url/scheme_host_port.h

// Copyright 2015 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef URL_SCHEME_HOST_PORT_H_
#define URL_SCHEME_HOST_PORT_H_

#include <stdint.h>

#include <string>

#include "base/component_export.h"
#include "base/strings/string_piece.h"

class GURL;

namespace url {

struct Parsed;

// This class represents a (scheme, host, port) tuple extracted from a URL.
//
// The primary purpose of this class is to represent relevant network-authority
// information for a URL. It is _not_ an Origin, as described in RFC 6454. In
// particular, it is generally NOT the right thing to use for security
// decisions.
//
// Instead, this class is a mechanism for simplifying URLs with standard schemes
// (that is, those which follow the generic syntax of RFC 3986) down to the
// uniquely identifying information necessary for network fetches. This makes it
// suitable as a cache key for a collection of active connections, for instance.
// It may, however, be inappropriate to use as a cache key for persistent
// storage associated with a host.
//
// In particular, note that:
//
// * SchemeHostPort can only represent schemes which follow the RFC 3986 syntax
//   (e.g. those registered with GURL as "standard schemes"). Non-standard
//   schemes such as "blob", "filesystem", "data", and "javascript" can only be
//   represented as invalid SchemeHostPort objects.
//
// * For example, the "file" scheme follows the standard syntax, but it is
//   important to note that the authority portion (host, port) is optional.
//   URLs without an authority portion will be represented with an empty string
//   for the host, and a port of 0 (e.g. "file:///etc/hosts" =>
//   ("file", "", 0)), and URLs with a host-only authority portion will be
//   represented with a port of 0 (e.g. "file://example.com/etc/hosts" =>
//   ("file", "example.com", 0)). See Section 3 of RFC 3986 to better understand
//   these constructs.
//
// * SchemeHostPort has no notion of the Origin concept (RFC 6454), and in
//   particular, it has no notion of an opaque Origin. If you need to take
//   opaque origins into account (and, if you're making security-relevant
//   decisions then you absolutely do), please use 'url::Origin' instead.
//
// Usage:
//
// * SchemeHostPort objects are commonly created from GURL objects:
//
//     GURL url("https://example.com/");
//     url::SchemeHostPort tuple(url);
//     tuple.scheme(); // "https"
//     tuple.host(); // "example.com"
//     tuple.port(); // 443
//
// * Objects may also be explicitly created and compared:
//
//     url::SchemeHostPort tuple(url::kHttpsScheme, "example.com", 443);
//     tuple.scheme(); // "https"
//     tuple.host(); // "example.com"
//     tuple.port(); // 443
//
//     GURL url("https://example.com/");
//     tuple == url::SchemeHostPort(url); // true
class COMPONENT_EXPORT(URL) SchemeHostPort {
 public:
  // Creates an invalid (scheme, host, port) tuple, which represents an invalid
  // or non-standard URL.
  SchemeHostPort();

  // Creates a (scheme, host, port) tuple. |host| must be a canonicalized
  // A-label (that is, '☃.net' must be provided as 'xn--n3h.net'). |scheme|
  // must be a standard scheme. |port| must be 0 if |scheme| does not support
  // ports (e.g. 'file').
  //
  // Copies the data in |scheme| and |host|.
  SchemeHostPort(base::StringPiece scheme,
                 base::StringPiece host,
                 uint16_t port);

  // Metadata influencing whether or not the constructor should sanity check
  // host canonicalization.
  enum ConstructPolicy { CHECK_CANONICALIZATION, ALREADY_CANONICALIZED };

  // Creates a (scheme, host, port) tuple without performing sanity checking
  // that the host and port are canonicalized. This should only be used when
  // converting between already normalized types, and should NOT be used for
  // IPC.
  SchemeHostPort(std::string scheme,
                 std::string host,
                 uint16_t port,
                 ConstructPolicy policy);

  // Creates a (scheme, host, port) tuple from |url|, as described at
  // https://tools.ietf.org/html/rfc6454#section-4
  //
  // If |url| is invalid or non-standard, the result will be an invalid
  // SchemeHostPort object.
  explicit SchemeHostPort(const GURL& url);

  // Copyable and movable.
  SchemeHostPort(const SchemeHostPort&) = default;
  SchemeHostPort& operator=(const SchemeHostPort&) = default;
  SchemeHostPort(SchemeHostPort&&) noexcept = default;
  SchemeHostPort& operator=(SchemeHostPort&&) noexcept = default;

  ~SchemeHostPort();

  // Returns the host component, in URL form. That is all IDN domain names will
  // be expressed as A-Labels ('☃.net' will be returned as 'xn--n3h.net'), and
  // and all IPv6 addresses will be enclosed in brackets ("[2001:db8::1]").
  const std::string& host() const { return host_; }
  const std::string& scheme() const { return scheme_; }
  uint16_t port() const { return port_; }
  bool IsValid() const;

  // Serializes the SchemeHostPort tuple to a canonical form.
  //
  // While this string form resembles the Origin serialization specified in
  // Section 6.2 of RFC 6454, it is important to note that invalid
  // SchemeHostPort tuples serialize to the empty string, rather than being
  // serialized as would an opaque Origin.
  std::string Serialize() const;

  // Efficiently returns what GURL(Serialize()) would return, without needing to
  // re-parse the URL. Note: this still performs allocations to copy data into
  // GURL, so please avoid using this method if you only need to work on
  // schemes, hosts, or ports individually.
  // For example, see crrev.com/c/3637099/comments/782360d0_e14757be.
  GURL GetURL() const;

  // Two SchemeHostPort objects are "equal" iff their schemes, hosts, and ports
  // are exact matches.
  //
  // Note that this comparison is _not_ the same as an origin-based comparison.
  // In particular, invalid SchemeHostPort objects match each other (and
  // themselves). Opaque origins, on the other hand, would not.
  bool operator==(const SchemeHostPort& other) const {
    return port_ == other.port() && scheme_ == other.scheme() &&
           host_ == other.host();
  }
  bool operator!=(const SchemeHostPort& other) const {
    return !(*this == other);
  }
  // Allows SchemeHostPort to be used as a key in STL (for example, a std::set
  // or std::map).
  bool operator<(const SchemeHostPort& other) const;

 private:
  std::string SerializeInternal(url::Parsed* parsed) const;

  std::string scheme_;
  std::string host_;
  uint16_t port_ = 0;
};

COMPONENT_EXPORT(URL)
std::ostream& operator<<(std::ostream& out,
                         const SchemeHostPort& scheme_host_port);

}  // namespace url

#endif  // URL_SCHEME_HOST_PORT_H_