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// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "net/cert/ct_log_response_parser.h"
#include "base/base64.h"
#include "base/json/json_reader.h"
#include "base/json/json_value_converter.h"
#include "base/logging.h"
#include "base/strings/string_piece.h"
#include "base/time/time.h"
#include "base/values.h"
#include "net/cert/ct_serialization.h"
#include "net/cert/signed_tree_head.h"
namespace net {
namespace ct {
namespace {
// Structure for making JSON decoding easier. The string fields
// are base64-encoded so will require further decoding.
struct JsonSignedTreeHead {
int tree_size;
double timestamp;
std::string sha256_root_hash;
DigitallySigned signature;
static void RegisterJSONConverter(
base::JSONValueConverter<JsonSignedTreeHead>* converted);
};
bool ConvertSHA256RootHash(const base::StringPiece& s, std::string* result) {
if (!base::Base64Decode(s, result)) {
DVLOG(1) << "Failed decoding sha256_root_hash";
return false;
}
if (result->length() != kSthRootHashLength) {
DVLOG(1) << "sha256_root_hash is expected to be 32 bytes, but is "
<< result->length() << " bytes.";
return false;
}
return true;
}
bool ConvertTreeHeadSignature(const base::StringPiece& s,
DigitallySigned* result) {
std::string tree_head_signature;
if (!base::Base64Decode(s, &tree_head_signature)) {
DVLOG(1) << "Failed decoding tree_head_signature";
return false;
}
base::StringPiece sp(tree_head_signature);
if (!DecodeDigitallySigned(&sp, result)) {
DVLOG(1) << "Failed decoding signature to DigitallySigned";
return false;
}
return true;
}
void JsonSignedTreeHead::RegisterJSONConverter(
base::JSONValueConverter<JsonSignedTreeHead>* converter) {
converter->RegisterIntField("tree_size", &JsonSignedTreeHead::tree_size);
converter->RegisterDoubleField("timestamp", &JsonSignedTreeHead::timestamp);
converter->RegisterCustomField("sha256_root_hash",
&JsonSignedTreeHead::sha256_root_hash,
&ConvertSHA256RootHash);
converter->RegisterCustomField<DigitallySigned>(
"tree_head_signature",
&JsonSignedTreeHead::signature,
&ConvertTreeHeadSignature);
}
bool IsJsonSTHStructurallyValid(const JsonSignedTreeHead& sth) {
if (sth.tree_size < 0) {
DVLOG(1) << "Tree size in Signed Tree Head JSON is negative: "
<< sth.tree_size;
return false;
}
if (sth.timestamp < 0) {
DVLOG(1) << "Timestamp in Signed Tree Head JSON is negative: "
<< sth.timestamp;
return false;
}
if (sth.sha256_root_hash.empty()) {
DVLOG(1) << "Missing SHA256 root hash from Signed Tree Head JSON.";
return false;
}
if (sth.signature.signature_data.empty()) {
DVLOG(1) << "Missing SHA256 root hash from Signed Tree Head JSON.";
return false;
}
return true;
}
} // namespace
bool FillSignedTreeHead(const base::StringPiece& json_signed_tree_head,
SignedTreeHead* signed_tree_head) {
base::JSONReader json_reader;
scoped_ptr<base::Value> json(json_reader.Read(json_signed_tree_head));
if (json.get() == NULL) {
DVLOG(1) << "Empty Signed Tree Head JSON.";
return false;
}
JsonSignedTreeHead parsed_sth;
base::JSONValueConverter<JsonSignedTreeHead> converter;
if (!converter.Convert(*json.get(), &parsed_sth)) {
DVLOG(1) << "Invalid Signed Tree Head JSON.";
return false;
}
if (!IsJsonSTHStructurallyValid(parsed_sth))
return false;
signed_tree_head->version = SignedTreeHead::V1;
signed_tree_head->tree_size = parsed_sth.tree_size;
signed_tree_head->timestamp =
base::Time::UnixEpoch() +
base::TimeDelta::FromMilliseconds(parsed_sth.timestamp);
signed_tree_head->signature = parsed_sth.signature;
memcpy(signed_tree_head->sha256_root_hash,
parsed_sth.sha256_root_hash.c_str(),
kSthRootHashLength);
return true;
}
} // namespace ct
} // namespace net
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