net/base/net_util.h

// Copyright (c) 2012 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 NET_BASE_NET_UTIL_H_
#define NET_BASE_NET_UTIL_H_

#include "build/build_config.h"

#if defined(OS_WIN)
#include <windows.h>
#include <ws2tcpip.h>
#elif defined(OS_POSIX)
#include <sys/types.h>
#include <sys/socket.h>
#endif

#include <string>
#include <vector>

#include "base/basictypes.h"
#include "base/strings/string16.h"
#include "net/base/address_family.h"
#include "net/base/escape.h"
#include "net/base/net_export.h"
#include "net/base/net_log.h"

class GURL;

namespace base {
class FilePath;
class Time;
}

namespace url_canon {
struct CanonHostInfo;
}

namespace url_parse {
struct Parsed;
}

namespace net {

// Used by FormatUrl to specify handling of certain parts of the url.
typedef uint32 FormatUrlType;
typedef uint32 FormatUrlTypes;

// IPAddressNumber is used to represent an IP address's numeric value as an
// array of bytes, from most significant to least significant. This is the
// network byte ordering.
//
// IPv4 addresses will have length 4, whereas IPv6 address will have length 16.
typedef std::vector<unsigned char> IPAddressNumber;
typedef std::vector<IPAddressNumber> IPAddressList;

static const size_t kIPv4AddressSize = 4;
static const size_t kIPv6AddressSize = 16;

// Nothing is ommitted.
NET_EXPORT extern const FormatUrlType kFormatUrlOmitNothing;

// If set, any username and password are removed.
NET_EXPORT extern const FormatUrlType kFormatUrlOmitUsernamePassword;

// If the scheme is 'http://', it's removed.
NET_EXPORT extern const FormatUrlType kFormatUrlOmitHTTP;

// Omits the path if it is just a slash and there is no query or ref.  This is
// meaningful for non-file "standard" URLs.
NET_EXPORT extern const FormatUrlType kFormatUrlOmitTrailingSlashOnBareHostname;

// Convenience for omitting all unecessary types.
NET_EXPORT extern const FormatUrlType kFormatUrlOmitAll;

// Returns the number of explicitly allowed ports; for testing.
NET_EXPORT_PRIVATE extern size_t GetCountOfExplicitlyAllowedPorts();

// Given the full path to a file name, creates a file: URL. The returned URL
// may not be valid if the input is malformed.
NET_EXPORT GURL FilePathToFileURL(const base::FilePath& path);

// Converts a file: URL back to a filename that can be passed to the OS. The
// file URL must be well-formed (GURL::is_valid() must return true); we don't
// handle degenerate cases here. Returns true on success, false if it isn't a
// valid file URL. On failure, *file_path will be empty.
NET_EXPORT bool FileURLToFilePath(const GURL& url, base::FilePath* file_path);

// Splits an input of the form <host>[":"<port>] into its consitituent parts.
// Saves the result into |*host| and |*port|. If the input did not have
// the optional port, sets |*port| to -1.
// Returns true if the parsing was successful, false otherwise.
// The returned host is NOT canonicalized, and may be invalid. If <host> is
// an IPv6 literal address, the returned host includes the square brackets.
NET_EXPORT bool ParseHostAndPort(
    std::string::const_iterator host_and_port_begin,
    std::string::const_iterator host_and_port_end,
    std::string* host,
    int* port);
NET_EXPORT bool ParseHostAndPort(
    const std::string& host_and_port,
    std::string* host,
    int* port);

// Returns a host:port string for the given URL.
NET_EXPORT std::string GetHostAndPort(const GURL& url);

// Returns a host[:port] string for the given URL, where the port is omitted
// if it is the default for the URL's scheme.
NET_EXPORT_PRIVATE std::string GetHostAndOptionalPort(const GURL& url);

// Returns true if |hostname| contains a non-registerable or non-assignable
// domain name (eg: a gTLD that has not been assigned by IANA) or an IP address
// that falls in an IANA-reserved range.
NET_EXPORT bool IsHostnameNonUnique(const std::string& hostname);

// Returns true if an IP address hostname is in a range reserved by the IANA.
// Works with both IPv4 and IPv6 addresses, and only compares against a given
// protocols's reserved ranges.
NET_EXPORT bool IsIPAddressReserved(const IPAddressNumber& address);

// Convenience struct for when you need a |struct sockaddr|.
struct SockaddrStorage {
  SockaddrStorage() : addr_len(sizeof(addr_storage)),
                      addr(reinterpret_cast<struct sockaddr*>(&addr_storage)) {}
  struct sockaddr_storage addr_storage;
  socklen_t addr_len;
  struct sockaddr* const addr;
};

// Extracts the IP address and port portions of a sockaddr. |port| is optional,
// and will not be filled in if NULL.
bool GetIPAddressFromSockAddr(const struct sockaddr* sock_addr,
                              socklen_t sock_addr_len,
                              const unsigned char** address,
                              size_t* address_len,
                              uint16* port);

// Returns the string representation of an IP address.
// For example: "192.168.0.1" or "::1".
NET_EXPORT std::string IPAddressToString(const uint8* address,
                                         size_t address_len);

// Returns the string representation of an IP address along with its port.
// For example: "192.168.0.1:99" or "[::1]:80".
NET_EXPORT std::string IPAddressToStringWithPort(const uint8* address,
                                                 size_t address_len,
                                                 uint16 port);

// Same as IPAddressToString() but for a sockaddr. This output will not include
// the IPv6 scope ID.
NET_EXPORT std::string NetAddressToString(const struct sockaddr* sa,
                                          socklen_t sock_addr_len);

// Same as IPAddressToStringWithPort() but for a sockaddr. This output will not
// include the IPv6 scope ID.
NET_EXPORT std::string NetAddressToStringWithPort(const struct sockaddr* sa,
                                                  socklen_t sock_addr_len);

// Same as IPAddressToString() but for an IPAddressNumber.
NET_EXPORT std::string IPAddressToString(const IPAddressNumber& addr);

// Same as IPAddressToStringWithPort() but for an IPAddressNumber.
NET_EXPORT std::string IPAddressToStringWithPort(
    const IPAddressNumber& addr, uint16 port);

// Returns the address as a sequence of bytes in network-byte-order.
NET_EXPORT std::string IPAddressToPackedString(const IPAddressNumber& addr);

// Returns the hostname of the current system. Returns empty string on failure.
NET_EXPORT std::string GetHostName();

// Extracts the unescaped username/password from |url|, saving the results
// into |*username| and |*password|.
NET_EXPORT_PRIVATE void GetIdentityFromURL(const GURL& url,
                                           base::string16* username,
                                           base::string16* password);

// Returns either the host from |url|, or, if the host is empty, the full spec.
NET_EXPORT std::string GetHostOrSpecFromURL(const GURL& url);

// Return the value of the HTTP response header with name 'name'.  'headers'
// should be in the format that URLRequest::GetResponseHeaders() returns.
// Returns the empty string if the header is not found.
NET_EXPORT std::string GetSpecificHeader(const std::string& headers,
                                         const std::string& name);

// Converts the given host name to unicode characters. This can be called for
// any host name, if the input is not IDN or is invalid in some way, we'll just
// return the ASCII source so it is still usable.
//
// The input should be the canonicalized ASCII host name from GURL. This
// function does NOT accept UTF-8!
//
// |languages| is a comma separated list of ISO 639 language codes. It
// is used to determine whether a hostname is 'comprehensible' to a user
// who understands languages listed. |host| will be converted to a
// human-readable form (Unicode) ONLY when each component of |host| is
// regarded as 'comprehensible'. Scipt-mixing is not allowed except that
// Latin letters in the ASCII range can be mixed with a limited set of
// script-language pairs (currently Han, Kana and Hangul for zh,ja and ko).
// When |languages| is empty, even that mixing is not allowed.
NET_EXPORT base::string16 IDNToUnicode(const std::string& host,
                                       const std::string& languages);

// Canonicalizes |host| and returns it.  Also fills |host_info| with
// IP address information.  |host_info| must not be NULL.
NET_EXPORT std::string CanonicalizeHost(const std::string& host,
                                        url_canon::CanonHostInfo* host_info);

// Returns true if |host| is not an IP address and is compliant with a set of
// rules based on RFC 1738 and tweaked to be compatible with the real world.
// The rules are:
//   * One or more components separated by '.'
//   * Each component begins with an alphanumeric character or '-'
//   * Each component contains only alphanumeric characters and '-' or '_'
//   * Each component ends with an alphanumeric character or '-'
//   * The last component begins with an alphanumeric character
//   * Optional trailing dot after last component (means "treat as FQDN")
// If |desired_tld| is non-NULL, the host will only be considered invalid if
// appending it as a trailing component still results in an invalid host.  This
// helps us avoid marking as "invalid" user attempts to open, say, "www.-9.com"
// by typing -, 9, <ctrl>+<enter>.
//
// NOTE: You should only pass in hosts that have been returned from
// CanonicalizeHost(), or you may not get accurate results.
NET_EXPORT bool IsCanonicalizedHostCompliant(const std::string& host,
                                             const std::string& desired_tld);

// Call these functions to get the html snippet for a directory listing.
// The return values of both functions are in UTF-8.
NET_EXPORT std::string GetDirectoryListingHeader(const base::string16& title);

// Given the name of a file in a directory (ftp or local) and
// other information (is_dir, size, modification time), it returns
// the html snippet to add the entry for the file to the directory listing.
// Currently, it's a script tag containing a call to a Javascript function
// |addRow|.
//
// |name| is the file name to be displayed. |raw_bytes| will be used
// as the actual target of the link (so for example, ftp links should use
// server's encoding). If |raw_bytes| is an empty string, UTF-8 encoded |name|
// will be used.
//
// Both |name| and |raw_bytes| are escaped internally.
NET_EXPORT std::string GetDirectoryListingEntry(const base::string16& name,
                                                const std::string& raw_bytes,
                                                bool is_dir, int64 size,
                                                base::Time modified);

// If text starts with "www." it is removed, otherwise text is returned
// unmodified.
NET_EXPORT base::string16 StripWWW(const base::string16& text);

// Runs |url|'s host through StripWWW().  |url| must be valid.
NET_EXPORT base::string16 StripWWWFromHost(const GURL& url);

// Generates a filename using the first successful method from the following (in
// order):
//
// 1) The raw Content-Disposition header in |content_disposition| as read from
//    the network.  |referrer_charset| is used to decode non-ASCII strings.
// 2) |suggested_name| if specified.  |suggested_name| is assumed to be in
//    UTF-8.
// 3) The filename extracted from the |url|.  |referrer_charset| will be used to
//    interpret the URL if there are non-ascii characters.
// 4) |default_name|.  If non-empty, |default_name| is assumed to be a filename
//    and shouldn't contain a path.  |default_name| is not subject to validation
//    or sanitization, and therefore shouldn't be a user supplied string.
// 5) The hostname portion from the |url|
//
// Then, leading and trailing '.'s will be removed.  On Windows, trailing spaces
// are also removed.  The string "download" is the final fallback if no filename
// is found or the filename is empty.
//
// Any illegal characters in the filename will be replaced by '-'.  If the
// filename doesn't contain an extension, and a |mime_type| is specified, the
// preferred extension for the |mime_type| will be appended to the filename.
// The resulting filename is then checked against a list of reserved names on
// Windows.  If the name is reserved, an underscore will be prepended to the
// filename.
//
// Note: |mime_type| should only be specified if this function is called from a
// thread that allows IO.
NET_EXPORT base::string16 GetSuggestedFilename(
    const GURL& url,
    const std::string& content_disposition,
    const std::string& referrer_charset,
    const std::string& suggested_name,
    const std::string& mime_type,
    const std::string& default_name);

// Similar to GetSuggestedFilename(), but returns a FilePath.
NET_EXPORT base::FilePath GenerateFileName(
    const GURL& url,
    const std::string& content_disposition,
    const std::string& referrer_charset,
    const std::string& suggested_name,
    const std::string& mime_type,
    const std::string& default_name);

// Valid components:
// * are not empty
// * are not Windows reserved names (CON, NUL.zip, etc.)
// * do not have trailing separators
// * do not equal kCurrentDirectory
// * do not reference the parent directory
// * do not contain illegal characters
// * do not end with Windows shell-integrated extensions (even on posix)
// * do not begin with '.' (which would hide them in most file managers)
// * do not end with ' ' or '.'
NET_EXPORT bool IsSafePortablePathComponent(const base::FilePath& component);

// Basenames of valid relative paths are IsSafePortableBasename(), and internal
// path components of valid relative paths are valid path components as
// described above IsSafePortableBasename(). Valid relative paths are not
// absolute paths.
NET_EXPORT bool IsSafePortableRelativePath(const base::FilePath& path);

// Ensures that the filename and extension is safe to use in the filesystem.
//
// Assumes that |file_path| already contains a valid path or file name.  On
// Windows if the extension causes the file to have an unsafe interaction with
// the shell (see net_util::IsShellIntegratedExtension()), then it will be
// replaced by the string 'download'.  If |file_path| doesn't contain an
// extension or |ignore_extension| is true then the preferred extension, if one
// exists, for |mime_type| will be used as the extension.
//
// On Windows, the filename will be checked against a set of reserved names, and
// if so, an underscore will be prepended to the name.
//
// |file_name| can either be just the file name or it can be a full path to a
// file.
//
// Note: |mime_type| should only be non-empty if this function is called from a
// thread that allows IO.
NET_EXPORT void GenerateSafeFileName(const std::string& mime_type,
                                     bool ignore_extension,
                                     base::FilePath* file_path);

// Checks |port| against a list of ports which are restricted by default.
// Returns true if |port| is allowed, false if it is restricted.
NET_EXPORT bool IsPortAllowedByDefault(int port);

// Checks |port| against a list of ports which are restricted by the FTP
// protocol.  Returns true if |port| is allowed, false if it is restricted.
NET_EXPORT_PRIVATE bool IsPortAllowedByFtp(int port);

// Check if banned |port| has been overriden by an entry in
// |explicitly_allowed_ports_|.
NET_EXPORT_PRIVATE bool IsPortAllowedByOverride(int port);

// Set socket to non-blocking mode
NET_EXPORT int SetNonBlocking(int fd);

// Formats the host in |url| and appends it to |output|.  The host formatter
// takes the same accept languages component as ElideURL().
NET_EXPORT void AppendFormattedHost(const GURL& url,
                                    const std::string& languages,
                                    base::string16* output);

// Creates a string representation of |url|. The IDN host name may be in Unicode
// if |languages| accepts the Unicode representation. |format_type| is a bitmask
// of FormatUrlTypes, see it for details. |unescape_rules| defines how to clean
// the URL for human readability. You will generally want |UnescapeRule::SPACES|
// for display to the user if you can handle spaces, or |UnescapeRule::NORMAL|
// if not. If the path part and the query part seem to be encoded in %-encoded
// UTF-8, decodes %-encoding and UTF-8.
//
// The last three parameters may be NULL.
//
// |new_parsed| will be set to the parsing parameters of the resultant URL.
//
// |prefix_end| will be the length before the hostname of the resultant URL.
//
// |offset[s]_for_adjustment| specifies one or more offsets into the original
// URL, representing insertion or selection points between characters: if the
// input is "http://foo.com/", offset 0 is before the entire URL, offset 7 is
// between the scheme and the host, and offset 15 is after the end of the URL.
// Valid input offsets range from 0 to the length of the input URL string.  On
// exit, each offset will have been modified to reflect any changes made to the
// output string.  For example, if |url| is "http://a:b@c.com/",
// |omit_username_password| is true, and an offset is 12 (pointing between 'c'
// and '.'), then on return the output string will be "http://c.com/" and the
// offset will be 8.  If an offset cannot be successfully adjusted (e.g. because
// it points into the middle of a component that was entirely removed or into
// the middle of an encoding sequence), it will be set to base::string16::npos.
// For consistency, if an input offset points between the scheme and the
// username/password, and both are removed, on output this offset will be 0
// rather than npos; this means that offsets at the starts and ends of removed
// components are always transformed the same way regardless of what other
// components are adjacent.
NET_EXPORT base::string16 FormatUrl(const GURL& url,
                                    const std::string& languages,
                                    FormatUrlTypes format_types,
                                    UnescapeRule::Type unescape_rules,
                                    url_parse::Parsed* new_parsed,
                                    size_t* prefix_end,
                                    size_t* offset_for_adjustment);
NET_EXPORT base::string16 FormatUrlWithOffsets(
    const GURL& url,
    const std::string& languages,
    FormatUrlTypes format_types,
    UnescapeRule::Type unescape_rules,
    url_parse::Parsed* new_parsed,
    size_t* prefix_end,
    std::vector<size_t>* offsets_for_adjustment);

// This is a convenience function for FormatUrl() with
// format_types = kFormatUrlOmitAll and unescape = SPACES.  This is the typical
// set of flags for "URLs to display to the user".  You should be cautious about
// using this for URLs which will be parsed or sent to other applications.
inline base::string16 FormatUrl(const GURL& url, const std::string& languages) {
  return FormatUrl(url, languages, kFormatUrlOmitAll, UnescapeRule::SPACES,
                   NULL, NULL, NULL);
}

// Returns whether FormatUrl() would strip a trailing slash from |url|, given a
// format flag including kFormatUrlOmitTrailingSlashOnBareHostname.
NET_EXPORT bool CanStripTrailingSlash(const GURL& url);

// Strip the portions of |url| that aren't core to the network request.
//   - user name / password
//   - reference section
NET_EXPORT_PRIVATE GURL SimplifyUrlForRequest(const GURL& url);

NET_EXPORT void SetExplicitlyAllowedPorts(const std::string& allowed_ports);

class NET_EXPORT ScopedPortException {
 public:
  explicit ScopedPortException(int port);
  ~ScopedPortException();

 private:
  int port_;

  DISALLOW_COPY_AND_ASSIGN(ScopedPortException);
};

// Returns true if it can determine that only loopback addresses are configured.
// i.e. if only 127.0.0.1 and ::1 are routable.
// Also returns false if it cannot determine this.
bool HaveOnlyLoopbackAddresses();

// Returns AddressFamily of the address.
NET_EXPORT_PRIVATE AddressFamily GetAddressFamily(
    const IPAddressNumber& address);

// Maps the given AddressFamily to either AF_INET, AF_INET6 or AF_UNSPEC.
int ConvertAddressFamily(AddressFamily address_family);

// Parses an IP address literal (either IPv4 or IPv6) to its numeric value.
// Returns true on success and fills |ip_number| with the numeric value.
NET_EXPORT_PRIVATE bool ParseIPLiteralToNumber(const std::string& ip_literal,
                                               IPAddressNumber* ip_number);

// Converts an IPv4 address to an IPv4-mapped IPv6 address.
// For example 192.168.0.1 would be converted to ::ffff:192.168.0.1.
NET_EXPORT_PRIVATE IPAddressNumber ConvertIPv4NumberToIPv6Number(
    const IPAddressNumber& ipv4_number);

// Returns true iff |address| is an IPv4-mapped IPv6 address.
NET_EXPORT_PRIVATE bool IsIPv4Mapped(const IPAddressNumber& address);

// Converts an IPv4-mapped IPv6 address to IPv4 address. Should only be called
// on IPv4-mapped IPv6 addresses.
NET_EXPORT_PRIVATE IPAddressNumber ConvertIPv4MappedToIPv4(
    const IPAddressNumber& address);

// Parses an IP block specifier from CIDR notation to an
// (IP address, prefix length) pair. Returns true on success and fills
// |*ip_number| with the numeric value of the IP address and sets
// |*prefix_length_in_bits| with the length of the prefix.
//
// CIDR notation literals can use either IPv4 or IPv6 literals. Some examples:
//
//    10.10.3.1/20
//    a:b:c::/46
//    ::1/128
NET_EXPORT bool ParseCIDRBlock(const std::string& cidr_literal,
                               IPAddressNumber* ip_number,
                               size_t* prefix_length_in_bits);

// Compares an IP address to see if it falls within the specified IP block.
// Returns true if it does, false otherwise.
//
// The IP block is given by (|ip_prefix|, |prefix_length_in_bits|) -- any
// IP address whose |prefix_length_in_bits| most significant bits match
// |ip_prefix| will be matched.
//
// In cases when an IPv4 address is being compared to an IPv6 address prefix
// and vice versa, the IPv4 addresses will be converted to IPv4-mapped
// (IPv6) addresses.
NET_EXPORT_PRIVATE bool IPNumberMatchesPrefix(const IPAddressNumber& ip_number,
                                              const IPAddressNumber& ip_prefix,
                                              size_t prefix_length_in_bits);

// Retuns the port field of the |sockaddr|.
const uint16* GetPortFieldFromSockaddr(const struct sockaddr* address,
                                       socklen_t address_len);
// Returns the value of port in |sockaddr| (in host byte ordering).
NET_EXPORT_PRIVATE int GetPortFromSockaddr(const struct sockaddr* address,
                                           socklen_t address_len);

// Returns true if |host| is one of the names (e.g. "localhost") or IP
// addresses (IPv4 127.0.0.0/8 or IPv6 ::1) that indicate a loopback.
//
// Note that this function does not check for IP addresses other than
// the above, although other IP addresses may point to the local
// machine.
NET_EXPORT_PRIVATE bool IsLocalhost(const std::string& host);

// struct that is used by GetNetworkList() to represent a network
// interface.
struct NET_EXPORT NetworkInterface {
  NetworkInterface();
  NetworkInterface(const std::string& name,
                   const IPAddressNumber& address,
                   size_t network_prefix);
  ~NetworkInterface();

  std::string name;
  IPAddressNumber address;
  size_t network_prefix;
};

typedef std::vector<NetworkInterface> NetworkInterfaceList;

// Returns list of network interfaces except loopback interface. If an
// interface has more than one address, a separate entry is added to
// the list for each address.
// Can be called only on a thread that allows IO.
NET_EXPORT bool GetNetworkList(NetworkInterfaceList* networks);

// General category of the IEEE 802.11 (wifi) physical layer operating mode.
enum WifiPHYLayerProtocol {
  // No wifi support or no associated AP.
  WIFI_PHY_LAYER_PROTOCOL_NONE,
  // An obsolete modes introduced by the original 802.11, e.g. IR, FHSS,
  WIFI_PHY_LAYER_PROTOCOL_ANCIENT,
  // 802.11a, OFDM-based rates.
  WIFI_PHY_LAYER_PROTOCOL_A,
  // 802.11b, DSSS or HR DSSS.
  WIFI_PHY_LAYER_PROTOCOL_B,
  // 802.11g, same rates as 802.11a but compatible with 802.11b.
  WIFI_PHY_LAYER_PROTOCOL_G,
  // 802.11n, HT rates.
  WIFI_PHY_LAYER_PROTOCOL_N,
  // Unclassified mode or failure to identify.
  WIFI_PHY_LAYER_PROTOCOL_UNKNOWN
};

// Characterize the PHY mode of the currently associated access point.
// Currently only available on OS_WIN.
NET_EXPORT WifiPHYLayerProtocol GetWifiPHYLayerProtocol();

// Returns number of matching initial bits between the addresses |a1| and |a2|.
unsigned CommonPrefixLength(const IPAddressNumber& a1,
                            const IPAddressNumber& a2);

// Computes the number of leading 1-bits in |mask|.
unsigned MaskPrefixLength(const IPAddressNumber& mask);

// Differentiated Services Code Point.
// See http://tools.ietf.org/html/rfc2474 for details.
enum DiffServCodePoint {
  DSCP_NO_CHANGE = -1,
  DSCP_DEFAULT = 0,  // Same as DSCP_CS0
  DSCP_CS0  = 0,   // The default
  DSCP_CS1  = 8,   // Bulk/background traffic
  DSCP_AF11 = 10,
  DSCP_AF12 = 12,
  DSCP_AF13 = 14,
  DSCP_CS2  = 16,
  DSCP_AF21 = 18,
  DSCP_AF22 = 20,
  DSCP_AF23 = 22,
  DSCP_CS3  = 24,
  DSCP_AF31 = 26,
  DSCP_AF32 = 28,
  DSCP_AF33 = 30,
  DSCP_CS4  = 32,
  DSCP_AF41 = 34,  // Video
  DSCP_AF42 = 36,  // Video
  DSCP_AF43 = 38,  // Video
  DSCP_CS5  = 40,  // Video
  DSCP_EF   = 46,  // Voice
  DSCP_CS6  = 48,  // Voice
  DSCP_CS7  = 56,  // Control messages
};

}  // namespace net

#endif  // NET_BASE_NET_UTIL_H_