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+#ifndef _GPRS_LLC_H
+#define _GPRS_LLC_H
+
+#include <stdint.h>
+#include <stdbool.h>
+#include <osmocom/sgsn/gprs_sgsn.h>
+#include <osmocom/sgsn/gprs_llc_xid.h>
+
+/* Section 4.7 LLC Layer Structure */
+enum gprs_llc_sapi {
+ GPRS_SAPI_GMM = 1,
+ GPRS_SAPI_TOM2 = 2,
+ GPRS_SAPI_SNDCP3 = 3,
+ GPRS_SAPI_SNDCP5 = 5,
+ GPRS_SAPI_SMS = 7,
+ GPRS_SAPI_TOM8 = 8,
+ GPRS_SAPI_SNDCP9 = 9,
+ GPRS_SAPI_SNDCP11 = 11,
+};
+
+/* Section 6.4 Commands and Responses */
+enum gprs_llc_u_cmd {
+ GPRS_LLC_U_DM_RESP = 0x01,
+ GPRS_LLC_U_DISC_CMD = 0x04,
+ GPRS_LLC_U_UA_RESP = 0x06,
+ GPRS_LLC_U_SABM_CMD = 0x07,
+ GPRS_LLC_U_FRMR_RESP = 0x08,
+ GPRS_LLC_U_XID = 0x0b,
+ GPRS_LLC_U_NULL_CMD = 0x00,
+};
+
+/* Section 6.4.1.6 / Table 6 */
+enum gprs_llc_xid_type {
+ GPRS_LLC_XID_T_VERSION = 0,
+ GPRS_LLC_XID_T_IOV_UI = 1,
+ GPRS_LLC_XID_T_IOV_I = 2,
+ GPRS_LLC_XID_T_T200 = 3,
+ GPRS_LLC_XID_T_N200 = 4,
+ GPRS_LLC_XID_T_N201_U = 5,
+ GPRS_LLC_XID_T_N201_I = 6,
+ GPRS_LLC_XID_T_mD = 7,
+ GPRS_LLC_XID_T_mU = 8,
+ GPRS_LLC_XID_T_kD = 9,
+ GPRS_LLC_XID_T_kU = 10,
+ GPRS_LLC_XID_T_L3_PAR = 11,
+ GPRS_LLC_XID_T_RESET = 12,
+};
+
+extern const struct value_string gprs_llc_xid_type_names[];
+
+/* TS 04.64 Section 7.1.2 Table 7: LLC layer primitives (GMM/SNDCP/SMS/TOM) */
+/* TS 04.65 Section 5.1.2 Table 2: Service primitives used by SNDCP */
+enum gprs_llc_primitive {
+ /* GMM <-> LLME */
+ LLGMM_ASSIGN_REQ, /* GMM tells us new TLLI: TLLI old, TLLI new, Kc, CiphAlg */
+ LLGMM_RESET_REQ, /* GMM tells us to perform XID negotiation: TLLI */
+ LLGMM_RESET_CNF, /* LLC informs GMM that XID has completed: TLLI */
+ LLGMM_SUSPEND_REQ, /* GMM tells us MS has suspended: TLLI, Page */
+ LLGMM_RESUME_REQ, /* GMM tells us MS has resumed: TLLI */
+ LLGMM_PAGE_IND, /* LLC asks GMM to page MS: TLLI */
+ LLGMM_IOV_REQ, /* GMM tells us to perform XID: TLLI */
+ LLGMM_STATUS_IND, /* LLC informs GMM about error: TLLI, Cause */
+ /* LLE <-> (GMM/SNDCP/SMS/TOM) */
+ LL_RESET_IND, /* TLLI */
+ LL_ESTABLISH_REQ, /* TLLI, XID Req */
+ LL_ESTABLISH_IND, /* TLLI, XID Req, N201-I, N201-U */
+ LL_ESTABLISH_RESP, /* TLLI, XID Negotiated */
+ LL_ESTABLISH_CONF, /* TLLI, XID Neg, N201-i, N201-U */
+ LL_RELEASE_REQ, /* TLLI, Local */
+ LL_RELEASE_IND, /* TLLI, Cause */
+ LL_RELEASE_CONF, /* TLLI */
+ LL_XID_REQ, /* TLLI, XID Requested */
+ LL_XID_IND, /* TLLI, XID Req, N201-I, N201-U */
+ LL_XID_RESP, /* TLLI, XID Negotiated */
+ LL_XID_CONF, /* TLLI, XID Neg, N201-I, N201-U */
+ LL_DATA_REQ, /* TLLI, SN-PDU, Ref, QoS, Radio Prio, Ciph */
+ LL_DATA_IND, /* TLLI, SN-PDU */
+ LL_DATA_CONF, /* TLLI, Ref */
+ LL_UNITDATA_REQ, /* TLLI, SN-PDU, Ref, QoS, Radio Prio, Ciph */
+ LL_UNITDATA_IND, /* TLLI, SN-PDU */
+ LL_STATUS_IND, /* TLLI, Cause */
+};
+
+/* Section 4.5.2 Logical Link States + Annex C.2 */
+enum gprs_llc_lle_state {
+ GPRS_LLES_UNASSIGNED = 1, /* No TLLI yet */
+ GPRS_LLES_ASSIGNED_ADM = 2, /* TLLI assigned */
+ GPRS_LLES_LOCAL_EST = 3, /* Local Establishment */
+ GPRS_LLES_REMOTE_EST = 4, /* Remote Establishment */
+ GPRS_LLES_ABM = 5,
+ GPRS_LLES_LOCAL_REL = 6, /* Local Release */
+ GPRS_LLES_TIMER_REC = 7, /* Timer Recovery */
+};
+
+enum gprs_llc_llme_state {
+ GPRS_LLMS_UNASSIGNED = 1, /* No TLLI yet */
+ GPRS_LLMS_ASSIGNED = 2, /* TLLI assigned */
+};
+
+/* Section 8.9.9 LLC layer parameter default values */
+struct gprs_llc_params {
+ uint16_t iov_i_exp;
+ uint16_t t200_201;
+ uint16_t n200;
+ uint16_t n201_u;
+ uint16_t n201_i;
+ uint16_t mD;
+ uint16_t mU;
+ uint16_t kD;
+ uint16_t kU;
+};
+
+/* Section 4.7.1: Logical Link Entity: One per DLCI (TLLI + SAPI) */
+struct gprs_llc_lle {
+ struct llist_head list;
+
+ uint32_t sapi;
+
+ struct gprs_llc_llme *llme;
+
+ enum gprs_llc_lle_state state;
+
+ struct osmo_timer_list t200;
+ struct osmo_timer_list t201; /* wait for acknowledgement */
+
+ uint16_t v_sent;
+ uint16_t v_ack;
+ uint16_t v_recv;
+
+ uint16_t vu_send;
+ uint16_t vu_recv;
+
+ /* non-standard LLC state */
+ uint16_t vu_recv_last;
+ uint16_t vu_recv_duplicates;
+
+ /* Overflow Counter for ABM */
+ uint32_t oc_i_send;
+ uint32_t oc_i_recv;
+
+ /* Overflow Counter for unconfirmed transfer */
+ uint32_t oc_ui_send;
+ uint32_t oc_ui_recv;
+
+ unsigned int retrans_ctr;
+
+ struct gprs_llc_params params;
+};
+
+#define NUM_SAPIS 16
+
+struct gprs_llc_llme {
+ struct llist_head list;
+
+ enum gprs_llc_llme_state state;
+
+ uint32_t tlli;
+ uint32_t old_tlli;
+
+ /* Crypto parameters */
+ enum gprs_ciph_algo algo;
+ uint8_t kc[16];
+ uint8_t cksn;
+ /* 3GPP TS 44.064 ยง 8.9.2: */
+ uint32_t iov_ui;
+
+ /* over which BSSGP BTS ctx do we need to transmit */
+ uint16_t bvci;
+ uint16_t nsei;
+ struct gprs_llc_lle lle[NUM_SAPIS];
+
+ /* Copy of the XID fields we have sent with the last
+ * network originated XID-Request. Since the phone
+ * may strip the optional fields in the confirmation
+ * we need to remeber those fields in order to be
+ * able to create the compression entity. */
+ struct llist_head *xid;
+
+ /* Compression entities */
+ struct {
+ /* In these two list_heads we will store the
+ * data and protocol compression entities,
+ * together with their compression states */
+ struct llist_head *proto;
+ struct llist_head *data;
+ } comp;
+
+ /* Internal management */
+ uint32_t age_timestamp;
+};
+
+#define GPRS_LLME_RESET_AGE (0)
+
+extern struct llist_head gprs_llc_llmes;
+
+/* LLC low level types */
+
+enum gprs_llc_cmd {
+ GPRS_LLC_NULL,
+ GPRS_LLC_RR,
+ GPRS_LLC_ACK,
+ GPRS_LLC_RNR,
+ GPRS_LLC_SACK,
+ GPRS_LLC_DM,
+ GPRS_LLC_DISC,
+ GPRS_LLC_UA,
+ GPRS_LLC_SABM,
+ GPRS_LLC_FRMR,
+ GPRS_LLC_XID,
+ GPRS_LLC_UI,
+};
+
+struct gprs_llc_hdr_parsed {
+ uint8_t sapi;
+ uint8_t is_cmd:1,
+ ack_req:1,
+ is_encrypted:1;
+ uint32_t seq_rx;
+ uint32_t seq_tx;
+ uint32_t fcs;
+ uint32_t fcs_calc;
+ uint8_t *data;
+ uint16_t data_len;
+ uint16_t crc_length;
+ enum gprs_llc_cmd cmd;
+};
+
+
+/* BSSGP-UL-UNITDATA.ind */
+int gprs_llc_rcvmsg(struct msgb *msg, struct tlv_parsed *tv);
+
+/* LL-UNITDATA.req */
+int gprs_llc_tx_ui(struct msgb *msg, uint8_t sapi, int command,
+ struct sgsn_mm_ctx *mmctx, bool encryptable);
+
+/* Chapter 7.2.1.2 LLGMM-RESET.req */
+int gprs_llgmm_reset(struct gprs_llc_llme *llme);
+int gprs_llgmm_reset_oldmsg(struct msgb* oldmsg, uint8_t sapi,
+ struct gprs_llc_llme *llme);
+
+/* Set of LL-XID negotiation (See also: TS 101 351, Section 7.2.2.4) */
+int gprs_ll_xid_req(struct gprs_llc_lle *lle,
+ struct gprs_llc_xid_field *l3_xid_field);
+
+/* 04.64 Chapter 7.2.1.1 LLGMM-ASSIGN */
+int gprs_llgmm_assign(struct gprs_llc_llme *llme,
+ uint32_t old_tlli, uint32_t new_tlli);
+int gprs_llgmm_unassign(struct gprs_llc_llme *llme);
+
+int gprs_llc_init(const char *cipher_plugin_path);
+int gprs_llc_vty_init(void);
+
+/**
+ * \short Check if N(U) should be considered a retransmit
+ *
+ * Implements the range check as of GSM 04.64 8.4.2
+ * Receipt of unacknowledged information.
+ *
+ * @returns Returns 1 if (V(UR)-32) <= N(U) < V(UR)
+ * @param nu N(U) unconfirmed sequence number of the UI frame
+ * @param vur V(UR) unconfirmend received state variable
+ */
+static inline int gprs_llc_is_retransmit(uint16_t nu, uint16_t vur)
+{
+ int delta = (vur - nu) & 0x1ff;
+ return 0 < delta && delta < 32;
+}
+
+/* LLC low level functions */
+void gprs_llme_copy_key(struct sgsn_mm_ctx *mm, struct gprs_llc_llme *llme);
+
+/* parse a GPRS LLC header, also check for invalid frames */
+int gprs_llc_hdr_parse(struct gprs_llc_hdr_parsed *ghp,
+ uint8_t *llc_hdr, int len);
+void gprs_llc_hdr_dump(struct gprs_llc_hdr_parsed *gph, struct gprs_llc_lle *lle);
+int gprs_llc_fcs(uint8_t *data, unsigned int len);
+
+
+/* LLME handling routines */
+struct llist_head *gprs_llme_list(void);
+struct gprs_llc_lle *gprs_lle_get_or_create(const uint32_t tlli, uint8_t sapi);
+
+
+#endif