Added downlink IP tunnel. Downlink user plane packets reach the UE.

lib/include/srslte/upper/gtpu.h

@@ -0,0 +1,95 @@
+/**
+ *
+ * \section COPYRIGHT
+ *
+ * Copyright 2013-2017 Software Radio Systems Limited
+ *
+ * \section LICENSE
+ *
+ * This file is part of the srsLTE library.
+ *
+ * srsUE is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version.
+ *
+ * srsUE is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * A copy of the GNU Affero General Public License can be found in
+ * the LICENSE file in the top-level directory of this distribution
+ * and at http://www.gnu.org/licenses/.
+ *
+ */
+
+#ifndef SRSLTE_GTPU_H
+#define SRSLTE_GTPU_H
+
+#include <stdint.h>
+#include "srslte/common/common.h"
+
+namespace srslte {
+
+/****************************************************************************
+ * GTPU Header
+ * Ref: 3GPP TS 29.281 v10.1.0 Section 5
+ *
+ *        | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 |
+ *
+ * 1      |  Version  |PT | * | E | S |PN |
+ * 2      |           Message Type        |
+ * 3      |         Length (1st Octet)    |
+ * 4      |         Length (2nd Octet)    |
+ * 5      |          TEID (1st Octet)     |
+ * 6      |          TEID (2nd Octet)     |
+ * 7      |          TEID (3rd Octet)     |
+ * 8      |          TEID (4th Octet)     |
+ ***************************************************************************/
+
+#define GTPU_HEADER_LEN 8
+
+typedef struct{
+  uint8_t   flags;          // Only support 0x30 - v1, PT1 (GTP), no other flags
+  uint8_t   message_type;   // Only support 0xFF - T-PDU type
+  uint16_t  length;
+  uint32_t  teid;
+}gtpu_header_t;
+
+
+bool gtpu_read_header(srslte::byte_buffer_t *pdu, gtpu_header_t *header);
+bool gtpu_write_header(gtpu_header_t *header, srslte::byte_buffer_t *pdu);
+
+inline void uint8_to_uint32(uint8_t *buf, uint32_t *i)
+{
+  *i =  (uint32_t)buf[0] << 24 |
+    (uint32_t)buf[1] << 16 |
+    (uint32_t)buf[2] << 8  |
+    (uint32_t)buf[3];
+}
+
+inline void uint32_to_uint8(uint32_t i, uint8_t *buf)
+{
+  buf[0] = (i >> 24) & 0xFF;
+  buf[1] = (i >> 16) & 0xFF;
+  buf[2] = (i >> 8) & 0xFF;
+  buf[3] = i & 0xFF;
+}
+
+inline void uint8_to_uint16(uint8_t *buf, uint16_t *i)
+{
+  *i =  (uint32_t)buf[0] << 8  |
+    (uint32_t)buf[1];
+}
+
+inline void uint16_to_uint8(uint16_t i, uint8_t *buf)
+{
+  buf[0] = (i >> 8) & 0xFF;
+  buf[1] = i & 0xFF;
+}
+
+
+}//namespace
+
+#endif

lib/src/upper/gtpu.cc

@@ -0,0 +1,96 @@
+/**
+ *
+ * \section COPYRIGHT
+ *
+ * Copyright 2013-2017 Software Radio Systems Limited
+ *
+ * \section LICENSE
+ *
+ * This file is part of the srsLTE library.
+ *
+ * srsUE is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version.
+ *
+ * srsUE is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * A copy of the GNU Affero General Public License can be found in
+ * the LICENSE file in the top-level directory of this distribution
+ * and at http://www.gnu.org/licenses/.
+ *
+ */
+
+
+#include "srslte/upper/gtpu.h"
+
+
+namespace srslte {
+
+/****************************************************************************
+ * Header pack/unpack helper functions
+ * Ref: 3GPP TS 29.281 v10.1.0 Section 5
+ ***************************************************************************/
+
+bool gtpu_write_header(gtpu_header_t *header, srslte::byte_buffer_t *pdu)
+{
+  if(header->flags != 0x30) {
+    //gtpu_log->error("gtpu_write_header - Unhandled header flags: 0x%x\n", header->flags);
+    return false;
+  }
+  if(header->message_type != 0xFF) {
+    //gtpu_log->error("gtpu_write_header - Unhandled message type: 0x%x\n", header->message_type);
+    return false;
+  }
+  if(pdu->get_headroom() < GTPU_HEADER_LEN) {
+    //gtpu_log->error("gtpu_write_header - No room in PDU for header\n");
+    return false;
+  }
+
+  pdu->msg      -= GTPU_HEADER_LEN;
+  pdu->N_bytes  += GTPU_HEADER_LEN;
+
+  uint8_t *ptr = pdu->msg;
+
+  *ptr = header->flags;
+  ptr++;
+  *ptr = header->message_type;
+  ptr++;
+  uint16_to_uint8(header->length, ptr);
+  ptr += 2;
+  uint32_to_uint8(header->teid, ptr);
+
+  return true;
+}
+
+bool gtpu_read_header(srslte::byte_buffer_t *pdu, gtpu_header_t *header)
+{
+  uint8_t *ptr  = pdu->msg;
+
+  pdu->msg      += GTPU_HEADER_LEN;
+  pdu->N_bytes  -= GTPU_HEADER_LEN;
+
+  header->flags         = *ptr;
+  ptr++;
+  header->message_type  = *ptr;
+  ptr++;
+  uint8_to_uint16(ptr, &header->length);
+  ptr += 2;
+  uint8_to_uint32(ptr, &header->teid);
+
+  if(header->flags != 0x30) {
+    //gtpu_log->error("gtpu_read_header - Unhandled header flags: 0x%x\n", header->flags);
+    return false;
+  }
+  if(header->message_type != 0xFF) {
+    //gtpu_log->error("gtpu_read_header - Unhandled message type: 0x%x\n", header->message_type);
+    return false;
+  }
+
+  return true;
+}
+
+} // namespace srslte

srsepc/src/mme/s1ap.cc

@@ -698,7 +698,7 @@ s1ap::handle_initial_context_setup_response(LIBLTE_S1AP_MESSAGE_INITIALCONTEXTSE
     m_s1ap_log->error("Could not find UE's context in active UE's map\n");
     return false;
   }
-  for(uint32_t i; i<in_ctxt_resp->E_RABSetupListCtxtSURes.len;i++)
+  for(uint32_t i=0; i<in_ctxt_resp->E_RABSetupListCtxtSURes.len;i++)
   {
     uint8_t erab_id = in_ctxt_resp->E_RABSetupListCtxtSURes.buffer[i].e_RAB_ID.E_RAB_ID;
     erab_ctx_t *erab_ctx = &ue_ctx_it->second->erabs_ctx[erab_id];

srsepc/src/spgw/spgw.cc

@@ -35,7 +35,7 @@
 #include <linux/if_tun.h>
 #include "spgw/spgw.h"
 #include "mme/mme_gtpc.h"
-
+#include "srslte/upper/gtpu.h"
 
 namespace srsepc{
 
@@ -328,11 +328,34 @@ spgw::handle_sgi_pdu(srslte::byte_buffer_t *msg)
     m_spgw_log->console("IP Packet is not for any UE\n");
     return;
   }
-  struct in_addr enb_addr;
-  enb_addr.s_addr = enb_fteid.ipv4;
-  m_spgw_log->console("UE F-TEID found, TEID 0x%x, eNB IP %s\n", enb_fteid.teid, inet_ntoa(enb_addr));
+  struct sockaddr_in enb_addr;
+  enb_addr.sin_family = AF_INET;
+  enb_addr.sin_port = htons(GTPU_RX_PORT);
+  enb_addr.sin_addr.s_addr = enb_fteid.ipv4;
+  m_spgw_log->console("UE F-TEID found, TEID 0x%x, eNB IP %s\n", enb_fteid.teid, inet_ntoa(enb_addr.sin_addr));
+
+  //Setup GTP-U header
+  srslte::gtpu_header_t header;
+  header.flags        = 0x30;
+  header.message_type = 0xFF;
+  header.length       = msg->N_bytes;
+  header.teid         = enb_fteid.teid;
+
+  //Write header into packet
+  if(!srslte::gtpu_write_header(&header, msg))
+  {
+    m_spgw_log->console("Error writing GTP-U header on PDU\n");
+  }
 
 
+  //Send packet to destination
+  int n = sendto(m_s1u,msg->msg,msg->N_bytes,0,(struct sockaddr*) &enb_addr,sizeof(enb_addr));
+  if(n<0)
+  {
+    m_spgw_log->console("Error sending packet to eNB\n");
+    return;
+  }
+  m_spgw_log->console("Sent packet to %s:%d. Bytes=%d\n",inet_ntoa(enb_addr.sin_addr), GTPU_RX_PORT,n);
   return;
 }