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676 lines
16 KiB
C
676 lines
16 KiB
C
/*
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* bootpgw.c - BOOTP GateWay
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* This program forwards BOOTP Request packets to a BOOTP server.
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*/
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/************************************************************************
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Copyright 1988, 1991 by Carnegie Mellon University
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All Rights Reserved
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Permission to use, copy, modify, and distribute this software and its
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documentation for any purpose and without fee is hereby granted, provided
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that the above copyright notice appear in all copies and that both that
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copyright notice and this permission notice appear in supporting
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documentation, and that the name of Carnegie Mellon University not be used
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in advertising or publicity pertaining to distribution of the software
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without specific, written prior permission.
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CARNEGIE MELLON UNIVERSITY DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS
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SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS.
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IN NO EVENT SHALL CMU BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL
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DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
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PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
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ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
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SOFTWARE.
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************************************************************************/
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#ifndef lint
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static char rcsid[] = "$Id: bootpgw.c,v 1.2 1994/08/22 22:14:48 gwr Exp $";
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#endif
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/*
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* BOOTPGW is typically used to forward BOOTP client requests from
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* one subnet to a BOOTP server on a different subnet.
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*/
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#include <sys/types.h>
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#include <sys/param.h>
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#include <sys/socket.h>
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#include <sys/ioctl.h>
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#include <sys/file.h>
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#include <sys/time.h>
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#include <sys/stat.h>
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#include <net/if.h>
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#include <netinet/in.h>
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#include <arpa/inet.h> /* inet_ntoa */
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#ifndef NO_UNISTD
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#include <unistd.h>
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#endif
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#include <stdlib.h>
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#include <signal.h>
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#include <stdio.h>
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#include <string.h>
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#include <errno.h>
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#include <ctype.h>
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#include <netdb.h>
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#include <syslog.h>
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#include <assert.h>
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#ifdef NO_SETSID
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# include <fcntl.h> /* for O_RDONLY, etc */
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#endif
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#ifndef USE_BFUNCS
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# include <memory.h>
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/* Yes, memcpy is OK here (no overlapped copies). */
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# define bcopy(a,b,c) memcpy(b,a,c)
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# define bzero(p,l) memset(p,0,l)
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# define bcmp(a,b,c) memcmp(a,b,c)
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#endif
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#include "bootp.h"
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#include "getif.h"
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#include "hwaddr.h"
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#include "report.h"
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#include "patchlevel.h"
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/* Local definitions: */
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#define MAX_MSG_SIZE (3*512) /* Maximum packet size */
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#define TRUE 1
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#define FALSE 0
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#define get_network_errmsg get_errmsg
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/*
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* Externals, forward declarations, and global variables
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*/
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#ifdef __STDC__
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#define P(args) args
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#else
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#define P(args) ()
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#endif
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static void usage P((void));
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static void handle_reply P((void));
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static void handle_request P((void));
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#undef P
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/*
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* IP port numbers for client and server obtained from /etc/services
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*/
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u_short bootps_port, bootpc_port;
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/*
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* Internet socket and interface config structures
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*/
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struct sockaddr_in bind_addr; /* Listening */
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struct sockaddr_in recv_addr; /* Packet source */
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struct sockaddr_in send_addr; /* destination */
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/*
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* option defaults
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*/
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int debug = 0; /* Debugging flag (level) */
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struct timeval actualtimeout =
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{ /* fifteen minutes */
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15 * 60L, /* tv_sec */
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0 /* tv_usec */
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};
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u_int maxhops = 4; /* Number of hops allowed for requests. */
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u_int minwait = 3; /* Number of seconds client must wait before
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its bootrequest packets are forwarded. */
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/*
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* General
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*/
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int s; /* Socket file descriptor */
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char *pktbuf; /* Receive packet buffer */
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int pktlen;
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char *progname;
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char *servername;
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int32 server_ipa; /* Real server IP address, network order. */
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char myhostname[64];
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struct in_addr my_ip_addr;
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/*
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* Initialization such as command-line processing is done and then the
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* main server loop is started.
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*/
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void
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main(argc, argv)
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int argc;
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char **argv;
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{
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struct timeval *timeout;
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struct bootp *bp;
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struct servent *servp;
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struct hostent *hep;
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char *stmp;
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int n, ba_len, ra_len;
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int nfound, readfds;
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int standalone;
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progname = strrchr(argv[0], '/');
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if (progname) progname++;
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else progname = argv[0];
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/*
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* Initialize logging.
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*/
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report_init(0); /* uses progname */
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/*
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* Log startup
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*/
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report(LOG_INFO, "version %s.%d", VERSION, PATCHLEVEL);
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/* Debugging for compilers with struct padding. */
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assert(sizeof(struct bootp) == BP_MINPKTSZ);
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/* Get space for receiving packets and composing replies. */
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pktbuf = malloc(MAX_MSG_SIZE);
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if (!pktbuf) {
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report(LOG_ERR, "malloc failed");
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exit(1);
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}
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bp = (struct bootp *) pktbuf;
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/*
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* Check to see if a socket was passed to us from inetd.
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*
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* Use getsockname() to determine if descriptor 0 is indeed a socket
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* (and thus we are probably a child of inetd) or if it is instead
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* something else and we are running standalone.
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*/
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s = 0;
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ba_len = sizeof(bind_addr);
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bzero((char *) &bind_addr, ba_len);
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errno = 0;
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standalone = TRUE;
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if (getsockname(s, (struct sockaddr *) &bind_addr, &ba_len) == 0) {
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/*
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* Descriptor 0 is a socket. Assume we are a child of inetd.
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*/
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if (bind_addr.sin_family == AF_INET) {
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standalone = FALSE;
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bootps_port = ntohs(bind_addr.sin_port);
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} else {
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/* Some other type of socket? */
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report(LOG_INFO, "getsockname: not an INET socket");
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}
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}
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/*
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* Set defaults that might be changed by option switches.
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*/
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stmp = NULL;
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timeout = &actualtimeout;
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gethostname(myhostname, sizeof(myhostname));
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hep = gethostbyname(myhostname);
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if (!hep) {
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printf("Can not get my IP address\n");
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exit(1);
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}
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bcopy(hep->h_addr, (char *)&my_ip_addr, sizeof(my_ip_addr));
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/*
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* Read switches.
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*/
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for (argc--, argv++; argc > 0; argc--, argv++) {
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if (argv[0][0] != '-')
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break;
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switch (argv[0][1]) {
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case 'd': /* debug level */
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if (argv[0][2]) {
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stmp = &(argv[0][2]);
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} else if (argv[1] && argv[1][0] == '-') {
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/*
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* Backwards-compatible behavior:
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* no parameter, so just increment the debug flag.
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*/
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debug++;
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break;
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} else {
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argc--;
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argv++;
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stmp = argv[0];
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}
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if (!stmp || (sscanf(stmp, "%d", &n) != 1) || (n < 0)) {
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fprintf(stderr,
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"%s: invalid debug level\n", progname);
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break;
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}
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debug = n;
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break;
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case 'h': /* hop count limit */
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if (argv[0][2]) {
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stmp = &(argv[0][2]);
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} else {
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argc--;
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argv++;
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stmp = argv[0];
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}
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if (!stmp || (sscanf(stmp, "%d", &n) != 1) ||
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(n < 0) || (n > 16))
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{
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fprintf(stderr,
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"bootpgw: invalid hop count limit\n");
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break;
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}
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maxhops = (u_int)n;
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break;
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case 'i': /* inetd mode */
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standalone = FALSE;
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break;
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case 's': /* standalone mode */
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standalone = TRUE;
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break;
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case 't': /* timeout */
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if (argv[0][2]) {
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stmp = &(argv[0][2]);
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} else {
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argc--;
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argv++;
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stmp = argv[0];
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}
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if (!stmp || (sscanf(stmp, "%d", &n) != 1) || (n < 0)) {
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fprintf(stderr,
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"%s: invalid timeout specification\n", progname);
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break;
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}
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actualtimeout.tv_sec = (int32) (60 * n);
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/*
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* If the actual timeout is zero, pass a NULL pointer
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* to select so it blocks indefinitely, otherwise,
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* point to the actual timeout value.
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*/
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timeout = (n > 0) ? &actualtimeout : NULL;
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break;
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case 'w': /* wait time */
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if (argv[0][2]) {
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stmp = &(argv[0][2]);
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} else {
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argc--;
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argv++;
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stmp = argv[0];
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}
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if (!stmp || (sscanf(stmp, "%d", &n) != 1) ||
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(n < 0) || (n > 60))
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{
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fprintf(stderr,
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"bootpgw: invalid wait time\n");
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break;
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}
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minwait = (u_int)n;
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break;
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default:
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fprintf(stderr, "%s: unknown switch: -%c\n",
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progname, argv[0][1]);
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usage();
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break;
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} /* switch */
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} /* for args */
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/* Make sure server name argument is suplied. */
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servername = argv[0];
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if (!servername) {
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fprintf(stderr, "bootpgw: missing server name\n");
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usage();
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}
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/*
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* Get address of real bootp server.
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*/
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if (isdigit(servername[0]))
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server_ipa = inet_addr(servername);
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else {
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hep = gethostbyname(servername);
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if (!hep) {
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fprintf(stderr, "bootpgw: can't get addr for %s\n", servername);
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exit(1);
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}
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bcopy(hep->h_addr, (char *)&server_ipa, sizeof(server_ipa));
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}
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if (standalone) {
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/*
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* Go into background and disassociate from controlling terminal.
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* XXX - This is not the POSIX way (Should use setsid). -gwr
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*/
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if (debug < 3) {
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if (fork())
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exit(0);
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#ifdef NO_SETSID
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setpgrp(0,0);
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#ifdef TIOCNOTTY
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n = open("/dev/tty", O_RDWR);
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if (n >= 0) {
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ioctl(n, TIOCNOTTY, (char *) 0);
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(void) close(n);
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}
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#endif /* TIOCNOTTY */
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#else /* SETSID */
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if (setsid() < 0)
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perror("setsid");
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#endif /* SETSID */
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} /* if debug < 3 */
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/*
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* Nuke any timeout value
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*/
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timeout = NULL;
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/*
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* Here, bootpd would do:
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* chdir
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* tzone_init
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* rdtab_init
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* readtab
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*/
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/*
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* Create a socket.
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*/
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if ((s = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
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report(LOG_ERR, "socket: %s", get_network_errmsg());
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exit(1);
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}
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/*
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* Get server's listening port number
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*/
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servp = getservbyname("bootps", "udp");
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if (servp) {
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bootps_port = ntohs((u_short) servp->s_port);
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} else {
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bootps_port = (u_short) IPPORT_BOOTPS;
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report(LOG_ERR,
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"udp/bootps: unknown service -- assuming port %d",
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bootps_port);
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}
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/*
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* Bind socket to BOOTPS port.
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*/
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bind_addr.sin_family = AF_INET;
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bind_addr.sin_port = htons(bootps_port);
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bind_addr.sin_addr.s_addr = INADDR_ANY;
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if (bind(s, (struct sockaddr *) &bind_addr,
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sizeof(bind_addr)) < 0)
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{
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report(LOG_ERR, "bind: %s", get_network_errmsg());
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exit(1);
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}
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} /* if standalone */
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/*
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* Get destination port number so we can reply to client
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*/
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servp = getservbyname("bootpc", "udp");
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if (servp) {
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bootpc_port = ntohs(servp->s_port);
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} else {
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report(LOG_ERR,
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"udp/bootpc: unknown service -- assuming port %d",
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IPPORT_BOOTPC);
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bootpc_port = (u_short) IPPORT_BOOTPC;
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}
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/* no signal catchers */
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/*
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* Process incoming requests.
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*/
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for (;;) {
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readfds = 1 << s;
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nfound = select(s + 1, (fd_set *)&readfds, NULL, NULL, timeout);
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if (nfound < 0) {
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if (errno != EINTR) {
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report(LOG_ERR, "select: %s", get_errmsg());
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}
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continue;
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}
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if (!(readfds & (1 << s))) {
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report(LOG_INFO, "exiting after %ld minutes of inactivity",
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actualtimeout.tv_sec / 60);
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exit(0);
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}
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ra_len = sizeof(recv_addr);
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n = recvfrom(s, pktbuf, MAX_MSG_SIZE, 0,
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(struct sockaddr *) &recv_addr, &ra_len);
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if (n <= 0) {
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continue;
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}
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if (debug > 3) {
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report(LOG_INFO, "recvd pkt from IP addr %s",
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inet_ntoa(recv_addr.sin_addr));
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}
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if (n < sizeof(struct bootp)) {
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if (debug) {
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report(LOG_INFO, "received short packet");
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}
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continue;
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}
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pktlen = n;
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switch (bp->bp_op) {
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case BOOTREQUEST:
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handle_request();
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break;
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case BOOTREPLY:
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handle_reply();
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break;
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}
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}
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}
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/*
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* Print "usage" message and exit
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*/
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static void
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usage()
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{
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fprintf(stderr,
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"usage: bootpgw [-d level] [-i] [-s] [-t timeout] server\n");
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fprintf(stderr, "\t -d n\tset debug level\n");
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fprintf(stderr, "\t -h n\tset max hop count\n");
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fprintf(stderr, "\t -i\tforce inetd mode (run as child of inetd)\n");
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fprintf(stderr, "\t -s\tforce standalone mode (run without inetd)\n");
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fprintf(stderr, "\t -t n\tset inetd exit timeout to n minutes\n");
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fprintf(stderr, "\t -w n\tset min wait time (secs)\n");
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exit(1);
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}
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/*
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* Process BOOTREQUEST packet.
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*
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* Note, this just forwards the request to a real server.
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*/
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static void
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handle_request()
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{
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struct bootp *bp = (struct bootp *) pktbuf;
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struct ifreq *ifr;
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u_short secs, hops;
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/* XXX - SLIP init: Set bp_ciaddr = recv_addr here? */
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if (debug) {
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report(LOG_INFO, "request from %s",
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inet_ntoa(recv_addr.sin_addr));
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}
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/* Has the client been waiting long enough? */
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secs = ntohs(bp->bp_secs);
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if (secs < minwait)
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return;
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/* Has this packet hopped too many times? */
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hops = ntohs(bp->bp_hops);
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if (++hops > maxhops) {
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report(LOG_NOTICE, "reqest from %s reached hop limit",
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inet_ntoa(recv_addr.sin_addr));
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return;
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}
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bp->bp_hops = htons(hops);
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/*
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* Here one might discard a request from the same subnet as the
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* real server, but we can assume that the real server will send
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* a reply to the client before it waits for minwait seconds.
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*/
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/* If gateway address is not set, put in local interface addr. */
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if (bp->bp_giaddr.s_addr == 0) {
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#if 0 /* BUG */
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struct sockaddr_in *sip;
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/*
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* XXX - This picks the wrong interface when the receive addr
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* is the broadcast address. There is no portable way to
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* find out which interface a broadcast was received on. -gwr
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* (Thanks to <walker@zk3.dec.com> for finding this bug!)
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*/
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ifr = getif(s, &recv_addr.sin_addr);
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if (!ifr) {
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report(LOG_NOTICE, "no interface for request from %s",
|
||
inet_ntoa(recv_addr.sin_addr));
|
||
return;
|
||
}
|
||
sip = (struct sockaddr_in *) &(ifr->ifr_addr);
|
||
bp->bp_giaddr = sip->sin_addr;
|
||
#else /* BUG */
|
||
/*
|
||
* XXX - Just set "giaddr" to our "official" IP address.
|
||
* RFC 1532 says giaddr MUST be set to the address of the
|
||
* interface on which the request was received. Setting
|
||
* it to our "default" IP address is not strictly correct,
|
||
* but is good enough to allow the real BOOTP server to
|
||
* get the reply back here. Then, before we forward the
|
||
* reply to the client, the giaddr field is corrected.
|
||
* (In case the client uses giaddr, which it should not.)
|
||
* See handle_reply()
|
||
*/
|
||
bp->bp_giaddr = my_ip_addr;
|
||
#endif /* BUG */
|
||
|
||
/*
|
||
* XXX - DHCP says to insert a subnet mask option into the
|
||
* options area of the request (if vendor magic == std).
|
||
*/
|
||
}
|
||
/* Set up socket address for send. */
|
||
send_addr.sin_family = AF_INET;
|
||
send_addr.sin_port = htons(bootps_port);
|
||
send_addr.sin_addr.s_addr = server_ipa;
|
||
|
||
/* Send reply with same size packet as request used. */
|
||
if (sendto(s, pktbuf, pktlen, 0,
|
||
(struct sockaddr *) &send_addr,
|
||
sizeof(send_addr)) < 0)
|
||
{
|
||
report(LOG_ERR, "sendto: %s", get_network_errmsg());
|
||
}
|
||
}
|
||
|
||
|
||
|
||
/*
|
||
* Process BOOTREPLY packet.
|
||
*/
|
||
static void
|
||
handle_reply()
|
||
{
|
||
struct bootp *bp = (struct bootp *) pktbuf;
|
||
struct ifreq *ifr;
|
||
struct sockaddr_in *sip;
|
||
u_char canon_haddr[MAXHADDRLEN];
|
||
unsigned char *ha;
|
||
int len;
|
||
|
||
if (debug) {
|
||
report(LOG_INFO, " reply for %s",
|
||
inet_ntoa(bp->bp_yiaddr));
|
||
}
|
||
/* Make sure client is directly accessible. */
|
||
ifr = getif(s, &(bp->bp_yiaddr));
|
||
if (!ifr) {
|
||
report(LOG_NOTICE, "no interface for reply to %s",
|
||
inet_ntoa(bp->bp_yiaddr));
|
||
return;
|
||
}
|
||
#if 1 /* Experimental (see BUG above) */
|
||
/* #ifdef CATER_TO_OLD_CLIENTS ? */
|
||
/*
|
||
* The giaddr field has been set to our "default" IP address
|
||
* which might not be on the same interface as the client.
|
||
* In case the client looks at giaddr, (which it should not)
|
||
* giaddr is now set to the address of the correct interface.
|
||
*/
|
||
sip = (struct sockaddr_in *) &(ifr->ifr_addr);
|
||
bp->bp_giaddr = sip->sin_addr;
|
||
#endif
|
||
|
||
/* Set up socket address for send to client. */
|
||
send_addr.sin_family = AF_INET;
|
||
send_addr.sin_addr = bp->bp_yiaddr;
|
||
send_addr.sin_port = htons(bootpc_port);
|
||
|
||
/* Create an ARP cache entry for the client. */
|
||
ha = bp->bp_chaddr;
|
||
len = bp->bp_hlen;
|
||
if (len > MAXHADDRLEN)
|
||
len = MAXHADDRLEN;
|
||
if (bp->bp_htype == HTYPE_IEEE802) {
|
||
haddr_conv802(ha, canon_haddr, len);
|
||
ha = canon_haddr;
|
||
}
|
||
if (debug > 1)
|
||
report(LOG_INFO, "setarp %s - %s",
|
||
inet_ntoa(bp->bp_yiaddr), haddrtoa(ha, len));
|
||
setarp(s, &bp->bp_yiaddr, ha, len);
|
||
|
||
/* Send reply with same size packet as request used. */
|
||
if (sendto(s, pktbuf, pktlen, 0,
|
||
(struct sockaddr *) &send_addr,
|
||
sizeof(send_addr)) < 0)
|
||
{
|
||
report(LOG_ERR, "sendto: %s", get_network_errmsg());
|
||
}
|
||
}
|
||
|
||
/*
|
||
* Local Variables:
|
||
* tab-width: 4
|
||
* c-indent-level: 4
|
||
* c-argdecl-indent: 4
|
||
* c-continued-statement-offset: 4
|
||
* c-continued-brace-offset: -4
|
||
* c-label-offset: -4
|
||
* c-brace-offset: 0
|
||
* End:
|
||
*/
|