The Postgres protocol uses STARTTLS with a custom start packet. This
functionality is supported by openssl s_client in the current openssl
master branch but not yet in any released version.
This patch detects whether the given openssl binary supports postgres
and runs the usual tests against a postgres server.
Example of no openssl support:
~/bin/testssl$ ./testssl.sh --quiet
--openssl=/opt/openssl/openssl-1.1.0c/bin/openssl --starttls=postgres
test.postgres.server.com:5432
Start 2016-12-07 18:03:24 -->> ip.add.re.ss:5432
(test.postgres.server.com:5432) <<--
Fatal error: Your /opt/openssl/openssl-1.1.0c/bin/openssl does not
support the "-starttls postgres" option
Example of openssl support:
~/bin/testssl$ ./testssl.sh --quiet
--openssl=/opt/openssl/openssl-2016-12-07/bin/openssl --startt ls=postgres
test.postgres.server.com:5432
Start 2016-12-07 18:06:03 -->> ip.add.re.ss:5432
(test.postgres.server.com:5432) <<--
Service set: STARTTLS via POSTGRES
Testing protocols (via openssl, SSLv2 via sockets)
SSLv2 not offered (OK)
SSLv3 offered (NOT ok)
TLS 1 offered
TLS 1.1 offered
TLS 1.2 offered (OK)
SPDY/NPN (SPDY is an HTTP protocol and thus not tested here)
HTTP2/ALPN (HTTP/2 is a HTTP protocol and thus not tested
here)
...
This PR fixes two issues related to curve X25519.
First, while OpenSSL 1.1.0 supports curve X25519, it is not included in the output of `$OPENSSL ecparam -list_curves`. I tried several versions of OpenSSL (and one version of LibreSSL), and every version output either "Error with command" or "unknown option" in response to `$OPENSSL s_client -curves $curve` if it either did not support the `-curves` option or did not support `$curve`. (When the `-curve` option was supported with `$curve`, a "connect" error was output.)
The second issue is that the "Server Temp Key" line in the output of `s_client` is different for curve X25519. For other elliptic curves, the output is
```
Server Temp Key: ECDH, P-256, 256 bits
```
For X25519 it is:
```
Server Temp Key: X25519, 253 bits
```
So, `read_dhbits_from_file()` needs to allow for `$what_dh` being "X25519" rather than "ECDH" and `run_pfs()` needs to allow for the possibility that the curve name will be the first field rather than the second.
