Add Support for Reject Handler with SmokescreenContext

[saurabhbhatia-stripe]

Description

Enhance Smokescreen to implement reject handler functionality. This handler will be invoked with the Smokescreen context when a connection failure occurs.

Testing Details

HTTP Connect Failure

HTTPS_PROXY=localhost:4750 curl https://localhost.com
curl: (56) CONNECT tunnel failed, response 504

Logs

{"conn_establish_time_ms":75001,"id":"crvobmqf8fl8sruiooeg","inbound_remote_addr":"[::1]:52672","level":"error","msg":"Timed out connecting to remote host: dial tcp 74.125.224.72:443: connect: operation timed out","project":"","proxy_type":"connect","requested_host":"localhost.com:443","role":"","start_time":"2024-10-04T06:06:19.38513Z","time":"2024-10-04T11:37:34+05:30","trace_id":""}
RejectResponseHandlerWithCtx Called

HTTP Connect Success

 HTTPS_PROXY=localhost:4750 curl https://api.github.com/zen 
Practicality beats purity.%       

Logs

{"allow":true,"decision_reason":"Egress ACL is not configured","dns_lookup_time_ms":60,"enforce_would_deny":false,"id":"crvoipaf8fl8sruioohg","inbound_remote_addr":"[::1]:53414","level":"info","msg":"CANONICAL-PROXY-DECISION","project":"","proxy_type":"connect","requested_host":"api.github.com:443","role":"","start_time":"2024-10-04T06:21:25.653434Z","time":"2024-10-04T11:51:25+05:30","trace_id":""}
{"level":"info","msg":"AcceptResponseHandler","stdlog":"1","time":"2024-10-04T11:51:25+05:30"}
{"bytes_in":4684,"bytes_out":594,"conn_establish_time_ms":97,"duration":0.416362375,"end_time":"2024-10-04T06:21:26.227127Z","error":"","id":"crvoipaf8fl8sruioohg","inbound_remote_addr":"[::1]:53414","last_activity":"2024-10-04T06:21:26.226825Z","level":"info","msg":"CANONICAL-PROXY-CN-CLOSE","outbound_local_addr":"10.246.129.166:53415","outbound_remote_addr":"20.207.73.85:443","project":"","proxy_type":"connect","requested_host":"api.github.com:443","role":"","start_time":"2024-10-04T06:21:25.653434Z","time":"2024-10-04T11:51:26+05:30","trace_id":""}

[coveralls]

Pull Request Test Coverage Report for Build 11231455598

Details

• 11 of 13 (84.62%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.1%) to 54.539%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
pkg/smokescreen/smokescreen.go	6	8	75.0%

Totals
Change from base Build 10911749373:	0.1%
Covered Lines:	1436
Relevant Lines:	2633

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💛 - Coveralls

[manishsb-stripe]

Looks good, just one comment.

[manishsb-stripe]

Is this supposed to be RejectResponseHandlerWithCtx? (Same in all places in this test)

[saurabhbhatia-stripe]

Yes, will update this comment.

[gauthamw-stripe]

Should we guard against configuring both this handler and the legacy one? If not, we'd need to document ordering of handler execution et all for consumers.

[saurabhbhatia-stripe]

Yes, it makes sense to only let users configure one of these handler since new one is the superset of legacy one.
I can mark legacy one as depreciated.