TlsTurnEndpoint: add method to know the peer certificate

This certificate is know after a successful connect().

Change-Id: Ie8a351a1c6b97ec65c7d92b8ef4432d412f357eb
Reviewed-by: Nicolas Jäger <nicolas.jager@savoirfairelinux.com>

src/peer_connection.cpp

@@ -210,6 +210,12 @@ TlsTurnEndpoint::write(const ValueType* buf, std::size_t len, std::error_code& e
     return pimpl_->tls->write(buf, len, ec);
 }
 
+dht::crypto::Certificate&
+TlsTurnEndpoint::peerCertificate() const
+{
+    return pimpl_->peerCertificate;
+}
+
 //==============================================================================
 
 TcpSocketEndpoint::TcpSocketEndpoint(const IpAddr& addr)

src/peer_connection.h

@@ -95,6 +95,8 @@ public:
 
     void connect();
 
+    dht::crypto::Certificate& peerCertificate() const;
+
 private:
     class Impl;
     std::unique_ptr<Impl> pimpl_;