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/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 strtol in order to handle overflow 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,
+                 int* result) {
+  const std::string s(begin, end);
+  char* endptr;
+  long int i = strtol(s.data(), &endptr, 10 /* base */);

[Ryan Sleevi, 2012/12/07 23:37:21]

BUG: I previously advised you not to use strtol, but this has not been fixed.

In particular, it's not safe to assume that long == int64, whereas an HTTP
delta-seconds *may* be 64-bit

[unsafe, 2012/12/08 09:22:42]

Not my code, but fixed.  StringToUint64 doesn't seem to handle negative numbers
correctly (it was failing the unit test due to returning true for negatives,
with a garbage result).  Also, one of the unit tests was expecting a value large
enough to overflow uint64 to return true; I shortened those values in the unit
test so they do not overflow uint64.

+  if (*endptr || i < 0)
+    return false;
+  if (i > kMaxHSTSAgeSecs)
+    i = kMaxHSTSAgeSecs;
+  *result = 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) {

[Ryan Sleevi, 2012/12/07 23:37:21]

i = pins.begin(); should fit on the previous line, as should i != pins.end();

You should only need to wrap for ++i

[unsafe, 2012/12/08 09:22:42]

Done.

+    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));

[Ryan Sleevi, 2012/12/07 23:37:21]

style nit: four space indent here

[unsafe, 2012/12/08 09:22:42]

Done.

+    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;
+
+  // This code has to assume that 32 bytes is SHA-256 and 20 bytes is SHA-1.

[Ryan Sleevi, 2012/12/07 23:37:21]

comment nit: This code does not assume that (because tag is directly supplied)

Just nuke 111-113

[unsafe, 2012/12/08 09:22:42]

Done.

+  // Currently, those are the only two possibilities, so the assumption is
+  // valid.
+  if (!base::Base64Decode(unquoted, &decoded))
+    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
+  int 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))

[Ryan Sleevi, 2012/12/07 23:37:21]

nit: add braces because the if condition spans multiple lines.

Also, it does not seem you need to wrap like this, which if correct, means you
should change the wrapping and no braces are needed.

If it does need to wrap, use
MaxAgeToInt(unquoted.begin(), unquoted.end(),
            &max_age_candidate)

[unsafe, 2012/12/08 09:22:42]

Done.

+          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;
+  int 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;
+      }

[Ryan Sleevi, 2012/12/07 23:37:21]

nit: no braces

[unsafe, 2012/12/08 09:22:42]

Done.

+    } else if (LowerCaseEqualsASCII(equals.first, "pin-sha256")) {
+      if (!ParseAndAppendPin(equals.second, HASH_VALUE_SHA256, &pins)) {
+        return false;
+      }

[Ryan Sleevi, 2012/12/07 23:37:21]

nit: no braces

[unsafe, 2012/12/08 09:22:42]

Done.

+    } 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
+