351 lines
7.6 KiB
C
351 lines
7.6 KiB
C
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/*
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* ip.c (C) 1995-1998 Darren Reed
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*
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* See the IPFILTER.LICENCE file for details on licencing.
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*/
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#if !defined(lint)
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static const char sccsid[] = "%W% %G% (C)1995";
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static const char rcsid[] = "@(#)$Id$";
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#endif
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#include <sys/param.h>
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#include <sys/types.h>
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#include <netinet/in_systm.h>
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#include <sys/socket.h>
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#include <net/if.h>
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#include <netinet/in.h>
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#include <netinet/ip.h>
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#include <sys/param.h>
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# include <net/route.h>
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# include <netinet/if_ether.h>
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# include <netinet/ip_var.h>
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#include <errno.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <string.h>
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#include "ipsend.h"
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static char *ipbuf = NULL, *ethbuf = NULL;
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u_short
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chksum(u_short *buf, int len)
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{
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u_long sum = 0;
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int nwords = len >> 1;
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for(; nwords > 0; nwords--)
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sum += *buf++;
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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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int
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send_ether(int nfd, char *buf, int len, struct in_addr gwip)
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{
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static struct in_addr last_gw;
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static char last_arp[6] = { 0, 0, 0, 0, 0, 0};
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ether_header_t *eh;
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char *s;
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int err;
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if (!ethbuf)
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ethbuf = (char *)calloc(1, 65536+1024);
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s = ethbuf;
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eh = (ether_header_t *)s;
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bcopy((char *)buf, s + sizeof(*eh), len);
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if (gwip.s_addr == last_gw.s_addr)
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{
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bcopy(last_arp, (char *) &eh->ether_dhost, 6);
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}
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else if (arp((char *)&gwip, (char *) &eh->ether_dhost) == -1)
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{
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perror("arp");
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return (-2);
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}
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eh->ether_type = htons(ETHERTYPE_IP);
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last_gw.s_addr = gwip.s_addr;
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err = sendip(nfd, s, sizeof(*eh) + len);
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return (err);
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}
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/*
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*/
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int
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send_ip(int nfd, int mtu, ip_t *ip, struct in_addr gwip, int frag)
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{
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static struct in_addr last_gw, local_ip;
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static char local_arp[6] = { 0, 0, 0, 0, 0, 0};
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static char last_arp[6] = { 0, 0, 0, 0, 0, 0};
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static u_short id = 0;
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ether_header_t *eh;
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ip_t ipsv;
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int err, iplen;
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if (!ipbuf)
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{
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ipbuf = (char *)malloc(65536);
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if (!ipbuf)
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{
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perror("malloc failed");
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return (-2);
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}
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}
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eh = (ether_header_t *)ipbuf;
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bzero((char *) &eh->ether_shost, sizeof(eh->ether_shost));
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if (last_gw.s_addr && (gwip.s_addr == last_gw.s_addr))
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{
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bcopy(last_arp, (char *) &eh->ether_dhost, 6);
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}
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else if (arp((char *)&gwip, (char *) &eh->ether_dhost) == -1)
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{
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perror("arp");
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return (-2);
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}
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bcopy((char *) &eh->ether_dhost, last_arp, sizeof(last_arp));
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eh->ether_type = htons(ETHERTYPE_IP);
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bcopy((char *)ip, (char *)&ipsv, sizeof(*ip));
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last_gw.s_addr = gwip.s_addr;
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iplen = ip->ip_len;
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ip->ip_len = htons(iplen);
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if (!(frag & 2)) {
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if (!IP_V(ip))
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IP_V_A(ip, IPVERSION);
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if (!ip->ip_id)
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ip->ip_id = htons(id++);
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if (!ip->ip_ttl)
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ip->ip_ttl = 60;
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}
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if (ip->ip_src.s_addr != local_ip.s_addr) {
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(void) arp((char *)&ip->ip_src, (char *) &local_arp);
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bcopy(local_arp, (char *) &eh->ether_shost,sizeof(last_arp));
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local_ip = ip->ip_src;
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} else
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bcopy(local_arp, (char *) &eh->ether_shost, 6);
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if (!frag || (sizeof(*eh) + iplen < mtu))
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{
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ip->ip_sum = 0;
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ip->ip_sum = chksum((u_short *)ip, IP_HL(ip) << 2);
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bcopy((char *)ip, ipbuf + sizeof(*eh), iplen);
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err = sendip(nfd, ipbuf, sizeof(*eh) + iplen);
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}
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else
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{
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/*
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* Actually, this is bogus because we're putting all IP
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* options in every packet, which isn't always what should be
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* done. Will do for now.
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*/
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ether_header_t eth;
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char optcpy[48], ol;
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char *s;
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int i, sent = 0, ts, hlen, olen;
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hlen = IP_HL(ip) << 2;
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if (mtu < (hlen + 8)) {
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fprintf(stderr, "mtu (%d) < ip header size (%d) + 8\n",
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mtu, hlen);
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fprintf(stderr, "can't fragment data\n");
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return (-2);
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}
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ol = (IP_HL(ip) << 2) - sizeof(*ip);
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for (i = 0, s = (char*)(ip + 1); ol > 0; )
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if (*s == IPOPT_EOL) {
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optcpy[i++] = *s;
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break;
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} else if (*s == IPOPT_NOP) {
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s++;
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ol--;
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} else
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{
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olen = (int)(*(u_char *)(s + 1));
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ol -= olen;
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if (IPOPT_COPIED(*s))
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{
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bcopy(s, optcpy + i, olen);
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i += olen;
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s += olen;
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}
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}
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if (i)
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{
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/*
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* pad out
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*/
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while ((i & 3) && (i & 3) != 3)
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optcpy[i++] = IPOPT_NOP;
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if ((i & 3) == 3)
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optcpy[i++] = IPOPT_EOL;
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}
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bcopy((char *)eh, (char *)ð, sizeof(eth));
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s = (char *)ip + hlen;
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iplen = ntohs(ip->ip_len) - hlen;
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ip->ip_off |= htons(IP_MF);
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while (1)
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{
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if ((sent + (mtu - hlen)) >= iplen)
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{
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ip->ip_off ^= htons(IP_MF);
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ts = iplen - sent;
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}
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else
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ts = (mtu - hlen);
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ip->ip_off &= htons(0xe000);
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ip->ip_off |= htons(sent >> 3);
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ts += hlen;
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ip->ip_len = htons(ts);
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ip->ip_sum = 0;
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ip->ip_sum = chksum((u_short *)ip, hlen);
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bcopy((char *)ip, ipbuf + sizeof(*eh), hlen);
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bcopy(s + sent, ipbuf + sizeof(*eh) + hlen, ts - hlen);
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err = sendip(nfd, ipbuf, sizeof(*eh) + ts);
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bcopy((char *)ð, ipbuf, sizeof(eth));
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sent += (ts - hlen);
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if (!(ntohs(ip->ip_off) & IP_MF))
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break;
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else if (!(ip->ip_off & htons(0x1fff)))
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{
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hlen = i + sizeof(*ip);
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IP_HL_A(ip, (sizeof(*ip) + i) >> 2);
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bcopy(optcpy, (char *)(ip + 1), i);
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}
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}
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}
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bcopy((char *)&ipsv, (char *)ip, sizeof(*ip));
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return (err);
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}
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/*
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* send a tcp packet.
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*/
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int
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send_tcp(int nfd, int mtu, ip_t *ip, struct in_addr gwip)
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{
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static tcp_seq iss = 2;
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tcphdr_t *t, *t2;
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int thlen, i, iplen, hlen;
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u_32_t lbuf[20];
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ip_t *ip2;
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iplen = ip->ip_len;
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hlen = IP_HL(ip) << 2;
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t = (tcphdr_t *)((char *)ip + hlen);
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ip2 = (struct ip *)lbuf;
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t2 = (tcphdr_t *)((char *)ip2 + hlen);
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thlen = TCP_OFF(t) << 2;
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if (!thlen)
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thlen = sizeof(tcphdr_t);
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bzero((char *)ip2, sizeof(*ip2) + sizeof(*t2));
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ip->ip_p = IPPROTO_TCP;
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ip2->ip_p = ip->ip_p;
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ip2->ip_src = ip->ip_src;
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ip2->ip_dst = ip->ip_dst;
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bcopy((char *)ip + hlen, (char *)t2, thlen);
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if (!t2->th_win)
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t2->th_win = htons(4096);
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iss += 63;
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i = sizeof(struct tcpiphdr) / sizeof(long);
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if ((t2->th_flags == TH_SYN) && !ntohs(ip->ip_off) &&
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(lbuf[i] != htonl(0x020405b4))) {
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lbuf[i] = htonl(0x020405b4);
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bcopy((char *)ip + hlen + thlen, (char *)ip + hlen + thlen + 4,
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iplen - thlen - hlen);
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thlen += 4;
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}
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TCP_OFF_A(t2, thlen >> 2);
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ip2->ip_len = htons(thlen);
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ip->ip_len = hlen + thlen;
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t2->th_sum = 0;
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t2->th_sum = chksum((u_short *)ip2, thlen + sizeof(ip_t));
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bcopy((char *)t2, (char *)ip + hlen, thlen);
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return (send_ip(nfd, mtu, ip, gwip, 1));
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}
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/*
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* send a udp packet.
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*/
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int
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send_udp(int nfd, int mtu, ip_t *ip, struct in_addr gwip)
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{
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struct tcpiphdr *ti;
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int thlen;
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u_long lbuf[20];
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ti = (struct tcpiphdr *)lbuf;
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bzero((char *)ti, sizeof(*ti));
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thlen = sizeof(udphdr_t);
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ti->ti_pr = ip->ip_p;
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ti->ti_src = ip->ip_src;
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ti->ti_dst = ip->ip_dst;
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bcopy((char *)ip + (IP_HL(ip) << 2),
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(char *)&ti->ti_sport, sizeof(udphdr_t));
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ti->ti_len = htons(thlen);
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ip->ip_len = (IP_HL(ip) << 2) + thlen;
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ti->ti_sum = 0;
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ti->ti_sum = chksum((u_short *)ti, thlen + sizeof(ip_t));
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bcopy((char *)&ti->ti_sport,
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(char *)ip + (IP_HL(ip) << 2), sizeof(udphdr_t));
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return (send_ip(nfd, mtu, ip, gwip, 1));
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}
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/*
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* send an icmp packet.
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*/
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int
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send_icmp(int nfd, int mtu, ip_t *ip, in_addr gwip)
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{
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struct icmp *ic;
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ic = (struct icmp *)((char *)ip + (IP_HL(ip) << 2));
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ic->icmp_cksum = 0;
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ic->icmp_cksum = chksum((u_short *)ic, sizeof(struct icmp));
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return (send_ip(nfd, mtu, ip, gwip, 1));
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}
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int
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send_packet(int nfd, int mtu, ip_t *ip, struct in_addr gwip)
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int nfd, mtu;
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ip_t *ip;
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struct in_addr gwip;
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{
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switch (ip->ip_p)
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{
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case IPPROTO_TCP :
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( return send_tcp(nfd, mtu, ip, gwip));
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case IPPROTO_UDP :
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( return send_udp(nfd, mtu, ip, gwip));
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case IPPROTO_ICMP :
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( return send_icmp(nfd, mtu, ip, gwip));
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default :
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( return send_ip(nfd, mtu, ip, gwip, 1));
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}
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}
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