I have this api routine that I use regularly to capture dos output. Recently a strange bug has been found where it doesn't seem to allow dns calls. For instance nslookup will return the "No response from server" error with Server: UnKnown. Ping will work if you supply it an IP address, but not if it has to make a dns call. This problem is completely isolated to this code.
Any insight into this problem would be appreciated. Winapi isn't my strongest area.
Edit: Sorry for adding all of the constants and types, but I made this into something you can paste into a module and run to test for yourself in an effort to make the problem easier to solve.
' STARTUPINFO flags
Private Const STARTF_USESHOWWINDOW = &H1
Private Const STARTF_USESTDHANDLES = &H100
' ShowWindow flag
Private Const SW_HIDE = 0
'CreatePipe buffer size
Private Const BUFSIZE = 1024
Private Type SECURITY_ATTRIBUTES
nLength As Long
lpSecurityDescriptor As Long
bInheritHandle As Long
End Type
Private Type STARTUPINFO
cb As Long
lpReserved As Long
lpDesktop As Long
lpTitle As Long
dwX As Long
dwY As Long
dwXSize As Long
dwYSize As Long
dwXCountChars As Long
dwYCountChars As Long
dwFillAttribute As Long
dwFlags As Long
wShowWindow As Integer
cbReserved2 As Integer
lpReserved2 As Long
hStdInput As Long
hStdOutput As Long
hStdError As Long
End Type
Private Type PROCESS_INFORMATION
hProcess As Long
hThread As Long
dwProcessId As Long
dwThreadId As Long
End Type
Private Declare Function CloseHandle Lib "kernel32.dll" (ByVal hObject As Long) As Long
Private Declare Function CreatePipe Lib "kernel32.dll" (ByRef phReadPipe As Long, ByRef phWritePipe As Long, ByRef lpPipeAttributes As SECURITY_ATTRIBUTES, ByVal nSize As Long) As Long
Private Declare Function CreateProcess Lib "kernel32.dll" Alias "CreateProcessA" (ByVal lpApplicationName As String, ByVal lpCommandLine As String, ByRef lpProcessAttributes As SECURITY_ATTRIBUTES, ByRef lpThreadAttributes As SECURITY_ATTRIBUTES, ByVal bInheritHandles As Long, ByVal dwCreationFlags As Long, ByRef lpEnvironment As Any, ByVal lpCurrentDriectory As String, ByRef lpStartupInfo As STARTUPINFO, ByRef lpProcessInformation As PROCESS_INFORMATION) As Long
Private Declare Sub GetStartupInfo Lib "kernel32.dll" Alias "GetStartupInfoA" (ByRef lpStartupInfo As STARTUPINFO)
Private Declare Function PeekNamedPipe Lib "kernel32.dll" (ByVal hNamedPipe As Long, ByRef lpBuffer As Any, ByVal nBufferSize As Long, ByRef lpBytesRead As Long, ByRef lpTotalBytesAvail As Long, ByRef lpBytesLeftThisMessage As Long) As Long
Private Declare Function ReadFile Lib "kernel32" (ByVal hFile As Long, ByVal lpBuffer As String, ByVal nNumberOfBytesToRead As Long, lpNumberOfBytesRead As Long, lpOverlapped As Any) As Long
Sub CreateprocessApiTest()
On Error GoTo errHandler
Dim pa As SECURITY_ATTRIBUTES
Dim pra As SECURITY_ATTRIBUTES
Dim tra As SECURITY_ATTRIBUTES
Dim si As STARTUPINFO
Dim pi As PROCESS_INFORMATION
Dim retVal As Long
Dim command As String
Dim ErrorDesc As String
Dim hRead As Long ' stdout + stderr
Dim hWrite As Long
Dim bAvail As Long ' pipe bytes available (PeekNamedPipe)
Dim bRead As Long ' pipe bytes fetched (ReadFile)
Dim bString As String ' our buffer
Dim s As String
command = "nslookup google.com"
pa.nLength = Len(pa)
pa.bInheritHandle = 1
pra.nLength = Len(pra)
tra.nLength = Len(tra)
retVal = CreatePipe(hRead, hWrite, pa, BUFSIZE)
With si
.cb = Len(si)
GetStartupInfo si
.dwFlags = STARTF_USESHOWWINDOW Or STARTF_USESTDHANDLES
.wShowWindow = SW_HIDE
.hStdOutput = hWrite
.hStdError = hWrite
End With
retVal = CreateProcess(vbNullString, command, pra, tra, 1, 0&, 0&, vbNullString, si, pi)
Do While PeekNamedPipe(hRead, ByVal 0, 0, ByVal 0, bAvail, ByVal 0)
DoEvents
If bAvail Then
bString = String(bAvail, 0)
ReadFile hRead, bString, bAvail, bRead, ByVal 0&
bString = Left(bString, bRead)
s = s & bString
CloseHandle hWrite
End If
Loop
CloseHandle hRead
CloseHandle pi.hThread
CloseHandle pi.hProcess
MsgBox s
exitRoutine:
Exit Sub
errHandler:
Debug.Print Err.Number, Err.Description
Resume exitRoutine
End Sub