1a17240f2Sderaadt /* $NetBSD: inet.c,v 1.4 1995/12/10 10:07:03 mycroft Exp $ */
2df930be7Sderaadt
3df930be7Sderaadt /*
4df930be7Sderaadt * The mrouted program is covered by the license in the accompanying file
5df930be7Sderaadt * named "LICENSE". Use of the mrouted program represents acceptance of
6df930be7Sderaadt * the terms and conditions listed in that file.
7df930be7Sderaadt *
8df930be7Sderaadt * The mrouted program is COPYRIGHT 1989 by The Board of Trustees of
9df930be7Sderaadt * Leland Stanford Junior University.
10df930be7Sderaadt */
11df930be7Sderaadt
12df930be7Sderaadt
13df930be7Sderaadt #include "defs.h"
14df930be7Sderaadt
15df930be7Sderaadt
16df930be7Sderaadt /*
17df930be7Sderaadt * Exported variables.
18df930be7Sderaadt */
19c1cfc344Sderaadt #define SNAMLEN 19
20c1cfc344Sderaadt char s1[SNAMLEN]; /* buffers to hold the string representations */
21c1cfc344Sderaadt char s2[SNAMLEN]; /* of IP addresses, to be passed to inet_fmt() */
22c1cfc344Sderaadt char s3[SNAMLEN]; /* or inet_fmts(). */
23c1cfc344Sderaadt char s4[SNAMLEN];
24df930be7Sderaadt
25df930be7Sderaadt
26df930be7Sderaadt /*
27df930be7Sderaadt * Verify that a given IP address is credible as a host address.
28df930be7Sderaadt * (Without a mask, cannot detect addresses of the form {subnet,0} or
29df930be7Sderaadt * {subnet,-1}.)
30df930be7Sderaadt */
31a17240f2Sderaadt int
inet_valid_host(u_int32_t naddr)325017e83eSderaadt inet_valid_host(u_int32_t naddr)
33df930be7Sderaadt {
34fcc7c6a8Stedu u_int32_t addr;
35df930be7Sderaadt
36df930be7Sderaadt addr = ntohl(naddr);
37df930be7Sderaadt
38df930be7Sderaadt return (!(IN_MULTICAST(addr) ||
39df930be7Sderaadt (addr & 0xff000000) == 0));
40df930be7Sderaadt }
41df930be7Sderaadt
42a17240f2Sderaadt /*
43a17240f2Sderaadt * Verify that a given netmask is plausible;
44a17240f2Sderaadt * make sure that it is a series of 1's followed by
45a17240f2Sderaadt * a series of 0's with no discontiguous 1's.
46a17240f2Sderaadt */
47a17240f2Sderaadt int
inet_valid_mask(u_int32_t mask)485017e83eSderaadt inet_valid_mask(u_int32_t mask)
49a17240f2Sderaadt {
50a17240f2Sderaadt if (~(((mask & -mask) - 1) | mask) != 0) {
51a17240f2Sderaadt /* Mask is not contiguous */
52a17240f2Sderaadt return (FALSE);
53a17240f2Sderaadt }
54a17240f2Sderaadt
55a17240f2Sderaadt return (TRUE);
56a17240f2Sderaadt }
57df930be7Sderaadt
58df930be7Sderaadt /*
59df930be7Sderaadt * Verify that a given subnet number and mask pair are credible.
60df930be7Sderaadt *
61df930be7Sderaadt * With CIDR, almost any subnet and mask are credible. mrouted still
62df930be7Sderaadt * can't handle aggregated class A's, so we still check that, but
63df930be7Sderaadt * otherwise the only requirements are that the subnet address is
64df930be7Sderaadt * within the [ABC] range and that the host bits of the subnet
65df930be7Sderaadt * are all 0.
66df930be7Sderaadt */
67a17240f2Sderaadt int
inet_valid_subnet(u_int32_t nsubnet,u_int32_t nmask)685017e83eSderaadt inet_valid_subnet(u_int32_t nsubnet, u_int32_t nmask)
69df930be7Sderaadt {
70fcc7c6a8Stedu u_int32_t subnet, mask;
71df930be7Sderaadt
72df930be7Sderaadt subnet = ntohl(nsubnet);
73df930be7Sderaadt mask = ntohl(nmask);
74df930be7Sderaadt
75df930be7Sderaadt if ((subnet & mask) != subnet) return (FALSE);
76df930be7Sderaadt
77a17240f2Sderaadt if (subnet == 0)
78a17240f2Sderaadt return (mask == 0);
79df930be7Sderaadt
80df930be7Sderaadt if (IN_CLASSA(subnet)) {
81df930be7Sderaadt if (mask < 0xff000000 ||
82a17240f2Sderaadt (subnet & 0xff000000) == 0x7f000000 ||
83a17240f2Sderaadt (subnet & 0xff000000) == 0x00000000) return (FALSE);
84df930be7Sderaadt }
85*ef8f8f93Sclaudio else if (IN_CLASSD(subnet)) {
86df930be7Sderaadt /* Above Class C address space */
87df930be7Sderaadt return (FALSE);
88df930be7Sderaadt }
89a17240f2Sderaadt if (subnet & ~mask) {
90df930be7Sderaadt /* Host bits are set in the subnet */
91df930be7Sderaadt return (FALSE);
92df930be7Sderaadt }
93a17240f2Sderaadt if (!inet_valid_mask(mask)) {
94a17240f2Sderaadt /* Netmask is not contiguous */
95a17240f2Sderaadt return (FALSE);
96a17240f2Sderaadt }
97df930be7Sderaadt
98df930be7Sderaadt return (TRUE);
99df930be7Sderaadt }
100df930be7Sderaadt
101df930be7Sderaadt
102df930be7Sderaadt /*
103df930be7Sderaadt * Convert an IP address in u_long (network) format into a printable string.
104df930be7Sderaadt */
105a17240f2Sderaadt char *
inet_fmt(u_int32_t addr,char * s)1065017e83eSderaadt inet_fmt(u_int32_t addr, char *s)
107df930be7Sderaadt {
108fcc7c6a8Stedu u_char *a;
109df930be7Sderaadt
110df930be7Sderaadt a = (u_char *)&addr;
111c1cfc344Sderaadt snprintf(s, SNAMLEN, "%u.%u.%u.%u", a[0], a[1], a[2], a[3]);
112df930be7Sderaadt return (s);
113df930be7Sderaadt }
114df930be7Sderaadt
115df930be7Sderaadt
116df930be7Sderaadt /*
117df930be7Sderaadt * Convert an IP subnet number in u_long (network) format into a printable
118df930be7Sderaadt * string including the netmask as a number of bits.
119df930be7Sderaadt */
120a17240f2Sderaadt char *
inet_fmts(u_int32_t addr,u_int32_t mask,char * s)1215017e83eSderaadt inet_fmts(u_int32_t addr, u_int32_t mask, char *s)
122df930be7Sderaadt {
123fcc7c6a8Stedu u_char *a, *m;
124df930be7Sderaadt int bits;
125df930be7Sderaadt
126df930be7Sderaadt if ((addr == 0) && (mask == 0)) {
127c1cfc344Sderaadt snprintf(s, SNAMLEN, "default");
128df930be7Sderaadt return (s);
129df930be7Sderaadt }
130df930be7Sderaadt a = (u_char *)&addr;
131df930be7Sderaadt m = (u_char *)&mask;
132df930be7Sderaadt bits = 33 - ffs(ntohl(mask));
133df930be7Sderaadt
134c1cfc344Sderaadt if (m[3] != 0)
135c1cfc344Sderaadt snprintf(s, SNAMLEN, "%u.%u.%u.%u/%d", a[0], a[1], a[2], a[3], bits);
136c1cfc344Sderaadt else if (m[2] != 0)
137c1cfc344Sderaadt snprintf(s, SNAMLEN, "%u.%u.%u/%d", a[0], a[1], a[2], bits);
138c1cfc344Sderaadt else if (m[1] != 0)
139c1cfc344Sderaadt snprintf(s, SNAMLEN, "%u.%u/%d", a[0], a[1], bits);
140c1cfc344Sderaadt else
141c1cfc344Sderaadt snprintf(s, SNAMLEN, "%u/%d", a[0], bits);
142df930be7Sderaadt
143df930be7Sderaadt return (s);
144df930be7Sderaadt }
145df930be7Sderaadt
146df930be7Sderaadt /*
147df930be7Sderaadt * Convert the printable string representation of an IP address into the
148df930be7Sderaadt * u_long (network) format. Return 0xffffffff on error. (To detect the
149df930be7Sderaadt * legal address with that value, you must explicitly compare the string
150df930be7Sderaadt * with "255.255.255.255".)
151df930be7Sderaadt */
152a17240f2Sderaadt u_int32_t
inet_parse(char * s)1535017e83eSderaadt inet_parse(char *s)
154df930be7Sderaadt {
155df930be7Sderaadt u_int32_t a = 0;
156df930be7Sderaadt u_int a0, a1, a2, a3;
157df930be7Sderaadt char c;
158df930be7Sderaadt
159df930be7Sderaadt if (sscanf(s, "%u.%u.%u.%u%c", &a0, &a1, &a2, &a3, &c) != 4 ||
160df930be7Sderaadt a0 > 255 || a1 > 255 || a2 > 255 || a3 > 255)
161df930be7Sderaadt return (0xffffffff);
162df930be7Sderaadt
163df930be7Sderaadt ((u_char *)&a)[0] = a0;
164df930be7Sderaadt ((u_char *)&a)[1] = a1;
165df930be7Sderaadt ((u_char *)&a)[2] = a2;
166df930be7Sderaadt ((u_char *)&a)[3] = a3;
167df930be7Sderaadt
168df930be7Sderaadt return (a);
169df930be7Sderaadt }
170df930be7Sderaadt
171df930be7Sderaadt
172df930be7Sderaadt /*
173df930be7Sderaadt * inet_cksum extracted from:
174df930be7Sderaadt * P I N G . C
175df930be7Sderaadt *
176df930be7Sderaadt * Author -
177df930be7Sderaadt * Mike Muuss
178df930be7Sderaadt * U. S. Army Ballistic Research Laboratory
179df930be7Sderaadt * December, 1983
180df930be7Sderaadt * Modified at Uc Berkeley
181df930be7Sderaadt *
182df930be7Sderaadt * (ping.c) Status -
183df930be7Sderaadt * Public Domain. Distribution Unlimited.
184df930be7Sderaadt *
185df930be7Sderaadt * I N _ C K S U M
186df930be7Sderaadt *
187df930be7Sderaadt * Checksum routine for Internet Protocol family headers (C Version)
188df930be7Sderaadt *
189df930be7Sderaadt */
190a17240f2Sderaadt int
inet_cksum(u_int16_t * addr,u_int len)1915017e83eSderaadt inet_cksum(u_int16_t *addr, u_int len)
192df930be7Sderaadt {
193fcc7c6a8Stedu int nleft = (int)len;
194fcc7c6a8Stedu u_int16_t *w = addr;
19508c1e0f4Sitojun u_int16_t answer = 0;
196fcc7c6a8Stedu int32_t sum = 0;
197df930be7Sderaadt
198df930be7Sderaadt /*
199df930be7Sderaadt * Our algorithm is simple, using a 32 bit accumulator (sum),
200df930be7Sderaadt * we add sequential 16 bit words to it, and at the end, fold
201df930be7Sderaadt * back all the carry bits from the top 16 bits into the lower
202df930be7Sderaadt * 16 bits.
203df930be7Sderaadt */
204df930be7Sderaadt while (nleft > 1) {
205df930be7Sderaadt sum += *w++;
206df930be7Sderaadt nleft -= 2;
207df930be7Sderaadt }
208df930be7Sderaadt
209df930be7Sderaadt /* mop up an odd byte, if necessary */
210df930be7Sderaadt if (nleft == 1) {
211df930be7Sderaadt *(u_char *) (&answer) = *(u_char *)w ;
212df930be7Sderaadt sum += answer;
213df930be7Sderaadt }
214df930be7Sderaadt
215df930be7Sderaadt /*
216df930be7Sderaadt * add back carry outs from top 16 bits to low 16 bits
217df930be7Sderaadt */
218df930be7Sderaadt sum = (sum >> 16) + (sum & 0xffff); /* add hi 16 to low 16 */
219df930be7Sderaadt sum += (sum >> 16); /* add carry */
220df930be7Sderaadt answer = ~sum; /* truncate to 16 bits */
221df930be7Sderaadt return (answer);
222df930be7Sderaadt }
223