comparison osx/include/kj/compat/http.h @ 62:0994c39f1e94

Cap'n Proto v0.6 + build for OSX

+// Copyright (c) 2017 Sandstorm Development Group, Inc. and contributors
+// Licensed under the MIT License:
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+#ifndef KJ_COMPAT_HTTP_H_
+#define KJ_COMPAT_HTTP_H_
+// The KJ HTTP client/server library.
+//
+// This is a simple library which can be used to implement an HTTP client or server. Properties
+// of this library include:
+// - Uses KJ async framework.
+// - Agnostic to transport layer -- you can provide your own.
+// - Header parsing is zero-copy -- it results in strings that point directly into the buffer
+//   received off the wire.
+// - Application code which reads and writes headers refers to headers by symbolic names, not by
+//   string literals, with lookups being array-index-based, not map-based. To make this possible,
+//   the application announces what headers it cares about in advance, in order to assign numeric
+//   values to them.
+// - Methods are identified by an enum.
+
+#include <kj/string.h>
+#include <kj/vector.h>
+#include <kj/memory.h>
+#include <kj/one-of.h>
+#include <kj/async-io.h>
+
+namespace kj {
+
+#define KJ_HTTP_FOR_EACH_METHOD(MACRO) \
+  MACRO(GET) \
+  MACRO(HEAD) \
+  MACRO(POST) \
+  MACRO(PUT) \
+  MACRO(DELETE) \
+  MACRO(PATCH) \
+  MACRO(PURGE) \
+  MACRO(OPTIONS) \
+  MACRO(TRACE) \
+  /* standard methods */ \
+  /* */ \
+  /* (CONNECT is intentionally omitted since it is handled specially in HttpHandler) */ \
+  \
+  MACRO(COPY) \
+  MACRO(LOCK) \
+  MACRO(MKCOL) \
+  MACRO(MOVE) \
+  MACRO(PROPFIND) \
+  MACRO(PROPPATCH) \
+  MACRO(SEARCH) \
+  MACRO(UNLOCK) \
+  /* WebDAV */ \
+  \
+  MACRO(REPORT) \
+  MACRO(MKACTIVITY) \
+  MACRO(CHECKOUT) \
+  MACRO(MERGE) \
+  /* Subversion */ \
+  \
+  MACRO(MSEARCH) \
+  MACRO(NOTIFY) \
+  MACRO(SUBSCRIBE) \
+  MACRO(UNSUBSCRIBE)
+  /* UPnP */
+
+#define KJ_HTTP_FOR_EACH_CONNECTION_HEADER(MACRO) \
+  MACRO(connection, "Connection") \
+  MACRO(contentLength, "Content-Length") \
+  MACRO(keepAlive, "Keep-Alive") \
+  MACRO(te, "TE") \
+  MACRO(trailer, "Trailer") \
+  MACRO(transferEncoding, "Transfer-Encoding") \
+  MACRO(upgrade, "Upgrade")
+
+enum class HttpMethod {
+  // Enum of known HTTP methods.
+  //
+  // We use an enum rather than a string to allow for faster parsing and switching and to reduce
+  // ambiguity.
+
+#define DECLARE_METHOD(id) id,
+KJ_HTTP_FOR_EACH_METHOD(DECLARE_METHOD)
+#undef DECALRE_METHOD
+};
+
+kj::StringPtr KJ_STRINGIFY(HttpMethod method);
+kj::Maybe<HttpMethod> tryParseHttpMethod(kj::StringPtr name);
+
+class HttpHeaderTable;
+
+class HttpHeaderId {
+  // Identifies an HTTP header by numeric ID that indexes into an HttpHeaderTable.
+  //
+  // The KJ HTTP API prefers that headers be identified by these IDs for a few reasons:
+  // - Integer lookups are much more efficient than string lookups.
+  // - Case-insensitivity is awkward to deal with when const strings are being passed to the lookup
+  //   method.
+  // - Writing out strings less often means fewer typos.
+  //
+  // See HttpHeaderTable for usage hints.
+
+public:
+  HttpHeaderId() = default;
+
+  inline bool operator==(const HttpHeaderId& other) const { return id == other.id; }
+  inline bool operator!=(const HttpHeaderId& other) const { return id != other.id; }
+  inline bool operator< (const HttpHeaderId& other) const { return id <  other.id; }
+  inline bool operator> (const HttpHeaderId& other) const { return id >  other.id; }
+  inline bool operator<=(const HttpHeaderId& other) const { return id <= other.id; }
+  inline bool operator>=(const HttpHeaderId& other) const { return id >= other.id; }
+
+  inline size_t hashCode() const { return id; }
+
+  kj::StringPtr toString() const;
+
+  void requireFrom(HttpHeaderTable& table) const;
+  // In debug mode, throws an exception if the HttpHeaderId is not from the given table.
+  //
+  // In opt mode, no-op.
+
+#define KJ_HTTP_FOR_EACH_BUILTIN_HEADER(MACRO) \
+  MACRO(HOST, "Host") \
+  MACRO(DATE, "Date") \
+  MACRO(LOCATION, "Location") \
+  MACRO(CONTENT_TYPE, "Content-Type")
+  // For convenience, these very-common headers are valid for all HttpHeaderTables. You can refer
+  // to them like:
+  //
+  //     HttpHeaderId::HOST
+  //
+  // TODO(0.7): Fill this out with more common headers.
+
+#define DECLARE_HEADER(id, name) \
+  static const HttpHeaderId id;
+  // Declare a constant for each builtin header, e.g.: HttpHeaderId::CONNECTION
+
+  KJ_HTTP_FOR_EACH_BUILTIN_HEADER(DECLARE_HEADER);
+#undef DECLARE_HEADER
+
+private:
+  HttpHeaderTable* table;
+  uint id;
+
+  inline explicit constexpr HttpHeaderId(HttpHeaderTable* table, uint id): table(table), id(id) {}
+  friend class HttpHeaderTable;
+  friend class HttpHeaders;
+};
+
+class HttpHeaderTable {
+  // Construct an HttpHeaderTable to declare which headers you'll be interested in later on, and
+  // to manufacture IDs for them.
+  //
+  // Example:
+  //
+  //     // Build a header table with the headers we are interested in.
+  //     kj::HttpHeaderTable::Builder builder;
+  //     const HttpHeaderId accept = builder.add("Accept");
+  //     const HttpHeaderId contentType = builder.add("Content-Type");
+  //     kj::HttpHeaderTable table(kj::mv(builder));
+  //
+  //     // Create an HTTP client.
+  //     auto client = kj::newHttpClient(table, network);
+  //
+  //     // Get http://example.com.
+  //     HttpHeaders headers(table);
+  //     headers.set(accept, "text/html");
+  //     auto response = client->send(kj::HttpMethod::GET, "http://example.com", headers)
+  //         .wait(waitScope);
+  //     auto msg = kj::str("Response content type: ", response.headers.get(contentType));
+
+  struct IdsByNameMap;
+
+public:
+  HttpHeaderTable();
+  // Constructs a table that only contains the builtin headers.
+
+  class Builder {
+  public:
+    Builder();
+    HttpHeaderId add(kj::StringPtr name);
+    Own<HttpHeaderTable> build();
+
+    HttpHeaderTable& getFutureTable();
+    // Get the still-unbuilt header table. You cannot actually use it until build() has been
+    // called.
+    //
+    // This method exists to help when building a shared header table -- the Builder may be passed
+    // to several components, each of which will register the headers they need and get a reference
+    // to the future table.
+
+  private:
+    kj::Own<HttpHeaderTable> table;
+  };
+
+  KJ_DISALLOW_COPY(HttpHeaderTable);  // Can't copy because HttpHeaderId points to the table.
+  ~HttpHeaderTable() noexcept(false);
+
+  uint idCount();
+  // Return the number of IDs in the table.
+
+  kj::Maybe<HttpHeaderId> stringToId(kj::StringPtr name);
+  // Try to find an ID for the given name. The matching is case-insensitive, per the HTTP spec.
+  //
+  // Note: if `name` contains characters that aren't allowed in HTTP header names, this may return
+  //   a bogus value rather than null, due to optimizations used in case-insensitive matching.
+
+  kj::StringPtr idToString(HttpHeaderId id);
+  // Get the canonical string name for the given ID.
+
+private:
+  kj::Vector<kj::StringPtr> namesById;
+  kj::Own<IdsByNameMap> idsByName;
+};
+
+class HttpHeaders {
+  // Represents a set of HTTP headers.
+  //
+  // This class guards against basic HTTP header injection attacks: Trying to set a header name or
+  // value containing a newline, carriage return, or other invalid character will throw an
+  // exception.
+
+public:
+  explicit HttpHeaders(HttpHeaderTable& table);
+
+  KJ_DISALLOW_COPY(HttpHeaders);
+  HttpHeaders(HttpHeaders&&) = default;
+  HttpHeaders& operator=(HttpHeaders&&) = default;
+
+  void clear();
+  // Clears all contents, as if the object was freshly-allocated. However, calling this rather
+  // than actually re-allocating the object may avoid re-allocation of internal objects.
+
+  HttpHeaders clone() const;
+  // Creates a deep clone of the HttpHeaders. The returned object owns all strings it references.
+
+  HttpHeaders cloneShallow() const;
+  // Creates a shallow clone of the HttpHeaders. The returned object references the same strings
+  // as the original, owning none of them.
+
+  kj::Maybe<kj::StringPtr> get(HttpHeaderId id) const;
+  // Read a header.
+
+  template <typename Func>
+  void forEach(Func&& func) const;
+  // Calls `func(name, value)` for each header in the set -- including headers that aren't mapped
+  // to IDs in the header table. Both inputs are of type kj::StringPtr.
+
+  void set(HttpHeaderId id, kj::StringPtr value);
+  void set(HttpHeaderId id, kj::String&& value);
+  // Sets a header value, overwriting the existing value.
+  //
+  // The String&& version is equivalent to calling the other version followed by takeOwnership().
+  //
+  // WARNING: It is the caller's responsibility to ensure that `value` remains valid until the
+  //   HttpHeaders object is destroyed. This allows string literals to be passed without making a
+  //   copy, but complicates the use of dynamic values. Hint: Consider using `takeOwnership()`.
+
+  void add(kj::StringPtr name, kj::StringPtr value);
+  void add(kj::StringPtr name, kj::String&& value);
+  void add(kj::String&& name, kj::String&& value);
+  // Append a header. `name` will be looked up in the header table, but if it's not mapped, the
+  // header will be added to the list of unmapped headers.
+  //
+  // The String&& versions are equivalent to calling the other version followed by takeOwnership().
+  //
+  // WARNING: It is the caller's responsibility to ensure that `name` and `value` remain valid
+  //   until the HttpHeaders object is destroyed. This allows string literals to be passed without
+  //   making a copy, but complicates the use of dynamic values. Hint: Consider using
+  //   `takeOwnership()`.
+
+  void unset(HttpHeaderId id);
+  // Removes a header.
+  //
+  // It's not possible to remove a header by string name because non-indexed headers would take
+  // O(n) time to remove. Instead, construct a new HttpHeaders object and copy contents.
+
+  void takeOwnership(kj::String&& string);
+  void takeOwnership(kj::Array<char>&& chars);
+  void takeOwnership(HttpHeaders&& otherHeaders);
+  // Takes overship of a string so that it lives until the HttpHeaders object is destroyed. Useful
+  // when you've passed a dynamic value to set() or add() or parse*().
+
+  struct ConnectionHeaders {
+    // These headers govern details of the specific HTTP connection or framing of the content.
+    // Hence, they are managed internally within the HTTP library, and never appear in an
+    // HttpHeaders structure.
+
+#define DECLARE_HEADER(id, name) \
+    kj::StringPtr id;
+    KJ_HTTP_FOR_EACH_CONNECTION_HEADER(DECLARE_HEADER)
+#undef DECLARE_HEADER
+  };
+
+  struct Request {
+    HttpMethod method;
+    kj::StringPtr url;
+    ConnectionHeaders connectionHeaders;
+  };
+  struct Response {
+    uint statusCode;
+    kj::StringPtr statusText;
+    ConnectionHeaders connectionHeaders;
+  };
+
+  kj::Maybe<Request> tryParseRequest(kj::ArrayPtr<char> content);
+  kj::Maybe<Response> tryParseResponse(kj::ArrayPtr<char> content);
+  // Parse an HTTP header blob and add all the headers to this object.
+  //
+  // `content` should be all text from the start of the request to the first occurrance of two
+  // newlines in a row -- including the first of these two newlines, but excluding the second.
+  //
+  // The parse is performed with zero copies: The callee clobbers `content` with '\0' characters
+  // to split it into a bunch of shorter strings. The caller must keep `content` valid until the
+  // `HttpHeaders` is destroyed, or pass it to `takeOwnership()`.
+
+  kj::String serializeRequest(HttpMethod method, kj::StringPtr url,
+                              const ConnectionHeaders& connectionHeaders) const;
+  kj::String serializeResponse(uint statusCode, kj::StringPtr statusText,
+                               const ConnectionHeaders& connectionHeaders) const;
+  // Serialize the headers as a complete request or response blob. The blob uses '\r\n' newlines
+  // and includes the double-newline to indicate the end of the headers.
+
+  kj::String toString() const;
+
+private:
+  HttpHeaderTable* table;
+
+  kj::Array<kj::StringPtr> indexedHeaders;
+  // Size is always table->idCount().
+
+  struct Header {
+    kj::StringPtr name;
+    kj::StringPtr value;
+  };
+  kj::Vector<Header> unindexedHeaders;
+
+  kj::Vector<kj::Array<char>> ownedStrings;
+
+  kj::Maybe<uint> addNoCheck(kj::StringPtr name, kj::StringPtr value);
+
+  kj::StringPtr cloneToOwn(kj::StringPtr str);
+
+  kj::String serialize(kj::ArrayPtr<const char> word1,
+                       kj::ArrayPtr<const char> word2,
+                       kj::ArrayPtr<const char> word3,
+                       const ConnectionHeaders& connectionHeaders) const;
+
+  bool parseHeaders(char* ptr, char* end, ConnectionHeaders& connectionHeaders);
+
+  // TODO(perf): Arguably we should store a map, but header sets are never very long
+  // TODO(perf): We could optimize for common headers by storing them directly as fields. We could
+  //   also add direct accessors for those headers.
+};
+
+class WebSocket {
+public:
+  WebSocket(kj::Own<kj::AsyncIoStream> stream);
+  // Create a WebSocket wrapping the given I/O stream.
+
+  kj::Promise<void> send(kj::ArrayPtr<const byte> message);
+  kj::Promise<void> send(kj::ArrayPtr<const char> message);
+};
+
+class HttpClient {
+  // Interface to the client end of an HTTP connection.
+  //
+  // There are two kinds of clients:
+  // * Host clients are used when talking to a specific host. The `url` specified in a request
+  //   is actually just a path. (A `Host` header is still required in all requests.)
+  // * Proxy clients are used when the target could be any arbitrary host on the internet.
+  //   The `url` specified in a request is a full URL including protocol and hostname.
+
+public:
+  struct Response {
+    uint statusCode;
+    kj::StringPtr statusText;
+    const HttpHeaders* headers;
+    kj::Own<kj::AsyncInputStream> body;
+    // `statusText` and `headers` remain valid until `body` is dropped.
+  };
+
+  struct Request {
+    kj::Own<kj::AsyncOutputStream> body;
+    // Write the request entity body to this stream, then drop it when done.
+    //
+    // May be null for GET and HEAD requests (which have no body) and requests that have
+    // Content-Length: 0.
+
+    kj::Promise<Response> response;
+    // Promise for the eventual respnose.
+  };
+
+  virtual Request request(HttpMethod method, kj::StringPtr url, const HttpHeaders& headers,
+                          kj::Maybe<uint64_t> expectedBodySize = nullptr) = 0;
+  // Perform an HTTP request.
+  //
+  // `url` may be a full URL (with protocol and host) or it may be only the path part of the URL,
+  // depending on whether the client is a proxy client or a host client.
+  //
+  // `url` and `headers` need only remain valid until `request()` returns (they can be
+  // stack-allocated).
+  //
+  // `expectedBodySize`, if provided, must be exactly the number of bytes that will be written to
+  // the body. This will trigger use of the `Content-Length` connection header. Otherwise,
+  // `Transfer-Encoding: chunked` will be used.
+
+  struct WebSocketResponse {
+    uint statusCode;
+    kj::StringPtr statusText;
+    const HttpHeaders* headers;
+    kj::OneOf<kj::Own<kj::AsyncInputStream>, kj::Own<WebSocket>> upstreamOrBody;
+    // `statusText` and `headers` remain valid until `upstreamOrBody` is dropped.
+  };
+  virtual kj::Promise<WebSocketResponse> openWebSocket(
+      kj::StringPtr url, const HttpHeaders& headers, kj::Own<WebSocket> downstream);
+  // Tries to open a WebSocket. Default implementation calls send() and never returns a WebSocket.
+  //
+  // `url` and `headers` are invalidated when the returned promise resolves.
+
+  virtual kj::Promise<kj::Own<kj::AsyncIoStream>> connect(kj::String host);
+  // Handles CONNECT requests. Only relevant for proxy clients. Default implementation throws
+  // UNIMPLEMENTED.
+};
+
+class HttpService {
+  // Interface which HTTP services should implement.
+  //
+  // This interface is functionally equivalent to HttpClient, but is intended for applications to
+  // implement rather than call. The ergonomics and performance of the method signatures are
+  // optimized for the serving end.
+  //
+  // As with clients, there are two kinds of services:
+  // * Host services are used when talking to a specific host. The `url` specified in a request
+  //   is actually just a path. (A `Host` header is still required in all requests, and the service
+  //   may in fact serve multiple origins via this header.)
+  // * Proxy services are used when the target could be any arbitrary host on the internet, i.e. to
+  //   implement an HTTP proxy. The `url` specified in a request is a full URL including protocol
+  //   and hostname.
+
+public:
+  class Response {
+  public:
+    virtual kj::Own<kj::AsyncOutputStream> send(
+        uint statusCode, kj::StringPtr statusText, const HttpHeaders& headers,
+        kj::Maybe<uint64_t> expectedBodySize = nullptr) = 0;
+    // Begin the response.
+    //
+    // `statusText` and `headers` need only remain valid until send() returns (they can be
+    // stack-allocated).
+  };
+
+  virtual kj::Promise<void> request(
+      HttpMethod method, kj::StringPtr url, const HttpHeaders& headers,
+      kj::AsyncInputStream& requestBody, Response& response) = 0;
+  // Perform an HTTP request.
+  //
+  // `url` may be a full URL (with protocol and host) or it may be only the path part of the URL,
+  // depending on whether the service is a proxy service or a host service.
+  //
+  // `url` and `headers` are invalidated on the first read from `requestBody` or when the returned
+  // promise resolves, whichever comes first.
+
+  class WebSocketResponse: public Response {
+  public:
+    kj::Own<WebSocket> startWebSocket(
+        uint statusCode, kj::StringPtr statusText, const HttpHeaders& headers,
+        WebSocket& upstream);
+    // Begin the response.
+    //
+    // `statusText` and `headers` need only remain valid until startWebSocket() returns (they can
+    // be stack-allocated).
+  };
+
+  virtual kj::Promise<void> openWebSocket(
+      kj::StringPtr url, const HttpHeaders& headers, WebSocketResponse& response);
+  // Tries to open a WebSocket. Default implementation calls request() and never returns a
+  // WebSocket.
+  //
+  // `url` and `headers` are invalidated when the returned promise resolves.
+
+  virtual kj::Promise<kj::Own<kj::AsyncIoStream>> connect(kj::String host);
+  // Handles CONNECT requests. Only relevant for proxy services. Default implementation throws
+  // UNIMPLEMENTED.
+};
+
+kj::Own<HttpClient> newHttpClient(HttpHeaderTable& responseHeaderTable, kj::Network& network,
+                                  kj::Maybe<kj::Network&> tlsNetwork = nullptr);
+// Creates a proxy HttpClient that connects to hosts over the given network.
+//
+// `responseHeaderTable` is used when parsing HTTP responses. Requests can use any header table.
+//
+// `tlsNetwork` is required to support HTTPS destination URLs. Otherwise, only HTTP URLs can be
+// fetched.
+
+kj::Own<HttpClient> newHttpClient(HttpHeaderTable& responseHeaderTable, kj::AsyncIoStream& stream);
+// Creates an HttpClient that speaks over the given pre-established connection. The client may
+// be used as a proxy client or a host client depending on whether the peer is operating as
+// a proxy.
+//
+// Note that since this client has only one stream to work with, it will try to pipeline all
+// requests on this stream. If one request or response has an I/O failure, all subsequent requests
+// fail as well. If the destination server chooses to close the connection after a response,
+// subsequent requests will fail. If a response takes a long time, it blocks subsequent responses.
+// If a WebSocket is opened successfully, all subsequent requests fail.
+
+kj::Own<HttpClient> newHttpClient(HttpService& service);
+kj::Own<HttpService> newHttpService(HttpClient& client);
+// Adapts an HttpClient to an HttpService and vice versa.
+
+struct HttpServerSettings {
+  kj::Duration headerTimeout = 15 * kj::SECONDS;
+  // After initial connection open, or after receiving the first byte of a pipelined request,
+  // the client must send the complete request within this time.
+
+  kj::Duration pipelineTimeout = 5 * kj::SECONDS;
+  // After one request/response completes, we'll wait up to this long for a pipelined request to
+  // arrive.
+};
+
+class HttpServer: private kj::TaskSet::ErrorHandler {
+  // Class which listens for requests on ports or connections and sends them to an HttpService.
+
+public:
+  typedef HttpServerSettings Settings;
+
+  HttpServer(kj::Timer& timer, HttpHeaderTable& requestHeaderTable, HttpService& service,
+             Settings settings = Settings());
+  // Set up an HttpServer that directs incoming connections to the given service. The service
+  // may be a host service or a proxy service depending on whether you are intending to implement
+  // an HTTP server or an HTTP proxy.
+
+  kj::Promise<void> drain();
+  // Stop accepting new connections or new requests on existing connections. Finish any requests
+  // that are already executing, then close the connections. Returns once no more requests are
+  // in-flight.
+
+  kj::Promise<void> listenHttp(kj::ConnectionReceiver& port);
+  // Accepts HTTP connections on the given port and directs them to the handler.
+  //
+  // The returned promise never completes normally. It may throw if port.accept() throws. Dropping
+  // the returned promise will cause the server to stop listening on the port, but already-open
+  // connections will continue to be served. Destroy the whole HttpServer to cancel all I/O.
+
+  kj::Promise<void> listenHttp(kj::Own<kj::AsyncIoStream> connection);
+  // Reads HTTP requests from the given connection and directs them to the handler. A successful
+  // completion of the promise indicates that all requests received on the connection resulted in
+  // a complete response, and the client closed the connection gracefully or drain() was called.
+  // The promise throws if an unparseable request is received or if some I/O error occurs. Dropping
+  // the returned promise will cancel all I/O on the connection and cancel any in-flight requests.
+
+private:
+  class Connection;
+
+  kj::Timer& timer;
+  HttpHeaderTable& requestHeaderTable;
+  HttpService& service;
+  Settings settings;
+
+  bool draining = false;
+  kj::ForkedPromise<void> onDrain;
+  kj::Own<kj::PromiseFulfiller<void>> drainFulfiller;
+
+  uint connectionCount = 0;
+  kj::Maybe<kj::Own<kj::PromiseFulfiller<void>>> zeroConnectionsFulfiller;
+
+  kj::TaskSet tasks;
+
+  HttpServer(kj::Timer& timer, HttpHeaderTable& requestHeaderTable, HttpService& service,
+             Settings settings, kj::PromiseFulfillerPair<void> paf);
+
+  kj::Promise<void> listenLoop(kj::ConnectionReceiver& port);
+
+  void taskFailed(kj::Exception&& exception) override;
+};
+
+// =======================================================================================
+// inline implementation
+
+inline void HttpHeaderId::requireFrom(HttpHeaderTable& table) const {
+  KJ_IREQUIRE(this->table == nullptr || this->table == &table,
+      "the provided HttpHeaderId is from the wrong HttpHeaderTable");
+}
+
+inline kj::Own<HttpHeaderTable> HttpHeaderTable::Builder::build() { return kj::mv(table); }
+inline HttpHeaderTable& HttpHeaderTable::Builder::getFutureTable() { return *table; }
+
+inline uint HttpHeaderTable::idCount() { return namesById.size(); }
+
+inline kj::StringPtr HttpHeaderTable::idToString(HttpHeaderId id) {
+  id.requireFrom(*this);
+  return namesById[id.id];
+}
+
+inline kj::Maybe<kj::StringPtr> HttpHeaders::get(HttpHeaderId id) const {
+  id.requireFrom(*table);
+  auto result = indexedHeaders[id.id];
+  return result == nullptr ? kj::Maybe<kj::StringPtr>(nullptr) : result;
+}
+
+inline void HttpHeaders::unset(HttpHeaderId id) {
+  id.requireFrom(*table);
+  indexedHeaders[id.id] = nullptr;
+}
+
+template <typename Func>
+inline void HttpHeaders::forEach(Func&& func) const {
+  for (auto i: kj::indices(indexedHeaders)) {
+    if (indexedHeaders[i] != nullptr) {
+      func(table->idToString(HttpHeaderId(table, i)), indexedHeaders[i]);
+    }
+  }
+
+  for (auto& header: unindexedHeaders) {
+    func(header.name, header.value);
+  }
+}
+
+}  // namespace kj
+
+#endif // KJ_COMPAT_HTTP_H_