pTcpTable.dwNumEntries - 1 do
begin
LAppName:=GetPIDName(SnapShot, pTcpTable.Table[i].dwOwningPid);
if SameText(LAppName, AppName) and (LPorts.IndexOf(IntToStr(pTcpTable.Table[i].dwLocalPort))=-1) then
LPorts.Add(IntToStr(pTcpTable.Table[i].dwLocalPort));
end;
finally
CloseHandle(SnapShot);
end;
finally
FreeMem(pTcpTable);
end;
Writeln(LPorts.Text);
finally
LPorts.Free;
end;
end;
var
hModule : THandle;
begin
try
hModule := LoadLibrary(iphlpapi);
try
GetExtendedTcpTable := GetProcAddress(hModule, 'GetExtendedTcpTable');
ShowTCPPortsUsed('Skype.exe');
finally
FreeLibrary(hModule);
end;
except
on E: Exception do
Writeln(E.ClassName, ': ', E.Message);
end;
Readln;
end.

Answer 2

In order to get the correct Port number you have to use ntohs()
if SameText(LAppName, AppName) and
(LPorts.IndexOf(IntToStr(pTcpTable.Table[i].dwLocalPort))=-1) then
LPorts.Add(IntToStr(ntohs(pTcpTable.Table[i].dwLocalPort)));
more info here