[331] | 1 | /*
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| 2 | * Copyright 2014-2016 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 | /* Custom extension utility functions */
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| 11 |
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| 12 | #include <openssl/ct.h>
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| 13 | #include "ssl_locl.h"
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| 14 |
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| 15 | /* Find a custom extension from the list. */
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| 16 | static custom_ext_method *custom_ext_find(const custom_ext_methods *exts,
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| 17 | unsigned int ext_type)
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| 18 | {
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| 19 | size_t i;
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| 20 | custom_ext_method *meth = exts->meths;
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| 21 | for (i = 0; i < exts->meths_count; i++, meth++) {
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| 22 | if (ext_type == meth->ext_type)
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| 23 | return meth;
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| 24 | }
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| 25 | return NULL;
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| 26 | }
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| 27 |
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| 28 | /*
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| 29 | * Initialise custom extensions flags to indicate neither sent nor received.
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| 30 | */
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| 31 | void custom_ext_init(custom_ext_methods *exts)
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| 32 | {
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| 33 | size_t i;
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| 34 | custom_ext_method *meth = exts->meths;
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| 35 | for (i = 0; i < exts->meths_count; i++, meth++)
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| 36 | meth->ext_flags = 0;
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| 37 | }
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| 38 |
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| 39 | /* Pass received custom extension data to the application for parsing. */
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| 40 | int custom_ext_parse(SSL *s, int server,
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| 41 | unsigned int ext_type,
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| 42 | const unsigned char *ext_data, size_t ext_size, int *al)
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| 43 | {
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| 44 | custom_ext_methods *exts = server ? &s->cert->srv_ext : &s->cert->cli_ext;
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| 45 | custom_ext_method *meth;
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| 46 | meth = custom_ext_find(exts, ext_type);
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| 47 | /* If not found return success */
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| 48 | if (!meth)
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| 49 | return 1;
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| 50 | if (!server) {
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| 51 | /*
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| 52 | * If it's ServerHello we can't have any extensions not sent in
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| 53 | * ClientHello.
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| 54 | */
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| 55 | if (!(meth->ext_flags & SSL_EXT_FLAG_SENT)) {
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| 56 | *al = TLS1_AD_UNSUPPORTED_EXTENSION;
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| 57 | return 0;
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| 58 | }
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| 59 | }
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| 60 | /* If already present it's a duplicate */
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| 61 | if (meth->ext_flags & SSL_EXT_FLAG_RECEIVED) {
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| 62 | *al = TLS1_AD_DECODE_ERROR;
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| 63 | return 0;
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| 64 | }
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| 65 | meth->ext_flags |= SSL_EXT_FLAG_RECEIVED;
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| 66 | /* If no parse function set return success */
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| 67 | if (!meth->parse_cb)
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| 68 | return 1;
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| 69 |
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| 70 | return meth->parse_cb(s, ext_type, ext_data, ext_size, al, meth->parse_arg);
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| 71 | }
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| 72 |
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| 73 | /*
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| 74 | * Request custom extension data from the application and add to the return
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| 75 | * buffer.
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| 76 | */
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| 77 | int custom_ext_add(SSL *s, int server,
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| 78 | unsigned char **pret, unsigned char *limit, int *al)
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| 79 | {
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| 80 | custom_ext_methods *exts = server ? &s->cert->srv_ext : &s->cert->cli_ext;
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| 81 | custom_ext_method *meth;
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| 82 | unsigned char *ret = *pret;
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| 83 | size_t i;
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| 84 |
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| 85 | for (i = 0; i < exts->meths_count; i++) {
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| 86 | const unsigned char *out = NULL;
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| 87 | size_t outlen = 0;
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| 88 | meth = exts->meths + i;
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| 89 |
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| 90 | if (server) {
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| 91 | /*
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| 92 | * For ServerHello only send extensions present in ClientHello.
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| 93 | */
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| 94 | if (!(meth->ext_flags & SSL_EXT_FLAG_RECEIVED))
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| 95 | continue;
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| 96 | /* If callback absent for server skip it */
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| 97 | if (!meth->add_cb)
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| 98 | continue;
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| 99 | }
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| 100 | if (meth->add_cb) {
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| 101 | int cb_retval = 0;
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| 102 | cb_retval = meth->add_cb(s, meth->ext_type,
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| 103 | &out, &outlen, al, meth->add_arg);
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| 104 | if (cb_retval < 0)
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| 105 | return 0; /* error */
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| 106 | if (cb_retval == 0)
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| 107 | continue; /* skip this extension */
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| 108 | }
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| 109 | if (4 > limit - ret || outlen > (size_t)(limit - ret - 4))
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| 110 | return 0;
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| 111 | s2n(meth->ext_type, ret);
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| 112 | s2n(outlen, ret);
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| 113 | if (outlen) {
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| 114 | memcpy(ret, out, outlen);
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| 115 | ret += outlen;
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| 116 | }
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| 117 | /*
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| 118 | * We can't send duplicates: code logic should prevent this.
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| 119 | */
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| 120 | OPENSSL_assert(!(meth->ext_flags & SSL_EXT_FLAG_SENT));
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| 121 | /*
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| 122 | * Indicate extension has been sent: this is both a sanity check to
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| 123 | * ensure we don't send duplicate extensions and indicates that it is
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| 124 | * not an error if the extension is present in ServerHello.
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| 125 | */
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| 126 | meth->ext_flags |= SSL_EXT_FLAG_SENT;
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| 127 | if (meth->free_cb)
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| 128 | meth->free_cb(s, meth->ext_type, out, meth->add_arg);
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| 129 | }
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| 130 | *pret = ret;
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| 131 | return 1;
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| 132 | }
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| 133 |
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| 134 | /* Copy table of custom extensions */
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| 135 | int custom_exts_copy(custom_ext_methods *dst, const custom_ext_methods *src)
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| 136 | {
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| 137 | if (src->meths_count) {
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| 138 | dst->meths =
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| 139 | OPENSSL_memdup(src->meths,
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| 140 | sizeof(custom_ext_method) * src->meths_count);
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| 141 | if (dst->meths == NULL)
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| 142 | return 0;
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| 143 | dst->meths_count = src->meths_count;
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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 | void custom_exts_free(custom_ext_methods *exts)
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| 149 | {
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| 150 | OPENSSL_free(exts->meths);
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| 151 | }
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| 152 |
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| 153 | /* Set callbacks for a custom extension. */
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| 154 | static int custom_ext_meth_add(custom_ext_methods *exts,
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| 155 | unsigned int ext_type,
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| 156 | custom_ext_add_cb add_cb,
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| 157 | custom_ext_free_cb free_cb,
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| 158 | void *add_arg,
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| 159 | custom_ext_parse_cb parse_cb, void *parse_arg)
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| 160 | {
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| 161 | custom_ext_method *meth, *tmp;
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| 162 | /*
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| 163 | * Check application error: if add_cb is not set free_cb will never be
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| 164 | * called.
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| 165 | */
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| 166 | if (!add_cb && free_cb)
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| 167 | return 0;
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| 168 | /*
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| 169 | * Don't add if extension supported internally, but make exception
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| 170 | * for extension types that previously were not supported, but now are.
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| 171 | */
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| 172 | if (SSL_extension_supported(ext_type) &&
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| 173 | ext_type != TLSEXT_TYPE_signed_certificate_timestamp)
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| 174 | return 0;
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| 175 | /* Extension type must fit in 16 bits */
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| 176 | if (ext_type > 0xffff)
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| 177 | return 0;
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| 178 | /* Search for duplicate */
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| 179 | if (custom_ext_find(exts, ext_type))
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| 180 | return 0;
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| 181 | tmp = OPENSSL_realloc(exts->meths,
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| 182 | (exts->meths_count + 1) * sizeof(custom_ext_method));
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| 183 |
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| 184 | if (tmp == NULL)
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| 185 | return 0;
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| 186 |
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| 187 | exts->meths = tmp;
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| 188 | meth = exts->meths + exts->meths_count;
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| 189 | memset(meth, 0, sizeof(*meth));
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| 190 | meth->parse_cb = parse_cb;
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| 191 | meth->add_cb = add_cb;
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| 192 | meth->free_cb = free_cb;
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| 193 | meth->ext_type = ext_type;
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| 194 | meth->add_arg = add_arg;
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| 195 | meth->parse_arg = parse_arg;
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| 196 | exts->meths_count++;
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| 197 | return 1;
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| 198 | }
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| 199 |
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| 200 | /* Return true if a client custom extension exists, false otherwise */
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| 201 | int SSL_CTX_has_client_custom_ext(const SSL_CTX *ctx, unsigned int ext_type)
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| 202 | {
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| 203 | return custom_ext_find(&ctx->cert->cli_ext, ext_type) != NULL;
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| 204 | }
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| 205 |
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| 206 | /* Application level functions to add custom extension callbacks */
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| 207 | int SSL_CTX_add_client_custom_ext(SSL_CTX *ctx, unsigned int ext_type,
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| 208 | custom_ext_add_cb add_cb,
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| 209 | custom_ext_free_cb free_cb,
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| 210 | void *add_arg,
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| 211 | custom_ext_parse_cb parse_cb, void *parse_arg)
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| 212 | {
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| 213 | #ifndef OPENSSL_NO_CT
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| 214 | /*
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| 215 | * We don't want applications registering callbacks for SCT extensions
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| 216 | * whilst simultaneously using the built-in SCT validation features, as
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| 217 | * these two things may not play well together.
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| 218 | */
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| 219 | if (ext_type == TLSEXT_TYPE_signed_certificate_timestamp &&
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| 220 | SSL_CTX_ct_is_enabled(ctx))
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| 221 | return 0;
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| 222 | #endif
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| 223 | return custom_ext_meth_add(&ctx->cert->cli_ext, ext_type, add_cb,
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| 224 | free_cb, add_arg, parse_cb, parse_arg);
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| 225 | }
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| 226 |
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| 227 | int SSL_CTX_add_server_custom_ext(SSL_CTX *ctx, unsigned int ext_type,
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| 228 | custom_ext_add_cb add_cb,
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| 229 | custom_ext_free_cb free_cb,
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| 230 | void *add_arg,
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| 231 | custom_ext_parse_cb parse_cb, void *parse_arg)
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| 232 | {
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| 233 | return custom_ext_meth_add(&ctx->cert->srv_ext, ext_type,
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| 234 | add_cb, free_cb, add_arg, parse_cb, parse_arg);
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| 235 | }
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| 236 |
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| 237 | int SSL_extension_supported(unsigned int ext_type)
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| 238 | {
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| 239 | switch (ext_type) {
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| 240 | /* Internally supported extensions. */
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| 241 | case TLSEXT_TYPE_application_layer_protocol_negotiation:
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| 242 | case TLSEXT_TYPE_ec_point_formats:
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| 243 | case TLSEXT_TYPE_elliptic_curves:
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| 244 | case TLSEXT_TYPE_heartbeat:
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| 245 | #ifndef OPENSSL_NO_NEXTPROTONEG
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| 246 | case TLSEXT_TYPE_next_proto_neg:
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| 247 | #endif
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| 248 | case TLSEXT_TYPE_padding:
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| 249 | case TLSEXT_TYPE_renegotiate:
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| 250 | case TLSEXT_TYPE_server_name:
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| 251 | case TLSEXT_TYPE_session_ticket:
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| 252 | case TLSEXT_TYPE_signature_algorithms:
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| 253 | case TLSEXT_TYPE_srp:
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| 254 | case TLSEXT_TYPE_status_request:
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| 255 | case TLSEXT_TYPE_signed_certificate_timestamp:
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| 256 | case TLSEXT_TYPE_use_srtp:
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| 257 | #ifdef TLSEXT_TYPE_encrypt_then_mac
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| 258 | case TLSEXT_TYPE_encrypt_then_mac:
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| 259 | #endif
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| 260 | return 1;
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| 261 | default:
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| 262 | return 0;
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| 263 | }
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| 264 | }
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