OpenSSL.jl/src/types.jl

# Returned from C as Ptr
struct SSL_Method ptr end
struct BIO_Method ptr end
struct SSL_Context ptr end

@enum TLSMode begin
    ClientMode
    ServerMode
end

struct CAChain
    cert
    key
end

mutable struct SSLContext <: IO
    data::Vector{UInt8}
    ptr::Ptr{SSL_Context}
    mode::TLSMode
    "Construct the SSLContext object, initializing its relatvie SSL_Context
    pointer.

    Might throw ErrorException if the ccall fails"
    function SSLContext(; mode::TLSMode = ClientMode)
        ssl_context = new()
        ssl_context.mode = mode
        method = mode == ServerMode ? TLS_server_method() : TLS_client_method()
	ssl_context.ptr = SSL_CTX_new(method)
	if ssl_context.ptr == C_NULL
            # TODO: check error stack and report the right exception
            throw(ErrorException("Could not create SSL context"))
	end
        ssl_context.data = UInt8[]
	ssl_context
    end
end

mutable struct SSLClient{T}
    rbio::Ptr{Cvoid}
    wbio::Ptr{Cvoid}
    context::SSLContext
    ssl::Ptr{Cvoid}
    io_on_read
    sock::T
    write_buf::Vector{UInt8}
    encrypt_buf::Vector{UInt8}

    function SSLClient(ctx::SSLContext, io::T) where T
        client = new{T}()
        client.context = ctx
        client.ssl = SSL_new(ctx)
        client.io_on_read = (data) -> append!(client.context.data, data)
        (ctx.mode == ServerMode ? SSL_accept_state : SSL_connect_state)(client)
        set_bio!(client, bio_new(), bio_new())
        client.write_buf = UInt8[]
        client.encrypt_buf = UInt8[]
        client.sock = io
        # finalizer(free, client)
        client
    end
end