Rajendra Kishore Bonumahanti created TS-4888:

             Summary: collapsed_forwarding plugin returns TSREMAP_DID_REMAP 
though it did not perform remap
                 Key: TS-4888
                 URL: https://issues.apache.org/jira/browse/TS-4888
             Project: Traffic Server
          Issue Type: Bug
          Components: Plugins
            Reporter: Rajendra Kishore Bonumahanti

Collapsed_forwarding plugin returns TSREMAP_DID_REMAP as a return value though 
it did not perform any remap. This causes ATS not to perform remap and makes 
the transaction failed due to DNS lookup error on "from url".

For more details..


I am testing collapsed_forwarding plugin 
 via ATS 6.2.x branch.

We observed an error "DNS error 2 for [testurl.com]" for cache-miss, when 
remap.config is configured with "collapsed_forwarding" to work alone as a remap 
plugin. We must modify TSRemapDoRemap() in the plugin to "return 
TSREMAP_NO_REMAP" to allow DNS lookup successful. It does not seem right for 
the plugin to do "return TSREMAP_NO_REMAP" when it did not.

Can someone help me to understand how this plugin needs to be used? Or does it 
require the fix I mentioned above?


== Sample remap.config entry and cach miss error when used 
"collapsed_forwarding" by itself == map http://testurl.com/ http://origin.com/ 
@plugin=collapsed_forwarding.so @pparam=--delay=10 @pparam=--retries=5

I observed that during cache-miss, DNS query happens on the 'from' url 
(hostname) in the remap and it gets failed.
[Sep  9 19:39:16.355] Server {0x2b170ea6c940} DEBUG: (dns) send query (qtype=1) 
for testurl.com to fd 43 [Sep  9 19:39:16.355] Server {0x2b170ea6c940} DEBUG: 
(dns) sent qname = testurl.com, id = 9287, nameserver = 1 [Sep  9 19:39:16.355] 
Server {0x2b170ea6c940} DEBUG: (dns) sent_one: failover_number for resolve 1 is 
1 [Sep  9 19:39:16.628] Server {0x2b170ea6c940} DEBUG: (dns) received packet 
size = 52 [Sep  9 19:39:16.628] Server {0x2b170ea6c940} DEBUG: (dns) 
round-robin: nameserver 1 DNS respons code = 0 [Sep  9 19:39:16.628] Server 
{0x2b170ea6c940} DEBUG: (dns) received rcode = 2 [Sep  9 19:39:16.628] Server 
{0x2b170ea6c940} DEBUG: (dns) DNS error 2 for [testurl.com] [Sep  9 
19:39:16.628] Server {0x2b170ea6c940} DEBUG: (dns) doing retry for testurl.com

I further looked in to the code and found that it is due to return code from 
the plugin is TSREMAP_DID_REMAP in TSRemapDoRemap(). It makes ATS not to 
perform remap.

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