This adds a single api on lws that allows querying elements from the
peer certificate on a connection.
The api works the same regardless of the TLS backend.
Like the simple hashes, these work the same regardless of if the backend is
OpenSSL or mbedTLS.
Also move into ./lib/tls/ and split into two specific to mbedtls or openssl
backends.
1) The original wrapper logic for accounting for partial
sends on mbedtls is broken... adapt it
2) mbedtls has an additional restriction you MUST come
back to retry with EXACTLY the unsent part that you
originally asked for, or it loses coherency in the TLS
tunnel.
3) the wrapper is inconsistent between read WANT state
dynamically reported from mbedtls apis and the
SSL_want() api results. Check both on read.
This enables selected things from -Wextra, can't use -Wextra because it is
fussy enough to complain about unused params on functions... they are
there for a reason.
-Wsign-compare
-Wignored-qualifiers
not -Wimplicit-fallthrough=3 ... only on gcc 7
-Wtype-limits
-Wuninitialized
not -Wclobbered ... only on gcc 7ish
fix the warnings everywhere they were found.
- introduce lib/tls/mbedtls lib/tls/openssl
- move wrapper into lib/tls/mbedtls/wrapper
- introduce private helpers to hide backend
This patch doesn't replace or remove the wrapper, it moves it
to lib/tls/mbedtls/wrapper.
But it should be now that the ONLY functions directly consuming
wrapper apis are isolated in
- lib/tls/mbedtls/client.c (180 lines)
- lib/tls/mbedtls/server.c (317 lines)
- lib/tls/mbedtls/ssl.c (325 lines)
In particular there are no uses of openssl or mbedtls-related
constants outside of ./lib/tls any more.
