Add wpi::HttpServerConnection and an example of its use (#1281)

wpiutil/src/main/native/cpp/HttpServerConnection.cpp

@@ -0,0 +1,126 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2018 FIRST. All Rights Reserved.                             */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include "wpi/HttpServerConnection.h"
+
+#include "wpi/SmallString.h"
+#include "wpi/SmallVector.h"
+#include "wpi/raw_uv_ostream.h"
+
+using namespace wpi;
+
+HttpServerConnection::HttpServerConnection(std::shared_ptr<uv::Stream> stream)
+    : m_stream(*stream) {
+  // process HTTP messages
+  m_request.messageComplete.connect([this](bool keepAlive) {
+    m_keepAlive = keepAlive;
+    ProcessRequest();
+  });
+
+  // pass incoming data to HTTP parser
+  stream->data.connect([this](uv::Buffer& buf, size_t size) {
+    m_request.Execute(StringRef{buf.base, size});
+    if (m_request.HasError()) {
+      // could not parse; just close the connection
+      m_stream.Close();
+    }
+  });
+
+  // close when remote side closes
+  stream->end.connect([h = stream.get()] { h->Close(); });
+
+  // start reading
+  stream->StartRead();
+}
+
+void HttpServerConnection::BuildCommonHeaders(raw_ostream& os) {
+  os << "Server: WebServer/1.0\r\n"
+        "Cache-Control: no-store, no-cache, must-revalidate, pre-check=0, "
+        "post-check=0, max-age=0\r\n"
+        "Pragma: no-cache\r\n"
+        "Expires: Mon, 3 Jan 2000 12:34:56 GMT\r\n";
+}
+
+void HttpServerConnection::BuildHeader(raw_ostream& os, int code,
+                                       const Twine& codeText,
+                                       const Twine& contentType,
+                                       uint64_t contentLength,
+                                       const Twine& extra) {
+  os << "HTTP/" << m_request.GetMajor() << '.' << m_request.GetMinor() << ' '
+     << code << ' ' << codeText << "\r\n";
+  if (contentLength == 0) m_keepAlive = false;
+  if (!m_keepAlive) os << "Connection: close\r\n";
+  BuildCommonHeaders(os);
+  os << "Content-Type: " << contentType << "\r\n";
+  if (contentLength != 0) os << "Content-Length: " << contentLength << "\r\n";
+  os << "Access-Control-Allow-Origin: *\r\nAccess-Control-Allow-Methods: *\r\n";
+  SmallString<128> extraBuf;
+  StringRef extraStr = extra.toStringRef(extraBuf);
+  if (!extraStr.empty()) os << extraStr << "\r\n";
+  os << "\r\n";  // header ends with a blank line
+}
+
+void HttpServerConnection::SendData(ArrayRef<uv::Buffer> bufs,
+                                    bool closeAfter) {
+  m_stream.Write(bufs, [ closeAfter, stream = &m_stream ](
+                           MutableArrayRef<uv::Buffer> bufs, uv::Error) {
+    for (auto&& buf : bufs) buf.Deallocate();
+    if (closeAfter) stream->Close();
+  });
+}
+
+void HttpServerConnection::SendResponse(int code, const Twine& codeText,
+                                        const Twine& contentType,
+                                        StringRef content,
+                                        const Twine& extraHeader) {
+  SmallVector<uv::Buffer, 4> toSend;
+  raw_uv_ostream os{toSend, 4096};
+  BuildHeader(os, code, codeText, contentType, content.size(), extraHeader);
+  os << content;
+  // close after write completes if we aren't keeping alive
+  SendData(os.bufs(), !m_keepAlive);
+}
+
+void HttpServerConnection::SendError(int code, const Twine& message) {
+  StringRef codeText, extra, baseMessage;
+  switch (code) {
+    case 401:
+      codeText = "Unauthorized";
+      extra = "WWW-Authenticate: Basic realm=\"CameraServer\"";
+      baseMessage = "401: Not Authenticated!";
+      break;
+    case 404:
+      codeText = "Not Found";
+      baseMessage = "404: Not Found!";
+      break;
+    case 500:
+      codeText = "Internal Server Error";
+      baseMessage = "500: Internal Server Error!";
+      break;
+    case 400:
+      codeText = "Bad Request";
+      baseMessage = "400: Not Found!";
+      break;
+    case 403:
+      codeText = "Forbidden";
+      baseMessage = "403: Forbidden!";
+      break;
+    case 503:
+      codeText = "Service Unavailable";
+      baseMessage = "503: Service Unavailable";
+      break;
+    default:
+      code = 501;
+      codeText = "Not Implemented";
+      baseMessage = "501: Not Implemented!";
+      break;
+  }
+  SmallString<256> content = baseMessage;
+  content += "\r\n";
+  message.toVector(content);
+  SendResponse(code, codeText, "text/plain", content, extra);
+}

wpiutil/src/main/native/include/wpi/HttpServerConnection.h

@@ -0,0 +1,123 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2018 FIRST. All Rights Reserved.                             */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#ifndef WPIUTIL_WPI_HTTPSERVERCONNECTION_H_
+#define WPIUTIL_WPI_HTTPSERVERCONNECTION_H_
+
+#include <memory>
+
+#include "wpi/ArrayRef.h"
+#include "wpi/HttpParser.h"
+#include "wpi/StringRef.h"
+#include "wpi/Twine.h"
+#include "wpi/uv/Stream.h"
+
+namespace wpi {
+
+class raw_ostream;
+
+class HttpServerConnection {
+ public:
+  explicit HttpServerConnection(std::shared_ptr<uv::Stream> stream);
+  virtual ~HttpServerConnection() = default;
+
+ protected:
+  /**
+   * Process an incoming HTTP request.  This is called after the incoming
+   * message completes (e.g. from the HttpParser::messageComplete callback).
+   *
+   * The implementation should read request details from m_request and call the
+   * appropriate Send() functions to send a response back to the client.
+   */
+  virtual void ProcessRequest() = 0;
+
+  /**
+   * Build common response headers.
+   *
+   * Called by SendHeader() to send headers common to every response.
+   * Each line must be terminated with \r\n.
+   *
+   * The default implementation sends the following:
+   * "Server: WebServer/1.0\r\n"
+   * "Cache-Control: no-store, no-cache, must-revalidate, pre-check=0, "
+   * "post-check=0, max-age=0\r\n"
+   * "Pragma: no-cache\r\n"
+   * "Expires: Mon, 3 Jan 2000 12:34:56 GMT\r\n"
+   *
+   * These parameters should ensure the browser does not cache the response.
+   * A browser should connect for each file and not serve files from its cache.
+   *
+   * @param os response stream
+   */
+  virtual void BuildCommonHeaders(raw_ostream& os);
+
+  /**
+   * Build HTTP response header, along with other header information like
+   * mimetype.  Calls BuildCommonHeaders().
+   *
+   * @param os response stream
+   * @param code HTTP response code (e.g. 200)
+   * @param codeText HTTP response code text (e.g. "OK")
+   * @param contentType MIME content type (e.g. "text/plain")
+   * @param contentLength Length of content.  If 0 is provided, m_keepAlive will
+   *                      be set to false.
+   * @param extra Extra HTTP headers to send, not including final "\r\n"
+   */
+  void BuildHeader(raw_ostream& os, int code, const Twine& codeText,
+                   const Twine& contentType, uint64_t contentLength,
+                   const Twine& extra = Twine{});
+
+  /**
+   * Send data to client.
+   *
+   * This is a convenience wrapper around m_stream.Write() to provide
+   * auto-close functionality.
+   *
+   * @param bufs Buffers to write.  Deallocate() will be called on each
+   *             buffer after the write completes.  If different behavior
+   *             is desired, call m_stream.Write() directly instead.
+   * @param closeAfter close the connection after the write completes
+   */
+  void SendData(ArrayRef<uv::Buffer> bufs, bool closeAfter = false);
+
+  /**
+   * Send HTTP response, along with other header information like mimetype.
+   * Calls BuildHeader().
+   *
+   * @param code HTTP response code (e.g. 200)
+   * @param codeText HTTP response code text (e.g. "OK")
+   * @param contentType MIME content type (e.g. "text/plain")
+   * @param content Response message content
+   * @param extraHeader Extra HTTP headers to send, not including final "\r\n"
+   */
+  void SendResponse(int code, const Twine& codeText, const Twine& contentType,
+                    StringRef content, const Twine& extraHeader = Twine{});
+
+  /**
+   * Send error header and message.
+   * This provides standard code responses for 400, 401, 403, 404, 500, and 503.
+   * Other codes will be reported as 501.  For arbitrary code handling, use
+   * SendResponse() instead.
+   *
+   * @param code HTTP error code (e.g. 404)
+   * @param message Additional message text
+   */
+  void SendError(int code, const Twine& message = Twine{});
+
+  /** The HTTP request. */
+  HttpParser m_request{HttpParser::kRequest};
+
+  /** Whether the connection should be kept alive. */
+  bool m_keepAlive = false;
+
+  /** The underlying stream for the connection. */
+  uv::Stream& m_stream;
+};
+
+}  // namespace wpi
+
+#endif  // WPIUTIL_WPI_HTTPSERVERCONNECTION_H_