Add support for handling Expect: 100-continue

HTTP/1.1 requests, either with an event (check_continue) or automatically, if no event handler is present.

Add client-side expect/continue support, tests.

Expound upon client requirements for expect/continue.

doc/api.markdown

@@ -1659,6 +1659,22 @@ This is an `EventEmitter` with the following events:
 Emitted each time there is request. Note that there may be multiple requests
 per connection (in the case of keep-alive connections).
 
+### Event: 'checkContinue'
+
+`function (request, response) {}`
+
+Emitted each time a request with an http Expect: 100-continue is received.
+If this event isn't listened for, the server will automatically respond
+with a 100 Continue as appropriate.
+
+Handling this event involves calling `response.writeContinue` if the client
+should continue to send the request body, or generating an appropriate HTTP
+response (e.g., 400 Bad Request) if the client should not continue to send the
+request body.
+
+Note that when this event is emitted and handled, the `request` event will
+not be emitted.
+
 ### Event: 'upgrade'
 
 `function (request, socket, head)`
@@ -1834,6 +1850,11 @@ authentication details.
 This object is created internally by a HTTP server--not by the user. It is
 passed as the second parameter to the `'request'` event. It is a `Writable Stream`.
 
+### response.writeContinue()
+
+Sends a HTTP/1.1 100 Continue message to the client, indicating that
+the request body should be sent. See the the `checkContinue` event on
+`Server`.
 
 ### response.writeHead(statusCode, [reasonPhrase], [headers])
 
@@ -1936,6 +1957,11 @@ There are a few special headers that should be noted.
 
 * Sending a 'Content-length' header will disable the default chunked encoding.
 
+* Sending an 'Expect' header will immediately send the request headers. 
+  Usually, when sending 'Expect: 100-continue', you should both set a timeout
+  and listen for the `continue` event. See RFC2616 Section 8.2.3 for more
+  information.
+
 
 ### Event: 'upgrade'
 
@@ -1947,6 +1973,15 @@ connections closed.
 
 See the description of the `upgrade` event for `http.Server` for further details.
 
+### Event: 'continue'
+
+`function ()`
+
+Emitted when the server sends a '100 Continue' HTTP response, usually because
+the request contained 'Expect: 100-continue'. This is an instruction that
+the client should send the request body.
+
+
 ### http.createClient(port, host='localhost', secure=false, [credentials])
 
 Constructs a new HTTP client. `port` and

lib/http.js

@@ -75,7 +75,7 @@ var parsers = new FreeList('parsers', 1000, function () {
       parser.incoming.method = info.method;
     } else {
       // client only
-      parser.incoming.statusCode = info.statusCode;
+      parser.incoming.statusCode = info.statusCode;  
     }
 
     parser.incoming.upgrade = info.upgrade;
@@ -178,6 +178,8 @@ var transferEncodingExpression = /Transfer-Encoding/i;
 var closeExpression = /close/i;
 var chunkExpression = /chunk/i;
 var contentLengthExpression = /Content-Length/i;
+var expectExpression = /Expect/i;
+var continueExpression = /100-continue/i;
 
 
 /* Abstract base class for ServerRequest and ClientResponse. */
@@ -302,7 +304,6 @@ sys.inherits(OutgoingMessage, events.EventEmitter);
 exports.OutgoingMessage = OutgoingMessage;
 
 // This abstract either writing directly to the socket or buffering it.
-// Rename to _writeRaw() ?
 OutgoingMessage.prototype._send = function (data, encoding) {
   // This is a shameful hack to get the headers and first body chunk onto
   // the same packet. Future versions of Node are going to take care of
@@ -316,7 +317,10 @@ OutgoingMessage.prototype._send = function (data, encoding) {
     }
     this._headerSent = true;
   }
+  this._writeRaw(data, encoding)
+}
 
+OutgoingMessage.prototype._writeRaw = function(data, encoding) {
   if (this.connection._outgoing[0] === this && this.connection.writable) {
     // There might be pending data in the this.output buffer.
     while (this.output.length) {
@@ -371,6 +375,7 @@ OutgoingMessage.prototype._storeHeader = function (firstLine, headers) {
   var sentConnectionHeader = false;
   var sentContentLengthHeader = false;
   var sentTransferEncodingHeader = false;
+  var sentExpect = false;
 
   // firstLine in the case of request is: "GET /index.html HTTP/1.1\r\n"
   // in the case of response it is: "HTTP/1.1 200 OK\r\n"
@@ -396,6 +401,9 @@ OutgoingMessage.prototype._storeHeader = function (firstLine, headers) {
     } else if (contentLengthExpression.test(field)) {
       sentContentLengthHeader = true;
 
+    } else if (expectExpression.test(field)) {
+      sentExpect = true;
+
     }
   }
 
@@ -451,7 +459,11 @@ OutgoingMessage.prototype._storeHeader = function (firstLine, headers) {
 
   this._header = messageHeader + CRLF;
   this._headerSent = false;
-  // wait until the first body chunk, or close(), is sent to flush.
+  // wait until the first body chunk, or close(), is sent to flush,
+  // UNLESS we're sending Expect: 100-continue.
+  if (sentExpect) {
+      this._send("");
+  }
 };
 
 
@@ -592,6 +604,10 @@ function ServerResponse (req) {
 sys.inherits(ServerResponse, OutgoingMessage);
 exports.ServerResponse = ServerResponse;
 
+ServerResponse.prototype.writeContinue = function () {
+     this._writeRaw("HTTP/1.1 100 Continue" + CRLF + CRLF, 'ascii');
+     this._sent100 = true;
+}
 
 ServerResponse.prototype.writeHead = function (statusCode) {
   var reasonPhrase, headers, headerIndex;
@@ -613,16 +629,28 @@ ServerResponse.prototype.writeHead = function (statusCode) {
   var statusLine = "HTTP/1.1 " + statusCode.toString() + " "
                   + reasonPhrase + CRLF;
 
-  if (statusCode === 204 || statusCode === 304) {
+  if (   statusCode === 204 
+      || statusCode === 304
+      || (statusCode >= 100 && statusCode <= 199)
+     ) {
     // RFC 2616, 10.2.5:
     // The 204 response MUST NOT include a message-body, and thus is always
     // terminated by the first empty line after the header fields.
     // RFC 2616, 10.3.5:
     // The 304 response MUST NOT contain a message-body, and thus is always
     // terminated by the first empty line after the header fields.
+    // RFC 2616, 10.1 Informational 1xx:
+    // This class of status code indicates a provisional response,
+    // consisting only of the Status-Line and optional headers, and is
+    // terminated by an empty line.
     this._hasBody = false;
   }
 
+  // don't keep alive connections where the client expects 100 Continue
+  // but we sent a final status; they may put extra bytes on the wire.
+  if (this._expect_continue && ! this._sent100) {
+      this._shouldKeepAlive = false;
+  }
 
   this._storeHeader(statusLine, headers);
 };
@@ -843,7 +871,19 @@ function connectionListener (socket) {
     res.shouldKeepAlive = shouldKeepAlive;
     socket._outgoing.push(res);
 
-    self.emit('request', req, res);
+    if ('expect' in req.headers
+       && (req.httpVersionMajor == 1 && req.httpVersionMinor == 1)
+       && continueExpression.test(req.headers['expect'])) {
+        res._expect_continue = true;
+        if (self.listeners("checkContinue").length) {
+            self.emit("checkContinue", req, res)
+        } else {
+            res.writeContinue();
+            self.emit('request', req, res);
+        }
+    } else {
+        self.emit('request', req, res);
+    }
     return false; // Not a HEAD response. (Not even a response!)
   };
 }
@@ -952,6 +992,12 @@ Client.prototype._initParser = function () {
     // A major oversight in HTTP. Hence this nastiness.
     var isHeadResponse = req.method == "HEAD";
     debug('isHeadResponse ' + isHeadResponse);
+      
+    if (res.statusCode == 100) {
+      // restart the parser, as this is a continue message.
+      req.emit("continue");
+      return true;
+    }
     
     if (req.shouldKeepAlive && res.headers.connection === 'close') {
       req.shouldKeepAlive = false;

test/simple/test-http-expect-continue.js

@@ -0,0 +1,67 @@
+var common = require("../common");
+var assert = common.assert;
+var sys = require("sys");
+var http = require("http");
+
+var outstanding_reqs = 0;
+var test_req_body = "some stuff...\n";
+var test_res_body = "other stuff!\n";
+var sent_continue = false;
+var got_continue = false;
+
+function handler(req, res) {
+  assert.equal(sent_continue, true, "Full response sent before 100 Continue");
+  common.debug("Server sending full response...");
+  res.writeHead(200, {
+      'Content-Type' : 'text/plain',
+      "ABCD" : "1"
+  });
+  res.end(test_res_body);
+}
+
+var server = http.createServer(handler);
+server.addListener("checkContinue", function(req, res) {
+    common.debug("Server got Expect: 100-continue...");
+    res.writeContinue();
+    sent_continue = true;
+    handler(req, res);
+});    
+server.listen(common.PORT);
+
+
+
+server.addListener("listening", function() {
+  var client = http.createClient(common.PORT);
+  req = client.request("POST", "/world", {
+      "Expect": "100-continue",
+  });
+  common.debug("Client sending request...");
+  outstanding_reqs++;
+  body = "";
+  req.addListener('continue', function () {
+      common.debug("Client got 100 Continue...");
+      got_continue = true;
+      req.end(test_req_body);
+  });
+  req.addListener('response', function (res) {
+    assert.equal(got_continue, true, 
+      "Full response received before 100 Continue"
+    );
+    assert.equal(200, res.statusCode, 
+      "Final status code was " + res.statusCode + ", not 200."
+    );
+    res.setEncoding("utf8");
+    res.addListener('data', function (chunk) { body += chunk; });
+    res.addListener('end', function () {
+      common.debug("Got full response.");
+      assert.equal(body, test_res_body, "Response body doesn't match.");
+//      common.debug(sys.inspect(res.headers));
+      assert.ok("abcd" in res.headers, "Response headers missing.");
+      outstanding_reqs--;
+      if (outstanding_reqs == 0) {
+        server.close();
+        process.exit();
+      }        
+    });
+  });
+});