getprotobynumber function (winsock.h)

Article
02/22/2024

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

Syntax

protoent * getprotobynumber(
  int proto
);

Parameters

proto

TBD

Return value

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 code	Meaning
WSANOTINITIALISED	A successful WSAStartup call must occur before using this function.
WSAENETDOWN	The network subsystem has failed.
WSAHOST_NOT_FOUND	Authoritative answer protocol not found.
WSATRY_AGAIN	A nonauthoritative 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.

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.

Windows Phone 8: This function is supported for Windows Phone Store apps on Windows Phone 8 and later.

Windows 8.1 and Windows Server 2012 R2: This function is supported for Windows Store apps on Windows 8.1, Windows Server 2012 R2, and later.

Requirements

Requirement	Value
Minimum supported client	Windows 8.1, Windows Vista [desktop apps \| UWP apps]
Minimum supported server	Windows Server 2003 [desktop apps \| UWP apps]
Target Platform	Windows
Header	winsock.h (include Winsock2.h)
Library	Ws2_32.lib
DLL	Ws2_32.dll