gtp: Allow setting callback to receive update_context_ind

This will be used by:
* SGSN: Get to know that RNC has gonne down according to GGSN (re-attempt
  Direct Tunnel or go back to tun SGSN<->GGSN).
* GGSN: Maybe find out that Direct Flags are used (should be handled
  internally directly in the rx path probably)

Related: OS#6512
Change-Id: Ic80a9a928c55b6ff85be96014920bb42793cb943
---
M TODO-RELEASE
M gtp/gsn.c
M gtp/gtp.c
M include/osmocom/gtp/gsn.h
M include/osmocom/gtp/gtp.h
5 files changed, 91 insertions(+), 27 deletions(-)

diff --git a/TODO-RELEASE b/TODO-RELEASE
index 1815fce..905c234 100644
--- a/TODO-RELEASE
+++ b/TODO-RELEASE
@@ -8,3 +8,5 @@
 # If any interfaces have been removed or changed since the last public release: c:r:0.
 #library	what			description / commit summary line
 libgtp    append new field  dir_tun_flags in struct pdp_t (older users not using the field should be fine since struct pdp_t is allocated internally)
+libgtp    ABI break  new field cb_create_context_ind in struct gsn_t
+libgtp    new API    gtp_set_cb_update_context_ind(), gtp_update_context_resp()
\ No newline at end of file
diff --git a/gtp/gsn.c b/gtp/gsn.c
index c23fb2a..612baf2 100644
--- a/gtp/gsn.c
+++ b/gtp/gsn.c
@@ -497,6 +497,7 @@
 
 	/* Initialise call back functions */
 	(*gsn)->cb_create_context_ind = 0;
+	(*gsn)->cb_update_context_ind = 0;
 	(*gsn)->cb_delete_context = 0;
 	(*gsn)->cb_unsup_ind = 0;
 	(*gsn)->cb_conf = 0;
@@ -563,6 +564,13 @@
 	return 0;
 }
 
+int gtp_set_cb_update_context_ind(struct gsn_t *gsn,
+				  int (*cb_update_context_ind)(struct pdp_t *pdp))
+{
+	gsn->cb_update_context_ind = cb_update_context_ind;
+	return 0;
+}
+
 int gtp_retrans(struct gsn_t *gsn)
 {
 	/* dummy API, deprecated. */
diff --git a/gtp/gtp.c b/gtp/gtp.c
index 9b68315..02cf8a3 100644
--- a/gtp/gtp.c
+++ b/gtp/gtp.c
@@ -1696,10 +1696,11 @@
 	return 0;
 }
 
+
 /* Send Update PDP Context Response */
 static int gtp_update_pdp_resp(struct gsn_t *gsn, uint8_t version,
 			struct sockaddr_in *peer, int fd,
-			void *pack, unsigned len,
+			uint16_t seq, uint64_t tid,
 			struct pdp_t *pdp, uint8_t cause)
 {
 
@@ -1760,7 +1761,22 @@
 	}
 
 	return gtp_resp(version, gsn, pdp, &packet, length, peer,
-			fd, get_seq(pack), get_tid(pack));
+			fd, seq, tid);
+}
+
+
+/* API: Application response to context indication */
+int gtp_update_context_resp(struct gsn_t *gsn, struct pdp_t *pdp, int cause)
+{
+
+	/* Now send off a reply to the peer */
+	gtp_update_pdp_resp(gsn, pdp->version, &pdp->sa_peer,
+			pdp->fd, pdp->seq, pdp->tid, pdp, cause);
+
+	if (!gtp_cause_successful(cause))
+		gtp_freepdp(gsn, pdp);
+
+	return 0;
 }
 
 /* Handle Update PDP Context Request */
@@ -1768,13 +1784,15 @@
 		       struct sockaddr_in *peer, int fd,
 		       void *pack, unsigned len)
 {
-	struct pdp_t *pdp;
+	struct pdp_t *pdp = NULL;
 	struct pdp_t pdp_backup;
 	union gtpie_member *ie[GTPIE_SIZE];
 	uint8_t recovery;
+	int rc;
 
 	uint16_t seq = get_seq(pack);
 	int hlen = get_hlen(pack);
+	uint64_t tid = get_tid(pack);
 
 	uint64_t imsi;
 	uint8_t nsapi;
@@ -1792,8 +1810,8 @@
 		if (0 == version)
 			return EOF;
 		else
-			return gtp_update_pdp_resp(gsn, version, peer, fd, pack,
-						   len, NULL,
+			return gtp_update_pdp_resp(gsn, version, peer, fd, seq,
+						   tid, NULL,
 						   GTPCAUSE_INVALID_MESSAGE);
 	}
 
@@ -1808,8 +1826,8 @@
 			GTP_LOGPKG(LOGL_ERROR, peer, pack, len,
 				   "Unknown PDP context: TID=0x%" PRIx64 "\n",
 				   get_tid(pack));
-			return gtp_update_pdp_resp(gsn, version, peer, fd, pack,
-						   len, NULL,
+			return gtp_update_pdp_resp(gsn, version, peer, fd, seq,
+						   tid, NULL,
 						   GTPCAUSE_NON_EXIST);
 		}
 
@@ -1821,8 +1839,8 @@
 			rate_ctr_inc2(gsn->ctrg, GSN_CTR_PKT_MISSING);
 			GTP_LOGPKG(LOGL_ERROR, peer, pack,
 				    len, "Missing mandatory information field\n");
-			return gtp_update_pdp_resp(gsn, version, peer, fd, pack,
-						   len, NULL,
+			return gtp_update_pdp_resp(gsn, version, peer, fd, seq,
+						   tid, NULL,
 						   GTPCAUSE_MAN_IE_MISSING);
 		}
 
@@ -1835,7 +1853,7 @@
 					   "Unknown PDP context: TEI=0x%" PRIx32 "\n",
 					   get_tei(pack));
 				return gtp_update_pdp_resp(gsn, version, peer,
-							   fd, pack, len, NULL,
+							   fd, seq, tid, NULL,
 							   GTPCAUSE_NON_EXIST);
 			}
 		} else {
@@ -1846,7 +1864,7 @@
 					   "Unknown PDP context: IMSI=0x%" PRIx64
 					   " NSAPI=%" PRIu8 "\n", imsi, nsapi);
 				return gtp_update_pdp_resp(gsn, version, peer,
-							   fd, pack, len, NULL,
+							   fd, seq, tid, NULL,
 							   GTPCAUSE_NON_EXIST);
 			}
 		}
@@ -1855,6 +1873,12 @@
 		return EOF;
 	}
 
+	/* Update internal state to be used when user calls gtp_update_context_resp(): */
+	pdp->seq = seq;
+	pdp->sa_peer = *peer;
+	pdp->fd = fd;
+	pdp->version = version;
+
 	/* Make a backup copy in case anything is wrong */
 	memcpy(&pdp_backup, pdp, sizeof(pdp_backup));
 
@@ -1865,8 +1889,8 @@
 			GTP_LOGPKG(LOGL_ERROR, peer, pack,
 				    len, "Missing mandatory information field\n");
 			memcpy(pdp, &pdp_backup, sizeof(pdp_backup));
-			return gtp_update_pdp_resp(gsn, version, peer, fd, pack,
-						   len, pdp,
+			return gtp_update_pdp_resp(gsn, version, peer, fd, seq,
+						   tid, pdp,
 						   GTPCAUSE_MAN_IE_MISSING);
 		}
 	}
@@ -1882,8 +1906,8 @@
 			GTP_LOGPKG(LOGL_ERROR, peer, pack,
 				    len, "Missing mandatory information field\n");
 			memcpy(pdp, &pdp_backup, sizeof(pdp_backup));
-			return gtp_update_pdp_resp(gsn, version, peer, fd, pack,
-						   len, pdp,
+			return gtp_update_pdp_resp(gsn, version, peer, fd, seq,
+						   tid, pdp,
 						   GTPCAUSE_MAN_IE_MISSING);
 		}
 
@@ -1892,8 +1916,8 @@
 			GTP_LOGPKG(LOGL_ERROR, peer, pack,
 				    len, "Missing mandatory information field\n");
 			memcpy(pdp, &pdp_backup, sizeof(pdp_backup));
-			return gtp_update_pdp_resp(gsn, version, peer, fd, pack,
-						   len, pdp,
+			return gtp_update_pdp_resp(gsn, version, peer, fd, seq,
+						   tid, pdp,
 						   GTPCAUSE_MAN_IE_MISSING);
 		}
 	}
@@ -1906,8 +1930,8 @@
 			GTP_LOGPKG(LOGL_ERROR, peer, pack,
 				    len, "Missing mandatory information field\n");
 			memcpy(pdp, &pdp_backup, sizeof(pdp_backup));
-			return gtp_update_pdp_resp(gsn, version, peer, fd, pack,
-						   len, pdp,
+			return gtp_update_pdp_resp(gsn, version, peer, fd, seq,
+						   tid, pdp,
 						   GTPCAUSE_MAN_IE_MISSING);
 		}
 
@@ -1923,8 +1947,8 @@
 			GTP_LOGPKG(LOGL_ERROR, peer, pack,
 				    len, "Missing mandatory information field\n");
 			memcpy(pdp, &pdp_backup, sizeof(pdp_backup));
-			return gtp_update_pdp_resp(gsn, version, peer, fd, pack,
-						   len, pdp,
+			return gtp_update_pdp_resp(gsn, version, peer, fd, seq,
+						   tid, pdp,
 						   GTPCAUSE_MAN_IE_MISSING);
 		}
 	}
@@ -1951,7 +1975,7 @@
 		GTP_LOGPKG(LOGL_ERROR, peer, pack, len,
 			    "Missing mandatory information field\n");
 		memcpy(pdp, &pdp_backup, sizeof(pdp_backup));
-		return gtp_update_pdp_resp(gsn, version, peer, fd, pack, len,
+		return gtp_update_pdp_resp(gsn, version, peer, fd, seq, tid,
 					   pdp, GTPCAUSE_MAN_IE_MISSING);
 	}
 
@@ -1963,7 +1987,7 @@
 		GTP_LOGPKG(LOGL_ERROR, peer, pack, len,
 			    "Missing mandatory information field\n");
 		memcpy(pdp, &pdp_backup, sizeof(pdp_backup));
-		return gtp_update_pdp_resp(gsn, version, peer, fd, pack, len,
+		return gtp_update_pdp_resp(gsn, version, peer, fd, seq, tid,
 					   pdp, GTPCAUSE_MAN_IE_MISSING);
 	}
 
@@ -1976,8 +2000,8 @@
 			GTP_LOGPKG(LOGL_ERROR, peer, pack,
 				    len, "Missing mandatory information field\n");
 			memcpy(pdp, &pdp_backup, sizeof(pdp_backup));
-			return gtp_update_pdp_resp(gsn, version, peer, fd, pack,
-						   len, pdp,
+			return gtp_update_pdp_resp(gsn, version, peer, fd, seq,
+						   tid, pdp,
 						   GTPCAUSE_MAN_IE_MISSING);
 		}
 
@@ -1994,9 +2018,17 @@
 		}
 	}
 
+	/* Callback function to validate login */
+	if (gsn->cb_update_context_ind != 0)
+		rc = gsn->cb_update_context_ind(pdp);
+	else {
+		/* Confirm to peer that things were "successful" */
+		rc = gtp_update_pdp_resp(gsn, version, peer, fd, seq, tid, pdp,
+					 GTPCAUSE_ACC_REQ);
+	}
+
 	/* Confirm to peer that things were "successful" */
-	return gtp_update_pdp_resp(gsn, version, peer, fd, pack, len, pdp,
-				   GTPCAUSE_ACC_REQ);
+	return rc;
 }
 
 /* Handle Update PDP Context Response */
diff --git a/include/osmocom/gtp/gsn.h b/include/osmocom/gtp/gsn.h
index 936db9b..006fdfd 100644
--- a/include/osmocom/gtp/gsn.h
+++ b/include/osmocom/gtp/gsn.h
@@ -99,6 +99,7 @@
 	/* Call back functions */
 	int (*cb_delete_context) (struct pdp_t *);
 	int (*cb_create_context_ind) (struct pdp_t *);
+	int (*cb_update_context_ind)(struct pdp_t *pdp);
 	int (*cb_unsup_ind) (struct sockaddr_in * peer);
 	int (*cb_extheader_ind) (struct sockaddr_in * peer);
 	int (*cb_ran_info_relay_ind) (struct sockaddr_in *peer, union gtpie_member **ie);
@@ -134,6 +135,8 @@
 					 int (*cb_create_context_ind) (struct
 								       pdp_t *
 								       pdp));
+extern int gtp_set_cb_update_context_ind(struct gsn_t *gsn,
+					 int (*cb_update_context_ind)(struct pdp_t *pdp));
 extern int gtp_set_cb_data_ind(struct gsn_t *gsn,
 			       int (*cb_data_ind) (struct pdp_t * pdp,
 						   void *pack, unsigned len));
diff --git a/include/osmocom/gtp/gtp.h b/include/osmocom/gtp/gtp.h
index e3c66c9..001a696 100644
--- a/include/osmocom/gtp/gtp.h
+++ b/include/osmocom/gtp/gtp.h
@@ -248,6 +248,9 @@
 extern int gtp_update_context(struct gsn_t *gsn, struct pdp_t *pdp,
 			      void *cbp, struct in_addr *inetaddr);
 
+extern int gtp_update_context_resp(struct gsn_t *gsn, struct pdp_t *pdp,
+				   int cause);
+
 extern int gtp_delete_context_req(struct gsn_t *gsn, struct pdp_t *pdp,
 				  void *cbp, int teardown)
 		OSMO_DEPRECATED("Use gtp_delete_context_req2() instead, to avoid freeing pdp ctx before reply");

