diff options
Diffstat (limited to 'src/frame_relay.c')
| -rw-r--r-- | src/frame_relay.c | 511 |
1 files changed, 511 insertions, 0 deletions
diff --git a/src/frame_relay.c b/src/frame_relay.c new file mode 100644 index 0000000..3990a1a --- /dev/null +++ b/src/frame_relay.c @@ -0,0 +1,511 @@ +#include <stdint.h> +#include <stdbool.h> +#include <unistd.h> + +#include <osmocom/core/utils.h> +#include <osmocom/core/logging.h> +#include <osmocom/core/linuxlist.h> +#include <osmocom/core/tdef.h> +#include <osmocom/core/timer.h> +#include <osmocom/core/msgb.h> + +#include <osmocom/gsm/tlv.h> + +#include "frame_relay.h" + +#define DFR DLGLOBAL + +/* Table 4-2/Q.931 */ +enum q931_msgtype { + /* Call establishment message */ + Q931_MSGT_ALERTING = 0x01, + Q931_MSGT_CALL_PROCEEDING = 0x02, + Q931_MSGT_CONNECT = 0x07, + Q931_MSGT_CONNECT_ACK = 0x0f, + Q931_MSGT_PROGRESS = 0x03, + Q931_MSGT_SETUP = 0x05, + Q931_MSGT_SETUP_ACK = 0x0d, + /* Call information phase message */ + Q931_MSGT_RESUME = 0x26, + Q931_MSGT_RESUME_ACK = 0x2e, + Q931_MSGT_RESUME_REJ = 0x22, + Q931_MSGT_SUSPEND = 0x25, + Q931_MSGT_SUSPEND_ACK = 0x2d, + Q931_MSGT_USER_INFO = 0x20, + /* Call clearing message */ + Q931_MSGT_DISCONNECT = 0x45, + Q931_MSGT_RELEASE = 0x4d, + Q931_MSGT_RELEASE_COMPLETE = 0x5a, + Q931_MSGT_RESTART = 0x46, + Q931_MSGT_RESTART_ACK = 0x4e, + /* Miscellaneous messages */ + Q931_MSGT_SEGMENT = 0x60, + Q931_MSGT_CONGESTION_CONTROL = 0x79, + Q931_MSGT_IFORMATION = 0x7b, + Q931_MSGT_NOTIFY = 0x6e, + Q931_MSGT_STATUS = 0x7d, + Q931_MSGT_STATUS_ENQUIRY = 0x75, +}; + + +/* Figure A.1/Q.933 Report type information element */ +enum q933_type_of_report { + Q933_REPT_FULL_STATUS = 0x00, + Q933_REPT_LINK_INTEGRITY_VERIF = 0x01, + Q933_REPT_SINGLE_PVC_ASYNC_STS = 0x02, +}; + +/* Q.933 Section A.3 */ +enum q933_iei { + Q933_IEI_REPORT_TYPE = 0x51, + Q933_IEI_LINK_INT_VERIF = 0x53, + Q933_IEI_PVC_STATUS = 0x57, +}; + +#define LAPF_UI 0x03 /* UI control word */ +#define Q931_PDISC_CC 0x08 /* protocol discriminator */ +#define LMI_Q933A_CALLREF 0x00 /* NULL call-ref */ + +/* LMI DLCI values */ +#define LMI_Q933A_DLCI 0 /* Q.933A DLCI */ +#define LMI_CISCO_DLCI 1023 /* Cisco DLCI */ + + +/* Message header of the L3 payload of a Q.933 Annex A message */ +struct q933_a_hdr { + uint8_t prot_disc; + uint8_t call_ref; + uint8_t msg_type; +} __attribute__((packed)); + +/* Value part of the Q.933 Annex A.3.3 IE */ +struct q933_a_pvc_sts { + uint8_t ext0:1, + spare:1, + dlci_msb:6; + uint8_t ext1:1, + dlci_lsb:4, + spare1:3; + uint8_t ext2:1, + spare2:3, + new:1, + delete:1, + active:1, + reserved:1; +} __attribute__((packed)); + +// RX Message: 14 [ 00 01 03 08 00 75 95 01 01 00 03 02 01 00 ] +// RX Message: 13 [ 00 01 03 08 00 75 51 01 00 53 02 01 00 ] + +/* Table A.4/Q.933 */ +struct osmo_tdef fr_tdefs[] = { + { + .T=391, + .default_val = 10, + .min_val = 5, + .max_val = 30, + .desc = "Link integrity verification polling timer" + }, { + .T=392, + .default_val = 15, + .min_val = 5, + .max_val = 30, + .desc = "Polling verification timer" + }, + {} +}; + +static const struct tlv_definition q933_att_tlvdef = { + .def = { + [Q933_IEI_REPORT_TYPE] = { TLV_TYPE_TLV }, + [Q933_IEI_LINK_INT_VERIF] = { TLV_TYPE_TLV }, + [Q933_IEI_PVC_STATUS] = { TLV_TYPE_TLV }, + }, +}; + +static inline uint16_t q922_to_dlci(const uint8_t *hdr) +{ + return ((hdr[0] & 0xFC) << 2) | ((hdr[1] & 0xF0) >> 4); +} + + +static inline void dlci_to_q922(uint8_t *hdr, uint16_t dlci) +{ + hdr[0] = (dlci >> 2) & 0xFC; + hdr[1] = ((dlci << 4) & 0xF0) | 0x01; +} + +/* allocate a message buffer and put Q.933 Annex A headers (L2 + L3) */ +static struct msgb *q933_msgb_alloc(uint16_t dlci, uint8_t prot_disc, uint8_t msg_type) +{ + struct msgb *msg = msgb_alloc_headroom(1600+64, 64, "FR Q.933 Tx"); + struct q933_a_hdr *qh; + + if (!msg) + return NULL; + + msg->l1h = msgb_put(msg, 2); + dlci_to_q922(msg->l1h, dlci); + + /* LAPF UI control */ + msg->l2h = msgb_put(msg, 1); + *msg->l2h = LAPF_UI; + + msg->l3h = msgb_put(msg, sizeof(*qh)); + qh = (struct q933_a_hdr *) msg->l3h; + qh->prot_disc = prot_disc; + qh->call_ref = LMI_Q933A_CALLREF; + qh->msg_type = msg_type; + + return msg; +} + +/* obtain the [next] transmit sequence number */ +static uint8_t fr_link_get_tx_seq(struct fr_link *link) +{ + /* The {user equipment, network} increments the send sequence + * counter using modulo 256. The value zero is skipped. */ + link->last_tx_seq++; + if (link->last_tx_seq == 0) + link->last_tx_seq++; + + return link->last_tx_seq; +} + +/* Append PVC Status IE according to Q.933 A.3.2 */ +static void msgb_put_link_int_verif(struct msgb *msg, struct fr_link *link) +{ + uint8_t link_int_tx[2]; + link_int_tx[0] = fr_link_get_tx_seq(link); + link_int_tx[1] = link->last_rx_seq; + msgb_tlv_put(msg, Q933_IEI_LINK_INT_VERIF, 2, link_int_tx); +} + +static void dlc_destroy(struct fr_dlc *dlc) +{ + llist_del(&dlc->list); + talloc_free(dlc); +} + +/* Append PVC Status IE according to Q.933 A.3.3 */ +static void msgb_put_pvc_status(struct msgb *msg, struct fr_dlc *dlc) +{ + uint8_t ie[3]; + + ie[0] = (dlc->dlci >> 4) & 0x3f; + ie[1] = 0x80 | ((dlc->dlci & 0xf) << 3); + ie[2] = 0x80; + + if (dlc->active) + ie[2] |= 0x02; + + if (dlc->new) { + ie[2] |= 0x08; + /* we've reported it as new once, reset the status */ + dlc->new = false; + } + + if (dlc->del) { + ie[2] |= 0x04; + /* we've reported it as deleted once, destroy it */ + dlc_destroy(dlc); + } + + msgb_tlv_put(msg, Q933_IEI_PVC_STATUS, 3, ie); +} + +/* Send a Q.933 STATUS ENQUIRY given type over given link */ +static int tx_lmi_q933_status_enq(struct fr_link *link, uint8_t rep_type) +{ + struct msgb *resp; + + resp = q933_msgb_alloc(0, Q931_PDISC_CC, Q931_MSGT_STATUS_ENQUIRY); + if (!resp) + return -1; + resp->dst = link; + + /* Table A.2/Q.933 */ + msgb_tlv_put(resp, Q933_IEI_REPORT_TYPE, 1, &rep_type); + msgb_put_link_int_verif(resp, link); + + return fr_tx(resp); +} + +/* Send a Q.933 STATUS of given type over given link */ +static int tx_lmi_q933_status(struct fr_link *link, uint8_t rep_type) +{ + struct fr_dlc *dlc, *dlc2; + struct msgb *resp; + + resp = q933_msgb_alloc(0, Q931_PDISC_CC, Q931_MSGT_STATUS); + if (!resp) + return -1; + resp->dst = link; + + /* Table A.1/Q.933 */ + msgb_tlv_put(resp, Q933_IEI_REPORT_TYPE, 1, &rep_type); + switch (rep_type) { + case Q933_REPT_FULL_STATUS: + msgb_put_link_int_verif(resp, link); + llist_for_each_entry_safe(dlc, dlc2, &link->dlc_list, list) + msgb_put_pvc_status(resp, dlc); + break; + case Q933_REPT_LINK_INTEGRITY_VERIF: + msgb_put_link_int_verif(resp, link); + break; + case Q933_REPT_SINGLE_PVC_ASYNC_STS: + llist_for_each_entry_safe(dlc, dlc2, &link->dlc_list, list) + msgb_put_pvc_status(resp, dlc); + break; + } + + return fr_tx(resp); +} + + +/* Q.933 */ +static int rx_lmi_q933_status_enq(struct msgb *msg, struct tlv_parsed *tp) +{ + struct fr_link *link = msg->dst; + const uint8_t *link_int_rx; + uint8_t rep_type; + + /* check for mandatory IEs */ + if (!TLVP_PRES_LEN(tp, Q933_IEI_REPORT_TYPE, 1) || + !TLVP_PRES_LEN(tp, Q933_IEI_LINK_INT_VERIF, 2)) + return -1; + + rep_type = *TLVP_VAL(tp, Q933_IEI_REPORT_TYPE); + + link_int_rx = TLVP_VAL(tp, Q933_IEI_LINK_INT_VERIF); + link->last_rx_seq = link_int_rx[0]; + + /* the network checks the receive sequence number received from + * the user equipment against its send sequence counter */ + if (link_int_rx[1] != link->last_tx_seq) + link->err_count++; + + /* The network responds to each STATUS ENQUIRY message with a + * STATUS message and resets the T392 timer */ + osmo_timer_schedule(&link->t392, osmo_tdef_get(link->net->T_defs, 392, OSMO_TDEF_S, 15), 0); + + return tx_lmi_q933_status(link, rep_type); +} + +static int rx_lmi_q933_status(struct msgb *msg, struct tlv_parsed *tp) +{ + struct fr_link *link = msg->dst; + const uint8_t *link_int_rx; + uint8_t rep_type; + + /* check for mandatory IEs */ + if (!TLVP_PRES_LEN(tp, Q933_IEI_REPORT_TYPE, 1)) + return -1; + rep_type = *TLVP_VAL(tp, Q933_IEI_REPORT_TYPE); + + switch (rep_type) { + case Q933_REPT_FULL_STATUS: + case Q933_REPT_LINK_INTEGRITY_VERIF: + if (!TLVP_PRES_LEN(tp, Q933_IEI_LINK_INT_VERIF, 2)) + return -1; + link_int_rx = TLVP_VAL(tp, Q933_IEI_LINK_INT_VERIF); + link->last_rx_seq = link_int_rx[0]; + /* The received receive sequence number is not valid if + * it is not equal to the last transmitted send sequence + * number. Ignore messages containing this error. As a + * result, timer T391 expires and the user then + * increments the error count. */ + if (link_int_rx[1] != link->last_tx_seq) + return 0; + break; + case Q933_REPT_SINGLE_PVC_ASYNC_STS: + break; + default: + return -1; + } + + /* FIXME: process any PVC Status IEs */ + + /* The network responds to each STATUS ENQUIRY message with a + * STATUS message and resets the T392 timer */ + osmo_timer_schedule(&link->t392, osmo_tdef_get(link->net->T_defs, 392, OSMO_TDEF_S, 15), 0); + + return tx_lmi_q933_status(link, rep_type); +} + + +static int fr_rx_lmi_q922(struct msgb *msg) +{ + struct q933_a_hdr *qh; + struct tlv_parsed tp; + uint8_t *lapf; + int rc; + + if (msgb_l2len(msg) < 1) + return -1; + lapf = msgb_l2(msg); + + /* we only support LAPF UI frames */ + if (lapf[0] != LAPF_UI) + return -1; + + msg->l3h = msg->l2h + 1; + if (msgb_l3len(msg) < 3) + return -1; + + qh = (struct q933_a_hdr *) msgb_l3(msg); + if (qh->prot_disc != Q931_PDISC_CC) { + LOGP(DFR, LOGL_NOTICE, "Rx unsupported LMI protocol discriminator %u\n", qh->prot_disc); + return -1; + } + + tlv_parse(&tp, &q933_att_tlvdef, msgb_l3(msg) + sizeof(*qh), msgb_l3len(msg) - sizeof(*qh), 0, 0); + + switch (qh->msg_type) { + case Q931_MSGT_STATUS_ENQUIRY: + rc = rx_lmi_q933_status_enq(msg, &tp); + break; + case Q931_MSGT_STATUS: + rc = rx_lmi_q933_status(msg, &tp); + break; + default: + LOGP(DFR, LOGL_NOTICE, "Rx unsupported LMI message type %u\n", qh->msg_type); + rc = -1; + break; + } + msgb_free(msg); + + return rc; +} + +int fr_rx(struct fr_link *link, struct msgb *msg) +{ + uint8_t *frh; + uint16_t dlci; + struct fr_dlc *dlc; + + msg->dst = link; + + if (msgb_length(msg) < 2) { + LOGP(DFR, LOGL_ERROR, "Short FR header: %u bytes\n", msgb_length(msg)); + msgb_free(msg); + return -1; + } + + frh = msg->l1h = msgb_data(msg); + if (frh[0] & 0x01) { + LOGP(DFR, LOGL_NOTICE, "Unsupported single-byte FR address\n"); + msgb_free(msg); + return 1; + } + if ((frh[1] & 0x0f) != 0x01) { + LOGP(DFR, LOGL_NOTICE, "Unknown second FR octet 0x%02x\n", frh[1]); + msgb_free(msg); + return -1; + } + dlci = q922_to_dlci(frh); + msg->l2h = frh + 2; + + switch (dlci) { + case LMI_Q933A_DLCI: + return fr_rx_lmi_q922(msg); + case LMI_CISCO_DLCI: + LOGP(DFR, LOGL_NOTICE, "Unsupported FR DLCI %u\n", dlci); + msgb_free(msg); + return 0; + } + + llist_for_each_entry(dlc, &link->dlc_list, list) { + if (dlc->dlci == dlci) { + /* dispatch to handler of respective DLC */ + return dlc->rx_cb(dlc, msg); + } + } + + if (link->unknown_dlc_rx_cb) + return link->unknown_dlc_rx_cb(NULL, msg); + else + LOGP(DFR, LOGL_NOTICE, "DLCI %u doesn't exist, discarding\n", dlci); + + return 0; +} + + + + + +/* Every T391 seconds, the user equipment sends a STATUS ENQUIRY + * message to the network and resets its polling timer (T391). */ +static void fr_t391_cb(void *data) +{ + struct fr_link *link = data; + + if (link->polling_count % link->net->n391 == 0) + tx_lmi_q933_status_enq(link, Q933_REPT_FULL_STATUS); + else + tx_lmi_q933_status_enq(link, Q933_REPT_LINK_INTEGRITY_VERIF); + link->polling_count++; + osmo_timer_schedule(&link->t391, osmo_tdef_get(link->net->T_defs, 391, OSMO_TDEF_S, 10), 0); +} + +static void fr_t392_cb(void *data) +{ + struct fr_link *link = data; + /* A.5 The network increments the error count .. Non-receipt of + * a STATUS ENQUIRY within T392, which results in restarting + * T392 */ + link->err_count++; + osmo_timer_schedule(&link->t392, osmo_tdef_get(link->net->T_defs, 392, OSMO_TDEF_S, 15), 0); +} + +/* allocate a frame relay network */ +struct fr_network *fr_network_alloc(void *ctx) +{ + struct fr_network *net = talloc_zero(ctx, struct fr_network); + + INIT_LLIST_HEAD(&net->links); + net->T_defs = fr_tdefs; + net->n391 = 6; + net->n392 = 3; + net->n393 = 4; + + return net; +} + +/* allocate a frame relay link in a given network */ +struct fr_link *fr_link_alloc(struct fr_network *net) +{ + struct fr_link *link = talloc_zero(net, struct fr_link); + if (!link) + return NULL; + + link->net = net; + INIT_LLIST_HEAD(&link->dlc_list); + osmo_timer_setup(&link->t391, fr_t391_cb, link); + osmo_timer_setup(&link->t392, fr_t392_cb, link); + + /* TODO: schedule any timers */ + + llist_add_tail(&link->list, &net->links); + + return link; +} + +/* allocate a data link connectoin on a given framerelay link */ +struct fr_dlc *fr_dlc_alloc(struct fr_link *link, uint16_t dlci) +{ + struct fr_dlc *dlc = talloc_zero(link, struct fr_dlc); + if (!dlc) + return NULL; + + dlc->link = link; + dlc->dlci = dlci; + dlc->active = true; // FIXME: HACK + + llist_add_tail(&dlc->list, &link->dlc_list); + + dlc->new = true; + tx_lmi_q933_status(link, Q933_IEI_PVC_STATUS); + + return dlc; +} |