#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <assert.h>
#include <string.h>

#include <osmocom/core/msgb.h>
#include <osmocom/core/utils.h>

#include "ccid_proto.h"

#define NR_SLOTS	8

struct ccid_pars_decoded {
	/* global for T0/T1 */
	uint8_t fi;
	uint8_t di;
	enum ccid_clock_stop clock_stop;
	bool inverse_convention;

	struct {
		uint8_t guard_time_etu;
		uint8_t waiting_integer;
	} t0;

	struct {
		enum ccid_t1_csum_type csum_type;
		uint8_t guard_time_t1;
		uint8_t bwi;
		uint8_t cwi;
		uint8_t ifsc;
		uint8_t nad;
	} t1;
};

struct ccid_slot {
	struct ccid_instance *ci;
	uint8_t slot_nr;
	bool icc_present;
	bool icc_powered;
	bool icc_in_reset;
	bool cmd_busy;
	struct ccid_pars_decoded pars;
};

/* decode on-the-wire T0 parameters into their parsed form */
static int decode_ccid_pars_t0(struct ccid_pars_decoded *out, const struct ccid_proto_data_t0 *in)
{
	/* input validation: only 0x00 and 0x02 permitted for bmTCCKST0 */
	if (in->bmTCCKST0 & 0xFD)
		return -11;
	/* input validation: only 0x00 to 0x03 permitted for bClockSTop */
	if (in->bClockStop & 0xFC)
		return -14;

	out->fi = in->bmFindexDindex >> 4;
	out->di = in->bmFindexDindex & 0xF;
	if (in->bmTCCKST0 & 2)
		out->inverse_convention = true;
	else
		out->inverse_convention = false;
	if (in->bGuardTimeT0 == 0xff)
		out->t0.guard_time_etu = 0;
	else
		out->t0.guard_time_etu = in->bGuardTimeT0;
	out->t0.waiting_integer = in->bWaitingIntegerT0;
	out->clock_stop = in->bClockStop & 0x03;

	return 0;
}

/* encode T0 parameters from parsed form into on-the-wire encoding */
static void encode_ccid_pars_t0(struct ccid_proto_data_t0 *out, const struct ccid_pars_decoded *in)
{
	out->bmFindexDindex = ((in->fi << 4) & 0xF0) | (in->di & 0x0F);
	if (in->inverse_convention)
		out->bmTCCKST0 = 0x02;
	else
		out->bmTCCKST0 = 0x00;
	out->bGuardTimeT0 = in->t0.guard_time_etu;
	out->bWaitingIntegerT0 = in->t0.waiting_integer;
	out->bClockStop = in->clock_stop & 0x03;
}

/* decode on-the-wire T1 parameters into their parsed form */
static int decode_ccid_pars_t1(struct ccid_pars_decoded *out, const struct ccid_proto_data_t1 *in)
{
	/* input validation: only some values permitted for bmTCCKST0 */
	if (in->bmTCCKST1 & 0xE8)
		return -11;
	/* input validation: only 0x00 to 0x9F permitted for bmWaitingIntegersT1 */
	if (in->bWaitingIntegersT1 > 0x9F)
		return -13;
	/* input validation: only 0x00 to 0x03 permitted for bClockSTop */
	if (in->bClockStop & 0xFC)
		return -14;
	/* input validation: only 0x00 to 0xFE permitted for bIFSC */
	if (in->bIFSC > 0xFE)
		return -15;

	out->fi = in->bmFindexDindex >> 4;
	out->di = in->bmFindexDindex & 0xF;
	if (in->bmTCCKST1 & 1)
		out->t1.csum_type = CCID_CSUM_TYPE_CRC;
	else
		out->t1.csum_type = CCID_CSUM_TYPE_LRC;
	if (in->bmTCCKST1 & 2)
		out->inverse_convention = true;
	else
		out->inverse_convention = false;
	out->t1.guard_time_t1 = in->bGuardTimeT1;
	out->t1.bwi = in->bWaitingIntegersT1 >> 4;
	out->t1.cwi = in->bWaitingIntegersT1 & 0xF;
	out->clock_stop = in->bClockStop & 0x03;
	out->t1.ifsc = in->bIFSC;
	out->t1.nad = in->bNadValue;

	return 0;
}

/* encode T1 parameters from parsed form into on-the-wire encoding */
static void encode_ccid_pars_t1(struct ccid_proto_data_t1 *out, const struct ccid_pars_decoded *in)
{
	out->bmFindexDindex = ((in->fi << 4) & 0xF0) | (in->di & 0x0F);
	out->bmTCCKST1 = 0x10;
	if (in->t1.csum_type == CCID_CSUM_TYPE_CRC)
		out->bmTCCKST1 |= 0x01;
	if (in->inverse_convention)
		out->bmTCCKST1 |= 0x02;
	out->bGuardTimeT1 = in->t1.guard_time_t1;
	out->bWaitingIntegersT1 = ((in->t1.bwi << 4) & 0xF0) | (in->t1.cwi & 0x0F);
	out->bClockStop = in->clock_stop & 0x03;
	out->bIFSC = in->t1.ifsc;
	out->bNadValue = in->t1.nad;
}

struct ccid_ops {
	int (*send_in)(struct ccid_instance *ci, struct msgb *msg);
};

struct ccid_instance {
	struct ccid_slot slot[NR_SLOTS];
	struct ccid_ops ops;
	const char *name;
};

#define msgb_ccid_out(x) (union ccid_pc_to_rdr *)msgb_data(x)
#define msgb_ccid_in(x) (union ccid_rdr_to_pc *)msgb_data(x)

#define LOGPCI(ci, lvl, fmt, args ...) LOGP(DCCID, lvl, "%s: " fmt, (ci)->name, ## args)
#define LOGPCS(cs, lvl, fmt, args ...) \
	LOGP(DCCID, lvl, "%s(%u): " fmt, (cc)->ci->name, (cc)->slot_nr, ## args)

static struct ccid_slot *get_ccid_slot(struct ccid_instance *ci, uint8_t slot_nr)
{
	if (slot_nr >= sizeof(ci->slot))
		return NULL;
	else
		return &ci->slot[slot_nr];
}

static uint8_t get_icc_status(const struct ccid_slot *cs)
{
	if (cs->icc_present && cs->icc_powered && !cs->icc_in_reset)
		return CCID_ICC_STATUS_PRES_ACT;
	else if (!cs->icc_present)
		return CCID_ICC_STATUS_NO_ICC;
	else
		return CCID_ICC_STATUS_PRES_INACT;
}

#define SET_HDR(x, msg_type, slot, seq) do {	\
	(x)->hdr.bMessageType = msg_type;	\
	(x)->hdr.dwLength = 0;		\
	(x)->hdr.bSlot = slot;			\
	(x)->hdr.bSeq = seq;			\
	} while (0)

#define SET_HDR_IN(x, msg_type, slot, seq, status, error) do {	\
	SET_HDR(&(x)->hdr, msg_type, slot, seq);		\
	(x)->hdr.bStatus = status;				\
	(x)->hdr.bError = error;				\
	} while (0)

#if 0
static uint8_t ccid_pc_to_rdr_get_seq(const struct ccid_pc_to_rdr *u)
{
	const struct ccid_header *ch = (const struct ccid_header *) u;
	return ch->bSeq;
}
#endif

/***********************************************************************
 * Message generation / sending
 ***********************************************************************/

static struct msgb *ccid_msgb_alloc(void)
{
	struct msgb *msg = msgb_alloc(512, "ccid");
	OSMO_ASSERT(msg);
	return msg;
}

/* Send given CCID message */
static int ccid_send(struct ccid_instance *ci, struct msgb *msg)
{
	return ci->ops.send_in(ci, msg);
}

/* Send given CCID message for given slot; patch bSlot into message */
static int ccid_slot_send(struct ccid_slot *cs, struct msgb *msg)
{
	struct ccid_header *ch = (struct ccid_header *) msgb_ccid_in(msg);

	/* patch bSlotNr into message */
	ch->bSlot = cs->slot_nr;
	return ccid_send(cs->ci, msg);
}

/* Send given CCID message and mark slot as un-busy */
static int ccid_slot_send_unbusy(struct ccid_slot *cs, struct msgb *msg)
{
	cs->cmd_busy = false;
	return ccid_slot_send(cs, msg);
}

/* Section 6.2.1 */
static struct msgb *ccid_gen_data_block_nr(uint8_t slot_nr, uint8_t icc_status, uint8_t seq,
					   uint8_t cmd_sts, enum ccid_error_code err,
					   const uint8_t *data, uint32_t data_len)
{
	struct msgb *msg = ccid_msgb_alloc();
	struct ccid_rdr_to_pc_data_block *db =
		(struct ccid_rdr_to_pc_data_block *) msgb_put(msg, sizeof(*db) + data_len);
	uint8_t sts = (cmd_sts & CCID_CMD_STATUS_MASK) | icc_status;

	SET_HDR_IN(db, RDR_to_PC_DataBlock, slot_nr, seq, sts, err);
	osmo_store32le(data_len, &db->hdr.hdr.dwLength);
	memcpy(db->abData, data, data_len);
	return msg;
}
static struct msgb *ccid_gen_data_block(struct ccid_slot *cs, uint8_t seq, uint8_t cmd_sts,
					 enum ccid_error_code err, const uint8_t *data,
					 uint32_t data_len)
{
	return ccid_gen_data_block_nr(cs->slot_nr, get_icc_status(cs), seq, cmd_sts, err, data, data_len);
}

/* Section 6.2.2 */
static struct msgb *ccid_gen_slot_status_nr(uint8_t slot_nr, uint8_t icc_status,
					    uint8_t seq, uint8_t cmd_sts,
					    enum ccid_error_code err)
{
	struct msgb *msg = ccid_msgb_alloc();
	struct ccid_rdr_to_pc_slot_status *ss =
		(struct ccid_rdr_to_pc_slot_status *) msgb_put(msg, sizeof(*ss));
	uint8_t sts = (cmd_sts & CCID_CMD_STATUS_MASK) | icc_status;

	SET_HDR_IN(ss, RDR_to_PC_SlotStatus, slot_nr, seq, sts, err);
	return msg;
}
static struct msgb *ccid_gen_slot_status(struct ccid_slot *cs, uint8_t seq, uint8_t cmd_sts,
					 enum ccid_error_code err)
{
	return ccid_gen_slot_status_nr(cs->slot_nr, get_icc_status(cs), seq, cmd_sts, err);
}

/* Section 6.2.3 */
static struct msgb *ccid_gen_parameters_t0_nr(uint8_t slot_nr, uint8_t icc_status,
					      uint8_t seq, uint8_t cmd_sts, enum ccid_error_code err,
					      const struct ccid_pars_decoded *dec_par)
{
	struct msgb *msg = ccid_msgb_alloc();
	struct ccid_rdr_to_pc_parameters *par =
		(struct ccid_rdr_to_pc_parameters *) msgb_put(msg, sizeof(par->hdr)+sizeof(par->abProtocolData.t0));
	uint8_t sts = (cmd_sts & CCID_CMD_STATUS_MASK) | icc_status;

	SET_HDR_IN(par, RDR_to_PC_Parameters, slot_nr, seq, sts, err);
	if (dec_par) {
		osmo_store32le(sizeof(par->abProtocolData.t0), &par->hdr.hdr.dwLength);
		encode_ccid_pars_t0(&par->abProtocolData.t0, dec_par);
	}
	return msg;
}
static struct msgb *ccid_gen_parameters_t0(struct ccid_slot *cs, uint8_t seq, uint8_t cmd_sts,
					   enum ccid_error_code err)
{
	return ccid_gen_parameters_t0_nr(cs->slot_nr, get_icc_status(cs), seq, cmd_sts, err, &cs->pars);
}

static struct msgb *ccid_gen_parameters_t1_nr(uint8_t slot_nr, uint8_t icc_status,
					      uint8_t seq, uint8_t cmd_sts, enum ccid_error_code err,
					      const struct ccid_pars_decoded *dec_par)
{
	struct msgb *msg = ccid_msgb_alloc();
	struct ccid_rdr_to_pc_parameters *par =
		(struct ccid_rdr_to_pc_parameters *) msgb_put(msg, sizeof(par->hdr)+sizeof(par->abProtocolData.t1));
	uint8_t sts = (cmd_sts & CCID_CMD_STATUS_MASK) | icc_status;

	SET_HDR_IN(par, RDR_to_PC_Parameters, slot_nr, seq, sts, err);
	if (dec_par) {
		osmo_store32le(sizeof(par->abProtocolData.t1), &par->hdr.hdr.dwLength);
		encode_ccid_pars_t1(&par->abProtocolData.t1, dec_par);
	}
	return msg;
}
static struct msgb *ccid_gen_parameters_t1(struct ccid_slot *cs, uint8_t seq, uint8_t cmd_sts,
					   enum ccid_error_code err)
{
	return ccid_gen_parameters_t1_nr(cs->slot_nr, get_icc_status(cs), seq, cmd_sts, err, &cs->pars);
}


/* Section 6.2.4 */
static struct msgb *ccid_gen_escape_nr(uint8_t slot_nr, uint8_t icc_status, uint8_t seq, uint8_t cmd_sts,
					enum ccid_error_code err, const uint8_t *data, uint32_t data_len)
{
	struct msgb *msg = ccid_msgb_alloc();
	struct ccid_rdr_to_pc_escape *esc =
		(struct ccid_rdr_to_pc_escape *) msgb_put(msg, sizeof(*esc) + data_len);
	uint8_t sts = (cmd_sts & CCID_CMD_STATUS_MASK) | icc_status;

	SET_HDR_IN(esc, RDR_to_PC_Escape, slot_nr, seq, sts, err);
	osmo_store32le(data_len, &esc->hdr.hdr.dwLength);
	memcpy(esc->abData, data, data_len);
	return msg;
}
static struct msgb *ccid_gen_escape(struct ccid_slot *cs, uint8_t seq, uint8_t cmd_sts,
				    enum ccid_error_code err, const uint8_t *data,
				    uint32_t data_len)
{
	return ccid_gen_escape_nr(cs->slot_nr, get_icc_status(cs), seq, cmd_sts, err, data, data_len);
}

/* Section 6.2.5 */
static struct msgb *ccid_gen_clock_and_rate_nr(uint8_t slot_nr, uint8_t icc_status, uint8_t seq,
						uint8_t cmd_sts, enum ccid_error_code err,
						uint32_t clock_khz, uint32_t rate_bps)
{
	struct msgb *msg = ccid_msgb_alloc();
	struct ccid_rdr_to_pc_data_rate_and_clock *drc =
		(struct ccid_rdr_to_pc_data_rate_and_clock *) msgb_put(msg, sizeof(*drc));
	uint8_t sts = (cmd_sts & CCID_CMD_STATUS_MASK) | icc_status;

	SET_HDR_IN(drc, RDR_to_PC_DataRateAndClockFrequency, slot_nr, seq, sts, err);
	osmo_store32le(8, &drc->hdr.hdr.dwLength); /* Message-specific data length (wtf?) */
	osmo_store32le(clock_khz, &drc->dwClockFrequency); /* kHz */
	osmo_store32le(rate_bps, &drc->dwDataRate); /* bps */
	return msg;
}
static struct msgb *ccid_gen_clock_and_rate(struct ccid_slot *cs, uint8_t seq, uint8_t cmd_sts,
					    enum ccid_error_code err, uint32_t clock_khz,
					    uint32_t rate_bps)
{
	return ccid_gen_clock_and_rate_nr(cs->slot_nr, get_icc_status(cs), seq, cmd_sts, err,
					  clock_khz, rate_bps);
}

/*! generate an error response for given input message_type/slot_nr/seq
 *  \param[in] msg_type CCID Message Type against which response is to be created
 *  \param[in] slot_nr CCID Slot Number
 *  \param[in] icc_status ICC Status of the slot
 *  \param[in] seq CCID Sequence number
 *  \param[in] err_code CCID Error Code to send
 *  \returns dynamically-allocated message buffer containing error response */
static struct msgb *gen_err_resp(enum ccid_msg_type msg_type, uint8_t slot_nr, uint8_t icc_status,
				 uint8_t seq, enum ccid_error_code err_code)
{
	struct msgb *resp = NULL;

	switch (msg_type) {
	case PC_to_RDR_IccPowerOn:
	case PC_to_RDR_XfrBlock:
	case PC_to_RDR_Secure:
		/* Return RDR_to_PC_DataBlock */
		resp = ccid_gen_data_block_nr(slot_nr, icc_status, seq, CCID_CMD_STATUS_FAILED,
						err_code, NULL, 0);
		break;

	case PC_to_RDR_IccPowerOff:
	case PC_to_RDR_GetSlotStatus:
	case PC_to_RDR_IccClock:
	case PC_to_RDR_T0APDU:
	case PC_to_RDR_Mechanical:
	case PC_to_RDR_Abort:
		/* Return RDR_to_PC_SlotStatus */
		resp = ccid_gen_slot_status_nr(slot_nr, icc_status, seq, CCID_CMD_STATUS_FAILED,
						err_code);
		break;

	case PC_to_RDR_GetParameters:
	case PC_to_RDR_ResetParameters:
	case PC_to_RDR_SetParameters:
		/* Return RDR_to_PC_Parameters */
		resp = ccid_gen_parameters_t0_nr(slot_nr, icc_status, seq, CCID_CMD_STATUS_FAILED,
						 err_code, NULL); /* FIXME: parameters? */
		break;

	case PC_to_RDR_Escape:
		/* Return RDR_to_PC_Escape */
		resp = ccid_gen_escape_nr(slot_nr, icc_status, seq, CCID_CMD_STATUS_FAILED,
					  err_code, NULL, 0);
		break;

	case PC_to_RDR_SetDataRateAndClockFrequency:
		/* Return RDR_to_PC_SlotStatus */
		resp = ccid_gen_slot_status_nr(slot_nr, icc_status, seq, CCID_CMD_STATUS_FAILED,
						err_code);
		break;

	default:
		/* generate general error */
		resp = ccid_gen_slot_status_nr(slot_nr, icc_status, seq, CCID_CMD_STATUS_FAILED,
						CCID_ERR_CMD_NOT_SUPPORTED);
		break;
	}
	return resp;
}

/***********************************************************************
 * Message reception / parsing
 ***********************************************************************/

/* Section 6.1.3 */
static int ccid_handle_get_slot_status(struct ccid_slot *cs, struct msgb *msg)
{
	const union ccid_pc_to_rdr *u = msgb_ccid_out(msg);
	const struct ccid_header *ch = (const struct ccid_header *) u;
	uint8_t seq = u->get_slot_status.hdr.bSeq;
	struct msgb *resp;

	resp = ccid_gen_slot_status(cs, seq, CCID_CMD_STATUS_OK, 0);

	return ccid_slot_send_unbusy(cs, resp);
}


/* Section 6.1.1 */
static int ccid_handle_icc_power_on(struct ccid_slot *cs, struct msgb *msg)
{
	const union ccid_pc_to_rdr *u = msgb_ccid_out(msg);
	const struct ccid_header *ch = (const struct ccid_header *) u;
	uint8_t seq = u->icc_power_on.hdr.bSeq;
	struct msgb *resp;

	/* TODO: send actual ATR; handle error cases */
	/* TODO: handle this asynchronously */
	resp = ccid_gen_data_block(cs, seq, CCID_CMD_STATUS_OK, 0, NULL, 0);

	return ccid_slot_send_unbusy(cs, resp);
}

/* Section 6.1.2 */
static int ccid_handle_icc_power_off(struct ccid_slot *cs, struct msgb *msg)
{
	const union ccid_pc_to_rdr *u = msgb_ccid_out(msg);
	const struct ccid_header *ch = (const struct ccid_header *) u;
	uint8_t seq = u->icc_power_off.hdr.bSeq;
	struct msgb *resp;

	/* FIXME */
	resp = ccid_gen_slot_status(cs, seq, CCID_CMD_STATUS_OK, 0);
	return ccid_slot_send_unbusy(cs, resp);
}

/* Section 6.1.4 */
static int ccid_handle_xfr_block(struct ccid_slot *cs, struct msgb *msg)
{
	const union ccid_pc_to_rdr *u = msgb_ccid_out(msg);
	const struct ccid_header *ch = (const struct ccid_header *) u;
	uint8_t seq = u->xfr_block.hdr.bSeq;
	struct msgb *resp;

	/* FIXME */
	resp = ccid_gen_data_block(cs, seq, CCID_CMD_STATUS_OK, 0, NULL, 0);
	return ccid_slot_send_unbusy(cs, resp);
}

/* Section 6.1.5 */
static int ccid_handle_get_parameters(struct ccid_slot *cs, struct msgb *msg)
{
	const union ccid_pc_to_rdr *u = msgb_ccid_out(msg);
	const struct ccid_header *ch = (const struct ccid_header *) u;
	uint8_t seq = u->get_parameters.hdr.bSeq;
	struct msgb *resp;

	/* FIXME: T=1 */
	resp = ccid_gen_parameters_t0(cs, seq, CCID_CMD_STATUS_OK, 0);
	return ccid_slot_send_unbusy(cs, resp);
}

/* Section 6.1.6 */
static int ccid_handle_reset_parameters(struct ccid_slot *cs, struct msgb *msg)
{
	const union ccid_pc_to_rdr *u = msgb_ccid_out(msg);
	const struct ccid_header *ch = (const struct ccid_header *) u;
	uint8_t seq = u->reset_parameters.hdr.bSeq;
	struct msgb *resp;

	/* FIXME: copy default parameters from somewhere */
	/* FIXME: T=1 */
	resp = ccid_gen_parameters_t0(cs, seq, CCID_CMD_STATUS_OK, 0);
	return ccid_slot_send_unbusy(cs, resp);
}

/* Section 6.1.7 */
static int ccid_handle_set_parameters(struct ccid_slot *cs, struct msgb *msg)
{
	const union ccid_pc_to_rdr *u = msgb_ccid_out(msg);
	const struct ccid_pc_to_rdr_set_parameters *spar = &u->set_parameters;
	const struct ccid_header *ch = (const struct ccid_header *) u;
	uint8_t seq = u->set_parameters.hdr.bSeq;
	struct ccid_pars_decoded pars_dec;
	struct msgb *resp;
	int rc;

	switch (spar->bProtocolNum) {
	case CCID_PROTOCOL_NUM_T0:
		rc = decode_ccid_pars_t0(&pars_dec, &spar->abProtocolData.t0);
		if (rc < 0)
			resp = ccid_gen_parameters_t0(cs, seq, CCID_CMD_STATUS_FAILED, -rc);
		/* FIXME: validate parameters; abort if they are not supported */
		cs->pars = pars_dec;
		resp = ccid_gen_parameters_t0(cs, seq, CCID_CMD_STATUS_OK, 0);
		break;
	case CCID_PROTOCOL_NUM_T1:
		rc = decode_ccid_pars_t1(&pars_dec, &spar->abProtocolData.t1);
		if (rc < 0)
			resp = ccid_gen_parameters_t1(cs, seq, CCID_CMD_STATUS_FAILED, -rc);
		/* FIXME: validate parameters; abort if they are not supported */
		cs->pars = pars_dec;
		resp = ccid_gen_parameters_t1(cs, seq, CCID_CMD_STATUS_OK, 0);
		break;
	default:
		resp = ccid_gen_parameters_t0(cs, seq, CCID_CMD_STATUS_FAILED, 0);
		break;
	}
	return ccid_slot_send_unbusy(cs, resp);
}

/* Section 6.1.8 */
static int ccid_handle_escape(struct ccid_slot *cs, struct msgb *msg)
{
	const union ccid_pc_to_rdr *u = msgb_ccid_out(msg);
	const struct ccid_header *ch = (const struct ccid_header *) u;
	uint8_t seq = u->escape.hdr.bSeq;
	struct msgb *resp;

	resp = ccid_gen_escape(cs, seq, CCID_CMD_STATUS_FAILED, CCID_ERR_CMD_NOT_SUPPORTED, NULL, 0);
	return ccid_slot_send_unbusy(cs, resp);
}

/* Section 6.1.9 */
static int ccid_handle_icc_clock(struct ccid_slot *cs, struct msgb *msg)
{
	const union ccid_pc_to_rdr *u = msgb_ccid_out(msg);
	const struct ccid_header *ch = (const struct ccid_header *) u;
	uint8_t seq = u->icc_clock.hdr.bSeq;
	struct msgb *resp;

	/* FIXME: Actually Stop/Start the clock */
	resp = ccid_gen_slot_status(cs, seq, CCID_CMD_STATUS_OK, 0);
	return ccid_slot_send_unbusy(cs, resp);
}

/* Section 6.1.10 */
static int ccid_handle_t0apdu(struct ccid_slot *cs, struct msgb *msg)
{
	const union ccid_pc_to_rdr *u = msgb_ccid_out(msg);
	const struct ccid_header *ch = (const struct ccid_header *) u;
	uint8_t seq = u->t0apdu.hdr.bSeq;
	struct msgb *resp;

	/* FIXME */
	//resp = ccid_gen_slot_status(cs, seq, CCID_CMD_STATUS_OK, 0);
	resp = ccid_gen_slot_status(cs, seq, CCID_CMD_STATUS_FAILED, CCID_ERR_CMD_NOT_SUPPORTED);
	return ccid_slot_send_unbusy(cs, resp);
}

/* Section 6.1.11 */
static int ccid_handle_secure(struct ccid_slot *cs, struct msgb *msg)
{
	const union ccid_pc_to_rdr *u = msgb_ccid_out(msg);
	const struct ccid_header *ch = (const struct ccid_header *) u;
	uint8_t seq = u->secure.hdr.bSeq;
	struct msgb *resp;

	/* FIXME */
	resp = ccid_gen_slot_status(cs, seq, CCID_CMD_STATUS_FAILED, CCID_ERR_CMD_NOT_SUPPORTED);
	return ccid_slot_send_unbusy(cs, resp);
}

/* Section 6.1.12 */
static int ccid_handle_mechanical(struct ccid_slot *cs, struct msgb *msg)
{
	const union ccid_pc_to_rdr *u = msgb_ccid_out(msg);
	const struct ccid_header *ch = (const struct ccid_header *) u;
	uint8_t seq = u->mechanical.hdr.bSeq;
	struct msgb *resp;

	resp = ccid_gen_slot_status(cs, seq, CCID_CMD_STATUS_FAILED, CCID_ERR_CMD_NOT_SUPPORTED);
	return ccid_slot_send_unbusy(cs, resp);
}

/* Section 6.1.13 */
static int ccid_handle_abort(struct ccid_slot *cs, struct msgb *msg)
{
	const union ccid_pc_to_rdr *u = msgb_ccid_out(msg);
	const struct ccid_header *ch = (const struct ccid_header *) u;
	uint8_t seq = u->abort.hdr.bSeq;
	struct msgb *resp;

	/* Check if the currently in-progress message is Abortable */
	switch (0/* FIXME */) {
	case PC_to_RDR_IccPowerOn:
	case PC_to_RDR_XfrBlock:
	case PC_to_RDR_Escape:
	case PC_to_RDR_Secure:
	case PC_to_RDR_Mechanical:
	//case PC_to_RDR_Abort: /* seriously? WTF! */
		break;
	default:
		/* CCID spec lists CMD_NOT_ABORTED, but gives no numberic value ?!? */
		resp = ccid_gen_slot_status(cs, seq, CCID_CMD_STATUS_FAILED, CCID_ERR_CMD_NOT_SUPPORTED);
		return ccid_slot_send_unbusy(cs, resp);
	}

	/* FIXME */
	resp = ccid_gen_slot_status(cs, seq, CCID_CMD_STATUS_OK, 0);
	return ccid_slot_send_unbusy(cs, resp);
}

/* Section 6.1.14 */
static int ccid_handle_set_rate_and_clock(struct ccid_slot *cs, struct msgb *msg)
{
	const union ccid_pc_to_rdr *u = msgb_ccid_out(msg);
	const struct ccid_header *ch = (const struct ccid_header *) u;
	uint8_t seq = u->set_rate_and_clock.hdr.bSeq;
	struct msgb *resp;

	/* FIXME */
	resp = ccid_gen_clock_and_rate(cs, seq, CCID_CMD_STATUS_OK, 0, 9600, 2500000);
	return ccid_slot_send_unbusy(cs, resp);
}

/*! Handle data arriving from the host on the OUT endpoint.
 *  \param[in] cs CCID Instance on which to operate
 *  \param[in] msgb received message buffer containing one CCID OUT EP message from the host
 *  \returns 0 on success; negative on error */
int ccid_handle_out(struct ccid_instance *ci, struct msgb *msg)
{
	const union ccid_pc_to_rdr *u = msgb_ccid_out(msg);
	const struct ccid_header *ch = (const struct ccid_header *) u;
	unsigned int len = msgb_length(msg);
	struct ccid_slot *cs;
	struct msgb *resp;
	int rc;

	if (len < sizeof(*ch)) {
		/* FIXME */
		return -1;
	}

	/* Check for invalid slot number */
	cs = get_ccid_slot(ci, ch->bSlot);
	if (!cs) {
		resp = gen_err_resp(ch->bMessageType, ch->bSlot, CCID_ICC_STATUS_NO_ICC, ch->bSeq, 5);
		return ccid_send(ci, resp);
	}

	/* Check if slot is already busy; Reject any additional commands meanwhile */
	if (cs->cmd_busy) {
		/* FIXME: ABORT logic as per section 5.3.1 of CCID Spec v1.1 */
		resp = gen_err_resp(ch->bMessageType, ch->bSlot, get_icc_status(cs), ch->bSeq,
					CCID_ERR_CMD_SLOT_BUSY);
		return ccid_send(ci, resp);
	}

	/* we're now processing a command for the slot; mark slot as busy */
	cs->cmd_busy = true;

	/* TODO: enqueue into the per-slot specific input queue */

	switch (ch->bMessageType) {
	case PC_to_RDR_GetSlotStatus:
		if (len != sizeof(u->get_slot_status))
			goto short_msg;
		rc = ccid_handle_get_slot_status(cs, msg);
		break;
	case PC_to_RDR_IccPowerOn:
		if (len != sizeof(u->icc_power_on))
			goto short_msg;
		rc = ccid_handle_icc_power_on(cs, msg);
		break;
	case PC_to_RDR_IccPowerOff:
		if (len != sizeof(u->icc_power_off))
			goto short_msg;
		rc = ccid_handle_icc_power_off(cs, msg);
		break;
	case PC_to_RDR_XfrBlock:
		if (len < sizeof(u->xfr_block))
			goto short_msg;
		rc = ccid_handle_xfr_block(cs, msg);
		break;
	case PC_to_RDR_GetParameters:
		if (len != sizeof(u->get_parameters))
			goto short_msg;
		rc = ccid_handle_get_parameters(cs, msg);
		break;
	case PC_to_RDR_ResetParameters:
		if (len != sizeof(u->reset_parameters))
			goto short_msg;
		rc = ccid_handle_reset_parameters(cs, msg);
		break;
	case PC_to_RDR_SetParameters:
		if (len != sizeof(u->set_parameters))
			goto short_msg;
		rc = ccid_handle_set_parameters(cs, msg);
		break;
	case PC_to_RDR_Escape:
		if (len < sizeof(u->escape))
			goto short_msg;
		rc = ccid_handle_escape(cs, msg);
		break;
	case PC_to_RDR_IccClock:
		if (len != sizeof(u->icc_clock))
			goto short_msg;
		rc = ccid_handle_icc_clock(cs, msg);
		break;
	case PC_to_RDR_T0APDU:
		if (len != /*FIXME*/ sizeof(u->t0apdu))
			goto short_msg;
		rc = ccid_handle_t0apdu(cs, msg);
		break;
	case PC_to_RDR_Secure:
		if (len < sizeof(u->secure))
			goto short_msg;
		rc = ccid_handle_secure(cs, msg);
		break;
	case PC_to_RDR_Mechanical:
		if (len != sizeof(u->mechanical))
			goto short_msg;
		rc = ccid_handle_mechanical(cs, msg);
		break;
	case PC_to_RDR_Abort:
		if (len != sizeof(u->abort))
			goto short_msg;
		rc = ccid_handle_abort(cs, msg);
		break;
	case PC_to_RDR_SetDataRateAndClockFrequency:
		if (len != sizeof(u->set_rate_and_clock))
			goto short_msg;
		rc = ccid_handle_set_rate_and_clock(cs, msg);
		break;
	default:
		/* generic response with bERror = 0 (command not supported) */
		resp = gen_err_resp(ch->bMessageType, ch->bSlot, CCID_ICC_STATUS_NO_ICC, ch->bSeq,
				    CCID_ERR_CMD_NOT_SUPPORTED);
		return ccid_slot_send_unbusy(cs, resp);
	}
	return 0;

short_msg:
	/* FIXME */
	return -1;
}