getprotobynumber

The Windows Sockets getprotobynumber function retrieves protocol information corresponding to a protocol number.

struct PROTOENT FAR * getprotobynumber (
  int number  
);

Parameters

number: [in] A protocol number, in host byte order.

Remarks

This getprotobynumber function returns a pointer to the PROTOENT structure as previously described in getprotobyname. The contents of the structure correspond to the given protocol number.

The pointer that is returned points to the structure allocated by Windows Sockets. The application must never attempt to modify this structure or to free any of its components. Furthermore, only one copy of this structure is allocated per thread, so the application should copy any information that it needs before issuing any other Windows Sockets function calls.

Return Values

If no error occurs, getprotobynumber returns a pointer to the PROTOENT structure. Otherwise, it returns a NULL pointer and a specific error number can be retrieved by calling WSAGetLastError.

Error Codes

WSANOTINITIALISED	A successful WSAStartup must occur before using this function.
WSAENETDOWN	The network subsystem has failed.
WSAHOST_NOT_FOUND	Authoritative Answer Protocol not found.
WSATRY_AGAIN	Non-Authoritative Protocol not found, or server failure.
WSANO_RECOVERY	Nonrecoverable errors, the protocols database is not accessible.
WSANO_DATA	Valid name, no data record of requested type.
WSAEINPROGRESS	A blocking Windows Sockets 1.1 call is in progress, or the service provider is still processing a callback function.
WSAEINTR	A blocking Windows Socket 1.1 call was canceled through WSACancelBlockingCall.

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