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ladybird/Userland/Libraries/LibWeb/Cookie/ParsedCookie.cpp
Daniel La Rocque 242d1d8eba LibWeb: Fail to parse cookie date when date does not exist 
Previously, the cookie date validation did not validate days in the
context of the month and year, resulting in dates that do not exist to
be successfully parsed (e.g. February 31st). We now validate that the
day does not exceed the number of days for the given month and year,
taking leap years into account.
2024-01-07 08:01:58 -05:00

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/*
* Copyright (c) 2021-2023, Tim Flynn <trflynn89@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include "ParsedCookie.h"
#include <AK/DateConstants.h>
#include <AK/Function.h>
#include <AK/StdLibExtras.h>
#include <AK/Time.h>
#include <AK/Vector.h>
#include <LibIPC/Decoder.h>
#include <LibIPC/Encoder.h>
#include <LibWeb/Infra/Strings.h>
#include <ctype.h>
namespace Web::Cookie {
static constexpr size_t s_max_cookie_size = 4096;
static void parse_attributes(ParsedCookie& parsed_cookie, StringView unparsed_attributes);
static void process_attribute(ParsedCookie& parsed_cookie, StringView attribute_name, StringView attribute_value);
static void on_expires_attribute(ParsedCookie& parsed_cookie, StringView attribute_value);
static void on_max_age_attribute(ParsedCookie& parsed_cookie, StringView attribute_value);
static void on_domain_attribute(ParsedCookie& parsed_cookie, StringView attribute_value);
static void on_path_attribute(ParsedCookie& parsed_cookie, StringView attribute_value);
static void on_secure_attribute(ParsedCookie& parsed_cookie);
static void on_http_only_attribute(ParsedCookie& parsed_cookie);
static void on_same_site_attribute(ParsedCookie& parsed_cookie, StringView attribute_value);
static Optional<UnixDateTime> parse_date_time(StringView date_string);
Optional<ParsedCookie> parse_cookie(StringView cookie_string)
{
// https://tools.ietf.org/html/rfc6265#section-5.2
if (cookie_string.length() > s_max_cookie_size)
return {};
StringView name_value_pair;
StringView unparsed_attributes;
// 1. If the set-cookie-string contains a %x3B (";") character:
if (auto position = cookie_string.find(';'); position.has_value()) {
// The name-value-pair string consists of the characters up to, but not including, the first %x3B (";"), and the unparsed-
// attributes consist of the remainder of the set-cookie-string (including the %x3B (";") in question).
name_value_pair = cookie_string.substring_view(0, position.value());
unparsed_attributes = cookie_string.substring_view(position.value());
} else {
// The name-value-pair string consists of all the characters contained in the set-cookie-string, and the unparsed-
// attributes is the empty string.
name_value_pair = cookie_string;
}
StringView name;
StringView value;
if (auto position = name_value_pair.find('='); position.has_value()) {
// 3. The (possibly empty) name string consists of the characters up to, but not including, the first %x3D ("=") character, and the
// (possibly empty) value string consists of the characters after the first %x3D ("=") character.
name = name_value_pair.substring_view(0, position.value());
if (position.value() < name_value_pair.length() - 1)
value = name_value_pair.substring_view(position.value() + 1);
} else {
// 2. If the name-value-pair string lacks a %x3D ("=") character, ignore the set-cookie-string entirely.
return {};
}
// 4. Remove any leading or trailing WSP characters from the name string and the value string.
name = name.trim_whitespace();
value = value.trim_whitespace();
// 5. If the name string is empty, ignore the set-cookie-string entirely.
if (name.is_empty())
return {};
// 6. The cookie-name is the name string, and the cookie-value is the value string.
ParsedCookie parsed_cookie { MUST(String::from_utf8(name)), MUST(String::from_utf8(value)) };
parse_attributes(parsed_cookie, unparsed_attributes);
return parsed_cookie;
}
void parse_attributes(ParsedCookie& parsed_cookie, StringView unparsed_attributes)
{
// 1. If the unparsed-attributes string is empty, skip the rest of these steps.
if (unparsed_attributes.is_empty())
return;
// 2. Discard the first character of the unparsed-attributes (which will be a %x3B (";") character).
unparsed_attributes = unparsed_attributes.substring_view(1);
StringView cookie_av;
// 3. If the remaining unparsed-attributes contains a %x3B (";") character:
if (auto position = unparsed_attributes.find(';'); position.has_value()) {
// Consume the characters of the unparsed-attributes up to, but not including, the first %x3B (";") character.
cookie_av = unparsed_attributes.substring_view(0, position.value());
unparsed_attributes = unparsed_attributes.substring_view(position.value());
} else {
// Consume the remainder of the unparsed-attributes.
cookie_av = unparsed_attributes;
unparsed_attributes = {};
}
StringView attribute_name;
StringView attribute_value;
// 4. If the cookie-av string contains a %x3D ("=") character:
if (auto position = cookie_av.find('='); position.has_value()) {
// The (possibly empty) attribute-name string consists of the characters up to, but not including, the first %x3D ("=")
// character, and the (possibly empty) attribute-value string consists of the characters after the first %x3D ("=") character.
attribute_name = cookie_av.substring_view(0, position.value());
if (position.value() < cookie_av.length() - 1)
attribute_value = cookie_av.substring_view(position.value() + 1);
} else {
// The attribute-name string consists of the entire cookie-av string, and the attribute-value string is empty.
attribute_name = cookie_av;
}
// 5. Remove any leading or trailing WSP characters from the attribute-name string and the attribute-value string.
attribute_name = attribute_name.trim_whitespace();
attribute_value = attribute_value.trim_whitespace();
// 6. Process the attribute-name and attribute-value according to the requirements in the following subsections.
// (Notice that attributes with unrecognized attribute-names are ignored.)
process_attribute(parsed_cookie, attribute_name, attribute_value);
// 7. Return to Step 1 of this algorithm.
parse_attributes(parsed_cookie, unparsed_attributes);
}
void process_attribute(ParsedCookie& parsed_cookie, StringView attribute_name, StringView attribute_value)
{
if (attribute_name.equals_ignoring_ascii_case("Expires"sv)) {
on_expires_attribute(parsed_cookie, attribute_value);
} else if (attribute_name.equals_ignoring_ascii_case("Max-Age"sv)) {
on_max_age_attribute(parsed_cookie, attribute_value);
} else if (attribute_name.equals_ignoring_ascii_case("Domain"sv)) {
on_domain_attribute(parsed_cookie, attribute_value);
} else if (attribute_name.equals_ignoring_ascii_case("Path"sv)) {
on_path_attribute(parsed_cookie, attribute_value);
} else if (attribute_name.equals_ignoring_ascii_case("Secure"sv)) {
on_secure_attribute(parsed_cookie);
} else if (attribute_name.equals_ignoring_ascii_case("HttpOnly"sv)) {
on_http_only_attribute(parsed_cookie);
} else if (attribute_name.equals_ignoring_ascii_case("SameSite"sv)) {
on_same_site_attribute(parsed_cookie, attribute_value);
}
}
void on_expires_attribute(ParsedCookie& parsed_cookie, StringView attribute_value)
{
// https://tools.ietf.org/html/rfc6265#section-5.2.1
if (auto expiry_time = parse_date_time(attribute_value); expiry_time.has_value())
parsed_cookie.expiry_time_from_expires_attribute = expiry_time.release_value();
}
void on_max_age_attribute(ParsedCookie& parsed_cookie, StringView attribute_value)
{
// https://tools.ietf.org/html/rfc6265#section-5.2.2
// If the first character of the attribute-value is not a DIGIT or a "-" character, ignore the cookie-av.
if (attribute_value.is_empty() || (!isdigit(attribute_value[0]) && (attribute_value[0] != '-')))
return;
// Let delta-seconds be the attribute-value converted to an integer.
if (auto delta_seconds = attribute_value.to_number<int>(); delta_seconds.has_value()) {
if (*delta_seconds <= 0) {
// If delta-seconds is less than or equal to zero (0), let expiry-time be the earliest representable date and time.
parsed_cookie.expiry_time_from_max_age_attribute = UnixDateTime::earliest();
} else {
// Otherwise, let the expiry-time be the current date and time plus delta-seconds seconds.
parsed_cookie.expiry_time_from_max_age_attribute = UnixDateTime::now() + Duration::from_seconds(*delta_seconds);
}
}
}
void on_domain_attribute(ParsedCookie& parsed_cookie, StringView attribute_value)
{
// https://tools.ietf.org/html/rfc6265#section-5.2.3
// If the attribute-value is empty, the behavior is undefined. However, the user agent SHOULD ignore the cookie-av entirely.
if (attribute_value.is_empty())
return;
StringView cookie_domain;
// If the first character of the attribute-value string is %x2E ("."):
if (attribute_value[0] == '.') {
// Let cookie-domain be the attribute-value without the leading %x2E (".") character.
cookie_domain = attribute_value.substring_view(1);
} else {
// Let cookie-domain be the entire attribute-value.
cookie_domain = attribute_value;
}
// Convert the cookie-domain to lower case.
parsed_cookie.domain = MUST(Infra::to_ascii_lowercase(cookie_domain));
}
void on_path_attribute(ParsedCookie& parsed_cookie, StringView attribute_value)
{
// https://tools.ietf.org/html/rfc6265#section-5.2.4
// If the attribute-value is empty or if the first character of the attribute-value is not %x2F ("/"):
if (attribute_value.is_empty() || attribute_value[0] != '/')
// Let cookie-path be the default-path.
return;
// Let cookie-path be the attribute-value
parsed_cookie.path = MUST(String::from_utf8(attribute_value));
}
void on_secure_attribute(ParsedCookie& parsed_cookie)
{
// https://tools.ietf.org/html/rfc6265#section-5.2.5
parsed_cookie.secure_attribute_present = true;
}
void on_http_only_attribute(ParsedCookie& parsed_cookie)
{
// https://tools.ietf.org/html/rfc6265#section-5.2.6
parsed_cookie.http_only_attribute_present = true;
}
// https://httpwg.org/http-extensions/draft-ietf-httpbis-rfc6265bis.html#name-the-samesite-attribute-2
void on_same_site_attribute(ParsedCookie& parsed_cookie, StringView attribute_value)
{
// 1. Let enforcement be "Default"
// 2. If cookie-av's attribute-value is a case-insensitive match for "None", set enforcement to "None".
// 3. If cookie-av's attribute-value is a case-insensitive match for "Strict", set enforcement to "Strict".
// 4. If cookie-av's attribute-value is a case-insensitive match for "Lax", set enforcement to "Lax".
parsed_cookie.same_site_attribute = same_site_from_string(attribute_value);
}
Optional<UnixDateTime> parse_date_time(StringView date_string)
{
// https://tools.ietf.org/html/rfc6265#section-5.1.1
unsigned hour = 0;
unsigned minute = 0;
unsigned second = 0;
unsigned day_of_month = 0;
unsigned month = 0;
unsigned year = 0;
auto to_uint = [](StringView token, unsigned& result) {
if (!all_of(token, isdigit))
return false;
if (auto converted = token.to_number<unsigned>(); converted.has_value()) {
result = *converted;
return true;
}
return false;
};
auto parse_time = [&](StringView token) {
Vector<StringView> parts = token.split_view(':');
if (parts.size() != 3)
return false;
for (const auto& part : parts) {
if (part.is_empty() || part.length() > 2)
return false;
}
return to_uint(parts[0], hour) && to_uint(parts[1], minute) && to_uint(parts[2], second);
};
auto parse_day_of_month = [&](StringView token) {
if (token.is_empty() || token.length() > 2)
return false;
return to_uint(token, day_of_month);
};
auto parse_month = [&](StringView token) {
for (unsigned i = 0; i < 12; ++i) {
if (token.equals_ignoring_ascii_case(short_month_names[i])) {
month = i + 1;
return true;
}
}
return false;
};
auto parse_year = [&](StringView token) {
if (token.length() != 2 && token.length() != 4)
return false;
return to_uint(token, year);
};
Function<bool(char)> is_delimiter = [](char ch) {
return ch == 0x09 || (ch >= 0x20 && ch <= 0x2f) || (ch >= 0x3b && ch <= 0x40) || (ch >= 0x5b && ch <= 0x60) || (ch >= 0x7b && ch <= 0x7e);
};
// 1. Using the grammar below, divide the cookie-date into date-tokens.
Vector<StringView> date_tokens = date_string.split_view_if(is_delimiter);
// 2. Process each date-token sequentially in the order the date-tokens appear in the cookie-date.
bool found_time = false;
bool found_day_of_month = false;
bool found_month = false;
bool found_year = false;
for (auto const& date_token : date_tokens) {
if (!found_time && parse_time(date_token)) {
found_time = true;
} else if (!found_day_of_month && parse_day_of_month(date_token)) {
found_day_of_month = true;
} else if (!found_month && parse_month(date_token)) {
found_month = true;
} else if (!found_year && parse_year(date_token)) {
found_year = true;
}
}
// 3. If the year-value is greater than or equal to 70 and less than or equal to 99, increment the year-value by 1900.
if (year >= 70 && year <= 99)
year += 1900;
// 4. If the year-value is greater than or equal to 0 and less than or equal to 69, increment the year-value by 2000.
if (year <= 69)
year += 2000;
// 5. Abort these steps and fail to parse the cookie-date if:
if (!found_time || !found_day_of_month || !found_month || !found_year)
return {};
if (day_of_month < 1 || day_of_month > 31)
return {};
if (year < 1601)
return {};
if (hour > 23)
return {};
if (minute > 59)
return {};
if (second > 59)
return {};
// 6. Let the parsed-cookie-date be the date whose day-of-month, month, year, hour, minute, and second (in UTC) are the
// day-of-month-value, the month-value, the year-value, the hour-value, the minute-value, and the second-value, respectively.
// If no such date exists, abort these steps and fail to parse the cookie-date.
if (day_of_month > static_cast<unsigned int>(days_in_month(year, month)))
return {};
// FIXME: This currently uses UNIX time, which is not equivalent to UTC due to leap seconds.
auto parsed_cookie_date = UnixDateTime::from_unix_time_parts(year, month, day_of_month, hour, minute, second, 0);
// 7. Return the parsed-cookie-date as the result of this algorithm.
return parsed_cookie_date;
}
}
template<>
ErrorOr<void> IPC::encode(Encoder& encoder, Web::Cookie::ParsedCookie const& cookie)
{
TRY(encoder.encode(cookie.name));
TRY(encoder.encode(cookie.value));
TRY(encoder.encode(cookie.expiry_time_from_expires_attribute));
TRY(encoder.encode(cookie.expiry_time_from_max_age_attribute));
TRY(encoder.encode(cookie.domain));
TRY(encoder.encode(cookie.path));
TRY(encoder.encode(cookie.secure_attribute_present));
TRY(encoder.encode(cookie.http_only_attribute_present));
TRY(encoder.encode(cookie.same_site_attribute));
return {};
}
template<>
ErrorOr<Web::Cookie::ParsedCookie> IPC::decode(Decoder& decoder)
{
auto name = TRY(decoder.decode<String>());
auto value = TRY(decoder.decode<String>());
auto expiry_time_from_expires_attribute = TRY(decoder.decode<Optional<UnixDateTime>>());
auto expiry_time_from_max_age_attribute = TRY(decoder.decode<Optional<UnixDateTime>>());
auto domain = TRY(decoder.decode<Optional<String>>());
auto path = TRY(decoder.decode<Optional<String>>());
auto secure_attribute_present = TRY(decoder.decode<bool>());
auto http_only_attribute_present = TRY(decoder.decode<bool>());
auto same_site_attribute = TRY(decoder.decode<Web::Cookie::SameSite>());
return Web::Cookie::ParsedCookie { move(name), move(value), same_site_attribute, move(expiry_time_from_expires_attribute), move(expiry_time_from_max_age_attribute), move(domain), move(path), secure_attribute_present, http_only_attribute_present };
}
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