EnumProtocolsA 函式 (nspapi.h)
EnumProtocols 函式會擷取本機主機上作用中之指定網路協定集的相關信息。
語法
INT EnumProtocolsA(
[in, optional] LPINT lpiProtocols,
[out] LPVOID lpProtocolBuffer,
[in, out] LPDWORD lpdwBufferLength
);
參數
[in, optional] lpiProtocols
null終止通訊協定標識子陣列的指標。 EnumProtocols 函式會擷取此陣列所指定通訊協議的相關信息。
如果 lpiProtocols
定義下列通訊協議標識碼值。
[out] lpProtocolBuffer
函式填入 PROTOCOL_INFO 數據結構數位之緩衝區的指標。
[in, out] lpdwBufferLength
在輸入時,變數的指標會指定 lpProtocolBuffer 所指向之緩衝區的大小,以位元組為單位。
在輸出時,函式會將此變數設定為擷取所有要求資訊所需的最小緩衝區大小。 若要讓函式成功,緩衝區必須至少是這個大小。
傳回值
如果函式成功,則傳回值是寫入 lpProtocolBuffer 所指向之緩衝區的 PROTOCOL_INFO 資料結構數目,。
如果函式失敗,傳回值會SOCKET_ERROR(–1)。 若要取得擴充錯誤資訊,請呼叫 getLastError
錯誤碼 | 意義 |
---|---|
|
lpProtocolBuffer 所指向的緩衝區 太小,無法接收所有相關 PROTOCOL_INFO 結構。 呼叫具有緩衝區的函式,其大小至少與 *lpdwBufferLength 中傳回的值一樣大,。 |
言論
在下列範例程式代碼中,EnumProtocols 函式會擷取系統上所有可用通訊協議的相關信息。 然後,程式代碼會更詳細地檢查每個通訊協定。
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#include <winsock2.h>
#include <ws2tcpip.h>
#include <Nspapi.h>
#include <stdlib.h>
#include <stdio.h>
// Need to link with Ws2_32.lib and Mswsock.lib
#pragma comment (lib, "Ws2_32.lib")
#pragma comment (lib, "Mswsock.lib")
int FindProtocol(BOOL Reliable,
BOOL MessageOriented, BOOL StreamOriented,
BOOL Connectionless, DWORD *ProtocolUsed);
int __cdecl main(int argc, char **argv)
{
WSADATA wsaData;
int ProtocolError = SOCKET_ERROR;
int iResult;
BOOLEAN bReliable = FALSE;
BOOLEAN bMessageOriented = FALSE;
BOOLEAN bStreamOriented = TRUE;
BOOLEAN bConnectionless = FALSE;
DWORD *pProtocols = NULL;
// Validate the parameters
if (argc != 2) {
printf("usage: %s servicename\n", argv[0]);
return 1;
}
// Initialize Winsock
iResult = WSAStartup(MAKEWORD(2,2), &wsaData);
if (iResult != 0) {
printf("WSAStartup failed with error: %d\n", iResult);
return 1;
}
ProtocolError = FindProtocol( bReliable, bMessageOriented,
bStreamOriented, bConnectionless, pProtocols);
if (ProtocolError == SOCKET_ERROR) {
printf("Unable to find a protocol to support the parameters requested\n");
return 1;
}
// Connect to the servicename ...
return 0;
}
#define MAX_PROTOCOLS 1024
int FindProtocol (
BOOL Reliable,
BOOL MessageOriented,
BOOL StreamOriented,
BOOL Connectionless,
DWORD *ProtocolUsed
)
{
// local variables
INT protocols[MAX_PROTOCOLS+1];
BYTE buffer[2048];
DWORD bytesRequired;
INT err;
PPROTOCOL_INFO protocolInfo;
INT protocolCount;
INT i;
DWORD protocolIndex;
// PCSADDR_INFO csaddrInfo;
// INT addressCount;
// SOCKET s;
// First look up the protocols installed on this computer.
//
bytesRequired = sizeof(buffer);
err = EnumProtocols( NULL, buffer, &bytesRequired );
if ( err <= 0 )
return SOCKET_ERROR;
// Walk through the available protocols and pick out the ones which
// support the desired characteristics.
//
protocolCount = err;
protocolInfo = (PPROTOCOL_INFO)buffer;
for ( i = 0, protocolIndex = 0;
i < protocolCount && protocolIndex < MAX_PROTOCOLS;
i++, protocolInfo++ ) {
// If connection-oriented support is requested, then check if
// supported by this protocol. We assume here that connection-
// oriented support implies fully reliable service.
//
if ( Reliable ) {
// Check to see if the protocol is reliable. It must
// guarantee both delivery of all data and the order in
// which the data arrives.
//
if ( (protocolInfo->dwServiceFlags &
XP_GUARANTEED_DELIVERY) == 0
||
(protocolInfo->dwServiceFlags &
XP_GUARANTEED_ORDER) == 0 ) {
continue;
}
// Check to see that the protocol matches the stream/message
// characteristics requested.
//
if ( StreamOriented &&
(protocolInfo->dwServiceFlags & XP_MESSAGE_ORIENTED)
!= 0 &&
(protocolInfo->dwServiceFlags & XP_PSEUDO_STREAM)
== 0 ) {
continue;
}
if ( MessageOriented &&
(protocolInfo->dwServiceFlags & XP_MESSAGE_ORIENTED)
== 0 ) {
continue;
}
}
else if ( Connectionless ) {
// Make sure that this is a connectionless protocol.
//
if ( (protocolInfo->dwServiceFlags & XP_CONNECTIONLESS)
!= 0 )
continue;
}
// This protocol fits all the criteria. Add it to the list of
// protocols in which we're interested.
//
protocols[protocolIndex++] = protocolInfo->iProtocol;
}
*ProtocolUsed = (INT) protocolIndex;
return 0;
}
注意
nspapi.h 標頭會將 EnumProtocols 定義為別名,根據 UNICODE 預處理器常數的定義,自動選取此函式的 ANSI 或 Unicode 版本。 混合使用編碼中性別名與非編碼中性的程序代碼,可能會導致編譯或運行時間錯誤不符。 如需詳細資訊,請參閱函式原型的
要求
要求 | 價值 |
---|---|
最低支援的用戶端 | Windows 2000 Professional [僅限傳統型應用程式] |
支援的最低伺服器 | Windows 2000 Server [僅限傳統型應用程式] |
目標平臺 | 窗戶 |
標頭 | nspapi.h |
連結庫 | Mswsock.lib |
DLL | Mswsock.dll |