fix EventSource (server and parsers)

I was really confused about the Server-Sent Events syntax. This new one
is compatible with actual web browsers and the spec:

 http://www.w3.org/TR/eventsource/

src/wormhole/blocking/eventsource.py

@@ -1,30 +1,18 @@
-from __future__ import print_function
+from __future__ import print_function, unicode_literals
-import six
 import requests
 
 class EventSourceFollower:
     def __init__(self, url, timeout):
-        self.resp = requests.get(url,
+        self._resp = requests.get(url,
                                   headers={"accept": "text/event-stream"},
                                   stream=True,
                                   timeout=timeout)
-        self.resp.raise_for_status()
+        self._resp.raise_for_status()
+        self._lines_iter = self._resp.iter_lines(chunk_size=1,
+                                                 decode_unicode=True)
 
     def close(self):
-        self.resp.close()
+        self._resp.close()
-
-    def _get_fields(self, lines):
-        while True:
-            first_line = next(lines) # raises StopIteration when closed
-            assert isinstance(first_line, type(six.u(""))), type(first_line)
-            fieldname, data = first_line.split(": ", 1)
-            data_lines = [data]
-            while True:
-                next_line = next(lines)
-                if not next_line: # empty string, original was "\n"
-                    yield (fieldname, "\n".join(data_lines))
-                    break
-                data_lines.append(next_line)
 
     def iter_events(self):
         # I think Request.iter_lines and .iter_content use chunk_size= in a
@@ -33,16 +21,29 @@ class EventSourceFollower:
         # for a long time. I'd prefer that chunk_size behaved like
         # read(size), and gave you 1<=x<=size bytes in response.
         eventtype = "message"
-        lines_iter = self.resp.iter_lines(chunk_size=1, decode_unicode=True)
+        current_lines = []
-        for (fieldname, data) in self._get_fields(lines_iter):
+        for line in self._lines_iter:
-            # fieldname/data are unicode on both py2 and py3. On py2, where
+            assert isinstance(line, type(u"")), type(line)
-            # ("abc"==u"abc" is True), this compares unicode against str,
+            if not line:
-            # which matches. On py3, where (b"abc"=="abc" is False), this
+                # blank line ends the field: deliver event, reset for next
-            # compares unicode against unicode, which matches.
+                yield (eventtype, "\n".join(current_lines))
-            if fieldname == "data":
-                yield (eventtype, data)
                 eventtype = "message"
-            elif fieldname == "event":
+                current_lines[:] = []
-                eventtype = data
+                continue
+            if ":" in line:
+                fieldname, data = line.split(":", 1)
+                if data.startswith(" "):
+                    data = data[1:]
             else:
-                print("weird fieldname", fieldname, type(fieldname), data)
+                fieldname = line
+                data = ""
+            if fieldname == "event":
+                eventtype = data
+            elif fieldname == "data":
+                current_lines.append(data)
+            elif fieldname in ("id", "retry"):
+                # documented but unhandled
+                pass
+            else:
+                #log.msg("weird fieldname", fieldname, data)
+                pass

src/wormhole/servers/relay_server.py

@@ -34,13 +34,10 @@ class EventsProtocol:
             # e.g. if name=foo, then the client web page should do:
             # (new EventSource(url)).addEventListener("foo", handlerfunc)
             # Note that this basically defaults to "message".
-            self.request.write(b"\n")
         if id:
             self.request.write(b"id: " + id.encode("utf-8") + b"\n")
-            self.request.write(b"\n")
         if retry:
             self.request.write(b"retry: " + retry + b"\n") # milliseconds
-            self.request.write(b"\n")
         for line in data.splitlines():
             self.request.write(b"data: " + line.encode("utf-8") + b"\n")
         self.request.write(b"\n")

src/wormhole/test/test_blocking.py

@@ -4,6 +4,7 @@ from twisted.trial import unittest
 from twisted.internet.defer import gatherResults, succeed
 from twisted.internet.threads import deferToThread
 from ..blocking.transcribe import Wormhole, UsageError, ChannelManager
+from ..blocking.eventsource import EventSourceFollower
 from .common import ServerBase
 
 APPID = u"appid"
@@ -297,3 +298,34 @@ class Blocking(ServerBase, unittest.TestCase):
         d.addCallback(_done)
         return d
     test_serialize.skip = "not yet implemented for the blocking flavor"
+
+data1 = u"""\
+event: welcome
+data: one and a
+data: two
+data:.
+
+data: three
+
+: this line is ignored
+event: e2
+: this line is ignored too
+i am a dataless field name
+data: four
+
+"""
+
+class NoNetworkESF(EventSourceFollower):
+    def __init__(self, text):
+        self._lines_iter = iter(text.splitlines())
+
+class EventSourceClient(unittest.TestCase):
+    def test_parser(self):
+        events = []
+        f = NoNetworkESF(data1)
+        events = list(f.iter_events())
+        self.failUnlessEqual(events,
+                             [(u"welcome", u"one and a\ntwo\n."),
+                              (u"message", u"three"),
+                              (u"e2", u"four"),
+                              ])

src/wormhole/test/test_twisted.py

@@ -3,6 +3,7 @@ import sys, json
 from twisted.trial import unittest
 from twisted.internet.defer import gatherResults, succeed
 from ..twisted.transcribe import Wormhole, UsageError, ChannelManager
+from ..twisted.eventsource_twisted import EventSourceParser
 from .common import ServerBase
 
 APPID = u"appid"
@@ -284,9 +285,41 @@ class Basic(ServerBase, unittest.TestCase):
         d.addCallback(_done)
         return d
 
+data1 = u"""\
+event: welcome
+data: one and a
+data: two
+data:.
+
+data: three
+
+: this line is ignored
+event: e2
+: this line is ignored too
+i am a dataless field name
+data: four
+
+"""
+
+class FakeTransport:
+    disconnecting = False
+
+class EventSourceClient(unittest.TestCase):
+    def test_parser(self):
+        events = []
+        p = EventSourceParser(lambda t,d: events.append((t,d)))
+        p.transport = FakeTransport()
+        p.dataReceived(data1)
+        self.failUnlessEqual(events,
+                             [(u"welcome", u"one and a\ntwo\n."),
+                              (u"message", u"three"),
+                              (u"e2", u"four"),
+                              ])
+
 if sys.version_info[0] >= 3:
     Channel.skip = "twisted is not yet sufficiently ported to py3"
     Basic.skip = "twisted is not yet sufficiently ported to py3"
+    EventSourceClient.skip = "twisted is not yet sufficiently ported to py3"
     # as of 15.4.0, Twisted is still missing:
     # * web.client.Agent (for all non-EventSource POSTs in transcribe.py)
     # * python.logfile (to allow daemonization of 'wormhole server')

src/wormhole/twisted/eventsource_twisted.py

@@ -14,6 +14,7 @@ from ..util.eventual import eventually
 #    to_unicode = str
 
 class EventSourceParser(basic.LineOnlyReceiver):
+    # http://www.w3.org/TR/eventsource/
     delimiter = "\n"
 
     def __init__(self, handler):
@@ -21,7 +22,7 @@ class EventSourceParser(basic.LineOnlyReceiver):
         self.current_lines = []
         self.handler = handler
         self.done_deferred = defer.Deferred()
-        self.eventtype = "message"
+        self.eventtype = u"message"
         self.encoding = "utf-8"
 
     def set_encoding(self, encoding):
@@ -44,27 +45,28 @@ class EventSourceParser(basic.LineOnlyReceiver):
             raise
 
     def lineReceived(self, line):
+        #line = to_unicode(line, self.encoding)
+        line = line.decode(self.encoding)
         if not line:
-            # blank line ends the field
+            # blank line ends the field: deliver event, reset for next
-            self.fieldReceived(self.current_field,
+            self.eventReceived(self.eventtype, "\n".join(self.current_lines))
-                               "\n".join(self.current_lines))
+            self.eventtype = u"message"
-            self.current_field = None
             self.current_lines[:] = []
             return
-        line = line.decode(self.encoding)
+        if u":" in line:
-        #line = to_unicode(line, self.encoding)
+            fieldname, data = line.split(u":", 1)
-        if self.current_field is None:
+            if data.startswith(u" "):
-            self.current_field, data = line.split(": ", 1)
+                data = data[1:]
-            self.current_lines.append(data)
         else:
-            self.current_lines.append(line)
+            fieldname = line
-
+            data = u""
-    def fieldReceived(self, fieldname, data):
+        if fieldname == u"event":
-        if fieldname == "event":
             self.eventtype = data
-        elif fieldname == "data":
+        elif fieldname == u"data":
-            self.eventReceived(self.eventtype, data)
+            self.current_lines.append(data)
-            self.eventtype = "message"
+        elif fieldname in (u"id", u"retry"):
+            # documented but unhandled
+            pass
         else:
             log.msg("weird fieldname", fieldname, data)