Gets service entry by port.
Standard C Library (libc.a)
#include <netdb.h>
int getservbyport_r(Port, Proto, servent, serv_data)
int Port;
const char *Proto;
struct servent *servent;
struct servent_data *serv_data;
The getservbyport_r subroutine retrieves an entry from the /etc/services file using a port number as a search key. An application program can use the getservbyport_r subroutine to access a service, service aliases, the protocol for the service, and a protocol port number for the service.
Upon locating a matching protocol and port number or upon locating a matching protocol where the Port parameter value equals 0, the getservbyport_r subroutine returns a pointer to a servent structure, which contains fields for a line of information in the /etc/services file. The netdb.h file defines the servent structure, the servert_data structure, and their fields.
The getservbyport routine overwrites static data returned on subsequent calls. The getservbyport_r routine does not.
Use the endservent_r subroutine to close the /etc/services file.
Item | Description |
---|---|
Port | Specifies the port where a service resides. |
Proto | Specifies a protocol for use with the service. |
servent | Points to the servent structure. |
serv_data | Points to the serv_data structure. |
The function returns a 0 if successful and a -1 if unsuccessful.
Item | Description |
---|---|
/etc/services | Contains service names. |