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Refactor ETag handling: extract check_if_not_modified and check_if_range methods for improved readability and maintainability

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This commit is contained in:
yhirose
2025-12-05 14:23:45 -05:00
parent 42e762ddd6
commit ec170f3ffa
1 changed files with 81 additions and 64 deletions
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145
httplib.h
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@@ -1258,6 +1258,10 @@ private:
bool routing(Request &req, Response &res, Stream &strm);
bool handle_file_request(Request &req, Response &res);
bool check_if_not_modified(const Request &req, Response &res,
const std::string &etag, time_t mtime) const;
bool check_if_range(Request &req, const std::string &etag,
time_t mtime) const;
bool dispatch_request(Request &req, Response &res,
const Handlers &handlers) const;
bool dispatch_request_for_content_reader(
@@ -8357,7 +8361,6 @@ inline bool Server::handle_file_request(Request &req, Response &res) {
res.set_header(kv.first, kv.second);
}
// Compute and set weak ETag based on mtime+size.
auto etag = detail::compute_etag(stat);
if (!etag.empty()) { res.set_header("ETag", etag); }
@@ -8368,70 +8371,9 @@ inline bool Server::handle_file_request(Request &req, Response &res) {
res.set_header("Last-Modified", last_modified);
}
// Handle conditional GET:
// 1. If-None-Match takes precedence (RFC 9110 Section 13.1.2)
// 2. If-Modified-Since is checked only when If-None-Match is absent
if (req.has_header("If-None-Match")) {
if (!etag.empty()) {
auto val = req.get_header_value("If-None-Match");
auto matched = false;
if (check_if_not_modified(req, res, etag, mtime)) { return true; }
// NOTE: We use exact string matching here. This works correctly
// because our server always generates weak ETags (W/"..."), and
// clients typically send back the same ETag they received.
// RFC 9110 Section 8.8.3.2 allows weak comparison for
// If-None-Match, where W/"x" and "x" would match, but this
// simplified implementation requires exact matches.
detail::split(val.data(), val.data() + val.size(), ',',
[&](const char *b, const char *e) {
if (!matched) {
auto tag = std::string(b, e);
matched = tag == "*" || tag == etag;
}
});
if (matched) {
res.status = StatusCode::NotModified_304;
return true;
}
}
} else if (req.has_header("If-Modified-Since")) {
auto val = req.get_header_value("If-Modified-Since");
auto t = detail::parse_http_date(val);
if (t != static_cast<time_t>(-1) && mtime <= t) {
res.status = StatusCode::NotModified_304;
return true;
}
}
// Handle If-Range for partial content requests (RFC 9110
// Section 13.1.5). If-Range is only evaluated when Range header is
// present. If the validator matches, serve partial content; otherwise
// serve full content.
if (!req.ranges.empty() && req.has_header("If-Range")) {
auto val = req.get_header_value("If-Range");
auto valid = false;
if (detail::is_strong_etag(val)) {
// RFC 9110 Section 13.1.5: If-Range requires strong ETag
// comparison.
valid = (!etag.empty() && val == etag);
} else if (detail::is_weak_etag(val)) {
// Weak ETags are not valid for If-Range (RFC 9110 Section 13.1.5)
valid = false;
} else {
// HTTP-date comparison
auto if_range_time = detail::parse_http_date(val);
valid = (if_range_time != static_cast<time_t>(-1) &&
mtime <= if_range_time);
}
if (!valid) {
// Validator doesn't match: ignore Range and serve full content
req.ranges.clear();
}
}
check_if_range(req, etag, mtime);
auto mm = std::make_shared<detail::mmap>(path.c_str());
if (!mm->is_open()) {
@@ -8462,6 +8404,81 @@ inline bool Server::handle_file_request(Request &req, Response &res) {
return false;
}
inline bool Server::check_if_not_modified(const Request &req, Response &res,
const std::string &etag,
time_t mtime) const {
// Handle conditional GET:
// 1. If-None-Match takes precedence (RFC 9110 Section 13.1.2)
// 2. If-Modified-Since is checked only when If-None-Match is absent
if (req.has_header("If-None-Match")) {
if (!etag.empty()) {
auto val = req.get_header_value("If-None-Match");
auto matched = false;
// NOTE: We use exact string matching here. This works correctly
// because our server always generates weak ETags (W/"..."), and
// clients typically send back the same ETag they received.
// RFC 9110 Section 8.8.3.2 allows weak comparison for
// If-None-Match, where W/"x" and "x" would match, but this
// simplified implementation requires exact matches.
detail::split(val.data(), val.data() + val.size(), ',',
[&](const char *b, const char *e) {
if (!matched) {
auto tag = std::string(b, e);
matched = tag == "*" || tag == etag;
}
});
if (matched) {
res.status = StatusCode::NotModified_304;
return true;
}
}
} else if (req.has_header("If-Modified-Since")) {
auto val = req.get_header_value("If-Modified-Since");
auto t = detail::parse_http_date(val);
if (t != static_cast<time_t>(-1) && mtime <= t) {
res.status = StatusCode::NotModified_304;
return true;
}
}
return false;
}
inline bool Server::check_if_range(Request &req, const std::string &etag,
time_t mtime) const {
// Handle If-Range for partial content requests (RFC 9110
// Section 13.1.5). If-Range is only evaluated when Range header is
// present. If the validator matches, serve partial content; otherwise
// serve full content.
if (!req.ranges.empty() && req.has_header("If-Range")) {
auto val = req.get_header_value("If-Range");
auto valid = false;
if (detail::is_strong_etag(val)) {
// RFC 9110 Section 13.1.5: If-Range requires strong ETag
// comparison.
valid = (!etag.empty() && val == etag);
} else if (detail::is_weak_etag(val)) {
// Weak ETags are not valid for If-Range (RFC 9110 Section 13.1.5)
valid = false;
} else {
// HTTP-date comparison
auto if_range_time = detail::parse_http_date(val);
valid =
(if_range_time != static_cast<time_t>(-1) && mtime <= if_range_time);
}
if (!valid) {
// Validator doesn't match: ignore Range and serve full content
req.ranges.clear();
return false;
}
}
return true;
}
inline socket_t
Server::create_server_socket(const std::string &host, int port,
int socket_flags,