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// |
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// $Id: dhcping.c,v 1.3 2002/01/27 01:57:15 mavetju Exp $ |
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// |
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|
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/* |
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* Copyright 2000, 2001, 2002 by Edwin Groothuis, edwin@mavetju.org |
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* |
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* Redistribution and use in source and binary forms, with or without |
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* modification, are permitted provided that the following conditions |
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* are met: |
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* 1. Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* 2. Redistributions in binary form must reproduce the above copyright |
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* notice, this list of conditions and the following disclaimer in the |
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* documentation and/or other materials provided with the distribution. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND |
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE |
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
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* SUCH DAMAGE. |
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* |
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*/ |
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|
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#include <sys/types.h> |
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#include <sys/socket.h> |
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#include <sys/time.h> |
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#include <sys/uio.h> |
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#include <netinet/in.h> |
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#include <unistd.h> |
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#include <netdb.h> |
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#include <stdio.h> |
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#include <stdlib.h> |
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#include <string.h> |
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#include <time.h> |
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|
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#include "dhcp_options.h" |
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|
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#define BUF_SIZ 256*256 |
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#define MAX_OPTIONS 256 |
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#define MAX_DATA 256 |
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|
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int offset=0; |
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void addpacket(char *pktbuf,char *msgbuf,int size) { |
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memcpy(pktbuf+offset,msgbuf,size); |
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offset+=size; |
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} |
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|
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void dhcp_setup(char *); |
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int dhcp_read(void); |
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void dhcp_close(void); |
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void dhcp_dump(unsigned char *buffer,int size); |
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void dhcp_inform(char *ipaddr,char *gwaddr,char *hardware); |
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void dhcp_request(char *ipaddr,char *gwaddr,char *hardware); |
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void dhcp_release(char *ipaddr,char *gwaddr,char *hardware); |
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void dhcp_packet(int type,char *ciaddr,char *opt50,char *gwaddr,char *hardware); |
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|
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int dhcp_socket; |
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struct sockaddr_in dhcp_to; |
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|
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int _serveripaddress; |
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|
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int inform,request,verbose,VERBOSE,quiet; |
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char *ci,*gi,*server,*hw; |
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unsigned char serveridentifier[4]; |
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int maxwait=3; |
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|
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typedef struct optpack cmdlineopt; |
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|
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struct optpack { |
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unsigned int option; |
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char data[MAX_DATA]; |
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} cmdlineopts[MAX_OPTIONS]; |
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|
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char sname[64]; |
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unsigned int opt = 0; |
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|
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void doargs(int argc,char **argv) { |
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char ch; |
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|
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inform=request=verbose=VERBOSE=quiet=0; |
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ci=gi=server="0.0.0.0"; |
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hw="00:00:00:00:00:00"; |
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|
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if (argc==1) { |
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printf("dhcping -S sname -c ciaddr -g giaddr -h chaddr -r -s server -t maxwait -i -v -q -o option:data\n"); |
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exit(1); |
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} |
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|
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while ((ch = getopt(argc,argv,"c:o:S:g:h:iqrs:t:vV"))>0) { |
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switch (ch) { |
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case 'c': ci=optarg;break; |
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case 'g': gi=optarg;break; |
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case 'h': hw=optarg;break; |
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case 'i': inform=1;break; |
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case 'q': quiet=1;break; |
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case 'r': request=1;break; |
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case 's': server=optarg;break; |
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case 't': maxwait=atoi(optarg);break; |
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case 'v': verbose=1;break; |
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case 'V': VERBOSE=1;break; |
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case 'o': if (opt > MAX_OPTIONS) { |
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printf ("Exceeded maximum options parameter(%d).\n", MAX_OPTIONS); |
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break; |
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} |
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char x[100+MAX_DATA]; |
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sprintf (x, "%%d:%%%ds", MAX_DATA); |
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sscanf (optarg, x, &cmdlineopts[opt].option, cmdlineopts[opt].data); |
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printf ("optarg: %s, opt: %d, cmd1: %d, cmd2: %s, x: %s" |
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, optarg, opt, cmdlineopts[opt].option, cmdlineopts[opt++].data, x); |
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break; |
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case 'S': sscanf (optarg, "%63s", sname);break; |
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} |
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} |
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|
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if (request && inform) { |
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fprintf(stderr,"Error: -r and -i are mutally exclusive.\n"); |
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exit(1); |
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} |
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|
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// DHCPREQUEST is by default. |
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if (!inform) request=1; |
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} |
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|
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int main(int argc,char **argv) { |
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fd_set read; |
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struct timeval timeout; |
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int foundpacket=0; |
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int returnvalue=0; |
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|
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if (geteuid()!=0) { |
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printf("This program should only be run by root or be installed as setuid root.\n"); |
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exit(1); |
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} |
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|
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doargs(argc,argv); |
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|
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if (VERBOSE) puts("setup"); |
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dhcp_setup(server); |
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|
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if (setuid(getuid())!=0) { |
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perror("setuid"); |
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printf("Can't drop privileges back to normal user, program aborted.\n"); |
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exit(1); |
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} |
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|
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if (inform) { |
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if (VERBOSE) puts("inform"); |
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dhcp_inform(ci,gi,hw); |
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} |
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if (request) { |
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if (VERBOSE) puts("request"); |
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dhcp_request(ci,gi,hw); |
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} |
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|
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while (!foundpacket) { |
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FD_ZERO(&read); |
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FD_SET(dhcp_socket,&read); |
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timeout.tv_sec=maxwait; |
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timeout.tv_usec=0; |
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if(select(dhcp_socket+1,&read,NULL,NULL,&timeout)<0) { |
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perror("select"); |
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exit(0); |
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} |
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if (FD_ISSET(dhcp_socket,&read)) { |
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if (VERBOSE) puts("read"); |
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/* If a expected packet was found, then also release it. */ |
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if ((foundpacket=dhcp_read())!=0) { |
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if (request) { |
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if (VERBOSE) puts("release"); |
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dhcp_release(ci,gi,hw); |
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} |
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} |
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} else { |
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if (!quiet) |
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fprintf(stderr,"no answer\n"); |
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returnvalue=1; |
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foundpacket=1; |
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} |
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} |
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if (VERBOSE) puts("close"); |
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dhcp_close(); |
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return returnvalue; |
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} |
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|
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|
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void dhcp_setup(char *serveripaddress) { |
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struct servent *servent,*clientent; |
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struct hostent *hostent; |
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int flag; |
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struct sockaddr_in name; |
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|
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/* |
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// setup sending socket |
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*/ |
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if ((servent=getservbyname("bootps",0))==NULL) { |
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perror("getservbyname: bootps"); |
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exit(1); |
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} |
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if ((hostent=gethostbyname(serveripaddress))==NULL) { |
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perror("gethostbyname"); |
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exit(1); |
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} |
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|
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dhcp_to.sin_family=AF_INET; |
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bcopy(hostent->h_addr,&dhcp_to.sin_addr.s_addr,hostent->h_length); |
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_serveripaddress=ntohl(dhcp_to.sin_addr.s_addr); |
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/* dhcp_to.sin_addr.s_addr=INADDR_BROADCAST; */ |
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dhcp_to.sin_port=servent->s_port; |
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|
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if ((dhcp_socket=socket(AF_INET,SOCK_DGRAM,IPPROTO_UDP))==-1) { |
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perror("dhcp_socket/socket"); |
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exit(1); |
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} |
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|
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flag=1; |
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if (setsockopt (dhcp_socket, SOL_SOCKET, SO_REUSEADDR, (char *)&flag, sizeof flag) < 0) { |
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perror("dhcp_socket/setsockopt: SO_REUSEADDR"); |
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exit(1); |
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} |
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|
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if (setsockopt(dhcp_socket,SOL_SOCKET,SO_BROADCAST,(char *)&flag, sizeof flag) < 0) { |
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perror ("dhcp_socket/setsockopt: SO_BROADCAST"); |
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exit(1); |
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} |
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|
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if ((clientent=getservbyname("bootpc",0))==NULL) { |
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perror("getservbyname: bootpc"); |
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exit(1); |
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} |
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name.sin_family = AF_INET; |
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name.sin_port = clientent->s_port; |
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name.sin_addr.s_addr = INADDR_ANY; |
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/* name.sin_addr.s_addr = INADDR_NONE; */ |
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memset (name.sin_zero, 0, sizeof (name.sin_zero)); |
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|
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if (bind (dhcp_socket, (struct sockaddr *)&name, sizeof name) < 0) { |
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perror("bind"); |
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exit(1); |
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} |
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} |
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|
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void dhcp_request(char *ipaddr,char *gwaddr,char *hardware) { |
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dhcp_packet(3,ipaddr,ipaddr,gwaddr,hardware); |
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} |
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void dhcp_release(char *ipaddr,char *gwaddr,char *hardware) { |
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dhcp_packet(7,ipaddr,NULL,gwaddr,hardware); |
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} |
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void dhcp_inform(char *ipaddr,char *gwaddr,char *hardware) { |
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dhcp_packet(8,ipaddr,NULL,gwaddr,hardware); |
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} |
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|
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|
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void dhcp_packet(int type,char *ipaddr,char *opt50,char *gwaddr,char *hardware) { |
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static time_t l=0; |
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unsigned char msgbuf[BUF_SIZ]; |
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unsigned char pktbuf[BUF_SIZ]; |
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int ip[4],gw[4],hw[16],ip50[4]; |
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int hwcount; |
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|
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sscanf(ipaddr,"%d.%d.%d.%d",&ip[0],&ip[1],&ip[2],&ip[3]); |
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sscanf(gwaddr,"%d.%d.%d.%d",&gw[0],&gw[1],&gw[2],&gw[3]); |
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if (opt50) |
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sscanf(opt50,"%d.%d.%d.%d",&ip50[0],&ip50[1],&ip50[2],&ip50[3]); |
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memset(&hw,0,sizeof(hw)); |
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hwcount=sscanf(hardware,"%x:%x:%x:%x:%x:%x:%x:%x:%x:%x:%x:%x:%x:%x:%x:%x", |
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&hw[0],&hw[1],&hw[2],&hw[3], |
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&hw[4],&hw[5],&hw[6],&hw[7], |
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&hw[8],&hw[9],&hw[10],&hw[11], |
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&hw[12],&hw[13],&hw[14],&hw[15]); |
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|
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memset(msgbuf,0,sizeof(msgbuf)); |
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sprintf(msgbuf,"\1\1%c%c",hwcount,0); |
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addpacket(pktbuf,msgbuf,4); |
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|
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/* xid */ |
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if (l>time(NULL)) |
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l++; |
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else |
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l=time(NULL); |
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memcpy(msgbuf,&l,4); |
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addpacket(pktbuf,msgbuf,4); |
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|
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/* secs and flags */ |
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memset(msgbuf,0,4); |
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addpacket(pktbuf,msgbuf,4); |
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/* sprintf(msgbuf,"%c%c",0x80,0x00); */ |
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/* sprintf(msgbuf,"%c%c",0x00,0x00); */ |
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/* addpacket(pktbuf,msgbuf,2); */ |
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|
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/* ciaddr */ |
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memset(msgbuf,0,4); |
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sprintf(msgbuf,"%c%c%c%c",ip[0],ip[1],ip[2],ip[3]); |
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addpacket(pktbuf,msgbuf,4); |
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|
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/* yiaddr */ |
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memset(msgbuf,0,4); |
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addpacket(pktbuf,msgbuf,4); |
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|
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/* siaddr */ |
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memset(msgbuf,0,4); |
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addpacket(pktbuf,msgbuf,4); |
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|
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/* giaddr */ |
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sprintf(msgbuf,"%c%c%c%c",gw[0],gw[1],gw[2],gw[3]); |
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addpacket(pktbuf,msgbuf,4); |
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|
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/* chaddr */ |
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sprintf(msgbuf,"%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c", |
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hw[0],hw[1],hw[2],hw[3],hw[4],hw[5],hw[6],hw[7], |
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hw[8],hw[9],hw[10],hw[11],hw[12],hw[13],hw[14],hw[15]); |
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addpacket(pktbuf,msgbuf,16); |
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|
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/* sname */ |
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memset(msgbuf,0,64); |
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printf("hallo!!!\n"); |
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if (strlen (sname) > 0) { |
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sprintf (msgbuf, "%s", sname); |
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} |
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addpacket(pktbuf,msgbuf,64); |
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|
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/* file */ |
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memset(msgbuf,0,128); |
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addpacket(pktbuf,msgbuf,128); |
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|
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/* options */ |
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{ |
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/* cookie */ |
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sprintf(msgbuf,"%c%c%c%c",99,130,83,99); |
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addpacket(pktbuf,msgbuf,4); |
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|
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/* dhcp-type */ |
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sprintf(msgbuf,"%c%c%c",53,1,type); |
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addpacket(pktbuf,msgbuf,3); |
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|
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/* Not for inform */ |
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if (type!=8) { |
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/* requested IP address */ |
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if (opt50) { |
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sprintf(msgbuf,"%c%c%c%c%c%c",50,4,ip50[0],ip50[1],ip50[2],ip50[3]); |
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addpacket(pktbuf,msgbuf,6); |
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} |
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|
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/* server-identifier */ |
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if (serveridentifier[0]) { |
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sprintf(msgbuf,"%c%c%c%c%c%c",54,4, |
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serveridentifier[0],serveridentifier[1], |
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serveridentifier[2],serveridentifier[3]); |
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addpacket(pktbuf,msgbuf,6); |
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} |
| 357 |
/* command line options */ |
| 358 |
while (opt--) { |
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sprintf (msgbuf, "%c%c%s", cmdlineopts[opt].option, (char *)(strlen (cmdlineopts[opt].data) + 1), cmdlineopts[opt].data); |
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addpacket(pktbuf, msgbuf, 2 + strlen (cmdlineopts[opt].data) + 1); |
| 361 |
} |
| 362 |
} |
| 363 |
|
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/* client-identifier */ |
| 365 |
// sprintf(msgbuf,"%c%c%c%c%c%c%c%c",61,6, |
| 366 |
// hw[0],hw[1],hw[2],hw[3],hw[4],hw[5]); |
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// addpacket(pktbuf,msgbuf,8); |
| 368 |
|
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/* parameter request list */ |
| 370 |
if (type==8) { |
| 371 |
sprintf(msgbuf,"%c%c%c",55,1,1); |
| 372 |
addpacket(pktbuf,msgbuf,3); |
| 373 |
} |
| 374 |
|
| 375 |
/* end of options */ |
| 376 |
sprintf(msgbuf,"%c",255); |
| 377 |
addpacket(pktbuf,msgbuf,1); |
| 378 |
} |
| 379 |
|
| 380 |
dhcp_dump(pktbuf,offset); |
| 381 |
|
| 382 |
sendto(dhcp_socket,pktbuf,offset,0,(struct sockaddr *)&dhcp_to,sizeof(dhcp_to)); |
| 383 |
|
| 384 |
offset=0; |
| 385 |
} |
| 386 |
|
| 387 |
|
| 388 |
int dhcp_read(void) { |
| 389 |
unsigned char msgbuf[BUF_SIZ]; |
| 390 |
struct sockaddr_in fromsock; |
| 391 |
socklen_t fromlen=sizeof(fromsock); |
| 392 |
int addr; |
| 393 |
int i; |
| 394 |
|
| 395 |
i=recvfrom(dhcp_socket,msgbuf,BUF_SIZ,0,(struct sockaddr *)&fromsock,&fromlen); |
| 396 |
addr=ntohl(fromsock.sin_addr.s_addr); |
| 397 |
|
| 398 |
if (!quiet) { |
| 399 |
printf( "Got answer from: %d.%d.%d.%d\n", |
| 400 |
( addr >> 24 ) & 0xFF, ( addr >> 16 ) & 0xFF, |
| 401 |
( addr >> 8 ) & 0xFF, ( addr ) & 0xFF |
| 402 |
); |
| 403 |
} |
| 404 |
|
| 405 |
if (_serveripaddress!=addr) { |
| 406 |
if (!quiet) |
| 407 |
fprintf(stderr,"received from %d.%d.%d.%d, expected from %d.%d.%d.%d\n", |
| 408 |
( addr >> 24 ) & 0xFF, ( addr >> 16 ) & 0xFF, |
| 409 |
( addr >> 8 ) & 0xFF, ( addr ) & 0xFF, |
| 410 |
( _serveripaddress >> 24 )&0xFF,(_serveripaddress >> 16 )&0xFF, |
| 411 |
( _serveripaddress >> 8 )&0xFF,(_serveripaddress )&0xFF |
| 412 |
); |
| 413 |
return 0; |
| 414 |
|
| 415 |
} |
| 416 |
|
| 417 |
|
| 418 |
dhcp_dump(msgbuf,i); |
| 419 |
return 1; |
| 420 |
} |
| 421 |
|
| 422 |
|
| 423 |
|
| 424 |
void dhcp_dump(unsigned char *buffer,int size) { |
| 425 |
int j; |
| 426 |
|
| 427 |
if (VERBOSE) |
| 428 |
printf("packet %d bytes\n",size); |
| 429 |
|
| 430 |
if (!VERBOSE) |
| 431 |
return; |
| 432 |
|
| 433 |
// |
| 434 |
// Are you sure you want to see this? Try dhcpdump, which is better |
| 435 |
// suited for this kind of work... See http://www.mavetju.org |
| 436 |
// |
| 437 |
j=0; |
| 438 |
while (j<size) { |
| 439 |
printf("%02x ",buffer[j]); |
| 440 |
if (j%16==15) printf("\n"); |
| 441 |
j++; |
| 442 |
} |
| 443 |
printf("\n"); |
| 444 |
|
| 445 |
printf("op: %d\n",buffer[0]); |
| 446 |
printf("htype: %d\n",buffer[1]); |
| 447 |
printf("hlen: %d\n",buffer[2]); |
| 448 |
printf("hops: %d\n",buffer[3]); |
| 449 |
|
| 450 |
printf("xid: %02x%02x%02x%02x\n", |
| 451 |
buffer[4],buffer[5],buffer[6],buffer[7]); |
| 452 |
printf("secs: %d\n",255*buffer[8]+buffer[9]); |
| 453 |
printf("flags: %x\n",255*buffer[10]+buffer[11]); |
| 454 |
|
| 455 |
printf("ciaddr: %d.%d.%d.%d\n", |
| 456 |
buffer[12],buffer[13],buffer[14],buffer[15]); |
| 457 |
printf("yiaddr: %d.%d.%d.%d\n", |
| 458 |
buffer[16],buffer[17],buffer[18],buffer[19]); |
| 459 |
printf("siaddr: %d.%d.%d.%d\n", |
| 460 |
buffer[20],buffer[21],buffer[22],buffer[23]); |
| 461 |
printf("giaddr: %d.%d.%d.%d\n", |
| 462 |
buffer[24],buffer[25],buffer[26],buffer[27]); |
| 463 |
printf("chaddr: %02x:%02x:%02x:%02x:%02x:%02x:%02x:%02x:%02x:%02x:%02x:%02x:%02x:%02x:%02x:%02x\n", |
| 464 |
buffer[28],buffer[29],buffer[30],buffer[31], |
| 465 |
buffer[32],buffer[33],buffer[34],buffer[35], |
| 466 |
buffer[36],buffer[37],buffer[38],buffer[39], |
| 467 |
buffer[40],buffer[41],buffer[42],buffer[43]); |
| 468 |
printf("sname : %s.\n",buffer+44); |
| 469 |
printf("fname : %s.\n",buffer+108); |
| 470 |
|
| 471 |
j=236; |
| 472 |
j+=4; /* cookie */ |
| 473 |
while (j<size && buffer[j]!=255) { |
| 474 |
printf("option %d %s\n",buffer[j],dhcp_options[buffer[j]]); |
| 475 |
|
| 476 |
switch (buffer[j]) { |
| 477 |
case 1: |
| 478 |
printf("\tSubnet mask: %d.%d.%d.%d\n", |
| 479 |
buffer[j+2],buffer[j+3],buffer[j+4],buffer[j+5]); |
| 480 |
break; |
| 481 |
case 3: |
| 482 |
printf("\tRouter: %d.%d.%d.%d\n", |
| 483 |
buffer[j+2],buffer[j+3],buffer[j+4],buffer[j+5]); |
| 484 |
break; |
| 485 |
case 50: |
| 486 |
printf("\tRequested IP address: %d.%d.%d.%d\n", |
| 487 |
buffer[j+2],buffer[j+3],buffer[j+4],buffer[j+5]); |
| 488 |
break; |
| 489 |
case 53: |
| 490 |
printf("\tDHCP message type: %d (%s)\n", |
| 491 |
buffer[j+2],dhcp_message_types[buffer[j+2]]); |
| 492 |
break; |
| 493 |
case 54: |
| 494 |
memcpy(serveridentifier,buffer+j+2,4); |
| 495 |
printf("\tServer identifier: %d.%d.%d.%d\n", |
| 496 |
serveridentifier[0],serveridentifier[1], |
| 497 |
serveridentifier[2],serveridentifier[3]); |
| 498 |
break; |
| 499 |
case 61: |
| 500 |
printf("\tClient identifier: %02x%02x%02x%02x%02x%02x\n", |
| 501 |
buffer[j+2],buffer[j+3],buffer[j+4], |
| 502 |
buffer[j+5],buffer[j+6],buffer[j+7]); |
| 503 |
break; |
| 504 |
} |
| 505 |
|
| 506 |
/* |
| 507 |
// This might go wrong if a mallformed packet is received. |
| 508 |
// Maybe from a bogus server which is instructed to reply |
| 509 |
// with invalid data and thus causing an exploit. |
| 510 |
// My head hurts... but I think it's solved by the checking |
| 511 |
// for j<size at the begin of the while-loop. |
| 512 |
*/ |
| 513 |
j+=buffer[j+1]+2; |
| 514 |
} |
| 515 |
} |
| 516 |
|
| 517 |
|
| 518 |
void dhcp_close(void) { |
| 519 |
close(dhcp_socket); |
| 520 |
} |
| 521 |
|
