Summary:
Per the documentation[1], any intermediate chain is to be
appended to the "cert" parameter. The "ca" parameter controls the
root CA used to authenticate the client certificate, if one is
provided, and is not used for intermediate certificate chains -- nor
has it ever been. It is not clear how this could have worked in the
past[2].
[1] https://nodejs.org/api/tls.html#tls_tls_createsecurecontext_options
[2] D15709
Test Plan:
Before this diff, with node 4.2.6 from Ubuntu packages:
```
$ openssl s_client -connect phabricator.dropboxer.net:22280 -verify 5 -CApath /etc/ssl/certs/
verify depth is 5
CONNECTED(00000003)
depth=0 C = US, ST = California, L = San Francisco, O = "Dropbox, Inc", OU = Dropbox Ops, CN = phabricator.dropboxer.net
verify error:num=20:unable to get local issuer certificate
verify return:1
depth=0 C = US, ST = California, L = San Francisco, O = "Dropbox, Inc", OU = Dropbox Ops, CN = phabricator.dropboxer.net
verify error:num=27:certificate not trusted
verify return:1
depth=0 C = US, ST = California, L = San Francisco, O = "Dropbox, Inc", OU = Dropbox Ops, CN = phabricator.dropboxer.net
verify error:num=21:unable to verify the first certificate
verify return:1
---
Certificate chain
0 s:/C=US/ST=California/L=San Francisco/O=Dropbox, Inc/OU=Dropbox Ops/CN=phabricator.dropboxer.net
i:/C=US/O=DigiCert Inc/OU=www.digicert.com/CN=DigiCert SHA2 High Assurance Server CA
```
After:
```
$ openssl s_client -connect phabricator.dropboxer.net:22280 -verify 5 -CApath /etc/ssl/certs/
verify depth is 5
CONNECTED(00000003)
depth=2 C = US, O = DigiCert Inc, OU = www.digicert.com, CN = DigiCert High Assurance EV Root CA
verify return:1
depth=1 C = US, O = DigiCert Inc, OU = www.digicert.com, CN = DigiCert SHA2 High Assurance Server CA
verify return:1
depth=0 C = US, ST = California, L = San Francisco, O = "Dropbox, Inc", OU = Dropbox Ops, CN = phabricator.dropboxer.net
verify return:1
---
Certificate chain
0 s:/C=US/ST=California/L=San Francisco/O=Dropbox, Inc/OU=Dropbox Ops/CN=phabricator.dropboxer.net
i:/C=US/O=DigiCert Inc/OU=www.digicert.com/CN=DigiCert SHA2 High Assurance Server CA
1 s:/C=US/ST=California/L=San Francisco/O=Dropbox, Inc/OU=Dropbox Ops/CN=phabricator.dropboxer.net
i:/C=US/O=DigiCert Inc/OU=www.digicert.com/CN=DigiCert SHA2 High Assurance Server CA
2 s:/C=US/O=DigiCert Inc/OU=www.digicert.com/CN=DigiCert SHA2 High Assurance Server CA
i:/C=US/O=DigiCert Inc/OU=www.digicert.com/CN=DigiCert High Assurance EV Root CA
```
Reviewers: #blessed_reviewers, epriestley
Reviewed By: #blessed_reviewers, epriestley
Subscribers: Korvin, epriestley
Differential Revision: https://secure.phabricator.com/D18181
11f1c13915