bypass PDCP for SRB0 processing chain

lib/include/srslte/interfaces/ue_interfaces.h

@@ -220,6 +220,7 @@ class rrc_interface_rlc
 public:
   virtual void max_retx_attempted() = 0;
   virtual std::string get_rb_name(uint32_t lcid) = 0;
+  virtual void        write_pdu(uint32_t lcid, srslte::unique_byte_buffer_t pdu) = 0;
 };
 
 
@@ -284,6 +285,7 @@ public:
   virtual void change_lcid(uint32_t old_lcid, uint32_t new_lcid) = 0;
   virtual bool has_bearer(uint32_t lcid) = 0;
   virtual bool has_data(const uint32_t lcid)                               = 0;
+  virtual void write_sdu(uint32_t lcid, srslte::unique_byte_buffer_t sdu, bool blocking = true) = 0;
 };
 
 // RLC interface for PDCP

lib/src/upper/rlc_tm.cc

@@ -183,7 +183,11 @@ void rlc_tm::write_pdu(uint8_t *payload, uint32_t nof_bytes)
     buf->N_bytes = nof_bytes;
     buf->set_timestamp();
     num_rx_bytes += nof_bytes;
+    if (rrc->get_rb_name(lcid) == "SRB0") {
+      rrc->write_pdu(lcid, std::move(buf));
+    } else {
       pdcp->write_pdu(lcid, std::move(buf));
+    }
   } else {
     log->error("Fatal Error: Couldn't allocate buffer in rlc_tm::write_pdu().\n");
   }

srsue/src/stack/rrc/rrc.cc

@@ -2153,7 +2153,7 @@ void rrc::send_ul_ccch_msg(const asn1::rrc::ul_ccch_msg_s& msg)
   uint32_t lcid = RB_ID_SRB0;
   log_rrc_message(get_rb_name(lcid).c_str(), Tx, pdcp_buf.get(), msg);
 
-  pdcp->write_sdu(lcid, std::move(pdcp_buf));
+  rlc->write_sdu(lcid, std::move(pdcp_buf));
 }
 
 void rrc::send_ul_dcch_msg(uint32_t lcid, const asn1::rrc::ul_dcch_msg_s& msg)