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1.1 root 1: /*
2: * Copyright (c) 1985 Regents of the University of California.
3: * All rights reserved.
4: *
5: * Redistribution and use in source and binary forms are permitted provided
6: * that: (1) source distributions retain this entire copyright notice and
7: * comment, and (2) distributions including binaries display the following
8: * acknowledgement: ``This product includes software developed by the
9: * University of California, Berkeley and its contributors'' in the
10: * documentation or other materials provided with the distribution and in
11: * all advertising materials mentioning features or use of this software.
12: * Neither the name of the University nor the names of its contributors may
13: * be used to endorse or promote products derived from this software without
14: * specific prior written permission.
15: * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
16: * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
17: * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
18: */
19:
20: #if defined(LIBC_SCCS) && !defined(lint)
21: static char sccsid[] = "@(#)res_comp.c 6.18 (Berkeley) 6/27/90";
22: #endif /* LIBC_SCCS and not lint */
23:
24: #include <sys/types.h>
25: #include <stdio.h>
26: #include <arpa/nameser.h>
27:
28: static dn_find();
29:
30: /*
31: * Expand compressed domain name 'comp_dn' to full domain name.
32: * 'msg' is a pointer to the begining of the message,
33: * 'eomorig' points to the first location after the message,
34: * 'exp_dn' is a pointer to a buffer of size 'length' for the result.
35: * Return size of compressed name or -1 if there was an error.
36: */
37: dn_expand(msg, eomorig, comp_dn, exp_dn, length)
38: u_char *msg, *eomorig, *comp_dn, *exp_dn;
39: int length;
40: {
41: register u_char *cp, *dn;
42: register int n, c;
43: u_char *eom;
44: int len = -1, checked = 0;
45:
46: dn = exp_dn;
47: cp = comp_dn;
48: eom = exp_dn + length;
49: /*
50: * fetch next label in domain name
51: */
52: while (n = *cp++) {
53: /*
54: * Check for indirection
55: */
56: switch (n & INDIR_MASK) {
57: case 0:
58: if (dn != exp_dn) {
59: if (dn >= eom)
60: return (-1);
61: *dn++ = '.';
62: }
63: if (dn+n >= eom)
64: return (-1);
65: checked += n + 1;
66: while (--n >= 0) {
67: if ((c = *cp++) == '.') {
68: if (dn + n + 2 >= eom)
69: return (-1);
70: *dn++ = '\\';
71: }
72: *dn++ = c;
73: if (cp >= eomorig) /* out of range */
74: return(-1);
75: }
76: break;
77:
78: case INDIR_MASK:
79: if (len < 0)
80: len = cp - comp_dn + 1;
81: cp = msg + (((n & 0x3f) << 8) | (*cp & 0xff));
82: if (cp < msg || cp >= eomorig) /* out of range */
83: return(-1);
84: checked += 2;
85: /*
86: * Check for loops in the compressed name;
87: * if we've looked at the whole message,
88: * there must be a loop.
89: */
90: if (checked >= eomorig - msg)
91: return (-1);
92: break;
93:
94: default:
95: return (-1); /* flag error */
96: }
97: }
98: *dn = '\0';
99: if (len < 0)
100: len = cp - comp_dn;
101: return (len);
102: }
103:
104: /*
105: * Compress domain name 'exp_dn' into 'comp_dn'.
106: * Return the size of the compressed name or -1.
107: * 'length' is the size of the array pointed to by 'comp_dn'.
108: * 'dnptrs' is a list of pointers to previous compressed names. dnptrs[0]
109: * is a pointer to the beginning of the message. The list ends with NULL.
110: * 'lastdnptr' is a pointer to the end of the arrary pointed to
111: * by 'dnptrs'. Side effect is to update the list of pointers for
112: * labels inserted into the message as we compress the name.
113: * If 'dnptr' is NULL, we don't try to compress names. If 'lastdnptr'
114: * is NULL, we don't update the list.
115: */
116: dn_comp(exp_dn, comp_dn, length, dnptrs, lastdnptr)
117: u_char *exp_dn, *comp_dn;
118: int length;
119: u_char **dnptrs, **lastdnptr;
120: {
121: register u_char *cp, *dn;
122: register int c, l;
123: u_char **cpp, **lpp, *sp, *eob;
124: u_char *msg;
125:
126: dn = exp_dn;
127: cp = comp_dn;
128: eob = cp + length;
129: if (dnptrs != NULL) {
130: if ((msg = *dnptrs++) != NULL) {
131: for (cpp = dnptrs; *cpp != NULL; cpp++)
132: ;
133: lpp = cpp; /* end of list to search */
134: }
135: } else
136: msg = NULL;
137: for (c = *dn++; c != '\0'; ) {
138: /* look to see if we can use pointers */
139: if (msg != NULL) {
140: if ((l = dn_find(dn-1, msg, dnptrs, lpp)) >= 0) {
141: if (cp+1 >= eob)
142: return (-1);
143: *cp++ = (l >> 8) | INDIR_MASK;
144: *cp++ = l % 256;
145: return (cp - comp_dn);
146: }
147: /* not found, save it */
148: if (lastdnptr != NULL && cpp < lastdnptr-1) {
149: *cpp++ = cp;
150: *cpp = NULL;
151: }
152: }
153: sp = cp++; /* save ptr to length byte */
154: do {
155: if (c == '.') {
156: c = *dn++;
157: break;
158: }
159: if (c == '\\') {
160: if ((c = *dn++) == '\0')
161: break;
162: }
163: if (cp >= eob) {
164: if (msg != NULL)
165: *lpp = NULL;
166: return (-1);
167: }
168: *cp++ = c;
169: } while ((c = *dn++) != '\0');
170: /* catch trailing '.'s but not '..' */
171: if ((l = cp - sp - 1) == 0 && c == '\0') {
172: cp--;
173: break;
174: }
175: if (l <= 0 || l > MAXLABEL) {
176: if (msg != NULL)
177: *lpp = NULL;
178: return (-1);
179: }
180: *sp = l;
181: }
182: if (cp >= eob) {
183: if (msg != NULL)
184: *lpp = NULL;
185: return (-1);
186: }
187: *cp++ = '\0';
188: return (cp - comp_dn);
189: }
190:
191: /*
192: * Skip over a compressed domain name. Return the size or -1.
193: */
194: dn_skipname(comp_dn, eom)
195: u_char *comp_dn, *eom;
196: {
197: register u_char *cp;
198: register int n;
199:
200: cp = comp_dn;
201: while (cp < eom && (n = *cp++)) {
202: /*
203: * check for indirection
204: */
205: switch (n & INDIR_MASK) {
206: case 0: /* normal case, n == len */
207: cp += n;
208: continue;
209: default: /* illegal type */
210: return (-1);
211: case INDIR_MASK: /* indirection */
212: cp++;
213: }
214: break;
215: }
216: return (cp - comp_dn);
217: }
218:
219: /*
220: * Search for expanded name from a list of previously compressed names.
221: * Return the offset from msg if found or -1.
222: * dnptrs is the pointer to the first name on the list,
223: * not the pointer to the start of the message.
224: */
225: static
226: dn_find(exp_dn, msg, dnptrs, lastdnptr)
227: u_char *exp_dn, *msg;
228: u_char **dnptrs, **lastdnptr;
229: {
230: register u_char *dn, *cp, **cpp;
231: register int n;
232: u_char *sp;
233:
234: for (cpp = dnptrs; cpp < lastdnptr; cpp++) {
235: dn = exp_dn;
236: sp = cp = *cpp;
237: while (n = *cp++) {
238: /*
239: * check for indirection
240: */
241: switch (n & INDIR_MASK) {
242: case 0: /* normal case, n == len */
243: while (--n >= 0) {
244: if (*dn == '.')
245: goto next;
246: if (*dn == '\\')
247: dn++;
248: if (*dn++ != *cp++)
249: goto next;
250: }
251: if ((n = *dn++) == '\0' && *cp == '\0')
252: return (sp - msg);
253: if (n == '.')
254: continue;
255: goto next;
256:
257: default: /* illegal type */
258: return (-1);
259:
260: case INDIR_MASK: /* indirection */
261: cp = msg + (((n & 0x3f) << 8) | *cp);
262: }
263: }
264: if (*dn == '\0')
265: return (sp - msg);
266: next: ;
267: }
268: return (-1);
269: }
270:
271: /*
272: * Routines to insert/extract short/long's. Must account for byte
273: * order and non-alignment problems. This code at least has the
274: * advantage of being portable.
275: *
276: * used by sendmail.
277: */
278:
279: u_short
280: _getshort(msgp)
281: u_char *msgp;
282: {
283: register u_char *p = (u_char *) msgp;
284: #ifdef vax
285: /*
286: * vax compiler doesn't put shorts in registers
287: */
288: register u_long u;
289: #else
290: register u_short u;
291: #endif
292:
293: u = *p++ << 8;
294: return ((u_short)(u | *p));
295: }
296:
297: u_long
298: _getlong(msgp)
299: u_char *msgp;
300: {
301: register u_char *p = (u_char *) msgp;
302: register u_long u;
303:
304: u = *p++; u <<= 8;
305: u |= *p++; u <<= 8;
306: u |= *p++; u <<= 8;
307: return (u | *p);
308: }
309:
310:
311: putshort(s, msgp)
312: register u_short s;
313: register u_char *msgp;
314: {
315:
316: msgp[1] = s;
317: msgp[0] = s >> 8;
318: }
319:
320: putlong(l, msgp)
321: register u_long l;
322: register u_char *msgp;
323: {
324:
325: msgp[3] = l;
326: msgp[2] = (l >>= 8);
327: msgp[1] = (l >>= 8);
328: msgp[0] = l >> 8;
329: }
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