1 // Copyright 2012 The Chromium Authors
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #include <limits>
6 #include <string_view>
7
8 #include "base/base64.h"
9 #include "base/check_op.h"
10 #include "base/notreached.h"
11 #include "base/strings/string_tokenizer.h"
12 #include "base/strings/string_util.h"
13 #include "net/base/parse_number.h"
14 #include "net/http/http_security_headers.h"
15 #include "net/http/http_util.h"
16 #include "url/gurl.h"
17
18 namespace net {
19
20 namespace {
21
22 enum MaxAgeParsing { REQUIRE_MAX_AGE, DO_NOT_REQUIRE_MAX_AGE };
23
24 // MaxAgeToLimitedInt converts a string representation of a "whole number" of
25 // seconds into a uint32_t. The string may contain an arbitrarily large number,
26 // which will be clipped to a supplied limit and which is guaranteed to fit
27 // within a 32-bit unsigned integer. False is returned on any parse error.
MaxAgeToLimitedInt(std::string_view s,uint32_t limit,uint32_t * result)28 bool MaxAgeToLimitedInt(std::string_view s, uint32_t limit, uint32_t* result) {
29 ParseIntError error;
30 if (!ParseUint32(s, ParseIntFormat::NON_NEGATIVE, result, &error)) {
31 if (error == ParseIntError::FAILED_OVERFLOW) {
32 *result = limit;
33 } else {
34 return false;
35 }
36 }
37
38 if (*result > limit)
39 *result = limit;
40
41 return true;
42 }
43
44 } // namespace
45
46 // Parse the Strict-Transport-Security header, as currently defined in
47 // http://tools.ietf.org/html/draft-ietf-websec-strict-transport-sec-14:
48 //
49 // Strict-Transport-Security = "Strict-Transport-Security" ":"
50 // [ directive ] *( ";" [ directive ] )
51 //
52 // directive = directive-name [ "=" directive-value ]
53 // directive-name = token
54 // directive-value = token | quoted-string
55 //
56 // 1. The order of appearance of directives is not significant.
57 //
58 // 2. All directives MUST appear only once in an STS header field.
59 // Directives are either optional or required, as stipulated in
60 // their definitions.
61 //
62 // 3. Directive names are case-insensitive.
63 //
64 // 4. UAs MUST ignore any STS header fields containing directives, or
65 // other header field value data, that does not conform to the
66 // syntax defined in this specification.
67 //
68 // 5. If an STS header field contains directive(s) not recognized by
69 // the UA, the UA MUST ignore the unrecognized directives and if the
70 // STS header field otherwise satisfies the above requirements (1
71 // through 4), the UA MUST process the recognized directives.
ParseHSTSHeader(std::string_view value,base::TimeDelta * max_age,bool * include_subdomains)72 bool ParseHSTSHeader(std::string_view value,
73 base::TimeDelta* max_age,
74 bool* include_subdomains) {
75 uint32_t max_age_value = 0;
76 bool max_age_seen = false;
77 bool include_subdomains_value = false;
78
79 HttpUtil::NameValuePairsIterator hsts_iterator(
80 value, ';', HttpUtil::NameValuePairsIterator::Values::NOT_REQUIRED,
81 HttpUtil::NameValuePairsIterator::Quotes::STRICT_QUOTES);
82 while (hsts_iterator.GetNext()) {
83 // Process `max-age`:
84 if (base::EqualsCaseInsensitiveASCII(hsts_iterator.name(), "max-age")) {
85 // Reject the header if `max-age` is specified more than once.
86 if (max_age_seen) {
87 return false;
88 }
89 max_age_seen = true;
90
91 // Reject the header if `max-age`'s value is invalid. Otherwise, store it
92 // in `max_age_value`.
93 if (!MaxAgeToLimitedInt(hsts_iterator.value(), kMaxHSTSAgeSecs,
94 &max_age_value)) {
95 return false;
96 }
97
98 // Process `includeSubDomains`:
99 } else if (base::EqualsCaseInsensitiveASCII(hsts_iterator.name(),
100 "includeSubDomains")) {
101 // Reject the header if `includeSubDomains` is specified more than once.
102 if (include_subdomains_value) {
103 return false;
104 }
105 // Reject the header if `includeSubDomains` has a value specified:
106 if (!hsts_iterator.value().empty() || hsts_iterator.value_is_quoted()) {
107 return false;
108 }
109
110 include_subdomains_value = true;
111
112 // Process unknown directives.
113 } else {
114 // Reject the header if a directive's name or unquoted value doesn't match
115 // the `token` grammar.
116 if (!HttpUtil::IsToken(hsts_iterator.name()) ||
117 hsts_iterator.name().empty()) {
118 return false;
119 }
120 if (!hsts_iterator.value().empty() && !hsts_iterator.value_is_quoted() &&
121 !HttpUtil::IsToken(hsts_iterator.value())) {
122 return false;
123 }
124 }
125 }
126
127 if (!hsts_iterator.valid()) {
128 return false;
129 }
130
131 // Reject the header if no `max-age` was set.
132 if (!max_age_seen) {
133 return false;
134 }
135
136 *max_age = base::Seconds(max_age_value);
137 *include_subdomains = include_subdomains_value;
138 return true;
139 }
140
141 } // namespace net
142