--- /dev/null
+/*
+ * Copyright 2014-2016 The OpenSSL Project Authors. All Rights Reserved.
+ *
+ * Licensed under the OpenSSL license (the "License"). You may not use
+ * this file except in compliance with the License. You can obtain a copy
+ * in the file LICENSE in the source distribution or at
+ * https://www.openssl.org/source/license.html
+ */
+
+/* Custom extension utility functions */
+
+#include <openssl/ct.h>
+#include "ssl_locl.h"
+
+/* Find a custom extension from the list. */
+static custom_ext_method *custom_ext_find(const custom_ext_methods *exts,
+ unsigned int ext_type)
+{
+ size_t i;
+ custom_ext_method *meth = exts->meths;
+ for (i = 0; i < exts->meths_count; i++, meth++) {
+ if (ext_type == meth->ext_type)
+ return meth;
+ }
+ return NULL;
+}
+
+/*
+ * Initialise custom extensions flags to indicate neither sent nor received.
+ */
+void custom_ext_init(custom_ext_methods *exts)
+{
+ size_t i;
+ custom_ext_method *meth = exts->meths;
+ for (i = 0; i < exts->meths_count; i++, meth++)
+ meth->ext_flags = 0;
+}
+
+/* Pass received custom extension data to the application for parsing. */
+int custom_ext_parse(SSL *s, int server,
+ unsigned int ext_type,
+ const unsigned char *ext_data, size_t ext_size, int *al)
+{
+ custom_ext_methods *exts = server ? &s->cert->srv_ext : &s->cert->cli_ext;
+ custom_ext_method *meth;
+ meth = custom_ext_find(exts, ext_type);
+ /* If not found return success */
+ if (!meth)
+ return 1;
+ if (!server) {
+ /*
+ * If it's ServerHello we can't have any extensions not sent in
+ * ClientHello.
+ */
+ if (!(meth->ext_flags & SSL_EXT_FLAG_SENT)) {
+ *al = TLS1_AD_UNSUPPORTED_EXTENSION;
+ return 0;
+ }
+ }
+ /* If already present it's a duplicate */
+ if (meth->ext_flags & SSL_EXT_FLAG_RECEIVED) {
+ *al = TLS1_AD_DECODE_ERROR;
+ return 0;
+ }
+ meth->ext_flags |= SSL_EXT_FLAG_RECEIVED;
+ /* If no parse function set return success */
+ if (!meth->parse_cb)
+ return 1;
+
+ return meth->parse_cb(s, ext_type, ext_data, ext_size, al, meth->parse_arg);
+}
+
+/*
+ * Request custom extension data from the application and add to the return
+ * buffer.
+ */
+int custom_ext_add(SSL *s, int server,
+ unsigned char **pret, unsigned char *limit, int *al)
+{
+ custom_ext_methods *exts = server ? &s->cert->srv_ext : &s->cert->cli_ext;
+ custom_ext_method *meth;
+ unsigned char *ret = *pret;
+ size_t i;
+
+ for (i = 0; i < exts->meths_count; i++) {
+ const unsigned char *out = NULL;
+ size_t outlen = 0;
+ meth = exts->meths + i;
+
+ if (server) {
+ /*
+ * For ServerHello only send extensions present in ClientHello.
+ */
+ if (!(meth->ext_flags & SSL_EXT_FLAG_RECEIVED))
+ continue;
+ /* If callback absent for server skip it */
+ if (!meth->add_cb)
+ continue;
+ }
+ if (meth->add_cb) {
+ int cb_retval = 0;
+ cb_retval = meth->add_cb(s, meth->ext_type,
+ &out, &outlen, al, meth->add_arg);
+ if (cb_retval < 0)
+ return 0; /* error */
+ if (cb_retval == 0)
+ continue; /* skip this extension */
+ }
+ if (4 > limit - ret || outlen > (size_t)(limit - ret - 4))
+ return 0;
+ s2n(meth->ext_type, ret);
+ s2n(outlen, ret);
+ if (outlen) {
+ memcpy(ret, out, outlen);
+ ret += outlen;
+ }
+ /*
+ * We can't send duplicates: code logic should prevent this.
+ */
+ OPENSSL_assert(!(meth->ext_flags & SSL_EXT_FLAG_SENT));
+ /*
+ * Indicate extension has been sent: this is both a sanity check to
+ * ensure we don't send duplicate extensions and indicates that it is
+ * not an error if the extension is present in ServerHello.
+ */
+ meth->ext_flags |= SSL_EXT_FLAG_SENT;
+ if (meth->free_cb)
+ meth->free_cb(s, meth->ext_type, out, meth->add_arg);
+ }
+ *pret = ret;
+ return 1;
+}
+
+/* Copy table of custom extensions */
+int custom_exts_copy(custom_ext_methods *dst, const custom_ext_methods *src)
+{
+ if (src->meths_count) {
+ dst->meths =
+ OPENSSL_memdup(src->meths,
+ sizeof(custom_ext_method) * src->meths_count);
+ if (dst->meths == NULL)
+ return 0;
+ dst->meths_count = src->meths_count;
+ }
+ return 1;
+}
+
+void custom_exts_free(custom_ext_methods *exts)
+{
+ OPENSSL_free(exts->meths);
+}
+
+/* Set callbacks for a custom extension. */
+static int custom_ext_meth_add(custom_ext_methods *exts,
+ unsigned int ext_type,
+ custom_ext_add_cb add_cb,
+ custom_ext_free_cb free_cb,
+ void *add_arg,
+ custom_ext_parse_cb parse_cb, void *parse_arg)
+{
+ custom_ext_method *meth, *tmp;
+ /*
+ * Check application error: if add_cb is not set free_cb will never be
+ * called.
+ */
+ if (!add_cb && free_cb)
+ return 0;
+ /*
+ * Don't add if extension supported internally, but make exception
+ * for extension types that previously were not supported, but now are.
+ */
+ if (SSL_extension_supported(ext_type) &&
+ ext_type != TLSEXT_TYPE_signed_certificate_timestamp)
+ return 0;
+ /* Extension type must fit in 16 bits */
+ if (ext_type > 0xffff)
+ return 0;
+ /* Search for duplicate */
+ if (custom_ext_find(exts, ext_type))
+ return 0;
+ tmp = OPENSSL_realloc(exts->meths,
+ (exts->meths_count + 1) * sizeof(custom_ext_method));
+
+ if (tmp == NULL) {
+ OPENSSL_free(exts->meths);
+ exts->meths = NULL;
+ exts->meths_count = 0;
+ return 0;
+ }
+
+ exts->meths = tmp;
+ meth = exts->meths + exts->meths_count;
+ memset(meth, 0, sizeof(*meth));
+ meth->parse_cb = parse_cb;
+ meth->add_cb = add_cb;
+ meth->free_cb = free_cb;
+ meth->ext_type = ext_type;
+ meth->add_arg = add_arg;
+ meth->parse_arg = parse_arg;
+ exts->meths_count++;
+ return 1;
+}
+
+/* Return true if a client custom extension exists, false otherwise */
+int SSL_CTX_has_client_custom_ext(const SSL_CTX *ctx, unsigned int ext_type)
+{
+ return custom_ext_find(&ctx->cert->cli_ext, ext_type) != NULL;
+}
+
+/* Application level functions to add custom extension callbacks */
+int SSL_CTX_add_client_custom_ext(SSL_CTX *ctx, unsigned int ext_type,
+ custom_ext_add_cb add_cb,
+ custom_ext_free_cb free_cb,
+ void *add_arg,
+ custom_ext_parse_cb parse_cb, void *parse_arg)
+{
+#ifndef OPENSSL_NO_CT
+ /*
+ * We don't want applications registering callbacks for SCT extensions
+ * whilst simultaneously using the built-in SCT validation features, as
+ * these two things may not play well together.
+ */
+ if (ext_type == TLSEXT_TYPE_signed_certificate_timestamp &&
+ SSL_CTX_ct_is_enabled(ctx))
+ return 0;
+#endif
+ return custom_ext_meth_add(&ctx->cert->cli_ext, ext_type, add_cb,
+ free_cb, add_arg, parse_cb, parse_arg);
+}
+
+int SSL_CTX_add_server_custom_ext(SSL_CTX *ctx, unsigned int ext_type,
+ custom_ext_add_cb add_cb,
+ custom_ext_free_cb free_cb,
+ void *add_arg,
+ custom_ext_parse_cb parse_cb, void *parse_arg)
+{
+ return custom_ext_meth_add(&ctx->cert->srv_ext, ext_type,
+ add_cb, free_cb, add_arg, parse_cb, parse_arg);
+}
+
+int SSL_extension_supported(unsigned int ext_type)
+{
+ switch (ext_type) {
+ /* Internally supported extensions. */
+ case TLSEXT_TYPE_application_layer_protocol_negotiation:
+ case TLSEXT_TYPE_ec_point_formats:
+ case TLSEXT_TYPE_elliptic_curves:
+ case TLSEXT_TYPE_heartbeat:
+#ifndef OPENSSL_NO_NEXTPROTONEG
+ case TLSEXT_TYPE_next_proto_neg:
+#endif
+ case TLSEXT_TYPE_padding:
+ case TLSEXT_TYPE_renegotiate:
+ case TLSEXT_TYPE_server_name:
+ case TLSEXT_TYPE_session_ticket:
+ case TLSEXT_TYPE_signature_algorithms:
+ case TLSEXT_TYPE_srp:
+ case TLSEXT_TYPE_status_request:
+ case TLSEXT_TYPE_signed_certificate_timestamp:
+ case TLSEXT_TYPE_use_srtp:
+#ifdef TLSEXT_TYPE_encrypt_then_mac
+ case TLSEXT_TYPE_encrypt_then_mac:
+#endif
+ return 1;
+ default:
+ return 0;
+ }
+}
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