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pcg |
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/* |
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ether_emu.C -- ethernet "emulator" library |
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This program is free software; you can redistribute it and/or modify |
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it 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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This program is distributed in the hope that it will be useful, |
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but WITHOUT ANY WARRANTY; without even the implied warranty of |
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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GNU General Public License for more details. |
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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. 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
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*/ |
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#include "config.h" |
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#include <map> |
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#include "vpn.h" |
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struct ether_emu : map<u32, int> { |
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typedef map<u32, int> ipv4map; |
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ipv4map ipv4; |
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bool tun_to_tap (tap_packet *pkt); |
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bool tap_to_tun (tap_packet *pkt); |
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void set_ipv4 (u32 ip, int dst) |
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{ |
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(ipv4.insert (pair<u32, int>(ip, dst)).first)->second = dst; |
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} |
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}; |
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static struct ether_emu ether_emu; |
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bool |
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ether_emu::tun_to_tap (tap_packet *pkt) |
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{ |
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int dst; |
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if (pkt->is_ipv4 ()) |
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{ |
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// update arp cache for _local_ hosts |
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set_ipv4 (pkt->ipv4_src (), THISNODE->id); |
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ipv4map::iterator i = ipv4.find (pkt->ipv4_dst ()); |
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if (i == ipv4.end ()) |
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{ |
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u32 ip_src = pkt->ipv4_src (); |
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u32 ip_dst = pkt->ipv4_dst (); |
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// throw away current packet and make it an arp request |
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(*pkt)[12] = 0x08; (*pkt)[13] = 0x06; |
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(*pkt)[14] = 0x00; (*pkt)[15] = 0x01; // hw |
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(*pkt)[16] = 0x08; (*pkt)[17] = 0x00; // prot |
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(*pkt)[18] = 0x06; // hw_len |
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(*pkt)[19] = 0x04; // prot_len |
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(*pkt)[20] = 0x00; (*pkt)[21] = 0x01; // op |
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id2mac (THISNODE->id, &(*pkt)[22]); |
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*(u32 *)&(*pkt)[28] = ip_src; |
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id2mac (0, &(*pkt)[32]); |
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*(u32 *)&(*pkt)[38] = ip_dst; |
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pkt->len = 42; |
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dst = 0; |
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} |
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else |
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dst = i->second; |
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} |
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else |
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dst = 0; // broadcast non-ip |
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id2mac (THISNODE->id, pkt->src); |
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id2mac (dst, pkt->dst); |
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return true; |
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} |
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bool |
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ether_emu::tap_to_tun (tap_packet *pkt) |
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{ |
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if (pkt->is_arp ()) |
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{ |
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u32 ip_src = *(u32 *)&(*pkt)[28]; |
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// always update with all info we can get. in this case, the arp sender. |
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set_ipv4 (ip_src, mac2id (&(*pkt)[22])); |
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//TODO: remove cache dumper |
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//for (ipv4map::iterator i = ipv4.begin (); i != ipv4.end (); ++i) printf ("%08lx => %d\n", i->first, i->second); |
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if ((*pkt)[20] == 0x00 && (*pkt)[21] == 0x01) // arp request |
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{ |
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// send a reply, if applicable |
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u32 ip_dst = *(u32 *)&(*pkt)[38]; |
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ipv4map::iterator i = ipv4.find (ip_dst); |
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// TODO: look up list of local networks and answer for them |
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if (i != ipv4.end () && i->second == THISNODE->id) |
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{ |
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// create an arp reply |
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tap_packet *rep = new tap_packet; |
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id2mac (THISNODE->id, rep->src); |
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memcpy (rep->dst, pkt->src, sizeof (mac)); |
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(*rep)[12] = 0x08; (*rep)[13] = 0x06; |
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(*rep)[14] = 0x00; (*rep)[15] = 0x01; // hw |
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(*rep)[16] = 0x08; (*rep)[17] = 0x00; // prot |
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(*rep)[18] = 0x06; // hw_len |
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(*rep)[19] = 0x04; // prot_len |
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(*rep)[20] = 0x00; (*rep)[21] = 0x02; // op |
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id2mac (THISNODE->id, &(*rep)[22]); |
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*(u32 *)&(*rep)[28] = ip_dst; |
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memcpy (&(*rep)[32], &(*pkt)[22], sizeof (mac)); |
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*(u32 *)&(*rep)[38] = ip_src; |
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rep->len = 42; |
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network.inject_data_packet (rep, mac2id (rep->dst)); |
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delete rep; |
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} |
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} |
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else if ((*pkt)[20] == 0x00 && (*pkt)[21] == 0x02) // arp reply |
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set_ipv4 (*(u32 *)&(*pkt)[28], mac2id (&(*pkt)[22])); |
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return false; |
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} |
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else if (pkt->is_ipv4 ()) |
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{ |
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// update arp cache |
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set_ipv4 (pkt->ipv4_src (), mac2id (pkt->src)); |
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set_ipv4 (pkt->ipv4_dst (), mac2id (pkt->dst)); |
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} |
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return true; |
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} |
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