getservbyport

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

struct servent FAR * getservbyport (
  int port,              
  const char FAR* proto  
);

Parameters

port: [in] The port for a service, in network byte order.
proto: [in] An 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.

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.

Return Values

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 Codes

WSANOTINITIALISED	A successful WSAStartup must occur before using this function.
WSAENETDOWN	The network subsystem has failed.
WSAHOST_NOT_FOUND	Authoritative Answer Service not found.
WSATRY_AGAIN	Non-Authoritative 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.

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