In response to your request in #572, this PR provides a starting point for addressing #120. It adds code to `run_logjam()` to try connecting to the server using any cipher that uses an ephemeral DH key. If successful, it gets the server's ephemeral key (in OpenSSL's PEM format) and then extracts the prime from the key and places it in `$dh_p`. So, all that needs to be done at this point is to compare `$dh_p` against a set of "bad" primes. I'm not sure if I'll be able to work on that part soon, so if someone else has the time, that would be great.
I actually found the `-msg` option easy to use. I moved the code in `parse_tls_serverhello()` that extracts the DH ephemeral public key from the ServerKeyExchange message into a separate function. Then, if using OpenSSL with the `-msg` option, I extract the ServerKeyExchange message from `$TMPFILE` and call this new function to extract the key and convert it to PEM format. That way the new code in `run_logjam()` can use either `$OPENSSL` or `tls_sockets()`.
This PR changes `run_http2()` so that it uses `tls_sockets()` rather than failing, if `$OPENSSL` does not support the `-alpn` option. If `$OPENSSL` supports the `-alpn` option (or if `$SSL_NATIVE` is true), then this PR has no effect.
This PR change `run_std_cipherlists()` to use sockets. As noted in isse #554, I have some questions about the definitions of the cipher lists, but I wrote the code so that the ciphers that are tested when using sockets are the same as those that are tested when using OpenSSL. For a few of the cipherlists, the sockets version tests a few additional ciphers; but these are ciphers that are not supported by OpenSSL, and whose definitions are consistent with the ciphers that OpenSSL includes.
As written, `std_cipherlists` will use sockets for testing by default, except in two cases:
* If the `$SSL_NATIVE` is true, then only OpenSSL is used, and if OpenSSL doesn't support any ciphers in the cipherlist, then the test is skipped.
* If `$FAST` is true (but `$SSL_NATIVE` is false), then OpenSSL is used whenever it supports at least one cipher from the cipherlist, and `tls_sockets()` (or `sslv2_sockets()`) is only used when OpenSSL doesn't support any ciphers from the cipherlist.
In a few places testssl.sh tries to determine $OPENSSL s_client's capabilities by calling `$OPENSSL s_client` without specifying a host to which to connect. For example:
```
$OPENSSL s_client -no_ssl2 2>&1
```
This idea is that `$OPENSSL s_client` should reveal something about its capabilities without actually trying to connect to a host.
This works in most cases. However, the manual pages for s_client states:
```
-connect host:port
This specifies the host and optional port to connect to. If not specified then an attempt is made to connect to the local host on port 4433.
```
So, the above call is actually trying to connect to the local host on port 4433. If the local host is running `$OPENSSL s_server`, then `$OPENSSL s_server` will by default be listening on port 4433, and the connection attempt will most likely succeed. Since the `OPENSSL s_client` command does not include a `< /dev/null`, the `OPENSSL s_client` will just hang waiting for additional input.
Adding `-connect x` to the `$OPENSSL s_client` prevents $OPENSSL from trying to connect to a host, but seems to still provide the necessary information about OpenSSL's capabilities.
This PR adds ",exp" to the bits column when `run_rc4()` is run in the "--wide" mode and the cipher is an export cipher. This makes the wide mode of `run_rc4()` align with other functions, such as `run_allciphers()`.
This PR adds the use of sockets to `run_server_preference()` to determine the "Negotiated cipher per proto." It only uses sockets in two cases:
* For SSLv2, if $OPENSSL does not support SSLv2.
* For SSLv2, if $OPENSSL does not support SSLv3.
This PR will have no effect if the provided OpenSSL binaries are used.
