DO decl
 
IF InitWinsock()
    = DisplayProtInfo ("tcp")
    = DisplayProtInfo ("udp")
    = WSACleanup()
ENDIF
* End of Main
 
PROCEDURE  DisplayProtInfo (lcProtName)
    LOCAL lnProtoentPtr
    lnProtoentPtr = getprotobyname(lcProtName)
 
    IF lnProtoentPtr = 0
    * no protocol found with this name
        ? lcProtName
        RETURN
    ENDIF
 
*| struct protoent {
*|   char FAR *        p_name;     0:4
*|   char FAR * FAR *  p_aliases;  4:4
*|   short             p_proto;    8:4
*| }; total bytes = 12
#DEFINE PROTOENT_SIZE  12
 
    LOCAL lcBuffer, lcProt, lcAliases, lnProt
    lcBuffer = Repli(Chr(0), PROTOENT_SIZE)
    = Heap2Str (@lcBuffer, lnProtoentPtr, PROTOENT_SIZE)
 
    lcProt    = GetMemStr(buf2dword(SUBSTR(lcBuffer, 1,4)))
    lcAliases = GetAliases(buf2dword(SUBSTR(lcBuffer, 5,4)))
    lnProt    = buf2word(SUBSTR(lcBuffer, 9,2))
 
    ? PADR(lcProt,20), STR(lnProt,5), lcAliases
RETURN
 
FUNCTION  GetAliases (lnArrayPtr)
* returns a string with alternate names for the protocol
* delimited with semicolons
    IF lnArrayPtr = 0
        EXIT
    ENDIF
 
    LOCAL lcResult, lnDataPtr, lcAlias
    lcResult = ""
 
    DO WHILE .T.
        * each array element contains a pointer to data
        lnDataPtr = buf2dword(GetMemBuf(lnArrayPtr, 4))
 
        IF lnDataPtr <> 0
            lcAlias = GetMemStr(lnDataPtr)
            lcResult = lcResult +;
                Iif(Empty(lcResult), "",";") + lcAlias
        ELSE
        * the last array element contains null
            EXIT
        ENDIF
        lnArrayPtr = lnArrayPtr + 4  && next array element
    ENDDO
RETURN  lcResult
 
FUNCTION  InitWinsock()
* Initializing the Winsock service for the application
#DEFINE WSADATA_SIZE 398
#DEFINE WS_VERSION 0x0202
    LOCAL lcWSADATA, lnInitResult
    lcWSADATA = Repli(Chr(0), WSADATA_SIZE)
    lnInitResult = WSAStartup (WS_VERSION, @lcWSADATA)
RETURN  (lnInitResult = 0)
 
FUNCTION  GetMemBuf (lnAddr, lnBufsize)
    LOCAL lcBuffer
    lcBuffer = Repli(Chr(0), lnBufsize)
    = Heap2Str (@lcBuffer, lnAddr, lnBufsize)
RETURN  lcBuffer
 
FUNCTION  GetMemStr (lnAddr)
* returning data from a memory block
* before the first occurence of a zero byte
    LOCAL lcBuffer
    lcBuffer = GetMemBuf (lnAddr, 250)
RETURN  SUBSTR(lcBuffer, 1, AT(Chr(0),lcBuffer)-1)
 
FUNCTION  buf2word (lcBuffer)
RETURN Asc(SUBSTR(lcBuffer, 1,1)) + ;
    Asc(SUBSTR(lcBuffer, 2,1)) * 256
 
FUNCTION  buf2dword (lcBuffer)
RETURN Asc(SUBSTR(lcBuffer, 1,1)) + ;
    Asc(SUBSTR(lcBuffer, 2,1)) * 256 +;
    Asc(SUBSTR(lcBuffer, 3,1)) * 65536 +;
    Asc(SUBSTR(lcBuffer, 4,1)) * 16777216
 
PROCEDURE  decl
    DECLARE INTEGER WSAStartup IN ws2_32 INTEGER wVerRq, STRING @lpWSAData
    DECLARE INTEGER WSACleanup IN ws2_32
    DECLARE INTEGER getprotobyname IN ws2_32 STRING name  
 
    DECLARE RtlMoveMemory IN kernel32 As Heap2Str;
        STRING @Dest, INTEGER Src, INTEGER nLength