GETSERVENT

Section: C Library Functions (3)
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BSD mandoc
BSD 4.2

NAME

getservent getservbyport getservbyname setservent endservent - get service entry

SYNOPSIS

Fd #include <netdb.h> Ft struct servent * Fn getservent Ft struct servent * Fn getservbyname char *name char *proto Ft struct servent * Fn getservbyport int port proto Ft void Fn setservent int stayopen Ft void Fn endservent void

DESCRIPTION

The Fn getservent , Fn getservbyname , and Fn getservbyport functions 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:

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

The Fn getservent function reads the next line of the file, opening the file if necessary.

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

The Fn endservent function closes the file.

The Fn getservbyname and Fn getservbyport functions 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.

HISTORY

The Fn getservent , Fn getservbyport , Fn getservbyname , Fn setservent , and Fn endservent functions appeared in BSD 4.2

BUGS

These functions use static data storage; if the data is needed for future use, it should be copied before any subsequent calls overwrite it. Expecting port numbers to fit in a 32 bit quantity is probably naive.

This document was created by man2html, using the manual pages.
Time: 15:52:53 GMT, January 15, 2023