1 |
/* |
2 |
ether_emu.C -- ethernet "emulator" library |
3 |
Copyright (C) 2003 Marc Lehmann <pcg@goof.com> |
4 |
|
5 |
This program is free software; you can redistribute it and/or modify |
6 |
it under the terms of the GNU General Public License as published by |
7 |
the Free Software Foundation; either version 2 of the License, or |
8 |
(at your option) any later version. |
9 |
|
10 |
This program is distributed in the hope that it will be useful, |
11 |
but WITHOUT ANY WARRANTY; without even the implied warranty of |
12 |
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
13 |
GNU General Public License for more details. |
14 |
|
15 |
You should have received a copy of the GNU General Public License |
16 |
along with this program; if not, write to the Free Software |
17 |
Foundation, Inc. 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
18 |
*/ |
19 |
|
20 |
#include "config.h" |
21 |
|
22 |
#include <map> |
23 |
|
24 |
#include "vpn.h" |
25 |
|
26 |
struct ether_emu : map<u32, int> { |
27 |
typedef map<u32, int> ipv4map; |
28 |
ipv4map ipv4; |
29 |
|
30 |
bool tun_to_tap (tap_packet *pkt); |
31 |
bool tap_to_tun (tap_packet *pkt); |
32 |
|
33 |
void set_ipv4 (u32 ip, int dst) |
34 |
{ |
35 |
(ipv4.insert (pair<u32, int>(ip, dst)).first)->second = dst; |
36 |
} |
37 |
}; |
38 |
|
39 |
static struct ether_emu ether_emu; |
40 |
|
41 |
bool |
42 |
ether_emu::tun_to_tap (tap_packet *pkt) |
43 |
{ |
44 |
int dst; |
45 |
|
46 |
if (pkt->is_ipv4 ()) |
47 |
{ |
48 |
// update arp cache for _local_ hosts |
49 |
set_ipv4 (pkt->ipv4_src (), THISNODE->id); |
50 |
|
51 |
ipv4map::iterator i = ipv4.find (pkt->ipv4_dst ()); |
52 |
|
53 |
if (i == ipv4.end ()) |
54 |
{ |
55 |
u32 ip_src = pkt->ipv4_src (); |
56 |
u32 ip_dst = pkt->ipv4_dst (); |
57 |
|
58 |
// throw away current packet and make it an arp request |
59 |
(*pkt)[12] = 0x08; (*pkt)[13] = 0x06; |
60 |
(*pkt)[14] = 0x00; (*pkt)[15] = 0x01; // hw |
61 |
(*pkt)[16] = 0x08; (*pkt)[17] = 0x00; // prot |
62 |
(*pkt)[18] = 0x06; // hw_len |
63 |
(*pkt)[19] = 0x04; // prot_len |
64 |
(*pkt)[20] = 0x00; (*pkt)[21] = 0x01; // op |
65 |
|
66 |
id2mac (THISNODE->id, &(*pkt)[22]); |
67 |
*(u32 *)&(*pkt)[28] = ip_src; |
68 |
id2mac (0, &(*pkt)[32]); |
69 |
*(u32 *)&(*pkt)[38] = ip_dst; |
70 |
|
71 |
pkt->len = 42; |
72 |
|
73 |
dst = 0; |
74 |
} |
75 |
else |
76 |
dst = i->second; |
77 |
} |
78 |
else |
79 |
dst = 0; // broadcast non-ip |
80 |
|
81 |
id2mac (THISNODE->id, pkt->src); |
82 |
id2mac (dst, pkt->dst); |
83 |
|
84 |
return true; |
85 |
} |
86 |
|
87 |
bool |
88 |
ether_emu::tap_to_tun (tap_packet *pkt) |
89 |
{ |
90 |
if (pkt->is_arp ()) |
91 |
{ |
92 |
u32 ip_src = *(u32 *)&(*pkt)[28]; |
93 |
|
94 |
// always update with all info we can get. in this case, the arp sender. |
95 |
set_ipv4 (ip_src, mac2id (&(*pkt)[22])); |
96 |
|
97 |
//TODO: remove cache dumper |
98 |
//for (ipv4map::iterator i = ipv4.begin (); i != ipv4.end (); ++i) printf ("%08lx => %d\n", i->first, i->second); |
99 |
|
100 |
if ((*pkt)[20] == 0x00 && (*pkt)[21] == 0x01) // arp request |
101 |
{ |
102 |
// send a reply, if applicable |
103 |
u32 ip_dst = *(u32 *)&(*pkt)[38]; |
104 |
ipv4map::iterator i = ipv4.find (ip_dst); |
105 |
|
106 |
// TODO: look up list of local networks and answer for them |
107 |
if (i != ipv4.end () && i->second == THISNODE->id) |
108 |
{ |
109 |
// create an arp reply |
110 |
tap_packet *rep = new tap_packet; |
111 |
|
112 |
id2mac (THISNODE->id, rep->src); |
113 |
memcpy (rep->dst, pkt->src, sizeof (mac)); |
114 |
|
115 |
(*rep)[12] = 0x08; (*rep)[13] = 0x06; |
116 |
(*rep)[14] = 0x00; (*rep)[15] = 0x01; // hw |
117 |
(*rep)[16] = 0x08; (*rep)[17] = 0x00; // prot |
118 |
(*rep)[18] = 0x06; // hw_len |
119 |
(*rep)[19] = 0x04; // prot_len |
120 |
(*rep)[20] = 0x00; (*rep)[21] = 0x02; // op |
121 |
|
122 |
id2mac (THISNODE->id, &(*rep)[22]); |
123 |
*(u32 *)&(*rep)[28] = ip_dst; |
124 |
memcpy (&(*rep)[32], &(*pkt)[22], sizeof (mac)); |
125 |
*(u32 *)&(*rep)[38] = ip_src; |
126 |
|
127 |
rep->len = 42; |
128 |
|
129 |
network.inject_data_packet (rep, mac2id (rep->dst)); |
130 |
|
131 |
delete rep; |
132 |
} |
133 |
} |
134 |
else if ((*pkt)[20] == 0x00 && (*pkt)[21] == 0x02) // arp reply |
135 |
set_ipv4 (*(u32 *)&(*pkt)[28], mac2id (&(*pkt)[22])); |
136 |
|
137 |
return false; |
138 |
} |
139 |
else if (pkt->is_ipv4 ()) |
140 |
{ |
141 |
// update arp cache |
142 |
set_ipv4 (pkt->ipv4_src (), mac2id (pkt->src)); |
143 |
set_ipv4 (pkt->ipv4_dst (), mac2id (pkt->dst)); |
144 |
} |
145 |
|
146 |
return true; |
147 |
} |
148 |
|