e26e7e9983
* Rework the DHCP code again to revert to sending full ethernet frames rather then relying on the kernel to do the right thing with our packets. git-svn-id: http://svn-archive.gnome.org/svn/NetworkManager/trunk@340 4912f4e0-d625-0410-9fb7-b9a5a253dbdc
120 lines
3.7 KiB
C
120 lines
3.7 KiB
C
/*
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* dhcpcd - DHCP client daemon -
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* Copyright (C) January, 1998 Sergei Viznyuk <sv@phystech.com>
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*
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* dhcpcd is an RFC2131 and RFC1541 compliant DHCP client daemon.
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*
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* This is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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* See the GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include <string.h>
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#include "udpipgen.h"
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#include "client.h"
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/*****************************************************************************/
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unsigned short in_cksum(unsigned short *addr, int len)
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{
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register int sum = 0;
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register u_short *w = addr;
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register int nleft = len;
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while ( nleft > 1 )
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{
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sum += *w++;
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nleft -= 2;
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}
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if ( nleft == 1 )
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{
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u_char a = 0;
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memcpy(&a,w,1);
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sum += a;
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}
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sum = (sum >> 16) + (sum & 0xffff);
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sum += (sum >> 16);
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return ~sum;
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}
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/*****************************************************************************/
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void udpipgen (udpiphdr *udpip, unsigned int saddr, unsigned int daddr, unsigned short *ip_id, int dhcp_msg_len)
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{
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/* Use local copy because udpip->ip is not aligned. */
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struct ip ip_local;
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struct ip *ip = &ip_local;
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struct ipovly *io = (struct ipovly *)udpip->ip;
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struct udphdr *udp = (struct udphdr *)udpip->udp;
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io->ih_next = io->ih_prev = 0;
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io->ih_x1 = 0;
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io->ih_pr = IPPROTO_UDP;
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io->ih_len = htons (dhcp_msg_len + sizeof (struct udphdr));
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io->ih_src.s_addr = saddr;
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io->ih_dst.s_addr = daddr;
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udp->source = htons (DHCP_CLIENT_PORT);
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udp->dest = htons (DHCP_SERVER_PORT);
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udp->len = io->ih_len;
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udp->check = 0;
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udp->check = in_cksum ((unsigned short *)udpip, dhcp_msg_len + sizeof (udpiphdr));
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if (udp->check == 0)
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udp->check = 0xffff;
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memcpy (ip,(struct ip *)udpip->ip, sizeof (ip_local));
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ip->ip_hl = 5;
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ip->ip_v = IPVERSION;
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ip->ip_tos = 0; /* normal service */
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ip->ip_len = htons (dhcp_msg_len + sizeof (udpiphdr));
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ip->ip_id = htons (*ip_id); *ip_id++;
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ip->ip_off = 0;
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ip->ip_ttl = IPDEFTTL; /* time to live, 64 by default */
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ip->ip_p = IPPROTO_UDP;
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ip->ip_src.s_addr = saddr;
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ip->ip_dst.s_addr = daddr;
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ip->ip_sum = 0;
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memcpy (udpip->ip, ip, sizeof (ip_local));
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ip->ip_sum = in_cksum ((unsigned short *)&ip_local, sizeof (struct ip));
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memcpy (udpip->ip, ip, sizeof (ip_local));
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}
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/*****************************************************************************/
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int udpipchk(udpiphdr *udpip)
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{
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int hl;
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struct ip save_ip;
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struct ip *ip = (struct ip *)udpip->ip;
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struct ipovly *io = (struct ipovly *)udpip->ip;
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struct udphdr *udp = (struct udphdr *)udpip->udp;
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udpiphdr *nudpip = udpip;
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hl = ip->ip_hl<<2;
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if (in_cksum ((unsigned short *)udpip, hl))
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return -1;
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memcpy (&save_ip, udpip->ip, sizeof (struct ip));
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hl -= sizeof (struct ip);
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if (hl)
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{
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/* thrash IP options */
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nudpip = (udpiphdr *)((char *)udpip + hl);
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memmove ((char *)nudpip, udpip, sizeof (struct ip));
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io = (struct ipovly *)nudpip->ip;
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ip = (struct ip *)nudpip->ip;
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udp = (struct udphdr *)nudpip->udp;
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}
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if (udp->check == 0)
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return 0; /* no checksum has been done by sender */
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io->ih_next = io->ih_prev = 0;
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io->ih_x1 = 0;
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io->ih_len = udp->len;
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hl = ntohs (udp->len) + sizeof (struct ip);
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if (in_cksum ((unsigned short *)nudpip, hl))
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return -2;
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memcpy (udpip->ip, &save_ip, sizeof(struct ip));
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return 0;
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}
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