Authentication error or maybe it isn't? - no user/password was provided

[dalmolin]

I have set up an Nginx as a front end to manage secure connection and
authorization for the Radicale calendar server which I use to synch my
Lightning calendar on my desktop, laptop and Android phone (it uses the
Caldav Synch app). It all works fine after a long and steep learning curve
for me at least. One strange thing I have noticed is that I keep getting an
error in the Nginx error log for the Android device, here are the
abbreviated logs from Nginx's access.log and error.log:

access.log entries:
199.7.156.144 - - [20/Oct/2013:15:38:49 -0400] "OPTIONS
/USERID/testcalhttps/ HTTP/1.1" 401 194 "-" "CalDAV-Sync (Android) (like
iOS/5.0.1 (9A405) dataaccessd/1.0) gzip" "-"

199.1.1.1 - MYUSERID [20/Oct/2013:15:38:50 -0400] "OPTIONS
/USERID/testcalhttps/ HTTP/1.1" 200 5 "-" "CalDAV-Sync (Android) (like
iOS/5.0.1 (9A405) dataaccessd/1.0) gzip" "-"

199.1.1.1 - MYUSERID [20/Oct/2013:15:38:50 -0400] "PROPFIND
/USERID/testcalhttps/ HTTP/1.1" 207 1646 "-" "CalDAV-Sync (Android) (like
iOS/5.0.1 (9A405) dataaccessd/1.0) gzip" "-"

199.1.1.1 - MYUSERID [20/Oct/2013:15:38:51 -0400] "REPORT
/USERID/testcalhttps/ HTTP/1.1" 207 8525 "-" "CalDAV-Sync (Android) (like
iOS/5.0.1 (9A405) dataaccessd/1.0) gzip" "-"

199.1.1.1 - MYUSERID [20/Oct/2013:15:38:53 -0400] "PUT
/USERID/testcalhttps/e024b939-a58c-4b42-8f65-77d75942541c.ics HTTP/1.1" 201
5 "-" "CalDAV-Sync (Android) (like iOS/5.0.1 (9A405) dataaccessd/1.0) gzip"
"-"

error.log entries:
2013/10/20 15:38:49 [error] 6797#0: *241 no user/password was provided for
basic authentication, client: 199.1.1.1, server: , request: "OPTIONS
/USERID/testcalhttps/ HTTP/1.1", host: "mysserver.com:1905"

The userid and password were correctly entered during setup of the calendar
on the client and as I said it all works fine... I can add, delete, modify
calendar entries and synch across all my devices. But I keep getting this
pesky error when using my phone. 

I noticed that in the access.log the first access corresponds to the error
message in the error log.... and then there are four more access messages
with my USERID appended to the IP address. So it looks like the
userid/password are processed after the first request somehow. Also, it may
be helpful to know that the phone is connecting to Nginx via the internet
and portforwarding via my router to the server. Might this error message
simply be the result of the way I am accessing the server... as I don't get
the same error when I access the server via the LAN and my laptop.

Thanks in advance!

Joseph

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,243871,243871#msg-243871