Move GTPV1U cmake code to subdirectory

Move the module cmake code to its subdirectory for better organization,
and  remove superfluous include_directories() that are not recommended
to be used (as it populates all other targets with those directories,
most of which don't need it anyway).

Slightly clean up the module by removing headers to unused dependencies.
The GTP module has a dependency to 4G and 5G RLC, which should not exist
(the RLC modules have a dependency on GTP, not the other way around),
but in this commit, make as little modifications as possible.

CMakeLists.txt

@@ -595,7 +595,6 @@ include_directories("${OPENAIR3_DIR}/S1AP")
 include_directories("${OPENAIR2_DIR}/X2AP")
 include_directories("${OPENAIR2_DIR}/M2AP")
 include_directories("${OPENAIR2_DIR}/F1AP")
-include_directories("${OPENAIR3_DIR}/ocp-gtpu")
 include_directories("${OPENAIR3_DIR}/M3AP")
 include_directories("${OPENAIR3_DIR}/MME_APP")
 include_directories("${OPENAIR_DIR}/radio/COMMON")
@@ -1381,14 +1380,6 @@ include_directories("${OPENAIR1_DIR}/SCHED_NR_UE")
 # CN libs
 ##########################
 
-add_library (GTPV1U
-  ${OPENAIR3_DIR}/ocp-gtpu/gtp_itf.cpp
-  ${OPENAIR3_DIR}/ocp-gtpu/gtpu_extensions.c
-  )
-target_link_libraries(GTPV1U PRIVATE asn1_nr_rrc_hdrs asn1_lte_rrc_hdrs)
-target_link_libraries(GTPV1U PRIVATE SIMU ds)
-include_directories(${OPENAIR3_DIR}/ocp-gtp)
-
 set (MME_APP_SRC
   ${OPENAIR3_DIR}/MME_APP/mme_app.c
   ${OPENAIR3_DIR}/MME_APP/mme_config.c

openair2/E1AP/CMakeLists.txt

@@ -4,7 +4,7 @@ add_subdirectory(lib)
 add_library(e1ap e1ap.c e1ap_common.c)
 target_link_libraries(e1ap
                       PUBLIC asn1_e1ap e1ap_lib
-                      PRIVATE asn1_nr_rrc_hdrs asn1_lte_rrc_hdrs asn1_f1ap UTIL e1_if)
+                      PRIVATE asn1_nr_rrc_hdrs asn1_lte_rrc_hdrs asn1_f1ap UTIL e1_if GTPV1U)
 target_include_directories(e1ap PUBLIC ${CMAKE_CURRENT_DIR})
 
 if(ENABLE_TESTS)

openair3/CMakeLists.txt

@@ -1,4 +1,5 @@
 add_subdirectory(LPP)
+add_subdirectory(ocp-gtpu)
 add_subdirectory(M3AP)
 add_subdirectory(S1AP)
 add_subdirectory(NAS)

openair3/ocp-gtpu/CMakeLists.txt

@@ -0,0 +1,4 @@
+add_library (GTPV1U gtp_itf.cpp gtpu_extensions.c)
+target_link_libraries(GTPV1U PRIVATE asn1_lte_rrc_hdrs asn1_nr_rrc_hdrs) # for ITTI
+target_link_libraries(GTPV1U PRIVATE SIMU ds)
+target_include_directories(GTPV1U PUBLIC ${CMAKE_CURRENT_SOURCE_DIR})

openair3/ocp-gtpu/gtp_itf.cpp

@@ -15,15 +15,15 @@ extern "C" {
 #include <openair3/UTILS/conversions.h>
 #include "common/utils/LOG/log.h"
 #include <common/utils/ocp_itti/intertask_interface.h>
-#include <openair2/COMMON/gtpv1_u_messages_types.h>
-#include <openair3/ocp-gtpu/gtp_itf.h>
-#include <openair2/LAYER2/PDCP_v10.1.0/pdcp.h>
-#include <openair2/LAYER2/nr_pdcp/nr_pdcp_oai_api.h>
-#include <openair2/LAYER2/nr_rlc/nr_rlc_oai_api.h>
-#include "openair2/SDAP/nr_sdap/nr_sdap.h"
-#include "openair3/ocp-gtpu/gtpu_extensions.h"
 #include "sim.h"
 
+// TODO these dependencies should not exist and be removed
+#include "openair2/LAYER2/nr_rlc/nr_rlc_oai_api.h"
+#include "openair2/LAYER2/RLC/rlc.h"
+
+#include "gtp_itf.h"
+#include "gtpu_extensions.h"
+
 #pragma pack(1)
 
 typedef struct Gtpv1uMsgHeader {