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// Copyright 2020 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "components/web_package/web_bundle_builder.h"
#include <string.h>
#include <ostream>
#include <string_view>
#include "base/numerics/byte_conversions.h"
namespace web_package {
namespace {
cbor::Value CreateByteString(std::string_view s) {
return cbor::Value(base::as_byte_span(s));
}
cbor::Value CreateHeaderMap(const WebBundleBuilder::Headers& headers) {
cbor::Value::MapValue map;
for (const auto& pair : headers) {
map.insert({CreateByteString(pair.first), CreateByteString(pair.second)});
}
return cbor::Value(std::move(map));
}
// TODO(myrzakereyms): replace this method with cbor::writer::GetNumUintBytes.
uint64_t GetNumUintBytes(uint64_t value) {
if (value < 24) {
return 0;
} else if (value <= 0xFF) {
return 1;
} else if (value <= 0xFFFF) {
return 2;
} else if (value <= 0xFFFFFFFF) {
return 4;
}
return 8;
}
} // namespace
WebBundleBuilder::WebBundleBuilder(BundleVersion version,
bool allow_invalid_utf8_strings_for_testing)
: version_(version) {
// Currently the only supported bundle format is b2.
DCHECK_EQ(version_, BundleVersion::kB2);
writer_config_.allow_invalid_utf8_for_testing =
allow_invalid_utf8_strings_for_testing;
}
WebBundleBuilder::~WebBundleBuilder() = default;
cbor::Value WebBundleBuilder::GetCborValueOfURL(std::string_view url) {
if (writer_config_.allow_invalid_utf8_for_testing) {
return cbor::Value::InvalidUTF8StringValueForTesting(url);
}
return cbor::Value(url);
}
void WebBundleBuilder::AddExchange(const GURL& url,
const Headers& response_headers,
std::string_view payload) {
AddExchange(url.spec(), response_headers, payload);
}
void WebBundleBuilder::AddExchange(std::string_view url,
const Headers& response_headers,
std::string_view payload) {
AddIndexEntry(url, AddResponse(response_headers, payload));
}
WebBundleBuilder::ResponseLocation WebBundleBuilder::AddResponse(
const Headers& headers,
std::string_view payload) {
cbor::Value::ArrayValue response_array;
response_array.emplace_back(Encode(CreateHeaderMap(headers)));
response_array.emplace_back(CreateByteString(payload));
cbor::Value response(response_array);
int64_t response_length = EncodedLength(response);
ResponseLocation result = {current_responses_offset_, response_length};
current_responses_offset_ += response_length;
responses_.emplace_back(std::move(response));
return result;
}
void WebBundleBuilder::AddIndexEntry(
const GURL& url,
const ResponseLocation& response_location) {
AddIndexEntry(url.spec(), response_location);
}
void WebBundleBuilder::AddIndexEntry(
std::string_view url,
const ResponseLocation& response_location) {
delayed_index_.insert({std::string{url}, response_location});
}
void WebBundleBuilder::AddSection(std::string_view name, cbor::Value section) {
section_lengths_.emplace_back(name);
section_lengths_.emplace_back(EncodedLength(section));
sections_.emplace_back(std::move(section));
}
void WebBundleBuilder::AddPrimaryURL(const GURL& url) {
AddPrimaryURL(url.spec());
}
void WebBundleBuilder::AddPrimaryURL(std::string_view url) {
AddSection("primary", GetCborValueOfURL(url));
}
std::vector<uint8_t> WebBundleBuilder::CreateBundle() {
// Now that we know how many responses will be in the bundle,
// we want to shift all the offsets by the bytes required
// for the CBOR Array header and actually construct the index
// section.
int64_t initial_offset = 1 + GetNumUintBytes(responses_.size());
cbor::Value::MapValue index;
for (auto& entry : delayed_index_) {
const ResponseLocation& location = entry.second;
cbor::Value::ArrayValue index_value_array;
index_value_array.emplace_back(location.offset + initial_offset);
index_value_array.emplace_back(location.length);
index.insert(
{GetCborValueOfURL(entry.first), cbor::Value(index_value_array)});
}
AddSection("index", cbor::Value(index));
AddSection("responses", cbor::Value(responses_));
return CreateTopLevel();
}
std::vector<uint8_t> WebBundleBuilder::CreateTopLevel() {
cbor::Value::ArrayValue toplevel_array;
toplevel_array.emplace_back(CreateByteString("🌐📦"));
toplevel_array.emplace_back(CreateByteString(std::string_view("b2\0\0", 4)));
toplevel_array.emplace_back(Encode(cbor::Value(section_lengths_)));
toplevel_array.emplace_back(sections_);
// Put a dummy 8-byte bytestring.
toplevel_array.emplace_back(cbor::Value::BinaryValue(8, 0));
std::vector<uint8_t> bundle = Encode(cbor::Value(toplevel_array));
// Overwrite the dummy bytestring with the actual size.
base::span(bundle).last(8u).copy_from(base::U64ToBigEndian(bundle.size()));
return bundle;
}
std::vector<uint8_t> WebBundleBuilder::Encode(const cbor::Value& value) {
return *cbor::Writer::Write(value, writer_config_);
}
int64_t WebBundleBuilder::EncodedLength(const cbor::Value& value) {
return Encode(value).size();
}
} // namespace web_package
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