Separate http_security_headers from transport_security_state

net/http/http_security_headers.cc

+// 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.
+
+#include "base/base64.h"
+#include "base/basictypes.h"
+#include "base/string_number_conversions.h"
+#include "base/string_tokenizer.h"
+#include "base/string_util.h"
+#include "net/http/http_security_headers.h"
+#include "net/http/http_util.h"
+
+namespace net {
+
+namespace {
+
+// MaxAgeToInt converts a string representation of a number of seconds
+// into a int. We use StringToInt64 in order to handle overflow and
+// negative numbers correctly.  The string may contain an arbitary
+// number which we should truncate correctly rather than throwing a
+// parse failure.
+
+bool MaxAgeToInt(std::string::const_iterator begin,
+                 std::string::const_iterator end,
+                 uint32* result) {
+  const std::string s(begin, end);
+  int64 i = 0;
+  /* Reject any parse failures *except* overflow, which is handled below */
+  if (!base::StringToInt64(s, &i) && i != kint64max)

[Ryan Sleevi, 2012/12/20 23:44:13]

If overflow happens, StringToInt64 will return false (by virtue of
IteratorRangeToNumber::Invoke returning false, by virtue of
IteratorRangeToNumber::Base::Invoke returning false, by virtue of
IteratorRangeToNumber::Positive::CheckBounds returning false.

Perhaps you meant by the comment "values greater than kMaxHSTSAgeSecs"

When you do update the comment, please follow the style of the rest of the file
of using C++ // comments rather than /* */, for consistency reasons.

[unsafe, 2012/12/21 02:56:49]

Clarified the comment.

+    return false;
+  if (i < 0)
+    return false;
+  COMPILE_ASSERT(kMaxHSTSAgeSecs <= kuint32max, kMaxHSTSAgeSecsTooLarge);

[Ryan Sleevi, 2012/12/20 23:44:13]

nit: You can move this line 33 to line 16 - the location of the COMPILE_ASSERT
in code doesn't matter, and it makes it easier to separate out the logic from
the pre-condition guarantees.

[unsafe, 2012/12/21 02:56:49]

Done.

+  if (i > kMaxHSTSAgeSecs)
+    i = kMaxHSTSAgeSecs;
+  *result = (uint32)i;
+  return true;
+}
+
+// Returns true iff there is an item in |pins| which is not present in
+// |from_cert_chain|. Such an SPKI hash is called a "backup pin".
+bool IsBackupPinPresent(const HashValueVector& pins,
+                        const HashValueVector& from_cert_chain) {
+  for (HashValueVector::const_iterator i = pins.begin(); i != pins.end();
+       ++i) {
+    HashValueVector::const_iterator j =
+        std::find_if(from_cert_chain.begin(), from_cert_chain.end(),
+                     HashValuesEqual(*i));
+    if (j == from_cert_chain.end())
+      return true;
+  }
+
+  return false;
+}
+
+// Returns true if the intersection of |a| and |b| is not empty. If either
+// |a| or |b| is empty, returns false.
+bool HashesIntersect(const HashValueVector& a,
+                     const HashValueVector& b) {
+  for (HashValueVector::const_iterator i = a.begin(); i != a.end(); ++i) {
+    HashValueVector::const_iterator j =
+        std::find_if(b.begin(), b.end(), HashValuesEqual(*i));
+    if (j != b.end())
+      return true;
+  }
+  return false;
+}
+
+// Returns true iff |pins| contains both a live and a backup pin. A live pin
+// is a pin whose SPKI is present in the certificate chain in |ssl_info|. A
+// backup pin is a pin intended for disaster recovery, not day-to-day use, and
+// thus must be absent from the certificate chain. The Public-Key-Pins header
+// specification requires both.
+bool IsPinListValid(const HashValueVector& pins,
+                    const HashValueVector& from_cert_chain) {
+  // Fast fail: 1 live + 1 backup = at least 2 pins. (Check for actual
+  // liveness and backupness below.)
+  if (pins.size() < 2)
+    return false;
+
+  if (from_cert_chain.empty())
+    return false;
+
+  return IsBackupPinPresent(pins, from_cert_chain) &&
+         HashesIntersect(pins, from_cert_chain);
+}
+
+std::string Strip(const std::string& source) {
+  if (source.empty())
+    return source;
+
+  std::string::const_iterator start = source.begin();
+  std::string::const_iterator end = source.end();
+  HttpUtil::TrimLWS(&start, &end);
+  return std::string(start, end);
+}
+
+typedef std::pair<std::string, std::string> StringPair;
+
+StringPair Split(const std::string& source, char delimiter) {
+  StringPair pair;
+  size_t point = source.find(delimiter);
+
+  pair.first = source.substr(0, point);
+  if (std::string::npos != point)
+    pair.second = source.substr(point + 1);
+
+  return pair;
+}
+
+bool ParseAndAppendPin(const std::string& value,
+                       HashValueTag tag,
+                       HashValueVector* hashes) {
+  std::string unquoted = HttpUtil::Unquote(value);
+  std::string decoded;
+
+  if (!base::Base64Decode(unquoted, &decoded))

[Ryan Sleevi, 2012/12/20 23:44:13]

BUG: Please add a check that !unquoted.empty() before calling B64Decode

[unsafe, 2012/12/21 02:56:49]

Done.

+    return false;
+
+  HashValue hash(tag);
+  if (decoded.size() != hash.size())
+    return false;
+
+  memcpy(hash.data(), decoded.data(), hash.size());
+  hashes->push_back(hash);
+  return true;
+}
+
+} // namespace
+
+// Parse the Strict-Transport-Security header, as currently defined in
+// http://tools.ietf.org/html/draft-ietf-websec-strict-transport-sec-14:
+//
+// Strict-Transport-Security = "Strict-Transport-Security" ":"
+//                             [ directive ]  *( ";" [ directive ] )
+//
+// directive                 = directive-name [ "=" directive-value ]
+// directive-name            = token
+// directive-value           = token | quoted-string
+//
+// 1.  The order of appearance of directives is not significant.
+//
+// 2.  All directives MUST appear only once in an STS header field.
+//     Directives are either optional or required, as stipulated in
+//     their definitions.
+//
+// 3.  Directive names are case-insensitive.
+//
+// 4.  UAs MUST ignore any STS header fields containing directives, or
+//     other header field value data, that does not conform to the
+//     syntax defined in this specification.
+//
+// 5.  If an STS header field contains directive(s) not recognized by
+//     the UA, the UA MUST ignore the unrecognized directives and if the
+//     STS header field otherwise satisfies the above requirements (1
+//     through 4), the UA MUST process the recognized directives.
+bool ParseHSTSHeader(const base::Time& now, const std::string& value,
+                     base::Time* expiry,         // OUT
+                     bool* include_subdomains) {  // OUT
+  uint32 max_age_candidate = 0;
+  bool include_subdomains_candidate = false;
+
+  // We must see max-age exactly once.
+  int max_age_observed = 0;
+  // We must see includeSubdomains exactly 0 or 1 times.
+  int include_subdomains_observed = 0;
+
+  enum ParserState {
+    START,
+    AFTER_MAX_AGE_LABEL,
+    AFTER_MAX_AGE_EQUALS,
+    AFTER_MAX_AGE,
+    AFTER_INCLUDE_SUBDOMAINS,
+    AFTER_UNKNOWN_LABEL,
+    DIRECTIVE_END
+  } state = START;
+
+  StringTokenizer tokenizer(value, " \t=;");
+  tokenizer.set_options(StringTokenizer::RETURN_DELIMS);
+  tokenizer.set_quote_chars("\"");
+  std::string unquoted;
+  while (tokenizer.GetNext()) {
+    DCHECK(!tokenizer.token_is_delim() || tokenizer.token().length() == 1);
+    switch (state) {
+      case START:
+      case DIRECTIVE_END:
+        if (IsAsciiWhitespace(*tokenizer.token_begin()))
+          continue;
+        if (LowerCaseEqualsASCII(tokenizer.token(), "max-age")) {
+          state = AFTER_MAX_AGE_LABEL;
+          max_age_observed++;
+        } else if (LowerCaseEqualsASCII(tokenizer.token(),
+                                        "includesubdomains")) {
+          state = AFTER_INCLUDE_SUBDOMAINS;
+          include_subdomains_observed++;
+          include_subdomains_candidate = true;
+        } else {
+          state = AFTER_UNKNOWN_LABEL;
+        }
+        break;
+
+      case AFTER_MAX_AGE_LABEL:
+        if (IsAsciiWhitespace(*tokenizer.token_begin()))
+          continue;
+        if (*tokenizer.token_begin() != '=')
+          return false;
+        DCHECK_EQ(tokenizer.token().length(), 1U);
+        state = AFTER_MAX_AGE_EQUALS;
+        break;
+
+      case AFTER_MAX_AGE_EQUALS:
+        if (IsAsciiWhitespace(*tokenizer.token_begin()))
+          continue;
+        unquoted = HttpUtil::Unquote(tokenizer.token());
+        if (!MaxAgeToInt(unquoted.begin(), unquoted.end(), &max_age_candidate))
+          return false;
+        state = AFTER_MAX_AGE;
+        break;
+
+      case AFTER_MAX_AGE:
+      case AFTER_INCLUDE_SUBDOMAINS:
+        if (IsAsciiWhitespace(*tokenizer.token_begin()))
+          continue;
+        else if (*tokenizer.token_begin() == ';')
+          state = DIRECTIVE_END;
+        else
+          return false;
+        break;
+
+      case AFTER_UNKNOWN_LABEL:
+        // Consume and ignore the post-label contents (if any).
+        if (*tokenizer.token_begin() != ';')
+          continue;
+        state = DIRECTIVE_END;
+        break;
+    }
+  }
+
+  // We've consumed all the input.  Let's see what state we ended up in.
+  if (max_age_observed != 1 ||
+      (include_subdomains_observed != 0 && include_subdomains_observed != 1)) {
+    return false;
+  }
+
+  switch (state) {
+    case AFTER_MAX_AGE:
+    case AFTER_INCLUDE_SUBDOMAINS:
+    case AFTER_UNKNOWN_LABEL:
+      *expiry = now + base::TimeDelta::FromSeconds(max_age_candidate);
+      *include_subdomains = include_subdomains_candidate;
+      return true;
+    case START:
+    case DIRECTIVE_END:
+    case AFTER_MAX_AGE_LABEL:
+    case AFTER_MAX_AGE_EQUALS:
+      return false;
+    default:
+      NOTREACHED();
+      return false;
+  }
+}
+
+// "Public-Key-Pins" ":"
+//     "max-age" "=" delta-seconds ";"
+//     "pin-" algo "=" base64 [ ";" ... ]
+bool ParseHPKPHeader(const base::Time& now,
+                     const std::string& value,
+                     const HashValueVector& chain_hashes,
+                     base::Time* expiry,
+                     HashValueVector* hashes) {
+  bool parsed_max_age = false;
+  uint32 max_age_candidate = 0;
+  HashValueVector pins;
+
+  std::string source = value;
+
+  while (!source.empty()) {
+    StringPair semicolon = Split(source, ';');
+    semicolon.first = Strip(semicolon.first);
+    semicolon.second = Strip(semicolon.second);
+    StringPair equals = Split(semicolon.first, '=');
+    equals.first = Strip(equals.first);
+    equals.second = Strip(equals.second);
+
+    if (LowerCaseEqualsASCII(equals.first, "max-age")) {
+      if (equals.second.empty() ||
+          !MaxAgeToInt(equals.second.begin(), equals.second.end(),
+                       &max_age_candidate)) {
+        return false;
+      }
+      parsed_max_age = true;
+    } else if (LowerCaseEqualsASCII(equals.first, "pin-sha1")) {
+      if (!ParseAndAppendPin(equals.second, HASH_VALUE_SHA1, &pins))
+        return false;
+    } else if (LowerCaseEqualsASCII(equals.first, "pin-sha256")) {
+      if (!ParseAndAppendPin(equals.second, HASH_VALUE_SHA256, &pins))
+        return false;
+    } else {
+      // Silently ignore unknown directives for forward compatibility.
+    }
+
+    source = semicolon.second;
+  }
+
+  if (!parsed_max_age)
+    return false;
+
+  if (!IsPinListValid(pins, chain_hashes))
+    return false;
+
+  *expiry = now + base::TimeDelta::FromSeconds(max_age_candidate);
+  for (HashValueVector::const_iterator i = pins.begin();
+       i != pins.end(); ++i) {
+    hashes->push_back(*i);
+  }
+
+  return true;
+}
+
+}  // namespace net