GETSERVENT

Section: Network Functions (3N)
Updated: May 19, 1986
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NAME

getservent, getservbyport, getservbyname, setservent, endservent - get service entry

SYNOPSIS

#include <netdb.h>

struct servent *getservent()

struct servent *getservbyname(name, proto)
char *name, *proto;

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

setservent(stayopen)
int stayopen

endservent()

DESCRIPTION

Getservent, getservbyname, and getservbyport each return a pointer to an object with the following structure containing the broken-out fields of a line in the network services data base, /etc/services.

struct  servent {
        char    *s_name;        /* official name of service */
        char    **s_aliases;    /* alias list */
        int     s_port;         /* port service resides at */
        char    *s_proto;       /* protocol to use */
};

The members of this structure are:

s_name: The official name of the service.
s_aliases: A zero terminated list of alternate names for the service.
s_port: The port number at which the service resides. Port numbers are returned in network byte order.
s_proto: The name of the protocol to use when contacting the service.

Getservent reads the next line of the file, opening the file if necessary.

Setservent opens and rewinds the file. If the stayopen flag is non-zero, the net data base will not be closed after each call to getservbyname or .IR getservbyport .

Endservent closes the file.

Getservbyname and getservbyport sequentially search from the beginning of the file until a matching protocol name or port number is found, or until EOF is encountered. If a protocol name is also supplied (non-NULL), searches must also match the protocol.

FILES

/etc/services

DIAGNOSTICS

Null pointer (0) returned on EOF or error.

BUGS

All information is contained in a static area so it must be copied if it is to be saved. Expecting port numbers to fit in a 32 bit quantity is probably naive.

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Time: 04:51:46 GMT, January 31, 2023