getservbyport function (winsock.h)

Article
02/22/2024

The getservbyport function retrieves service information corresponding to a port and protocol.

Syntax

servent * getservbyport(
  [in] int        port,
  [in] const char *proto
);

Parameters

[in] port

Port for a service, in network byte order.

[in] proto

Optional pointer to a protocol name. If this is null, getservbyport returns the first service entry for which the port matches the s_port of the servent structure. Otherwise, getservbyport matches both the port and the proto parameters.

Return value

If no error occurs, getservbyport returns a pointer to the servent 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 Service not found.
WSATRY_AGAIN	A nonauthoritative Service not found, or server failure.
WSANO_RECOVERY	Nonrecoverable errors, the services 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.
WSAEFAULT	The proto parameter is not a valid part of the user address space.
WSAEINTR	A blocking Windows Socket 1.1 call was canceled through WSACancelBlockingCall.

Remarks

The getservbyport function returns a pointer to a servent structure as it does in the getservbyname function.

The servent structure is 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 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