Mercurial > dropbear

annotate libtomcrypt/src/pk/asn1/der/octet/der_decode_octet_string.c @ 404:a588558bfc94

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Fix potential null pointer dereference found by Klokwork
author Matt Johnston <matt@ucc.asn.au>
date Sat, 03 Feb 2007 09:58:14 +0000
parents 1b9e69c058d2
children 0cbe8f6dbf9e
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
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285
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1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis
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2 *
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3 * LibTomCrypt is a library that provides various cryptographic
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4 * algorithms in a highly modular and flexible manner.
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5 *
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6 * The library is free for all purposes without any express
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7 * guarantee it works.
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8 *
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9 * Tom St Denis, [email protected], http://libtomcrypt.org
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10 */
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11 #include "tomcrypt.h"
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12
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13 /**
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14 @file der_decode_octet_string.c
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15 ASN.1 DER, encode a OCTET STRING, Tom St Denis
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16 */
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17
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18
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19 #ifdef LTC_DER
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20
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21 /**
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22 Store a OCTET STRING
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23 @param in The DER encoded OCTET STRING
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24 @param inlen The size of the DER OCTET STRING
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25 @param out [out] The array of octets stored (one per char)
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26 @param outlen [in/out] The number of octets stored
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27 @return CRYPT_OK if successful
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28 */
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29 int der_decode_octet_string(const unsigned char *in, unsigned long inlen,
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30 unsigned char *out, unsigned long *outlen)
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31 {
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32 unsigned long x, y, len;
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33
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34 LTC_ARGCHK(in != NULL);
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35 LTC_ARGCHK(out != NULL);
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36 LTC_ARGCHK(outlen != NULL);
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37
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38 /* must have header at least */
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39 if (inlen < 2) {
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40 return CRYPT_INVALID_PACKET;
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41 }
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42
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43 /* check for 0x04 */
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44 if ((in[0] & 0x1F) != 0x04) {
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45 return CRYPT_INVALID_PACKET;
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46 }
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47 x = 1;
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48
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49 /* decode the length */
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50 if (in[x] & 0x80) {
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51 /* valid # of bytes in length are 1,2,3 */
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52 y = in[x] & 0x7F;
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53 if ((y == 0) || (y > 3) || ((x + y) > inlen)) {
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54 return CRYPT_INVALID_PACKET;
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55 }
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56
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57 /* read the length in */
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58 len = 0;
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59 ++x;
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60 while (y--) {
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61 len = (len << 8) | in[x++];
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62 }
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63 } else {
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64 len = in[x++] & 0x7F;
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65 }
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66
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67 /* is it too long? */
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68 if (len > *outlen) {
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69 return CRYPT_BUFFER_OVERFLOW;
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70 }
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71
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72 if (len + x > inlen) {
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73 return CRYPT_INVALID_PACKET;
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74 }
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75
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76 /* read the data */
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77 for (y = 0; y < len; y++) {
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78 out[y] = in[x++];
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79 }
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80
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81 *outlen = y;
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82
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83 return CRYPT_OK;
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84 }
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85
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86 #endif
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87
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88 /* $Source: /cvs/libtom/libtomcrypt/src/pk/asn1/der/octet/der_decode_octet_string.c,v $ */
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89 /* $Revision: 1.1 $ */
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90 /* $Date: 2005/05/16 15:08:11 $ */