Bindings to ngx_http_lua_ffi_balancer_set_ssl_ctx

[james-callahan]

Depends on openresty/lua-nginx-module#1282

Here is an FFI snippet to create the most basic SSL_CTX* which is useful for testing (do not use for production traffic! it doesn't set expected security parameters):

local ffi = require "ffi"
ffi.cdef [[
	typedef struct ssl_method_st SSL_METHOD;
	typedef struct ssl_ctx_st SSL_CTX;
	const SSL_METHOD *TLS_client_method(void);
	SSL_CTX *SSL_CTX_new(const SSL_METHOD *meth);
	void SSL_CTX_free(SSL_CTX *);
]]
local openssl = ffi.load "ssl"

local function new_ssl_ctx()
	local ssl_ctx = openssl.SSL_CTX_new(openssl.TLS_client_method())
	if ssl_ctx == ffi.NULL then
		error("no memory")
	end
	return ffi.gc(ssl_ctx, openssl.SSL_CTX_free)
end

I hereby granted the copyright of the changes in this pull request
to the authors of this lua-resty-core project.