Caddy: self_signed certs now causing browser errors

[dobbs]

1. What version of Caddy are you using (caddy -version)?

I have confirmed this behavior in two different versions:
first one just freshly downloaded from https://caddyserver.com/download/darwin/amd64?license=
Caddy 0.10.11 (non-commercial use only)

the other installed on Mac OS (High Sierra) with brew install caddy
Caddy 0.10.11 (unofficial)

2. What are you trying to do?

I have been using caddy to run a TLS reverse proxy in front of a web application on my laptop. This has been working fine for months. All of my browsers started refusing the self_signed certs yesterday. I don't think I changed anything yesterday, but based on my troubleshooting, I think I must have upgraded my things to use caddy 0.10.11.

3. What is your entire Caddyfile?

I can reproduce the symptoms without any Caddyfile.

4. How did you run Caddy (give the full command and describe the execution environment)?

caddy 'tls self_signed' browse

5. Please paste any relevant HTTP request(s) here.

Visiting this url with any of my browers shows errors that are not the typical untrusted certificate errors.
https://localhost:2015

In case it's relevant, here are the browser versions I've tested:
Mac OS: 10.13.3 (17D102)
Firefox: 59.0.1 (64-bit)
Google Chrome: Version 65.0.3325.162 (Official Build) (64-bit)
Safari: Version 11.0.3 (13604.5.6)
Curl:

curl 7.54.0 (x86_64-apple-darwin17.0) libcurl/7.54.0 LibreSSL/2.0.20 zlib/1.2.11 nghttp2/1.24.0
Protocols: dict file ftp ftps gopher http https imap imaps ldap ldaps pop3 pop3s rtsp smb smbs smtp smtps telnet tftp
Features: AsynchDNS IPv6 Largefile GSS-API Kerberos SPNEGO NTLM NTLM_WB SSL libz HTTP2 UnixSockets HTTPS-proxy

This curl command also demonstrates a failure

curl -vvv -I https://localhost:2015

6. What did you expect to see?

In the browsers expect to see a listing of the current working directory.
In the curl command I expected to see 200 OK among the response headers.

7. What did you see instead (give full error messages and/or log)?

Firefox's error message:

Secure Connection Failed

An error occurred during a connection to localhost:2015. Peer reports
it experienced an internal error. 
Error code: SSL_ERROR_INTERNAL_ERROR_ALERT

And a screenshot:

Other browser errors are similarly uninformative, but decidedly NOT the usual warning about untrusted, self-signed certificates.

And what curl had to say about it:

* Rebuilt URL to: https://localhost:2015/
*   Trying ::1...
* TCP_NODELAY set
* Connected to localhost (::1) port 2015 (#0)
* ALPN, offering h2
* ALPN, offering http/1.1
* Cipher selection: ALL:!EXPORT:!EXPORT40:!EXPORT56:!aNULL:!LOW:!RC4:@STRENGTH
* successfully set certificate verify locations:
*   CAfile: /etc/ssl/cert.pem
  CApath: none
* TLSv1.2 (OUT), TLS handshake, Client hello (1):
* TLSv1.2 (IN), TLS alert, Server hello (2):
* error:14077438:SSL routines:SSL23_GET_SERVER_HELLO:tlsv1 alert internal error
* stopped the pause stream!
* Closing connection 0
curl: (35) error:14077438:SSL routines:SSL23_GET_SERVER_HELLO:tlsv1 alert internal error

8. How can someone who is starting from scratch reproduce the bug as minimally as possible?

caddy 'tls self_signed' browse
open https://localhost:2015
curl -vvv -I https://localhost:2015

[dobbs]

I have also just confirmed that browsers are accepting self-signed certs from caddy version 0.10.10.

Well, to be precise, they're complaining the same way they usually do about untrusted certificates, but providing the usual UX to accept the risks.

[mholt]

Can you build the latest source from the master branch and try again? It's working fine here.

[dobbs]

I'll give that a try. Also gonna try to repeat these symptoms on a different computer for good measure.

[dobbs]

I got 0.10.11 installed on a different computer faster. I can confirm the self-signed certs work just as expected. It's running older MacOS, and slightly different Safari, identical Firefox and Chrome:

MacOS: 10.11.6
Safari: 11.0.3 (11604.5.6.1.1))

I cannot explain why self-signed certs for 0.10.10 work for all three browsers and curl on my laptop where they fail in all three browsers and curl for 0.10.11.

I will try compiling master in case it reveals anything informative.

[dobbs]

While installing go I did run one more test. The browsers on the other computer report the same error when I attempt to connect to caddy 0.10.11 running on my laptop. And they behave normally when connecting to caddy 0.10.10.

[dobbs]

I've confirmed that compiled from master the self-signed certs work as expected.

I did also git reset --hard v0.10.11 and compiled that to double-check. Sure enough that tag displays the same symptoms reported here.

[francislavoie]

Weird. You could https://git-scm.com/docs/git-bisect to find which commit caused it/fixed it, if you feel like it!

[whitestrake]

Looks like https://github.com/mholt/caddy/issues/2035 again - should be fixed in master as of https://github.com/mholt/caddy/pull/2037.

[dobbs]

I did play with git-bisect and confirm what @whitestrake says.

This commit displays the expected behavior (the browsers whine about untrusted certs, but let me proceed if I accept the risk): https://github.com/mholt/caddy/commit/6e2de19d9fc29f8dec059c5345819a68a13832f2

[dobbs]

In case this is helpful, here's the script I used with git bisect.

#!/bin/bash
set -euo pipefail
IFS=$'\t\n\r'

cd $GOPATH/src/github.com/mholt/caddy/caddy
go run build.go
./caddy --version
./caddy 'tls self_signed' browse 2>&1 >../bisect.log &
sleep 3
curl -IksS https://localhost:2015 \
    | grep -q 200 \
    && echo CERT_OK \
    || echo CERT_NOT_OK
killall caddy
# move binary to revision-specific file for sanity-checking
mv caddy{,-$(git rev-parse --short HEAD)}

[mholt]

Great, thanks! Really appreciate your details and the script you used to bisect.