This PR adds the option to generate HTML. The code was created as follows:
* For each output function (`out()`, `outln()`, `pr_liteblue()`, etc.) I created two functions: one that just outputs to the terminal and one that outputs to the terminal and to the HTML file (if an HTML file is to be created).
* I modified the code so that any output that should appear in the HTML file in addition to being displayed on the terminal is sent through one of the display functions: out()`, `outln()`, `pr_liteblue()`, etc.
* I created a new function `retstring()` to use in place of `out()` when a function is creating a string to be "captured" by the calling function.
* I modified the code so that no string returned by a function includes color-coding escape characters.
In the revised code that was created to address #587, nothing is printed after "OCSP URI" if there is neither an OCSP URI nor a CRL URI. Instead, "--" should be printed.
I still believe that there is an inconsistency in the reporting of the output, however. At the moment, the "Certificate Revocation List" and "OCSP URI" lines indicate it is acceptable as long as the certificate contains either a CRL URI or an OCSP URI. However, the "OCSP stapling" line reports a minor finding if an OCSP response was not included in the server's reply. Shouldn't we just assume that if the certificate doesn't include an OCSP URI, then it wouldn't be possible for the server to obtain an OCSP response to staple to its reply? If so, then it seems that no OCSP stapling should only be considered a finding if an OCSP URI is present.
This PR fixes issue #601.
The fix for OCSP URLs was easy. I don't entirely understand the first `awk` command in the line to extract the CRL URLs, but I tested it on several certificates and it seems to work correctly (ensuring that the only "URI" lines in the input to the second `awk` command are from the CRL Distribution Points extension).
RFC 4492 introduced the Supported Elliptic Curves Extension, but this extension was renamed Supported Groups in RFC 7919. Following RFC 7919 (and TLSv1.3), `parse_tls_serverhello()` refers to this extension as "supported groups/#10". Since, at the moment, OpenSSL's s_client refers to this extension as "elliptic curves/#10", the extension sometimes appears twice in the "TLS extensions" line, if it is detected by both OpenSSL (in `get_server_certificate()`) and `tls_sockets()` (in `determine_tls_extensions()`):
```
TLS extensions (standard) "renegotiation info/#65281" "elliptic curves/#10" "EC point formats/#11" "supported groups/#10"
```
This PR fixes the problem of the extension appearing twice in the "TLS extensions" line by replacing any instances of "elliptic curves/#10" with "supported_groups/#10" in the `$tls_extensions` line extracted from `$OPENSSL s_client`. This PR also changes "supported groups/#10" to "supported_groups/#10" in `parse_tls_serverhello()`, since the current development branch of OpenSSL uses "supported_groups" to refer to this extension (see https://github.com/openssl/openssl/pull/1825).
This PR increases the width of the "Encryption" column printed by `neat_list()` in order to allow room to print "CamelliaGCM."
This is the alternative fix to the problem that was first addressed in #524. This PR obsoletes PR #530.
Dirk
David Cooper
Thomas Ward
AlGreed