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*/
1 /*
2 * NET3 IP device support routines.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation; either version
7 * 2 of the License, or (at your option) any later version.
8 *
9 * Derived from the IP parts of dev.c 1.0.19
10 * Authors: Ross Biro, <bir7@leland.Stanford.Edu>
11 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
12 * Mark Evans, <evansmp@uhura.aston.ac.uk>
13 *
14 * Additional Authors:
15 * Alan Cox, <gw4pts@gw4pts.ampr.org>
16 */
17
18 #include <asm/segment.h>
19 #include <asm/system.h>
20 #include <asm/bitops.h>
21 #include <linux/config.h>
22 #include <linux/types.h>
23 #include <linux/kernel.h>
24 #include <linux/sched.h>
25 #include <linux/string.h>
26 #include <linux/mm.h>
27 #include <linux/socket.h>
28 #include <linux/sockios.h>
29 #include <linux/in.h>
30 #include <linux/errno.h>
31 #include <linux/interrupt.h>
32 #include <linux/if_ether.h>
33 #include <linux/inet.h>
34 #include <linux/netdevice.h>
35 #include <linux/etherdevice.h>
36 #include "ip.h"
37 #include "route.h"
38 #include "protocol.h"
39 #include "tcp.h"
40 #include <linux/skbuff.h>
41 #include "sock.h"
42 #include "arp.h"
43
44 /*
45 * Determine a default network mask, based on the IP address.
46 */
47
48 unsigned long ip_get_mask(unsigned long addr)
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*/
49 {
50 unsigned long dst;
51
52 if (addr == 0L)
53 return(0L); /* special case */
54
55 dst = ntohl(addr);
56 if (IN_CLASSA(dst))
57 return(htonl(IN_CLASSA_NET));
58 if (IN_CLASSB(dst))
59 return(htonl(IN_CLASSB_NET));
60 if (IN_CLASSC(dst))
61 return(htonl(IN_CLASSC_NET));
62
63 /*
64 * Something else, probably a multicast.
65 */
66
67 return(0);
68 }
69
70 /*
71 * Perform an IP address matching operation
72 */
73
74 int ip_addr_match(unsigned long me, unsigned long him)
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*/
75 {
76 int i;
77 unsigned long mask=0xFFFFFFFF;
78
79 /*
80 * Simple case
81 */
82 if (me == him)
83 return(1);
84
85 /*
86 * Look for a match ending in all 1's
87 */
88
89 for (i = 0; i < 4; i++, me >>= 8, him >>= 8, mask >>= 8)
90 {
91 if ((me & 0xFF) != (him & 0xFF))
92 {
93 /*
94 * The only way this could be a match is for
95 * the rest of addr1 to be 0 or 255.
96 */
97 if (me != 0 && me != mask)
98 return(0);
99 return(1);
100 }
101 }
102 return(1);
103 }
104
105
106 /*
107 * Check the address for our address, broadcasts, etc.
108 *
109 * I intend to fix this to at the very least cache the last
110 * resolved entry.
111 */
112
113 int ip_chk_addr(unsigned long addr)
/* */
114 {
115 struct device *dev;
116 unsigned long mask;
117
118 /*
119 * Accept both `all ones' and `all zeros' as BROADCAST.
120 * (Support old BSD in other words). This old BSD
121 * support will go very soon as it messes other things
122 * up.
123 */
124
125 if (addr == INADDR_ANY || addr == INADDR_BROADCAST)
126 return IS_BROADCAST;
127
128 mask = ip_get_mask(addr);
129
130 /*
131 * Accept all of the `loopback' class A net.
132 */
133
134 if ((addr & mask) == htonl(0x7F000000L))
135 return IS_MYADDR;
136
137 /*
138 * OK, now check the interface addresses.
139 */
140
141 for (dev = dev_base; dev != NULL; dev = dev->next)
142 {
143 if (!(dev->flags & IFF_UP))
144 continue;
145 /*
146 * If the protocol address of the device is 0 this is special
147 * and means we are address hunting (eg bootp).
148 */
149
150 if ((dev->pa_addr == 0)/* || (dev->flags&IFF_PROMISC)*/)
151 return IS_MYADDR;
152 /*
153 * Is it the exact IP address?
154 */
155
156 if (addr == dev->pa_addr)
157 return IS_MYADDR;
158 /*
159 * Is it our broadcast address?
160 */
161
162 if ((dev->flags & IFF_BROADCAST) && addr == dev->pa_brdaddr)
163 return IS_BROADCAST;
164 /*
165 * Nope. Check for a subnetwork broadcast.
166 */
167
168 if (((addr ^ dev->pa_addr) & dev->pa_mask) == 0)
169 {
170 if ((addr & ~dev->pa_mask) == 0)
171 return IS_BROADCAST;
172 if ((addr & ~dev->pa_mask) == ~dev->pa_mask)
173 return IS_BROADCAST;
174 }
175
176 /*
177 * Nope. Check for Network broadcast.
178 */
179
180 if (((addr ^ dev->pa_addr) & mask) == 0)
181 {
182 if ((addr & ~mask) == 0)
183 return IS_BROADCAST;
184 if ((addr & ~mask) == ~mask)
185 return IS_BROADCAST;
186 }
187 }
188 return 0; /* no match at all */
189 }
190
191
192 /*
193 * Retrieve our own address.
194 *
195 * Because the loopback address (127.0.0.1) is already recognized
196 * automatically, we can use the loopback interface's address as
197 * our "primary" interface. This is the address used by IP et
198 * al when it doesn't know which address to use (i.e. it does not
199 * yet know from or to which interface to go...).
200 */
201
202 unsigned long ip_my_addr(void)
/* */
203 {
204 struct device *dev;
205
206 for (dev = dev_base; dev != NULL; dev = dev->next)
207 {
208 if (dev->flags & IFF_LOOPBACK)
209 return(dev->pa_addr);
210 }
211 return(0);
212 }
213
214 /*
215 * Find an interface that can handle addresses for a certain address.
216 *
217 * This needs optimising, since its relatively trivial to collapse
218 * the two loops into one.
219 */
220
221 struct device * ip_dev_check(unsigned long addr)
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*/
222 {
223 struct device *dev;
224
225 for (dev = dev_base; dev; dev = dev->next)
226 {
227 if (!(dev->flags & IFF_UP))
228 continue;
229 if (!(dev->flags & IFF_POINTOPOINT))
230 continue;
231 if (addr != dev->pa_dstaddr)
232 continue;
233 return dev;
234 }
235 for (dev = dev_base; dev; dev = dev->next)
236 {
237 if (!(dev->flags & IFF_UP))
238 continue;
239 if (dev->flags & IFF_POINTOPOINT)
240 continue;
241 if (dev->pa_mask & (addr ^ dev->pa_addr))
242 continue;
243 return dev;
244 }
245 return NULL;
246 }
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*/