TypeError: http header key must be a string

[Massimo]

The current version in PyPI (0.8.3) leads to

2019-11-29 10:14:46,122 Trac[main] ERROR: [10.190.226.173] Internal Server Error: <RequestWithSession "POST '/tracfieldtooltip/tooltip.jsonrpc'">, referrer 'https://project-pb/trac-pp/ticket/155'
Traceback (most recent call last):
  File "/mnt/data/trac/.local/lib64/python2.7/site-packages/trac/web/main.py", line 639, in dispatch_request
    dispatcher.dispatch(req)
  File "/mnt/data/trac/.local/lib64/python2.7/site-packages/trac/web/main.py", line 250, in dispatch
    resp = chosen_handler.process_request(req)
  File "build/bdist.linux-x86_64/egg/tracfieldtooltip/tooltip.py", line 176, in process_request
    req.end_headers()
  File "/mnt/data/trac/.local/lib64/python2.7/site-packages/trac/web/api.py", line 732, in end_headers
    exc_info)
TypeError: http header key must be a string

I double checked with the build from last SVN version TracFieldTooltip-0.8.3-py2.7.egg, same issue. Last working version is FieldTooltip-0.7.3-py2.7.egg

[matobaa]

Worksforme. (python 2.7.16 64bit on windows 10)

Could you show your "System Information" at "about trac" and /etc/*-release?

[Jun Omae]

The error message is used in uwsgi at ​https://github.com/unbit/uwsgi/blob/master/plugins/python/wsgi_headers.c#L118.

[Jun Omae]

BTW, according to ​https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/ETag, ETag header should be ETag: W/"<etag_value>" or ETag: "<etag_value>".

I think the value should be enclosed with double quote characters.

source:fieldtooltipplugin/0.12/tracfieldtooltip/tooltip.py@17587:175#L175​

-        req.send_header('ETag', "%s" % id(self.pages))
+        req.send_header('ETag', '"%s"' % id(self.pages))

[matobaa]

In 17601:

FieldTooltipPlugin: Closes #13701

[Jun Omae]

When If-None-Match header is missing, AttributeError occurs.

Traceback (most recent call last):
  File "/dev/shm/venv/lib/python2.7/site-packages/trac/web/main.py", line 647, in _dispatch_request
    dispatcher.dispatch(req)
  File "/dev/shm/venv/lib/python2.7/site-packages/trac/web/main.py", line 248, in dispatch
    resp = chosen_handler.process_request(req)
  File "/dev/shm/venv/lib/python2.7/site-packages/tracfieldtooltip/tooltip.py", line 164, in process_request
    if req.get_header('If-None-Match').strip('"') == str(id(self.pages)):
AttributeError: 'NoneType' object has no attribute 'strip'

Another issue, the ETag value is not stable if web server is multiprocess (e.g. mod_wsgi, uwsgi, ...).

I don't think id() should be used for ETag value because id() returns the address of the object in memory. See also ​https://docs.python.org/2/library/functions.html#id. hashlib.sha1() should be used rather than id().

Also, trivial thing, we could use b'header' rather than str('header').

$ for i in $(seq 1 10); do
>   curl -v -o /dev/null -X POST \
>     -H 'Content-Type: application/json' -H 'If-None-Match: X' \
>     -d '{"method":"wiki.getPage"}' \
>     http://127.0.0.1:3000/tracenv/tracfieldtooltip/tooltip.jsonrpc 2>&1 \
>     | grep '^< ETag:'
> done
< ETag: "140066037392280"
< ETag: "140066037441152"
< ETag: "140066037392280"
< ETag: "140066037441152"
< ETag: "140066037392280"
< ETag: "140066037441152"
< ETag: "140066037392280"
< ETag: "140066037441152"
< ETag: "140066037392280"
< ETag: "140066037441152"

Proposed patch:

fieldtooltipplugin/0.12/tracfieldtooltip/tooltip.py

@@ -12 +12 @@
 from trac.cache import cached
 from trac.core import Component, implements
 from trac.util import arity
+from trac.util.text import to_utf8
 from trac.web.api import IRequestHandler, IRequestFilter
 from trac.web.chrome import ITemplateProvider, add_script, add_stylesheet, web_context
 from trac.wiki.api import IWikiChangeListener, WikiSystem
 from trac.wiki.formatter import format_to_html
 from trac.wiki.model import WikiPage
+import binascii
+import hashlib
 import json
 
 
@@ -156 +159 @@
     def process_request(self, req):
         def to_html(dom):
             return format_to_html(self.env, web_context(req), dom, False)
+        def build_etag(pages):
+            h = hashlib.sha1()
+            for name in sorted(pages):
+                h.update(to_utf8(name))
+                h.update(b'\0')
+                h.update(to_utf8(pages[name]))
+                h.update(b'\0')
+            return '"%s"' % binascii.hexlify(h.digest())
         payload = json.load(req)
         if 'method' not in payload or not payload['method'] == 'wiki.getPage':
             req.send_response(501)  # Method Not Implemented
             req.end_headers()
             return
-        if req.get_header('If-None-Match').strip('"') == str(id(self.pages)):
+        etag = build_etag(self.pages)
+        if req.get_header('If-None-Match') == etag:
             req.send_response(304)  # Not Modified
             req.end_headers()
             return
@@ -170 +182 @@
             'defaults': {page: to_html(self._default_pages[page]) for page in self._default_pages},
         }, indent=4)
         req.send_response(200)
-        req.send_header(str('Content-Type'), 'application/json')
-        req.send_header(str('Content-Length'), len(content))
-        req.send_header(str('ETag'), '"%s"' % id(self.pages))
+        req.send_header(b'Content-Type', 'application/json')
+        req.send_header(b'Content-Length', len(content))
+        req.send_header(b'ETag', etag)
         req.end_headers()
         req.write(content)
 

[Massimo]

Replying to Jun Omae:

When If-None-Match header is missing, AttributeError occurs. ...

If this is still blocking this ticket, please reopen or open a new one.

[matobaa]

In [17606]:

FieldTooltipPlugin: Closes #13701