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naiveproxy/net/http/http_response_headers.cc
klzgrad 46caed9b9c Import chromium-70.0.3538.110
2018-12-09 21:59:24 -05:00

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// 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.
// The rules for header parsing were borrowed from Firefox:
// http://lxr.mozilla.org/seamonkey/source/netwerk/protocol/http/src/nsHttpResponseHead.cpp
// The rules for parsing content-types were also borrowed from Firefox:
// http://lxr.mozilla.org/mozilla/source/netwerk/base/src/nsURLHelper.cpp#834
#include "net/http/http_response_headers.h"
#include <algorithm>
#include <memory>
#include <unordered_map>
#include <utility>
#include "base/format_macros.h"
#include "base/logging.h"
#include "base/metrics/histogram_macros.h"
#include "base/pickle.h"
#include "base/strings/string_number_conversions.h"
#include "base/strings/string_piece.h"
#include "base/strings/string_util.h"
#include "base/strings/stringprintf.h"
#include "base/time/time.h"
#include "base/values.h"
#include "net/base/escape.h"
#include "net/base/parse_number.h"
#include "net/http/http_byte_range.h"
#include "net/http/http_log_util.h"
#include "net/http/http_util.h"
#include "net/log/net_log_capture_mode.h"
using base::StringPiece;
using base::Time;
using base::TimeDelta;
namespace net {
//-----------------------------------------------------------------------------
namespace {
// These headers are RFC 2616 hop-by-hop headers;
// not to be stored by caches.
const char* const kHopByHopResponseHeaders[] = {
"connection",
"proxy-connection",
"keep-alive",
"trailer",
"transfer-encoding",
"upgrade"
};
// These headers are challenge response headers;
// not to be stored by caches.
const char* const kChallengeResponseHeaders[] = {
"www-authenticate",
"proxy-authenticate"
};
// These headers are cookie setting headers;
// not to be stored by caches or disclosed otherwise.
const char* const kCookieResponseHeaders[] = {
"set-cookie",
"set-cookie2",
"clear-site-data",
};
// By default, do not cache Strict-Transport-Security or Public-Key-Pins.
// This avoids erroneously re-processing them on page loads from cache ---
// they are defined to be valid only on live and error-free HTTPS
// connections.
const char* const kSecurityStateHeaders[] = {
"strict-transport-security",
"public-key-pins"
};
// These response headers are not copied from a 304/206 response to the cached
// response headers. This list is based on Mozilla's nsHttpResponseHead.cpp.
const char* const kNonUpdatedHeaders[] = {
"connection",
"proxy-connection",
"keep-alive",
"www-authenticate",
"proxy-authenticate",
"trailer",
"transfer-encoding",
"upgrade",
"etag",
"x-frame-options",
"x-xss-protection",
};
// Some header prefixes mean "Don't copy this header from a 304 response.".
// Rather than listing all the relevant headers, we can consolidate them into
// this list:
const char* const kNonUpdatedHeaderPrefixes[] = {
"content-",
"x-content-",
"x-webkit-"
};
bool ShouldUpdateHeader(base::StringPiece name) {
for (size_t i = 0; i < arraysize(kNonUpdatedHeaders); ++i) {
if (base::LowerCaseEqualsASCII(name, kNonUpdatedHeaders[i]))
return false;
}
for (size_t i = 0; i < arraysize(kNonUpdatedHeaderPrefixes); ++i) {
if (base::StartsWith(name, kNonUpdatedHeaderPrefixes[i],
base::CompareCase::INSENSITIVE_ASCII))
return false;
}
return true;
}
void CheckDoesNotHaveEmbededNulls(const std::string& str) {
// Care needs to be taken when adding values to the raw headers string to
// make sure it does not contain embeded NULLs. Any embeded '\0' may be
// understood as line terminators and change how header lines get tokenized.
CHECK(str.find('\0') == std::string::npos);
}
} // namespace
const char HttpResponseHeaders::kContentRange[] = "Content-Range";
struct HttpResponseHeaders::ParsedHeader {
// A header "continuation" contains only a subsequent value for the
// preceding header. (Header values are comma separated.)
bool is_continuation() const { return name_begin == name_end; }
std::string::const_iterator name_begin;
std::string::const_iterator name_end;
std::string::const_iterator value_begin;
std::string::const_iterator value_end;
};
//-----------------------------------------------------------------------------
HttpResponseHeaders::HttpResponseHeaders(const std::string& raw_input)
: response_code_(-1) {
Parse(raw_input);
// The most important thing to do with this histogram is find out
// the existence of unusual HTTP status codes. As it happens
// right now, there aren't double-constructions of response headers
// using this constructor, so our counts should also be accurate,
// without instantiating the histogram in two places. It is also
// important that this histogram not collect data in the other
// constructor, which rebuilds an histogram from a pickle, since
// that would actually create a double call between the original
// HttpResponseHeader that was serialized, and initialization of the
// new object from that pickle.
UMA_HISTOGRAM_CUSTOM_ENUMERATION("Net.HttpResponseCode",
HttpUtil::MapStatusCodeForHistogram(
response_code_),
// Note the third argument is only
// evaluated once, see macro
// definition for details.
HttpUtil::GetStatusCodesForHistogram());
}
HttpResponseHeaders::HttpResponseHeaders(base::PickleIterator* iter)
: response_code_(-1) {
std::string raw_input;
if (iter->ReadString(&raw_input))
Parse(raw_input);
}
void HttpResponseHeaders::Persist(base::Pickle* pickle,
PersistOptions options) {
if (options == PERSIST_RAW) {
pickle->WriteString(raw_headers_);
return; // Done.
}
HeaderSet filter_headers;
// Construct set of headers to filter out based on options.
if ((options & PERSIST_SANS_NON_CACHEABLE) == PERSIST_SANS_NON_CACHEABLE)
AddNonCacheableHeaders(&filter_headers);
if ((options & PERSIST_SANS_COOKIES) == PERSIST_SANS_COOKIES)
AddCookieHeaders(&filter_headers);
if ((options & PERSIST_SANS_CHALLENGES) == PERSIST_SANS_CHALLENGES)
AddChallengeHeaders(&filter_headers);
if ((options & PERSIST_SANS_HOP_BY_HOP) == PERSIST_SANS_HOP_BY_HOP)
AddHopByHopHeaders(&filter_headers);
if ((options & PERSIST_SANS_RANGES) == PERSIST_SANS_RANGES)
AddHopContentRangeHeaders(&filter_headers);
if ((options & PERSIST_SANS_SECURITY_STATE) == PERSIST_SANS_SECURITY_STATE)
AddSecurityStateHeaders(&filter_headers);
std::string blob;
blob.reserve(raw_headers_.size());
// This copies the status line w/ terminator null.
// Note raw_headers_ has embedded nulls instead of \n,
// so this just copies the first header line.
blob.assign(raw_headers_.c_str(), strlen(raw_headers_.c_str()) + 1);
for (size_t i = 0; i < parsed_.size(); ++i) {
DCHECK(!parsed_[i].is_continuation());
// Locate the start of the next header.
size_t k = i;
while (++k < parsed_.size() && parsed_[k].is_continuation()) {}
--k;
std::string header_name = base::ToLowerASCII(
base::StringPiece(parsed_[i].name_begin, parsed_[i].name_end));
if (filter_headers.find(header_name) == filter_headers.end()) {
// Make sure there is a null after the value.
blob.append(parsed_[i].name_begin, parsed_[k].value_end);
blob.push_back('\0');
}
i = k;
}
blob.push_back('\0');
pickle->WriteString(blob);
}
void HttpResponseHeaders::Update(const HttpResponseHeaders& new_headers) {
DCHECK(new_headers.response_code() == 304 ||
new_headers.response_code() == 206);
// Copy up to the null byte. This just copies the status line.
std::string new_raw_headers(raw_headers_.c_str());
new_raw_headers.push_back('\0');
HeaderSet updated_headers;
// NOTE: we write the new headers then the old headers for convenience. The
// order should not matter.
// Figure out which headers we want to take from new_headers:
for (size_t i = 0; i < new_headers.parsed_.size(); ++i) {
const HeaderList& new_parsed = new_headers.parsed_;
DCHECK(!new_parsed[i].is_continuation());
// Locate the start of the next header.
size_t k = i;
while (++k < new_parsed.size() && new_parsed[k].is_continuation()) {}
--k;
base::StringPiece name(new_parsed[i].name_begin, new_parsed[i].name_end);
if (ShouldUpdateHeader(name)) {
std::string name_lower = base::ToLowerASCII(name);
updated_headers.insert(name_lower);
// Preserve this header line in the merged result, making sure there is
// a null after the value.
new_raw_headers.append(new_parsed[i].name_begin, new_parsed[k].value_end);
new_raw_headers.push_back('\0');
}
i = k;
}
// Now, build the new raw headers.
MergeWithHeaders(new_raw_headers, updated_headers);
}
void HttpResponseHeaders::MergeWithHeaders(const std::string& raw_headers,
const HeaderSet& headers_to_remove) {
std::string new_raw_headers(raw_headers);
for (size_t i = 0; i < parsed_.size(); ++i) {
DCHECK(!parsed_[i].is_continuation());
// Locate the start of the next header.
size_t k = i;
while (++k < parsed_.size() && parsed_[k].is_continuation()) {}
--k;
std::string name = base::ToLowerASCII(
base::StringPiece(parsed_[i].name_begin, parsed_[i].name_end));
if (headers_to_remove.find(name) == headers_to_remove.end()) {
// It's ok to preserve this header in the final result.
new_raw_headers.append(parsed_[i].name_begin, parsed_[k].value_end);
new_raw_headers.push_back('\0');
}
i = k;
}
new_raw_headers.push_back('\0');
// Make this object hold the new data.
raw_headers_.clear();
parsed_.clear();
Parse(new_raw_headers);
}
void HttpResponseHeaders::RemoveHeader(const std::string& name) {
// Copy up to the null byte. This just copies the status line.
std::string new_raw_headers(raw_headers_.c_str());
new_raw_headers.push_back('\0');
std::string lowercase_name = base::ToLowerASCII(name);
HeaderSet to_remove;
to_remove.insert(lowercase_name);
MergeWithHeaders(new_raw_headers, to_remove);
}
void HttpResponseHeaders::RemoveHeaders(
const std::unordered_set<std::string>& header_names) {
// Copy up to the null byte. This just copies the status line.
std::string new_raw_headers(raw_headers_.c_str());
new_raw_headers.push_back('\0');
HeaderSet to_remove;
for (const auto& header_name : header_names) {
to_remove.insert(base::ToLowerASCII(header_name));
}
MergeWithHeaders(new_raw_headers, to_remove);
}
void HttpResponseHeaders::RemoveHeaderLine(const std::string& name,
const std::string& value) {
std::string name_lowercase = base::ToLowerASCII(name);
std::string new_raw_headers(GetStatusLine());
new_raw_headers.push_back('\0');
new_raw_headers.reserve(raw_headers_.size());
size_t iter = 0;
std::string old_header_name;
std::string old_header_value;
while (EnumerateHeaderLines(&iter, &old_header_name, &old_header_value)) {
std::string old_header_name_lowercase = base::ToLowerASCII(old_header_name);
if (name_lowercase == old_header_name_lowercase &&
value == old_header_value)
continue;
new_raw_headers.append(old_header_name);
new_raw_headers.push_back(':');
new_raw_headers.push_back(' ');
new_raw_headers.append(old_header_value);
new_raw_headers.push_back('\0');
}
new_raw_headers.push_back('\0');
// Make this object hold the new data.
raw_headers_.clear();
parsed_.clear();
Parse(new_raw_headers);
}
void HttpResponseHeaders::AddHeader(const std::string& header) {
CheckDoesNotHaveEmbededNulls(header);
DCHECK_EQ('\0', raw_headers_[raw_headers_.size() - 2]);
DCHECK_EQ('\0', raw_headers_[raw_headers_.size() - 1]);
// Don't copy the last null.
std::string new_raw_headers(raw_headers_, 0, raw_headers_.size() - 1);
new_raw_headers.append(header);
new_raw_headers.push_back('\0');
new_raw_headers.push_back('\0');
// Make this object hold the new data.
raw_headers_.clear();
parsed_.clear();
Parse(new_raw_headers);
}
void HttpResponseHeaders::AddCookie(const std::string& cookie_string) {
AddHeader("Set-Cookie: " + cookie_string);
}
void HttpResponseHeaders::ReplaceStatusLine(const std::string& new_status) {
CheckDoesNotHaveEmbededNulls(new_status);
// Copy up to the null byte. This just copies the status line.
std::string new_raw_headers(new_status);
new_raw_headers.push_back('\0');
HeaderSet empty_to_remove;
MergeWithHeaders(new_raw_headers, empty_to_remove);
}
void HttpResponseHeaders::UpdateWithNewRange(const HttpByteRange& byte_range,
int64_t resource_size,
bool replace_status_line) {
DCHECK(byte_range.IsValid());
DCHECK(byte_range.HasFirstBytePosition());
DCHECK(byte_range.HasLastBytePosition());
const char kLengthHeader[] = "Content-Length";
const char kRangeHeader[] = "Content-Range";
RemoveHeader(kLengthHeader);
RemoveHeader(kRangeHeader);
int64_t start = byte_range.first_byte_position();
int64_t end = byte_range.last_byte_position();
int64_t range_len = end - start + 1;
if (replace_status_line)
ReplaceStatusLine("HTTP/1.1 206 Partial Content");
AddHeader(base::StringPrintf("%s: bytes %" PRId64 "-%" PRId64 "/%" PRId64,
kRangeHeader, start, end, resource_size));
AddHeader(base::StringPrintf("%s: %" PRId64, kLengthHeader, range_len));
}
void HttpResponseHeaders::Parse(const std::string& raw_input) {
raw_headers_.reserve(raw_input.size());
// ParseStatusLine adds a normalized status line to raw_headers_
std::string::const_iterator line_begin = raw_input.begin();
std::string::const_iterator line_end =
std::find(line_begin, raw_input.end(), '\0');
// has_headers = true, if there is any data following the status line.
// Used by ParseStatusLine() to decide if a HTTP/0.9 is really a HTTP/1.0.
bool has_headers = (line_end != raw_input.end() &&
(line_end + 1) != raw_input.end() &&
*(line_end + 1) != '\0');
ParseStatusLine(line_begin, line_end, has_headers);
raw_headers_.push_back('\0'); // Terminate status line with a null.
if (line_end == raw_input.end()) {
raw_headers_.push_back('\0'); // Ensure the headers end with a double null.
DCHECK_EQ('\0', raw_headers_[raw_headers_.size() - 2]);
DCHECK_EQ('\0', raw_headers_[raw_headers_.size() - 1]);
return;
}
// Including a terminating null byte.
size_t status_line_len = raw_headers_.size();
// Now, we add the rest of the raw headers to raw_headers_, and begin parsing
// it (to populate our parsed_ vector).
raw_headers_.append(line_end + 1, raw_input.end());
// Ensure the headers end with a double null.
while (raw_headers_.size() < 2 ||
raw_headers_[raw_headers_.size() - 2] != '\0' ||
raw_headers_[raw_headers_.size() - 1] != '\0') {
raw_headers_.push_back('\0');
}
// Adjust to point at the null byte following the status line
line_end = raw_headers_.begin() + status_line_len - 1;
HttpUtil::HeadersIterator headers(line_end + 1, raw_headers_.end(),
std::string(1, '\0'));
while (headers.GetNext()) {
AddHeader(headers.name_begin(),
headers.name_end(),
headers.values_begin(),
headers.values_end());
}
DCHECK_EQ('\0', raw_headers_[raw_headers_.size() - 2]);
DCHECK_EQ('\0', raw_headers_[raw_headers_.size() - 1]);
}
bool HttpResponseHeaders::GetNormalizedHeader(const std::string& name,
std::string* value) const {
// If you hit this assertion, please use EnumerateHeader instead!
DCHECK(!HttpUtil::IsNonCoalescingHeader(name));
value->clear();
bool found = false;
size_t i = 0;
while (i < parsed_.size()) {
i = FindHeader(i, name);
if (i == std::string::npos)
break;
if (found)
value->append(", ");
found = true;
std::string::const_iterator value_begin = parsed_[i].value_begin;
std::string::const_iterator value_end = parsed_[i].value_end;
while (++i < parsed_.size() && parsed_[i].is_continuation())
value_end = parsed_[i].value_end;
value->append(value_begin, value_end);
}
return found;
}
std::string HttpResponseHeaders::GetStatusLine() const {
// copy up to the null byte.
return std::string(raw_headers_.c_str());
}
std::string HttpResponseHeaders::GetStatusText() const {
// GetStatusLine() is already normalized, so it has the format:
// '<http_version> SP <response_code>' or
// '<http_version> SP <response_code> SP <status_text>'.
std::string status_text = GetStatusLine();
std::string::const_iterator begin = status_text.begin();
std::string::const_iterator end = status_text.end();
// Seek to beginning of <response_code>.
begin = std::find(begin, end, ' ');
CHECK(begin != end);
++begin;
CHECK(begin != end);
// See if there is another space.
begin = std::find(begin, end, ' ');
if (begin == end)
return std::string();
++begin;
CHECK(begin != end);
return std::string(begin, end);
}
bool HttpResponseHeaders::EnumerateHeaderLines(size_t* iter,
std::string* name,
std::string* value) const {
size_t i = *iter;
if (i == parsed_.size())
return false;
DCHECK(!parsed_[i].is_continuation());
name->assign(parsed_[i].name_begin, parsed_[i].name_end);
std::string::const_iterator value_begin = parsed_[i].value_begin;
std::string::const_iterator value_end = parsed_[i].value_end;
while (++i < parsed_.size() && parsed_[i].is_continuation())
value_end = parsed_[i].value_end;
value->assign(value_begin, value_end);
*iter = i;
return true;
}
bool HttpResponseHeaders::EnumerateHeader(size_t* iter,
const base::StringPiece& name,
std::string* value) const {
size_t i;
if (!iter || !*iter) {
i = FindHeader(0, name);
} else {
i = *iter;
if (i >= parsed_.size()) {
i = std::string::npos;
} else if (!parsed_[i].is_continuation()) {
i = FindHeader(i, name);
}
}
if (i == std::string::npos) {
value->clear();
return false;
}
if (iter)
*iter = i + 1;
value->assign(parsed_[i].value_begin, parsed_[i].value_end);
return true;
}
bool HttpResponseHeaders::HasHeaderValue(const base::StringPiece& name,
const base::StringPiece& value) const {
// The value has to be an exact match. This is important since
// 'cache-control: no-cache' != 'cache-control: no-cache="foo"'
size_t iter = 0;
std::string temp;
while (EnumerateHeader(&iter, name, &temp)) {
if (base::EqualsCaseInsensitiveASCII(value, temp))
return true;
}
return false;
}
bool HttpResponseHeaders::HasHeader(const base::StringPiece& name) const {
return FindHeader(0, name) != std::string::npos;
}
HttpResponseHeaders::~HttpResponseHeaders() = default;
// Note: this implementation implicitly assumes that line_end points at a valid
// sentinel character (such as '\0').
// static
HttpVersion HttpResponseHeaders::ParseVersion(
std::string::const_iterator line_begin,
std::string::const_iterator line_end) {
std::string::const_iterator p = line_begin;
// RFC2616 sec 3.1: HTTP-Version = "HTTP" "/" 1*DIGIT "." 1*DIGIT
// TODO: (1*DIGIT apparently means one or more digits, but we only handle 1).
// TODO: handle leading zeros, which is allowed by the rfc1616 sec 3.1.
if (!base::StartsWith(base::StringPiece(line_begin, line_end), "http",
base::CompareCase::INSENSITIVE_ASCII)) {
DVLOG(1) << "missing status line";
return HttpVersion();
}
p += 4;
if (p >= line_end || *p != '/') {
DVLOG(1) << "missing version";
return HttpVersion();
}
std::string::const_iterator dot = std::find(p, line_end, '.');
if (dot == line_end) {
DVLOG(1) << "malformed version";
return HttpVersion();
}
++p; // from / to first digit.
++dot; // from . to second digit.
if (!(base::IsAsciiDigit(*p) && base::IsAsciiDigit(*dot))) {
DVLOG(1) << "malformed version number";
return HttpVersion();
}
uint16_t major = *p - '0';
uint16_t minor = *dot - '0';
return HttpVersion(major, minor);
}
// Note: this implementation implicitly assumes that line_end points at a valid
// sentinel character (such as '\0').
void HttpResponseHeaders::ParseStatusLine(
std::string::const_iterator line_begin,
std::string::const_iterator line_end,
bool has_headers) {
// Extract the version number
HttpVersion parsed_http_version = ParseVersion(line_begin, line_end);
// Clamp the version number to one of: {0.9, 1.0, 1.1, 2.0}
if (parsed_http_version == HttpVersion(0, 9) && !has_headers) {
http_version_ = HttpVersion(0, 9);
raw_headers_ = "HTTP/0.9";
} else if (parsed_http_version == HttpVersion(2, 0)) {
http_version_ = HttpVersion(2, 0);
raw_headers_ = "HTTP/2.0";
} else if (parsed_http_version >= HttpVersion(1, 1)) {
http_version_ = HttpVersion(1, 1);
raw_headers_ = "HTTP/1.1";
} else {
// Treat everything else like HTTP 1.0
http_version_ = HttpVersion(1, 0);
raw_headers_ = "HTTP/1.0";
}
if (parsed_http_version != http_version_) {
DVLOG(1) << "assuming HTTP/" << http_version_.major_value() << "."
<< http_version_.minor_value();
}
// TODO(eroman): this doesn't make sense if ParseVersion failed.
std::string::const_iterator p = std::find(line_begin, line_end, ' ');
if (p == line_end) {
DVLOG(1) << "missing response status; assuming 200 OK";
raw_headers_.append(" 200 OK");
response_code_ = 200;
return;
}
// Skip whitespace.
while (p < line_end && *p == ' ')
++p;
std::string::const_iterator code = p;
while (p < line_end && base::IsAsciiDigit(*p))
++p;
if (p == code) {
DVLOG(1) << "missing response status number; assuming 200";
raw_headers_.append(" 200");
response_code_ = 200;
return;
}
raw_headers_.push_back(' ');
raw_headers_.append(code, p);
base::StringToInt(StringPiece(code, p), &response_code_);
// Skip whitespace.
while (p < line_end && *p == ' ')
++p;
// Trim trailing whitespace.
while (line_end > p && line_end[-1] == ' ')
--line_end;
if (p == line_end)
return;
raw_headers_.push_back(' ');
raw_headers_.append(p, line_end);
}
size_t HttpResponseHeaders::FindHeader(size_t from,
const base::StringPiece& search) const {
for (size_t i = from; i < parsed_.size(); ++i) {
if (parsed_[i].is_continuation())
continue;
base::StringPiece name(parsed_[i].name_begin, parsed_[i].name_end);
if (base::EqualsCaseInsensitiveASCII(search, name))
return i;
}
return std::string::npos;
}
bool HttpResponseHeaders::GetCacheControlDirective(const StringPiece& directive,
TimeDelta* result) const {
StringPiece name("cache-control");
std::string value;
size_t directive_size = directive.size();
size_t iter = 0;
while (EnumerateHeader(&iter, name, &value)) {
if (value.size() > directive_size + 1 &&
base::StartsWith(value, directive,
base::CompareCase::INSENSITIVE_ASCII) &&
value[directive_size] == '=') {
int64_t seconds;
base::StringToInt64(
StringPiece(value.begin() + directive_size + 1, value.end()),
&seconds);
*result = TimeDelta::FromSeconds(seconds);
return true;
}
}
return false;
}
void HttpResponseHeaders::AddHeader(std::string::const_iterator name_begin,
std::string::const_iterator name_end,
std::string::const_iterator values_begin,
std::string::const_iterator values_end) {
// If the header can be coalesced, then we should split it up.
if (values_begin == values_end ||
HttpUtil::IsNonCoalescingHeader(name_begin, name_end)) {
AddToParsed(name_begin, name_end, values_begin, values_end);
} else {
HttpUtil::ValuesIterator it(values_begin, values_end, ',');
while (it.GetNext()) {
AddToParsed(name_begin, name_end, it.value_begin(), it.value_end());
// clobber these so that subsequent values are treated as continuations
name_begin = name_end = raw_headers_.end();
}
}
}
void HttpResponseHeaders::AddToParsed(std::string::const_iterator name_begin,
std::string::const_iterator name_end,
std::string::const_iterator value_begin,
std::string::const_iterator value_end) {
ParsedHeader header;
header.name_begin = name_begin;
header.name_end = name_end;
header.value_begin = value_begin;
header.value_end = value_end;
parsed_.push_back(header);
}
void HttpResponseHeaders::AddNonCacheableHeaders(HeaderSet* result) const {
// Add server specified transients. Any 'cache-control: no-cache="foo,bar"'
// headers present in the response specify additional headers that we should
// not store in the cache.
const char kCacheControl[] = "cache-control";
const char kPrefix[] = "no-cache=\"";
const size_t kPrefixLen = sizeof(kPrefix) - 1;
std::string value;
size_t iter = 0;
while (EnumerateHeader(&iter, kCacheControl, &value)) {
// If the value is smaller than the prefix and a terminal quote, skip
// it.
if (value.size() <= kPrefixLen ||
value.compare(0, kPrefixLen, kPrefix) != 0) {
continue;
}
// if it doesn't end with a quote, then treat as malformed
if (value[value.size()-1] != '\"')
continue;
// process the value as a comma-separated list of items. Each
// item can be wrapped by linear white space.
std::string::const_iterator item = value.begin() + kPrefixLen;
std::string::const_iterator end = value.end() - 1;
while (item != end) {
// Find the comma to compute the length of the current item,
// and the position of the next one.
std::string::const_iterator item_next = std::find(item, end, ',');
std::string::const_iterator item_end = end;
if (item_next != end) {
// Skip over comma for next position.
item_end = item_next;
item_next++;
}
// trim off leading and trailing whitespace in this item.
HttpUtil::TrimLWS(&item, &item_end);
// assuming the header is not empty, lowercase and insert into set
if (item_end > item) {
result->insert(
base::ToLowerASCII(base::StringPiece(&*item, item_end - item)));
}
// Continue to next item.
item = item_next;
}
}
}
void HttpResponseHeaders::AddHopByHopHeaders(HeaderSet* result) {
for (size_t i = 0; i < arraysize(kHopByHopResponseHeaders); ++i)
result->insert(std::string(kHopByHopResponseHeaders[i]));
}
void HttpResponseHeaders::AddCookieHeaders(HeaderSet* result) {
for (size_t i = 0; i < arraysize(kCookieResponseHeaders); ++i)
result->insert(std::string(kCookieResponseHeaders[i]));
}
void HttpResponseHeaders::AddChallengeHeaders(HeaderSet* result) {
for (size_t i = 0; i < arraysize(kChallengeResponseHeaders); ++i)
result->insert(std::string(kChallengeResponseHeaders[i]));
}
void HttpResponseHeaders::AddHopContentRangeHeaders(HeaderSet* result) {
result->insert(kContentRange);
}
void HttpResponseHeaders::AddSecurityStateHeaders(HeaderSet* result) {
for (size_t i = 0; i < arraysize(kSecurityStateHeaders); ++i)
result->insert(std::string(kSecurityStateHeaders[i]));
}
void HttpResponseHeaders::GetMimeTypeAndCharset(std::string* mime_type,
std::string* charset) const {
mime_type->clear();
charset->clear();
std::string name = "content-type";
std::string value;
bool had_charset = false;
size_t iter = 0;
while (EnumerateHeader(&iter, name, &value))
HttpUtil::ParseContentType(value, mime_type, charset, &had_charset, NULL);
}
bool HttpResponseHeaders::GetMimeType(std::string* mime_type) const {
std::string unused;
GetMimeTypeAndCharset(mime_type, &unused);
return !mime_type->empty();
}
bool HttpResponseHeaders::GetCharset(std::string* charset) const {
std::string unused;
GetMimeTypeAndCharset(&unused, charset);
return !charset->empty();
}
bool HttpResponseHeaders::IsRedirect(std::string* location) const {
if (!IsRedirectResponseCode(response_code_))
return false;
// If we lack a Location header, then we can't treat this as a redirect.
// We assume that the first non-empty location value is the target URL that
// we want to follow. TODO(darin): Is this consistent with other browsers?
size_t i = std::string::npos;
do {
i = FindHeader(++i, "location");
if (i == std::string::npos)
return false;
// If the location value is empty, then it doesn't count.
} while (parsed_[i].value_begin == parsed_[i].value_end);
if (location) {
// Escape any non-ASCII characters to preserve them. The server should
// only be returning ASCII here, but for compat we need to do this.
*location = EscapeNonASCII(
std::string(parsed_[i].value_begin, parsed_[i].value_end));
}
return true;
}
// static
bool HttpResponseHeaders::IsRedirectResponseCode(int response_code) {
// Users probably want to see 300 (multiple choice) pages, so we don't count
// them as redirects that need to be followed.
return (response_code == 301 ||
response_code == 302 ||
response_code == 303 ||
response_code == 307 ||
response_code == 308);
}
// From RFC 2616 section 13.2.4:
//
// The calculation to determine if a response has expired is quite simple:
//
// response_is_fresh = (freshness_lifetime > current_age)
//
// Of course, there are other factors that can force a response to always be
// validated or re-fetched.
//
// From RFC 5861 section 3, a stale response may be used while revalidation is
// performed in the background if
//
// freshness_lifetime + stale_while_revalidate > current_age
//
ValidationType HttpResponseHeaders::RequiresValidation(
const Time& request_time,
const Time& response_time,
const Time& current_time) const {
FreshnessLifetimes lifetimes = GetFreshnessLifetimes(response_time);
if (lifetimes.freshness.is_zero() && lifetimes.staleness.is_zero())
return VALIDATION_SYNCHRONOUS;
TimeDelta age = GetCurrentAge(request_time, response_time, current_time);
if (lifetimes.freshness > age)
return VALIDATION_NONE;
if (lifetimes.freshness + lifetimes.staleness > age)
return VALIDATION_ASYNCHRONOUS;
return VALIDATION_SYNCHRONOUS;
}
// From RFC 2616 section 13.2.4:
//
// The max-age directive takes priority over Expires, so if max-age is present
// in a response, the calculation is simply:
//
// freshness_lifetime = max_age_value
//
// Otherwise, if Expires is present in the response, the calculation is:
//
// freshness_lifetime = expires_value - date_value
//
// Note that neither of these calculations is vulnerable to clock skew, since
// all of the information comes from the origin server.
//
// Also, if the response does have a Last-Modified time, the heuristic
// expiration value SHOULD be no more than some fraction of the interval since
// that time. A typical setting of this fraction might be 10%:
//
// freshness_lifetime = (date_value - last_modified_value) * 0.10
//
// If the stale-while-revalidate directive is present, then it is used to set
// the |staleness| time, unless it overridden by another directive.
//
HttpResponseHeaders::FreshnessLifetimes
HttpResponseHeaders::GetFreshnessLifetimes(const Time& response_time) const {
FreshnessLifetimes lifetimes;
// Check for headers that force a response to never be fresh. For backwards
// compat, we treat "Pragma: no-cache" as a synonym for "Cache-Control:
// no-cache" even though RFC 2616 does not specify it.
if (HasHeaderValue("cache-control", "no-cache") ||
HasHeaderValue("cache-control", "no-store") ||
HasHeaderValue("pragma", "no-cache")) {
return lifetimes;
}
// Cache-Control directive must_revalidate overrides stale-while-revalidate.
bool must_revalidate = HasHeaderValue("cache-control", "must-revalidate");
if (must_revalidate || !GetStaleWhileRevalidateValue(&lifetimes.staleness)) {
DCHECK_EQ(TimeDelta(), lifetimes.staleness);
}
// NOTE: "Cache-Control: max-age" overrides Expires, so we only check the
// Expires header after checking for max-age in GetFreshnessLifetimes. This
// is important since "Expires: <date in the past>" means not fresh, but
// it should not trump a max-age value.
if (GetMaxAgeValue(&lifetimes.freshness))
return lifetimes;
// If there is no Date header, then assume that the server response was
// generated at the time when we received the response.
Time date_value;
if (!GetDateValue(&date_value))
date_value = response_time;
Time expires_value;
if (GetExpiresValue(&expires_value)) {
// The expires value can be a date in the past!
if (expires_value > date_value) {
lifetimes.freshness = expires_value - date_value;
return lifetimes;
}
DCHECK_EQ(TimeDelta(), lifetimes.freshness);
return lifetimes;
}
// From RFC 2616 section 13.4:
//
// A response received with a status code of 200, 203, 206, 300, 301 or 410
// MAY be stored by a cache and used in reply to a subsequent request,
// subject to the expiration mechanism, unless a cache-control directive
// prohibits caching.
// ...
// A response received with any other status code (e.g. status codes 302
// and 307) MUST NOT be returned in a reply to a subsequent request unless
// there are cache-control directives or another header(s) that explicitly
// allow it.
//
// From RFC 2616 section 14.9.4:
//
// When the must-revalidate directive is present in a response received by
// a cache, that cache MUST NOT use the entry after it becomes stale to
// respond to a subsequent request without first revalidating it with the
// origin server. (I.e., the cache MUST do an end-to-end revalidation every
// time, if, based solely on the origin server's Expires or max-age value,
// the cached response is stale.)
//
// https://datatracker.ietf.org/doc/draft-reschke-http-status-308/ is an
// experimental RFC that adds 308 permanent redirect as well, for which "any
// future references ... SHOULD use one of the returned URIs."
if ((response_code_ == 200 || response_code_ == 203 ||
response_code_ == 206) &&
!must_revalidate) {
// TODO(darin): Implement a smarter heuristic.
Time last_modified_value;
if (GetLastModifiedValue(&last_modified_value)) {
// The last-modified value can be a date in the future!
if (last_modified_value <= date_value) {
lifetimes.freshness = (date_value - last_modified_value) / 10;
return lifetimes;
}
}
}
// These responses are implicitly fresh (unless otherwise overruled):
if (response_code_ == 300 || response_code_ == 301 || response_code_ == 308 ||
response_code_ == 410) {
lifetimes.freshness = TimeDelta::Max();
lifetimes.staleness = TimeDelta(); // It should never be stale.
return lifetimes;
}
// Our heuristic freshness estimate for this resource is 0 seconds, in
// accordance with common browser behaviour. However, stale-while-revalidate
// may still apply.
DCHECK_EQ(TimeDelta(), lifetimes.freshness);
return lifetimes;
}
// From RFC 7234 section 4.2.3:
//
// The following data is used for the age calculation:
//
// age_value
//
// The term "age_value" denotes the value of the Age header field
// (Section 5.1), in a form appropriate for arithmetic operation; or
// 0, if not available.
//
// date_value
//
// The term "date_value" denotes the value of the Date header field,
// in a form appropriate for arithmetic operations. See Section
// 7.1.1.2 of [RFC7231] for the definition of the Date header field,
// and for requirements regarding responses without it.
//
// now
//
// The term "now" means "the current value of the clock at the host
// performing the calculation". A host ought to use NTP ([RFC5905])
// or some similar protocol to synchronize its clocks to Coordinated
// Universal Time.
//
// request_time
//
// The current value of the clock at the host at the time the request
// resulting in the stored response was made.
//
// response_time
//
// The current value of the clock at the host at the time the
// response was received.
//
// The age is then calculated as
//
// apparent_age = max(0, response_time - date_value);
// response_delay = response_time - request_time;
// corrected_age_value = age_value + response_delay;
// corrected_initial_age = max(apparent_age, corrected_age_value);
// resident_time = now - response_time;
// current_age = corrected_initial_age + resident_time;
//
TimeDelta HttpResponseHeaders::GetCurrentAge(const Time& request_time,
const Time& response_time,
const Time& current_time) const {
// If there is no Date header, then assume that the server response was
// generated at the time when we received the response.
Time date_value;
if (!GetDateValue(&date_value))
date_value = response_time;
// If there is no Age header, then assume age is zero. GetAgeValue does not
// modify its out param if the value does not exist.
TimeDelta age_value;
GetAgeValue(&age_value);
TimeDelta apparent_age = std::max(TimeDelta(), response_time - date_value);
TimeDelta response_delay = response_time - request_time;
TimeDelta corrected_age_value = age_value + response_delay;
TimeDelta corrected_initial_age = std::max(apparent_age, corrected_age_value);
TimeDelta resident_time = current_time - response_time;
TimeDelta current_age = corrected_initial_age + resident_time;
return current_age;
}
bool HttpResponseHeaders::GetMaxAgeValue(TimeDelta* result) const {
return GetCacheControlDirective("max-age", result);
}
bool HttpResponseHeaders::GetAgeValue(TimeDelta* result) const {
std::string value;
if (!EnumerateHeader(nullptr, "Age", &value))
return false;
// Parse the delta-seconds as 1*DIGIT.
uint32_t seconds;
ParseIntError error;
if (!ParseUint32(value, &seconds, &error)) {
if (error == ParseIntError::FAILED_OVERFLOW) {
// If the Age value cannot fit in a uint32_t, saturate it to a maximum
// value. This is similar to what RFC 2616 says in section 14.6 for how
// caches should transmit values that overflow.
seconds = std::numeric_limits<decltype(seconds)>::max();
} else {
return false;
}
}
*result = TimeDelta::FromSeconds(seconds);
return true;
}
bool HttpResponseHeaders::GetDateValue(Time* result) const {
return GetTimeValuedHeader("Date", result);
}
bool HttpResponseHeaders::GetLastModifiedValue(Time* result) const {
return GetTimeValuedHeader("Last-Modified", result);
}
bool HttpResponseHeaders::GetExpiresValue(Time* result) const {
return GetTimeValuedHeader("Expires", result);
}
bool HttpResponseHeaders::GetStaleWhileRevalidateValue(
TimeDelta* result) const {
return GetCacheControlDirective("stale-while-revalidate", result);
}
bool HttpResponseHeaders::GetTimeValuedHeader(const std::string& name,
Time* result) const {
std::string value;
if (!EnumerateHeader(nullptr, name, &value))
return false;
// When parsing HTTP dates it's beneficial to default to GMT because:
// 1. RFC2616 3.3.1 says times should always be specified in GMT
// 2. Only counter-example incorrectly appended "UTC" (crbug.com/153759)
// 3. When adjusting cookie expiration times for clock skew
// (crbug.com/135131) this better matches our cookie expiration
// time parser which ignores timezone specifiers and assumes GMT.
// 4. This is exactly what Firefox does.
// TODO(pauljensen): The ideal solution would be to return false if the
// timezone could not be understood so as to avoid makeing other calculations
// based on an incorrect time. This would require modifying the time
// library or duplicating the code. (http://crbug.com/158327)
return Time::FromUTCString(value.c_str(), result);
}
// We accept the first value of "close" or "keep-alive" in a Connection or
// Proxy-Connection header, in that order. Obeying "keep-alive" in HTTP/1.1 or
// "close" in 1.0 is not strictly standards-compliant, but we'd like to
// avoid looking at the Proxy-Connection header whenever it is reasonable to do
// so.
// TODO(ricea): Measure real-world usage of the "Proxy-Connection" header,
// with a view to reducing support for it in order to make our Connection header
// handling more RFC 7230 compliant.
bool HttpResponseHeaders::IsKeepAlive() const {
// NOTE: It is perhaps risky to assume that a Proxy-Connection header is
// meaningful when we don't know that this response was from a proxy, but
// Mozilla also does this, so we'll do the same.
static const char* const kConnectionHeaders[] = {
"connection", "proxy-connection"};
struct KeepAliveToken {
const char* const token;
bool keep_alive;
};
static const KeepAliveToken kKeepAliveTokens[] = {{"keep-alive", true},
{"close", false}};
if (http_version_ < HttpVersion(1, 0))
return false;
for (const char* header : kConnectionHeaders) {
size_t iterator = 0;
std::string token;
while (EnumerateHeader(&iterator, header, &token)) {
for (const KeepAliveToken& keep_alive_token : kKeepAliveTokens) {
if (base::LowerCaseEqualsASCII(token, keep_alive_token.token))
return keep_alive_token.keep_alive;
}
}
}
return http_version_ != HttpVersion(1, 0);
}
bool HttpResponseHeaders::HasStrongValidators() const {
std::string etag_header;
EnumerateHeader(nullptr, "etag", &etag_header);
std::string last_modified_header;
EnumerateHeader(nullptr, "Last-Modified", &last_modified_header);
std::string date_header;
EnumerateHeader(nullptr, "Date", &date_header);
return HttpUtil::HasStrongValidators(GetHttpVersion(),
etag_header,
last_modified_header,
date_header);
}
bool HttpResponseHeaders::HasValidators() const {
std::string etag_header;
EnumerateHeader(NULL, "etag", &etag_header);
std::string last_modified_header;
EnumerateHeader(NULL, "Last-Modified", &last_modified_header);
return HttpUtil::HasValidators(GetHttpVersion(), etag_header,
last_modified_header);
}
// From RFC 2616:
// Content-Length = "Content-Length" ":" 1*DIGIT
int64_t HttpResponseHeaders::GetContentLength() const {
return GetInt64HeaderValue("content-length");
}
int64_t HttpResponseHeaders::GetInt64HeaderValue(
const std::string& header) const {
size_t iter = 0;
std::string content_length_val;
if (!EnumerateHeader(&iter, header, &content_length_val))
return -1;
if (content_length_val.empty())
return -1;
if (content_length_val[0] == '+')
return -1;
int64_t result;
bool ok = base::StringToInt64(content_length_val, &result);
if (!ok || result < 0)
return -1;
return result;
}
bool HttpResponseHeaders::GetContentRangeFor206(
int64_t* first_byte_position,
int64_t* last_byte_position,
int64_t* instance_length) const {
size_t iter = 0;
std::string content_range_spec;
if (!EnumerateHeader(&iter, kContentRange, &content_range_spec)) {
*first_byte_position = *last_byte_position = *instance_length = -1;
return false;
}
return HttpUtil::ParseContentRangeHeaderFor206(
content_range_spec, first_byte_position, last_byte_position,
instance_length);
}
std::unique_ptr<base::Value> HttpResponseHeaders::NetLogCallback(
NetLogCaptureMode capture_mode) const {
auto dict = std::make_unique<base::DictionaryValue>();
auto headers = std::make_unique<base::ListValue>();
headers->AppendString(EscapeNonASCII(GetStatusLine()));
size_t iterator = 0;
std::string name;
std::string value;
while (EnumerateHeaderLines(&iterator, &name, &value)) {
std::string log_value =
ElideHeaderValueForNetLog(capture_mode, name, value);
std::string escaped_name = EscapeNonASCII(name);
std::string escaped_value = EscapeNonASCII(log_value);
headers->AppendString(base::StringPrintf("%s: %s", escaped_name.c_str(),
escaped_value.c_str()));
}
dict->Set("headers", std::move(headers));
return std::move(dict);
}
bool HttpResponseHeaders::IsChunkEncoded() const {
// Ignore spurious chunked responses from HTTP/1.0 servers and proxies.
return GetHttpVersion() >= HttpVersion(1, 1) &&
HasHeaderValue("Transfer-Encoding", "chunked");
}
bool HttpResponseHeaders::IsCookieResponseHeader(StringPiece name) {
for (const char* cookie_header : kCookieResponseHeaders) {
if (base::EqualsCaseInsensitiveASCII(cookie_header, name))
return true;
}
return false;
}
} // namespace net
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