1 | /*
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2 | * Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.
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3 | *
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4 | * Licensed under the OpenSSL license (the "License"). You may not use
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5 | * this file except in compliance with the License. You can obtain a copy
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6 | * in the file LICENSE in the source distribution or at
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7 | * https://www.openssl.org/source/license.html
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8 | */
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9 |
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10 | /*-
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11 | From: Arne Ansper <arne@cyber.ee>
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12 |
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13 | Why BIO_f_reliable?
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14 |
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15 | I wrote function which took BIO* as argument, read data from it
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16 | and processed it. Then I wanted to store the input file in
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17 | encrypted form. OK I pushed BIO_f_cipher to the BIO stack
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18 | and everything was OK. BUT if user types wrong password
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19 | BIO_f_cipher outputs only garbage and my function crashes. Yes
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20 | I can and I should fix my function, but BIO_f_cipher is
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21 | easy way to add encryption support to many existing applications
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22 | and it's hard to debug and fix them all.
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23 |
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24 | So I wanted another BIO which would catch the incorrect passwords and
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25 | file damages which cause garbage on BIO_f_cipher's output.
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26 |
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27 | The easy way is to push the BIO_f_md and save the checksum at
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28 | the end of the file. However there are several problems with this
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29 | approach:
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30 |
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31 | 1) you must somehow separate checksum from actual data.
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32 | 2) you need lot's of memory when reading the file, because you
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33 | must read to the end of the file and verify the checksum before
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34 | letting the application to read the data.
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35 |
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36 | BIO_f_reliable tries to solve both problems, so that you can
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37 | read and write arbitrary long streams using only fixed amount
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38 | of memory.
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39 |
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40 | BIO_f_reliable splits data stream into blocks. Each block is prefixed
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41 | with it's length and suffixed with it's digest. So you need only
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42 | several Kbytes of memory to buffer single block before verifying
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43 | it's digest.
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44 |
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45 | BIO_f_reliable goes further and adds several important capabilities:
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46 |
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47 | 1) the digest of the block is computed over the whole stream
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48 | -- so nobody can rearrange the blocks or remove or replace them.
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49 |
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50 | 2) to detect invalid passwords right at the start BIO_f_reliable
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51 | adds special prefix to the stream. In order to avoid known plain-text
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52 | attacks this prefix is generated as follows:
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53 |
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54 | *) digest is initialized with random seed instead of
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55 | standardized one.
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56 | *) same seed is written to output
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57 | *) well-known text is then hashed and the output
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58 | of the digest is also written to output.
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59 |
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60 | reader can now read the seed from stream, hash the same string
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61 | and then compare the digest output.
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62 |
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63 | Bad things: BIO_f_reliable knows what's going on in EVP_Digest. I
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64 | initially wrote and tested this code on x86 machine and wrote the
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65 | digests out in machine-dependent order :( There are people using
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66 | this code and I cannot change this easily without making existing
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67 | data files unreadable.
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68 |
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69 | */
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70 |
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71 | #include <stdio.h>
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72 | #include <errno.h>
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73 | #include <assert.h>
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74 | #include "internal/cryptlib.h"
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75 | #include <openssl/buffer.h>
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76 | #include "internal/bio.h"
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77 | #include <openssl/evp.h>
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78 | #include <openssl/rand.h>
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79 | #include "internal/evp_int.h"
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80 |
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81 | static int ok_write(BIO *h, const char *buf, int num);
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82 | static int ok_read(BIO *h, char *buf, int size);
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83 | static long ok_ctrl(BIO *h, int cmd, long arg1, void *arg2);
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84 | static int ok_new(BIO *h);
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85 | static int ok_free(BIO *data);
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86 | static long ok_callback_ctrl(BIO *h, int cmd, bio_info_cb *fp);
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87 |
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88 | static __owur int sig_out(BIO *b);
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89 | static __owur int sig_in(BIO *b);
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90 | static __owur int block_out(BIO *b);
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91 | static __owur int block_in(BIO *b);
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92 | #define OK_BLOCK_SIZE (1024*4)
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93 | #define OK_BLOCK_BLOCK 4
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94 | #define IOBS (OK_BLOCK_SIZE+ OK_BLOCK_BLOCK+ 3*EVP_MAX_MD_SIZE)
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95 | #define WELLKNOWN "The quick brown fox jumped over the lazy dog's back."
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96 |
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97 | typedef struct ok_struct {
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98 | size_t buf_len;
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99 | size_t buf_off;
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100 | size_t buf_len_save;
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101 | size_t buf_off_save;
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102 | int cont; /* <= 0 when finished */
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103 | int finished;
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104 | EVP_MD_CTX *md;
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105 | int blockout; /* output block is ready */
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106 | int sigio; /* must process signature */
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107 | unsigned char buf[IOBS];
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108 | } BIO_OK_CTX;
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109 |
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110 | static const BIO_METHOD methods_ok = {
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111 | BIO_TYPE_CIPHER, "reliable",
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112 | ok_write,
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113 | ok_read,
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114 | NULL, /* ok_puts, */
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115 | NULL, /* ok_gets, */
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116 | ok_ctrl,
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117 | ok_new,
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118 | ok_free,
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119 | ok_callback_ctrl,
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120 | };
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121 |
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122 | const BIO_METHOD *BIO_f_reliable(void)
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123 | {
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124 | return (&methods_ok);
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125 | }
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126 |
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127 | static int ok_new(BIO *bi)
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128 | {
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129 | BIO_OK_CTX *ctx;
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130 |
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131 | ctx = OPENSSL_zalloc(sizeof(*ctx));
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132 | if (ctx == NULL)
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133 | return 0;
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134 |
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135 | ctx->cont = 1;
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136 | ctx->sigio = 1;
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137 | ctx->md = EVP_MD_CTX_new();
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138 | if (ctx->md == NULL) {
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139 | OPENSSL_free(ctx);
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140 | return 0;
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141 | }
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142 | BIO_set_init(bi, 0);
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143 | BIO_set_data(bi, ctx);
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144 |
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145 | return 1;
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146 | }
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147 |
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148 | static int ok_free(BIO *a)
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149 | {
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150 | BIO_OK_CTX *ctx;
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151 |
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152 | if (a == NULL)
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153 | return 0;
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154 |
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155 | ctx = BIO_get_data(a);
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156 |
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157 | EVP_MD_CTX_free(ctx->md);
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158 | OPENSSL_clear_free(ctx, sizeof(BIO_OK_CTX));
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159 | BIO_set_data(a, NULL);
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160 | BIO_set_init(a, 0);
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161 |
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162 | return 1;
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163 | }
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164 |
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165 | static int ok_read(BIO *b, char *out, int outl)
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166 | {
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167 | int ret = 0, i, n;
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168 | BIO_OK_CTX *ctx;
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169 | BIO *next;
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170 |
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171 | if (out == NULL)
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172 | return 0;
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173 |
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174 | ctx = BIO_get_data(b);
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175 | next = BIO_next(b);
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176 |
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177 | if ((ctx == NULL) || (next == NULL) || (BIO_get_init(b) == 0))
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178 | return 0;
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179 |
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180 | while (outl > 0) {
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181 |
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182 | /* copy clean bytes to output buffer */
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183 | if (ctx->blockout) {
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184 | i = ctx->buf_len - ctx->buf_off;
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185 | if (i > outl)
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186 | i = outl;
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187 | memcpy(out, &(ctx->buf[ctx->buf_off]), i);
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188 | ret += i;
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189 | out += i;
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190 | outl -= i;
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191 | ctx->buf_off += i;
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192 |
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193 | /* all clean bytes are out */
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194 | if (ctx->buf_len == ctx->buf_off) {
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195 | ctx->buf_off = 0;
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196 |
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197 | /*
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198 | * copy start of the next block into proper place
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199 | */
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200 | if (ctx->buf_len_save - ctx->buf_off_save > 0) {
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201 | ctx->buf_len = ctx->buf_len_save - ctx->buf_off_save;
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202 | memmove(ctx->buf, &(ctx->buf[ctx->buf_off_save]),
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203 | ctx->buf_len);
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204 | } else {
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205 | ctx->buf_len = 0;
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206 | }
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207 | ctx->blockout = 0;
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208 | }
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209 | }
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210 |
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211 | /* output buffer full -- cancel */
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212 | if (outl == 0)
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213 | break;
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214 |
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215 | /* no clean bytes in buffer -- fill it */
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216 | n = IOBS - ctx->buf_len;
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217 | i = BIO_read(next, &(ctx->buf[ctx->buf_len]), n);
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218 |
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219 | if (i <= 0)
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220 | break; /* nothing new */
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221 |
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222 | ctx->buf_len += i;
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223 |
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224 | /* no signature yet -- check if we got one */
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225 | if (ctx->sigio == 1) {
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226 | if (!sig_in(b)) {
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227 | BIO_clear_retry_flags(b);
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228 | return 0;
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229 | }
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230 | }
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231 |
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232 | /* signature ok -- check if we got block */
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233 | if (ctx->sigio == 0) {
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234 | if (!block_in(b)) {
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235 | BIO_clear_retry_flags(b);
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236 | return 0;
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237 | }
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238 | }
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239 |
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240 | /* invalid block -- cancel */
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241 | if (ctx->cont <= 0)
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242 | break;
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243 |
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244 | }
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245 |
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246 | BIO_clear_retry_flags(b);
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247 | BIO_copy_next_retry(b);
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248 | return ret;
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249 | }
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250 |
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251 | static int ok_write(BIO *b, const char *in, int inl)
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252 | {
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253 | int ret = 0, n, i;
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254 | BIO_OK_CTX *ctx;
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255 | BIO *next;
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256 |
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257 | if (inl <= 0)
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258 | return inl;
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259 |
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260 | ctx = BIO_get_data(b);
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261 | next = BIO_next(b);
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262 | ret = inl;
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263 |
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264 | if ((ctx == NULL) || (next == NULL) || (BIO_get_init(b) == 0))
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265 | return (0);
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266 |
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267 | if (ctx->sigio && !sig_out(b))
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268 | return 0;
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269 |
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270 | do {
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271 | BIO_clear_retry_flags(b);
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272 | n = ctx->buf_len - ctx->buf_off;
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273 | while (ctx->blockout && n > 0) {
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274 | i = BIO_write(next, &(ctx->buf[ctx->buf_off]), n);
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275 | if (i <= 0) {
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276 | BIO_copy_next_retry(b);
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277 | if (!BIO_should_retry(b))
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278 | ctx->cont = 0;
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279 | return (i);
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280 | }
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281 | ctx->buf_off += i;
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282 | n -= i;
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283 | }
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284 |
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285 | /* at this point all pending data has been written */
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286 | ctx->blockout = 0;
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287 | if (ctx->buf_len == ctx->buf_off) {
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288 | ctx->buf_len = OK_BLOCK_BLOCK;
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289 | ctx->buf_off = 0;
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290 | }
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291 |
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292 | if ((in == NULL) || (inl <= 0))
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293 | return (0);
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294 |
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295 | n = (inl + ctx->buf_len > OK_BLOCK_SIZE + OK_BLOCK_BLOCK) ?
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296 | (int)(OK_BLOCK_SIZE + OK_BLOCK_BLOCK - ctx->buf_len) : inl;
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297 |
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298 | memcpy(&ctx->buf[ctx->buf_len], in, n);
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299 | ctx->buf_len += n;
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300 | inl -= n;
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301 | in += n;
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302 |
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303 | if (ctx->buf_len >= OK_BLOCK_SIZE + OK_BLOCK_BLOCK) {
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304 | if (!block_out(b)) {
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305 | BIO_clear_retry_flags(b);
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306 | return 0;
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307 | }
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308 | }
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309 | } while (inl > 0);
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310 |
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311 | BIO_clear_retry_flags(b);
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312 | BIO_copy_next_retry(b);
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313 | return (ret);
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314 | }
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315 |
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316 | static long ok_ctrl(BIO *b, int cmd, long num, void *ptr)
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317 | {
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318 | BIO_OK_CTX *ctx;
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319 | EVP_MD *md;
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320 | const EVP_MD **ppmd;
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321 | long ret = 1;
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322 | int i;
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323 | BIO *next;
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324 |
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325 | ctx = BIO_get_data(b);
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326 | next = BIO_next(b);
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327 |
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328 | switch (cmd) {
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329 | case BIO_CTRL_RESET:
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330 | ctx->buf_len = 0;
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331 | ctx->buf_off = 0;
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332 | ctx->buf_len_save = 0;
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333 | ctx->buf_off_save = 0;
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334 | ctx->cont = 1;
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335 | ctx->finished = 0;
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336 | ctx->blockout = 0;
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337 | ctx->sigio = 1;
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338 | ret = BIO_ctrl(next, cmd, num, ptr);
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339 | break;
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340 | case BIO_CTRL_EOF: /* More to read */
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341 | if (ctx->cont <= 0)
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342 | ret = 1;
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343 | else
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344 | ret = BIO_ctrl(next, cmd, num, ptr);
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345 | break;
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346 | case BIO_CTRL_PENDING: /* More to read in buffer */
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347 | case BIO_CTRL_WPENDING: /* More to read in buffer */
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348 | ret = ctx->blockout ? ctx->buf_len - ctx->buf_off : 0;
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349 | if (ret <= 0)
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350 | ret = BIO_ctrl(next, cmd, num, ptr);
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351 | break;
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352 | case BIO_CTRL_FLUSH:
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353 | /* do a final write */
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354 | if (ctx->blockout == 0)
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355 | if (!block_out(b))
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356 | return 0;
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357 |
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358 | while (ctx->blockout) {
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359 | i = ok_write(b, NULL, 0);
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360 | if (i < 0) {
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361 | ret = i;
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362 | break;
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363 | }
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364 | }
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365 |
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366 | ctx->finished = 1;
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367 | ctx->buf_off = ctx->buf_len = 0;
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368 | ctx->cont = (int)ret;
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369 |
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370 | /* Finally flush the underlying BIO */
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371 | ret = BIO_ctrl(next, cmd, num, ptr);
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372 | break;
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373 | case BIO_C_DO_STATE_MACHINE:
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374 | BIO_clear_retry_flags(b);
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375 | ret = BIO_ctrl(next, cmd, num, ptr);
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376 | BIO_copy_next_retry(b);
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377 | break;
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378 | case BIO_CTRL_INFO:
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379 | ret = (long)ctx->cont;
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380 | break;
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381 | case BIO_C_SET_MD:
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382 | md = ptr;
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383 | if (!EVP_DigestInit_ex(ctx->md, md, NULL))
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384 | return 0;
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385 | BIO_set_init(b, 1);
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386 | break;
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387 | case BIO_C_GET_MD:
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388 | if (BIO_get_init(b)) {
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389 | ppmd = ptr;
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390 | *ppmd = EVP_MD_CTX_md(ctx->md);
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391 | } else
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392 | ret = 0;
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393 | break;
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394 | default:
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395 | ret = BIO_ctrl(next, cmd, num, ptr);
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396 | break;
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397 | }
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398 | return ret;
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399 | }
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400 |
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401 | static long ok_callback_ctrl(BIO *b, int cmd, bio_info_cb *fp)
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402 | {
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403 | long ret = 1;
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404 | BIO *next;
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405 |
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406 | next = BIO_next(b);
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407 |
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408 | if (next == NULL)
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409 | return 0;
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410 |
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411 | switch (cmd) {
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412 | default:
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413 | ret = BIO_callback_ctrl(next, cmd, fp);
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414 | break;
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415 | }
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416 |
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417 | return ret;
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418 | }
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419 |
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420 | static void longswap(void *_ptr, size_t len)
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421 | {
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422 | const union {
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423 | long one;
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424 | char little;
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425 | } is_endian = {
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426 | 1
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427 | };
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428 |
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429 | if (is_endian.little) {
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430 | size_t i;
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431 | unsigned char *p = _ptr, c;
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432 |
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433 | for (i = 0; i < len; i += 4) {
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434 | c = p[0], p[0] = p[3], p[3] = c;
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435 | c = p[1], p[1] = p[2], p[2] = c;
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436 | }
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437 | }
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438 | }
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439 |
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440 | static int sig_out(BIO *b)
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441 | {
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442 | BIO_OK_CTX *ctx;
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443 | EVP_MD_CTX *md;
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444 | const EVP_MD *digest;
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445 | int md_size;
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446 | void *md_data;
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447 |
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448 | ctx = BIO_get_data(b);
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449 | md = ctx->md;
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450 | digest = EVP_MD_CTX_md(md);
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451 | md_size = EVP_MD_size(digest);
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452 | md_data = EVP_MD_CTX_md_data(md);
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453 |
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454 | if (ctx->buf_len + 2 * md_size > OK_BLOCK_SIZE)
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455 | return 1;
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456 |
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457 | if (!EVP_DigestInit_ex(md, digest, NULL))
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458 | goto berr;
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459 | /*
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460 | * FIXME: there's absolutely no guarantee this makes any sense at all,
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461 | * particularly now EVP_MD_CTX has been restructured.
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462 | */
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463 | if (RAND_bytes(md_data, md_size) <= 0)
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464 | goto berr;
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465 | memcpy(&(ctx->buf[ctx->buf_len]), md_data, md_size);
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466 | longswap(&(ctx->buf[ctx->buf_len]), md_size);
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467 | ctx->buf_len += md_size;
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468 |
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469 | if (!EVP_DigestUpdate(md, WELLKNOWN, strlen(WELLKNOWN)))
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470 | goto berr;
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471 | if (!EVP_DigestFinal_ex(md, &(ctx->buf[ctx->buf_len]), NULL))
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472 | goto berr;
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473 | ctx->buf_len += md_size;
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474 | ctx->blockout = 1;
|
---|
475 | ctx->sigio = 0;
|
---|
476 | return 1;
|
---|
477 | berr:
|
---|
478 | BIO_clear_retry_flags(b);
|
---|
479 | return 0;
|
---|
480 | }
|
---|
481 |
|
---|
482 | static int sig_in(BIO *b)
|
---|
483 | {
|
---|
484 | BIO_OK_CTX *ctx;
|
---|
485 | EVP_MD_CTX *md;
|
---|
486 | unsigned char tmp[EVP_MAX_MD_SIZE];
|
---|
487 | int ret = 0;
|
---|
488 | const EVP_MD *digest;
|
---|
489 | int md_size;
|
---|
490 | void *md_data;
|
---|
491 |
|
---|
492 | ctx = BIO_get_data(b);
|
---|
493 | md = ctx->md;
|
---|
494 | digest = EVP_MD_CTX_md(md);
|
---|
495 | md_size = EVP_MD_size(digest);
|
---|
496 | md_data = EVP_MD_CTX_md_data(md);
|
---|
497 |
|
---|
498 | if ((int)(ctx->buf_len - ctx->buf_off) < 2 * md_size)
|
---|
499 | return 1;
|
---|
500 |
|
---|
501 | if (!EVP_DigestInit_ex(md, digest, NULL))
|
---|
502 | goto berr;
|
---|
503 | memcpy(md_data, &(ctx->buf[ctx->buf_off]), md_size);
|
---|
504 | longswap(md_data, md_size);
|
---|
505 | ctx->buf_off += md_size;
|
---|
506 |
|
---|
507 | if (!EVP_DigestUpdate(md, WELLKNOWN, strlen(WELLKNOWN)))
|
---|
508 | goto berr;
|
---|
509 | if (!EVP_DigestFinal_ex(md, tmp, NULL))
|
---|
510 | goto berr;
|
---|
511 | ret = memcmp(&(ctx->buf[ctx->buf_off]), tmp, md_size) == 0;
|
---|
512 | ctx->buf_off += md_size;
|
---|
513 | if (ret == 1) {
|
---|
514 | ctx->sigio = 0;
|
---|
515 | if (ctx->buf_len != ctx->buf_off) {
|
---|
516 | memmove(ctx->buf, &(ctx->buf[ctx->buf_off]),
|
---|
517 | ctx->buf_len - ctx->buf_off);
|
---|
518 | }
|
---|
519 | ctx->buf_len -= ctx->buf_off;
|
---|
520 | ctx->buf_off = 0;
|
---|
521 | } else {
|
---|
522 | ctx->cont = 0;
|
---|
523 | }
|
---|
524 | return 1;
|
---|
525 | berr:
|
---|
526 | BIO_clear_retry_flags(b);
|
---|
527 | return 0;
|
---|
528 | }
|
---|
529 |
|
---|
530 | static int block_out(BIO *b)
|
---|
531 | {
|
---|
532 | BIO_OK_CTX *ctx;
|
---|
533 | EVP_MD_CTX *md;
|
---|
534 | unsigned long tl;
|
---|
535 | const EVP_MD *digest;
|
---|
536 | int md_size;
|
---|
537 |
|
---|
538 | ctx = BIO_get_data(b);
|
---|
539 | md = ctx->md;
|
---|
540 | digest = EVP_MD_CTX_md(md);
|
---|
541 | md_size = EVP_MD_size(digest);
|
---|
542 |
|
---|
543 | tl = ctx->buf_len - OK_BLOCK_BLOCK;
|
---|
544 | ctx->buf[0] = (unsigned char)(tl >> 24);
|
---|
545 | ctx->buf[1] = (unsigned char)(tl >> 16);
|
---|
546 | ctx->buf[2] = (unsigned char)(tl >> 8);
|
---|
547 | ctx->buf[3] = (unsigned char)(tl);
|
---|
548 | if (!EVP_DigestUpdate(md,
|
---|
549 | (unsigned char *)&(ctx->buf[OK_BLOCK_BLOCK]), tl))
|
---|
550 | goto berr;
|
---|
551 | if (!EVP_DigestFinal_ex(md, &(ctx->buf[ctx->buf_len]), NULL))
|
---|
552 | goto berr;
|
---|
553 | ctx->buf_len += md_size;
|
---|
554 | ctx->blockout = 1;
|
---|
555 | return 1;
|
---|
556 | berr:
|
---|
557 | BIO_clear_retry_flags(b);
|
---|
558 | return 0;
|
---|
559 | }
|
---|
560 |
|
---|
561 | static int block_in(BIO *b)
|
---|
562 | {
|
---|
563 | BIO_OK_CTX *ctx;
|
---|
564 | EVP_MD_CTX *md;
|
---|
565 | unsigned long tl = 0;
|
---|
566 | unsigned char tmp[EVP_MAX_MD_SIZE];
|
---|
567 | int md_size;
|
---|
568 |
|
---|
569 | ctx = BIO_get_data(b);
|
---|
570 | md = ctx->md;
|
---|
571 | md_size = EVP_MD_size(EVP_MD_CTX_md(md));
|
---|
572 |
|
---|
573 | assert(sizeof(tl) >= OK_BLOCK_BLOCK); /* always true */
|
---|
574 | tl = ctx->buf[0];
|
---|
575 | tl <<= 8;
|
---|
576 | tl |= ctx->buf[1];
|
---|
577 | tl <<= 8;
|
---|
578 | tl |= ctx->buf[2];
|
---|
579 | tl <<= 8;
|
---|
580 | tl |= ctx->buf[3];
|
---|
581 |
|
---|
582 | if (ctx->buf_len < tl + OK_BLOCK_BLOCK + md_size)
|
---|
583 | return 1;
|
---|
584 |
|
---|
585 | if (!EVP_DigestUpdate(md,
|
---|
586 | (unsigned char *)&(ctx->buf[OK_BLOCK_BLOCK]), tl))
|
---|
587 | goto berr;
|
---|
588 | if (!EVP_DigestFinal_ex(md, tmp, NULL))
|
---|
589 | goto berr;
|
---|
590 | if (memcmp(&(ctx->buf[tl + OK_BLOCK_BLOCK]), tmp, md_size) == 0) {
|
---|
591 | /* there might be parts from next block lurking around ! */
|
---|
592 | ctx->buf_off_save = tl + OK_BLOCK_BLOCK + md_size;
|
---|
593 | ctx->buf_len_save = ctx->buf_len;
|
---|
594 | ctx->buf_off = OK_BLOCK_BLOCK;
|
---|
595 | ctx->buf_len = tl + OK_BLOCK_BLOCK;
|
---|
596 | ctx->blockout = 1;
|
---|
597 | } else {
|
---|
598 | ctx->cont = 0;
|
---|
599 | }
|
---|
600 | return 1;
|
---|
601 | berr:
|
---|
602 | BIO_clear_retry_flags(b);
|
---|
603 | return 0;
|
---|
604 | }
|
---|