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// Copyright 2019 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.
#ifndef QUICHE_COMMON_STRUCTURED_HEADERS_H_
#define QUICHE_COMMON_STRUCTURED_HEADERS_H_
#include <algorithm>
#include <map>
#include <string>
#include <tuple>
#include <vector>
#include "absl/strings/string_view.h"
#include "absl/types/optional.h"
#include "absl/types/variant.h"
#include "quiche/common/platform/api/quiche_export.h"
#include "quiche/common/platform/api/quiche_logging.h"
namespace quiche {
namespace structured_headers {
// This file implements parsing of HTTP structured headers, as defined in
// RFC8941 (https://www.rfc-editor.org/rfc/rfc8941.html). For compatibility with
// the shipped implementation of Web Packaging, this file also supports a
// previous revision of the standard, referred to here as "Draft 9".
// (https://datatracker.ietf.org/doc/draft-ietf-httpbis-header-structure/09/)
//
// The major difference between the two revisions is in the various list
// formats: Draft 9 describes "parameterised lists" and "lists-of-lists", while
// the final RFC uses a single "list" syntax, whose members may be inner lists.
// There should be no ambiguity, however, as the code which calls this parser
// should be expecting only a single type for a given header.
//
// References within the code are tagged with either [SH09] or [RFC8941],
// depending on which revision they refer to.
//
// Currently supported data types are:
// Item:
// integer: 123
// string: "abc"
// token: abc
// byte sequence: *YWJj*
// Parameterised list: abc_123;a=1;b=2; cdef_456, ghi;q="9";r="w"
// List-of-lists: "foo";"bar", "baz", "bat"; "one"
// List: "foo", "bar", "It was the best of times."
// ("foo" "bar"), ("baz"), ("bat" "one"), ()
// abc;a=1;b=2; cde_456, (ghi jkl);q="9";r=w
// Dictionary: a=(1 2), b=3, c=4;aa=bb, d=(5 6);valid=?0
//
// Functions are provided to parse each of these, which are intended to be
// called with the complete value of an HTTP header (that is, any
// sub-structure will be handled internally by the parser; the exported
// functions are not intended to be called on partial header strings.) Input
// values should be ASCII byte strings (non-ASCII characters should not be
// present in Structured Header values, and will cause the entire header to fail
// to parse.)
class QUICHE_EXPORT_PRIVATE Item {
public:
enum ItemType {
kNullType,
kIntegerType,
kDecimalType,
kStringType,
kTokenType,
kByteSequenceType,
kBooleanType
};
Item();
explicit Item(int64_t value);
explicit Item(double value);
explicit Item(bool value);
// Constructors for string-like items: Strings, Tokens and Byte Sequences.
Item(const char* value, Item::ItemType type = kStringType);
Item(std::string value, Item::ItemType type = kStringType);
QUICHE_EXPORT_PRIVATE friend bool operator==(const Item& lhs,
const Item& rhs);
inline friend bool operator!=(const Item& lhs, const Item& rhs) {
return !(lhs == rhs);
}
bool is_null() const { return Type() == kNullType; }
bool is_integer() const { return Type() == kIntegerType; }
bool is_decimal() const { return Type() == kDecimalType; }
bool is_string() const { return Type() == kStringType; }
bool is_token() const { return Type() == kTokenType; }
bool is_byte_sequence() const { return Type() == kByteSequenceType; }
bool is_boolean() const { return Type() == kBooleanType; }
int64_t GetInteger() const {
const auto* value = absl::get_if<int64_t>(&value_);
QUICHE_CHECK(value);
return *value;
}
double GetDecimal() const {
const auto* value = absl::get_if<double>(&value_);
QUICHE_CHECK(value);
return *value;
}
bool GetBoolean() const {
const auto* value = absl::get_if<bool>(&value_);
QUICHE_CHECK(value);
return *value;
}
// TODO(iclelland): Split up accessors for String, Token and Byte Sequence.
const std::string& GetString() const {
struct Visitor {
const std::string* operator()(const absl::monostate&) { return nullptr; }
const std::string* operator()(const int64_t&) { return nullptr; }
const std::string* operator()(const double&) { return nullptr; }
const std::string* operator()(const std::string& value) { return &value; }
const std::string* operator()(const bool&) { return nullptr; }
};
const std::string* value = absl::visit(Visitor(), value_);
QUICHE_CHECK(value);
return *value;
}
ItemType Type() const { return static_cast<ItemType>(value_.index()); }
private:
absl::variant<absl::monostate, int64_t, double, std::string, std::string,
std::string, bool>
value_;
};
// Holds a ParameterizedIdentifier (draft 9 only). The contained Item must be a
// Token, and there may be any number of parameters. Parameter ordering is not
// significant.
struct QUICHE_EXPORT_PRIVATE ParameterisedIdentifier {
using Parameters = std::map<std::string, Item>;
Item identifier;
Parameters params;
ParameterisedIdentifier();
ParameterisedIdentifier(const ParameterisedIdentifier&);
ParameterisedIdentifier& operator=(const ParameterisedIdentifier&);
ParameterisedIdentifier(Item, Parameters);
~ParameterisedIdentifier();
};
inline bool operator==(const ParameterisedIdentifier& lhs,
const ParameterisedIdentifier& rhs) {
return std::tie(lhs.identifier, lhs.params) ==
std::tie(rhs.identifier, rhs.params);
}
using Parameters = std::vector<std::pair<std::string, Item>>;
struct QUICHE_EXPORT_PRIVATE ParameterizedItem {
Item item;
Parameters params;
ParameterizedItem();
ParameterizedItem(const ParameterizedItem&);
ParameterizedItem& operator=(const ParameterizedItem&);
ParameterizedItem(Item, Parameters);
~ParameterizedItem();
};
inline bool operator==(const ParameterizedItem& lhs,
const ParameterizedItem& rhs) {
return std::tie(lhs.item, lhs.params) == std::tie(rhs.item, rhs.params);
}
inline bool operator!=(const ParameterizedItem& lhs,
const ParameterizedItem& rhs) {
return !(lhs == rhs);
}
// Holds a ParameterizedMember, which may be either an single Item, or an Inner
// List of ParameterizedItems, along with any number of parameters. Parameter
// ordering is significant.
struct QUICHE_EXPORT_PRIVATE ParameterizedMember {
std::vector<ParameterizedItem> member;
// If false, then |member| should only hold one Item.
bool member_is_inner_list = false;
Parameters params;
ParameterizedMember();
ParameterizedMember(const ParameterizedMember&);
ParameterizedMember& operator=(const ParameterizedMember&);
ParameterizedMember(std::vector<ParameterizedItem>, bool member_is_inner_list,
Parameters);
// Shorthand constructor for a member which is an inner list.
ParameterizedMember(std::vector<ParameterizedItem>, Parameters);
// Shorthand constructor for a member which is a single Item.
ParameterizedMember(Item, Parameters);
~ParameterizedMember();
};
inline bool operator==(const ParameterizedMember& lhs,
const ParameterizedMember& rhs) {
return std::tie(lhs.member, lhs.member_is_inner_list, lhs.params) ==
std::tie(rhs.member, rhs.member_is_inner_list, rhs.params);
}
using DictionaryMember = std::pair<std::string, ParameterizedMember>;
// Structured Headers RFC8941 Dictionary.
class QUICHE_EXPORT_PRIVATE Dictionary {
public:
using iterator = std::vector<DictionaryMember>::iterator;
using const_iterator = std::vector<DictionaryMember>::const_iterator;
Dictionary();
Dictionary(const Dictionary&);
explicit Dictionary(std::vector<DictionaryMember> members);
~Dictionary();
Dictionary& operator=(const Dictionary&) = default;
iterator begin();
const_iterator begin() const;
iterator end();
const_iterator end() const;
// operator[](size_t) and at(size_t) will both abort the program in case of
// out of bounds access.
ParameterizedMember& operator[](std::size_t idx);
const ParameterizedMember& operator[](std::size_t idx) const;
ParameterizedMember& at(std::size_t idx);
const ParameterizedMember& at(std::size_t idx) const;
// Consistent with std::map, if |key| does not exist in the Dictionary, then
// operator[](absl::string_view) will create an entry for it, but at() will
// abort the entire program.
ParameterizedMember& operator[](absl::string_view key);
ParameterizedMember& at(absl::string_view key);
const ParameterizedMember& at(absl::string_view key) const;
bool empty() const;
std::size_t size() const;
bool contains(absl::string_view key) const;
friend bool operator==(const Dictionary& lhs, const Dictionary& rhs);
friend bool operator!=(const Dictionary& lhs, const Dictionary& rhs);
private:
// Uses a vector to hold pairs of key and dictionary member. This makes
// look up by index and serialization much easier.
std::vector<DictionaryMember> members_;
};
inline bool operator==(const Dictionary& lhs, const Dictionary& rhs) {
return lhs.members_ == rhs.members_;
}
inline bool operator!=(const Dictionary& lhs, const Dictionary& rhs) {
return !(lhs == rhs);
}
// Structured Headers Draft 09 Parameterised List.
using ParameterisedList = std::vector<ParameterisedIdentifier>;
// Structured Headers Draft 09 List of Lists.
using ListOfLists = std::vector<std::vector<Item>>;
// Structured Headers RFC8941 List.
using List = std::vector<ParameterizedMember>;
// Returns the result of parsing the header value as an Item, if it can be
// parsed as one, or nullopt if it cannot. Note that this uses the Draft 15
// parsing rules, and so applies tighter range limits to integers.
QUICHE_EXPORT_PRIVATE absl::optional<ParameterizedItem> ParseItem(
absl::string_view str);
// Returns the result of parsing the header value as an Item with no parameters,
// or nullopt if it cannot. Note that this uses the Draft 15 parsing rules, and
// so applies tighter range limits to integers.
QUICHE_EXPORT_PRIVATE absl::optional<Item> ParseBareItem(absl::string_view str);
// Returns the result of parsing the header value as a Parameterised List, if it
// can be parsed as one, or nullopt if it cannot. Note that parameter keys will
// be returned as strings, which are guaranteed to be ASCII-encoded. List items,
// as well as parameter values, will be returned as Items. This method uses the
// Draft 09 parsing rules for Items, so integers have the 64-bit int range.
// Structured-Headers Draft 09 only.
QUICHE_EXPORT_PRIVATE absl::optional<ParameterisedList> ParseParameterisedList(
absl::string_view str);
// Returns the result of parsing the header value as a List of Lists, if it can
// be parsed as one, or nullopt if it cannot. Inner list items will be returned
// as Items. This method uses the Draft 09 parsing rules for Items, so integers
// have the 64-bit int range.
// Structured-Headers Draft 09 only.
QUICHE_EXPORT_PRIVATE absl::optional<ListOfLists> ParseListOfLists(
absl::string_view str);
// Returns the result of parsing the header value as a general List, if it can
// be parsed as one, or nullopt if it cannot.
// Structured-Headers Draft 15 only.
QUICHE_EXPORT_PRIVATE absl::optional<List> ParseList(absl::string_view str);
// Returns the result of parsing the header value as a general Dictionary, if it
// can be parsed as one, or nullopt if it cannot. Structured-Headers Draft 15
// only.
QUICHE_EXPORT_PRIVATE absl::optional<Dictionary> ParseDictionary(
const absl::string_view& str);
// Serialization is implemented for Structured-Headers Draft 15 only.
QUICHE_EXPORT_PRIVATE absl::optional<std::string> SerializeItem(
const Item& value);
QUICHE_EXPORT_PRIVATE absl::optional<std::string> SerializeItem(
const ParameterizedItem& value);
QUICHE_EXPORT_PRIVATE absl::optional<std::string> SerializeList(
const List& value);
QUICHE_EXPORT_PRIVATE absl::optional<std::string> SerializeDictionary(
const Dictionary& value);
} // namespace structured_headers
} // namespace quiche
#endif // QUICHE_COMMON_STRUCTURED_HEADERS_H_