biff_notify.c

[詳解]

/*++
/* NAME
/*  biff_notify 3
/* SUMMARY
/*  send biff notification
/* SYNOPSIS
/*  #include <biff_notify.h>
/*
/*  void    biff_notify(text, len)
/*  const char *text;
/*  ssize_t len;
/* DESCRIPTION
/*  biff_notify() sends a \fBBIFF\fR notification request to the
/*  \fBcomsat\fR daemon.
/*
/*  Arguments:
/* .IP text
/*  Null-terminated text (username@mailbox-offset).
/* .IP len
/*  Length of text, including null terminator.
/* BUGS
/*  The \fBBIFF\fR "service" can be a noticeable load for
/*  systems that have many logged-in users.
/* LICENSE
/* .ad
/* .fi
/*  The Secure Mailer license must be distributed with this software.
/* AUTHOR(S)
/*  Wietse Venema
/*  IBM T.J. Watson Research
/*  P.O. Box 704
/*  Yorktown Heights, NY 10598, USA
/*--*/

/* System library. */

#include "sys_defs.h"
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <string.h>

/* Utility library. */

#include <msg.h>
#include <iostuff.h>

/* Application-specific. */

#include <biff_notify.h>

/* biff_notify - notify recipient via the biff "protocol" */

void    biff_notify(const char *text, ssize_t len)
{
    static struct sockaddr_in sin;
    static int sock = -1;
    struct hostent *hp;
    struct servent *sp;

    /*
     * Initialize a socket address structure, or re-use an existing one.
     */
    if (sin.sin_family == 0) {
    if ((sp = getservbyname("biff", "udp")) == 0) {
        msg_warn("service not found: biff/udp");
        return;
    }
    if ((hp = gethostbyname("localhost")) == 0) {
        msg_warn("host not found: localhost");
        return;
    }
    if ((int) hp->h_length > (int) sizeof(sin.sin_addr)) {
        msg_warn("bad address size %d for localhost", hp->h_length);
        return;
    }
    sin.sin_family = hp->h_addrtype;
    sin.sin_port = sp->s_port;
    memcpy((void *) &sin.sin_addr, hp->h_addr_list[0], hp->h_length);
    }

    /*
     * Open a socket, or re-use an existing one.
     */
    if (sock < 0) {
    if ((sock = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
        msg_warn("socket: %m");
        return;
    }
    close_on_exec(sock, CLOSE_ON_EXEC);
    }

    /*
     * Biff!
     */
    if (sendto(sock, text, len, 0, (struct sockaddr *) &sin, sizeof(sin)) != len)
    msg_warn("biff_notify: %m");
}