ttcn3: streamline DRB and SRB Tx interface

use the same tx interface with const uint8_t* and length byte instead of std::string

srsue/test/ttcn3/hdr/ttcn3_srb_interface.h

@@ -49,12 +49,11 @@ public:
     return port_listen();
   }
 
-  void tx(std::string out)
+  void tx(const uint8_t* buffer, uint32_t len)
   {
     if (initialized) {
-      log->info_hex(
-          reinterpret_cast<const uint8_t*>(out.c_str()), out.length(), "Sending %ld B to Titan\n", out.length());
-      send(reinterpret_cast<const uint8_t*>(out.c_str()), out.length());
+      log->info_hex(buffer, len, "Sending %d B to Titan\n", len);
+      send(buffer, len);
     } else {
       log->error("Trying to transmit but port not connected.\n");
     }

srsue/test/ttcn3/src/ttcn3_syssim.cc

@@ -1026,11 +1026,9 @@ void ttcn3_syssim::write_pdu(uint32_t lcid, unique_byte_buffer_t pdu)
   // push content to Titan
   if (lcid <= 2) {
     std::string out = ttcn3_helpers::get_rrc_pdu_ind_for_pdu(tti, lcid, cells[pcell_idx]->name, std::move(pdu));
-
-    srb.tx(out);
+    srb.tx(reinterpret_cast<const uint8_t*>(out.c_str()), out.length());
   } else {
     std::string out = ttcn3_helpers::get_drb_common_ind_for_pdu(tti, lcid, cells[pcell_idx]->name, std::move(pdu));
-    log->error("DRB send:\n%s", out.c_str());
     drb.tx(reinterpret_cast<const uint8_t*>(out.c_str()), out.length());
   }
 }