Add unset_libsodium_keys()

Still untested

src/UDPConnection.cpp

@@ -2084,11 +2084,22 @@ void UDPC_set_libsodium_keys(UDPC_HContext ctx, unsigned char *sk, unsigned char
         return;
     }
 
+    std::lock_guard<std::mutex> lock(c->mutex);
     std::memcpy(c->sk, sk, crypto_sign_SECRETKEYBYTES);
     std::memcpy(c->pk, pk, crypto_sign_PUBLICKEYBYTES);
     c->keysSet.store(true);
 }
 
+void UDPC_unset_libsodium_keys(UDPC_HContext ctx) {
+    UDPC::Context *c = UDPC::verifyContext(ctx);
+    if(!c || !c->flags.test(2)) {
+        return;
+    }
+
+    std::lock_guard<std::mutex> lock(c->mutex);
+    c->keysSet.store(false);
+}
+
 const char *UDPC_atostr_cid(UDPC_HContext ctx, UDPC_ConnectionId connectionId) {
     return UDPC_atostr(ctx, connectionId.addr);
 }

src/UDPConnection.h

@@ -186,6 +186,8 @@ UDPC_PacketInfo UDPC_get_received(UDPC_HContext ctx, unsigned long *remaining);
 
 void UDPC_set_libsodium_keys(UDPC_HContext ctx, unsigned char *sk, unsigned char *pk);
 
+void UDPC_unset_libsodium_keys(UDPC_HContext ctx);
+
 const char *UDPC_atostr_cid(UDPC_HContext ctx, UDPC_ConnectionId connectionId);
 
 const char *UDPC_atostr(UDPC_HContext ctx, UDPC_IPV6_ADDR_TYPE addr);