Annotation of src/usr.bin/ssh/bufaux.c, Revision 1.19
1.1 deraadt 1: /*
1.6 deraadt 2: * Author: Tatu Ylonen <ylo@cs.hut.fi>
3: * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
4: * All rights reserved
1.13 deraadt 5: * Auxiliary functions for storing and retrieving various data types to/from
6: * Buffers.
1.11 markus 7: *
1.13 deraadt 8: * As far as I am concerned, the code I have written for this software
9: * can be used freely for any purpose. Any derived versions of this
10: * software must be clearly marked as such, and if the derived work is
11: * incompatible with the protocol description in the RFC file, it must be
12: * called by a name other than "ssh" or "Secure Shell".
1.11 markus 13: *
1.6 deraadt 14: *
1.9 markus 15: * SSH2 packet format added by Markus Friedl
1.13 deraadt 16: * Copyright (c) 2000 Markus Friedl. All rights reserved.
1.9 markus 17: *
1.13 deraadt 18: * Redistribution and use in source and binary forms, with or without
19: * modification, are permitted provided that the following conditions
20: * are met:
21: * 1. Redistributions of source code must retain the above copyright
22: * notice, this list of conditions and the following disclaimer.
23: * 2. Redistributions in binary form must reproduce the above copyright
24: * notice, this list of conditions and the following disclaimer in the
25: * documentation and/or other materials provided with the distribution.
26: *
27: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
28: * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
29: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
30: * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
31: * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
32: * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
33: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
34: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
35: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
36: * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
1.6 deraadt 37: */
1.1 deraadt 38:
39: #include "includes.h"
1.19 ! deraadt 40: RCSID("$OpenBSD: bufaux.c,v 1.18 2001/12/05 10:06:12 deraadt Exp $");
1.1 deraadt 41:
1.10 markus 42: #include <openssl/bn.h>
1.1 deraadt 43: #include "bufaux.h"
44: #include "xmalloc.h"
45: #include "getput.h"
1.17 markus 46: #include "log.h"
1.1 deraadt 47:
1.6 deraadt 48: /*
49: * Stores an BIGNUM in the buffer with a 2-byte msb first bit count, followed
50: * by (bits+7)/8 bytes of binary data, msb first.
51: */
1.2 provos 52: void
53: buffer_put_bignum(Buffer *buffer, BIGNUM *value)
1.1 deraadt 54: {
1.5 markus 55: int bits = BN_num_bits(value);
56: int bin_size = (bits + 7) / 8;
1.14 markus 57: u_char *buf = xmalloc(bin_size);
1.5 markus 58: int oi;
59: char msg[2];
60:
61: /* Get the value of in binary */
62: oi = BN_bn2bin(value, buf);
63: if (oi != bin_size)
64: fatal("buffer_put_bignum: BN_bn2bin() failed: oi %d != bin_size %d",
1.19 ! deraadt 65: oi, bin_size);
1.5 markus 66:
67: /* Store the number of bits in the buffer in two bytes, msb first. */
68: PUT_16BIT(msg, bits);
69: buffer_append(buffer, msg, 2);
70: /* Store the binary data. */
1.8 markus 71: buffer_append(buffer, (char *)buf, oi);
1.7 markus 72:
1.5 markus 73: memset(buf, 0, bin_size);
74: xfree(buf);
1.1 deraadt 75: }
76:
1.6 deraadt 77: /*
78: * Retrieves an BIGNUM from the buffer.
79: */
1.2 provos 80: int
81: buffer_get_bignum(Buffer *buffer, BIGNUM *value)
1.1 deraadt 82: {
1.5 markus 83: int bits, bytes;
1.14 markus 84: u_char buf[2], *bin;
1.1 deraadt 85:
1.5 markus 86: /* Get the number for bits. */
87: buffer_get(buffer, (char *) buf, 2);
88: bits = GET_16BIT(buf);
89: /* Compute the number of binary bytes that follow. */
90: bytes = (bits + 7) / 8;
91: if (buffer_len(buffer) < bytes)
92: fatal("buffer_get_bignum: input buffer too small");
1.16 deraadt 93: bin = (u_char *) buffer_ptr(buffer);
1.5 markus 94: BN_bin2bn(bin, bytes, value);
95: buffer_consume(buffer, bytes);
1.2 provos 96:
1.5 markus 97: return 2 + bytes;
1.1 deraadt 98: }
99:
1.6 deraadt 100: /*
1.9 markus 101: * Stores an BIGNUM in the buffer in SSH2 format.
102: */
103: void
104: buffer_put_bignum2(Buffer *buffer, BIGNUM *value)
105: {
106: int bytes = BN_num_bytes(value) + 1;
1.14 markus 107: u_char *buf = xmalloc(bytes);
1.9 markus 108: int oi;
109: int hasnohigh = 0;
110: buf[0] = '\0';
111: /* Get the value of in binary */
112: oi = BN_bn2bin(value, buf+1);
113: if (oi != bytes-1)
114: fatal("buffer_put_bignum: BN_bn2bin() failed: oi %d != bin_size %d",
1.19 ! deraadt 115: oi, bytes);
1.9 markus 116: hasnohigh = (buf[1] & 0x80) ? 0 : 1;
117: if (value->neg) {
118: /**XXX should be two's-complement */
119: int i, carry;
1.14 markus 120: u_char *uc = buf;
1.9 markus 121: log("negativ!");
1.19 ! deraadt 122: for (i = bytes-1, carry = 1; i>=0; i--) {
1.9 markus 123: uc[i] ^= 0xff;
1.18 deraadt 124: if (carry)
1.9 markus 125: carry = !++uc[i];
126: }
127: }
128: buffer_put_string(buffer, buf+hasnohigh, bytes-hasnohigh);
129: memset(buf, 0, bytes);
130: xfree(buf);
131: }
132:
133: int
134: buffer_get_bignum2(Buffer *buffer, BIGNUM *value)
135: {
136: /**XXX should be two's-complement */
137: int len;
1.14 markus 138: u_char *bin = (u_char *)buffer_get_string(buffer, (u_int *)&len);
1.9 markus 139: BN_bin2bn(bin, len, value);
140: xfree(bin);
141: return len;
142: }
143:
144: /*
1.6 deraadt 145: * Returns an integer from the buffer (4 bytes, msb first).
146: */
1.14 markus 147: u_int
1.5 markus 148: buffer_get_int(Buffer *buffer)
1.1 deraadt 149: {
1.14 markus 150: u_char buf[4];
1.5 markus 151: buffer_get(buffer, (char *) buf, 4);
152: return GET_32BIT(buf);
1.1 deraadt 153: }
154:
1.15 markus 155: u_int64_t
156: buffer_get_int64(Buffer *buffer)
157: {
158: u_char buf[8];
159: buffer_get(buffer, (char *) buf, 8);
160: return GET_64BIT(buf);
161: }
162:
1.6 deraadt 163: /*
164: * Stores an integer in the buffer in 4 bytes, msb first.
165: */
1.11 markus 166: void
1.14 markus 167: buffer_put_int(Buffer *buffer, u_int value)
1.1 deraadt 168: {
1.5 markus 169: char buf[4];
170: PUT_32BIT(buf, value);
171: buffer_append(buffer, buf, 4);
1.15 markus 172: }
173:
174: void
175: buffer_put_int64(Buffer *buffer, u_int64_t value)
176: {
177: char buf[8];
178: PUT_64BIT(buf, value);
179: buffer_append(buffer, buf, 8);
1.1 deraadt 180: }
181:
1.6 deraadt 182: /*
183: * Returns an arbitrary binary string from the buffer. The string cannot
184: * be longer than 256k. The returned value points to memory allocated
185: * with xmalloc; it is the responsibility of the calling function to free
186: * the data. If length_ptr is non-NULL, the length of the returned data
187: * will be stored there. A null character will be automatically appended
188: * to the returned string, and is not counted in length.
189: */
1.5 markus 190: char *
1.14 markus 191: buffer_get_string(Buffer *buffer, u_int *length_ptr)
1.1 deraadt 192: {
1.14 markus 193: u_int len;
1.5 markus 194: char *value;
195: /* Get the length. */
196: len = buffer_get_int(buffer);
197: if (len > 256 * 1024)
198: fatal("Received packet with bad string length %d", len);
199: /* Allocate space for the string. Add one byte for a null character. */
200: value = xmalloc(len + 1);
201: /* Get the string. */
202: buffer_get(buffer, value, len);
203: /* Append a null character to make processing easier. */
204: value[len] = 0;
205: /* Optionally return the length of the string. */
206: if (length_ptr)
207: *length_ptr = len;
208: return value;
1.1 deraadt 209: }
210:
1.6 deraadt 211: /*
212: * Stores and arbitrary binary string in the buffer.
213: */
1.11 markus 214: void
1.14 markus 215: buffer_put_string(Buffer *buffer, const void *buf, u_int len)
1.1 deraadt 216: {
1.5 markus 217: buffer_put_int(buffer, len);
218: buffer_append(buffer, buf, len);
1.9 markus 219: }
1.11 markus 220: void
1.9 markus 221: buffer_put_cstring(Buffer *buffer, const char *s)
222: {
223: buffer_put_string(buffer, s, strlen(s));
1.1 deraadt 224: }
225:
1.6 deraadt 226: /*
227: * Returns a character from the buffer (0 - 255).
228: */
1.11 markus 229: int
1.5 markus 230: buffer_get_char(Buffer *buffer)
1.1 deraadt 231: {
1.5 markus 232: char ch;
233: buffer_get(buffer, &ch, 1);
1.14 markus 234: return (u_char) ch;
1.1 deraadt 235: }
236:
1.6 deraadt 237: /*
238: * Stores a character in the buffer.
239: */
1.11 markus 240: void
1.5 markus 241: buffer_put_char(Buffer *buffer, int value)
1.1 deraadt 242: {
1.5 markus 243: char ch = value;
244: buffer_append(buffer, &ch, 1);
1.1 deraadt 245: }
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