`certificate_info()` does not correctly display the Issuer name for CAs that use domain component attributes.
There is a server on the NIST intra-net that I test against that has a certificate issued by a NIST CA, and the issuer name in the certificate is of the form: `/DC=net/DC=example/DC=internal/CN=CAname`
Since there is no organizational name, testssl.sh displays the name as:
```
Issuer "CAname" ("")
```
In this PR, if the Issuer name has 'DC=' attributes, but does not have an 'O=' attribute, the "DC=" attributes are combined into a DNS name that is used as if it were the organizational name:
```
Issuer "CAname" ("internal.example.net")
```
I should note, however, that I have not been able to find any other examples of TLS server certificates that have been issued by CAs that have domain components ("DC=") in their names. So, it may not be worthwhile to change the code to try to accommodate such CAs.
`certificate_info()` currently outputs `$issuer` to the JSON file, where is should be outputting `$issuer_CN` in order for the information in the JSON file to match the information that is displayed.
This PR also fixes the problem that if an Issuer name contains a domain component attribute (DC=) then it will be mistakenly treated as a country attribute (C=).
Rather than try each curve one at a time, follow model in `cipher_pref_check()`. First include all curves in ClientHello, then successively remove from the ClientHello those curves that have been offered by the server until the connection fails. This makes the number of calls to `$OPENSSL s_client` one more than the number of supported curves rather than the number of curves in NamedCurve supported by $OPENSSL.
Note, however, that OpenSSL defines MAX_CURVELIST as 28 and fails if the `-curves` option includes more than 28 curves. Since OpenSSL 1.1.0 offers 29 curves from NamedCurve, this PR breaks the list of supported curves in 2. At the cost of one additional calls to `$OPENSSL s_client` it ensures that the number of curves provides to the `-curves` option is below the limit.
Found another NPN test (for the case where server doesn't specify cipher order?) that wasn't using SNI.
Also found a comment saying proxies don't support NPN => removed `$PROXY` from all modified lines.
I noticed the NPN parts of this test were not returning any ECDSA ciphers where I expected them to match the results of the immediately preceding TLS 1.2 test. Found it wasn't using SNI so my test server was using the default domain (snakeoil RSA certificate) instead of the tested domain (dual ECDSA/RSA certificates).
On FreeBSD, sed does not support "\n" in the replacement string of a substitution. The SANs are currently output all together inside a single pair of quotes and each separated with an "n" character, needless to say this is very difficult to read.
After a little digging, it seems this is a somewhat recent regression of the fix in #173. I believe `tr` would be a more cross-platform way to do this, and several sources (including the author of that PR) would seem to agree - assuming the newline is now necessary.
It doesn't appear to matter what order the newline replacement happens amongst all the other replacements, so I have placed it first simply to avoid extending any already-long lines. Please correct me if this deduction is false.
