// SPDX-License-Identifier: GPL-2.0-or-later

  /*

   *
   * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
   */
  #include <linux/errno.h>
  #include <linux/types.h>
  #include <linux/socket.h>
  #include <linux/in.h>
  #include <linux/kernel.h>

  #include <linux/timer.h>
  #include <linux/string.h>
  #include <linux/sockios.h>
  #include <linux/net.h>

  #include <linux/slab.h>

  #include <net/ax25.h>
  #include <linux/inet.h>
  #include <linux/netdevice.h>
  #include <linux/skbuff.h>
  #include <net/sock.h>

  #include <net/tcp_states.h>

  #include <linux/fcntl.h>
  #include <linux/mm.h>
  #include <linux/interrupt.h>
  #include <net/rose.h>
  
  static int rose_create_facilities(unsigned char *buffer, struct rose_sock *rose);
  
  /*
   *	This routine purges all of the queues of frames.
   */
  void rose_clear_queues(struct sock *sk)
  {
  	skb_queue_purge(&sk->sk_write_queue);
  	skb_queue_purge(&rose_sk(sk)->ack_queue);
  }
  
  /*
   * This routine purges the input queue of those frames that have been
   * acknowledged. This replaces the boxes labelled "V(a) <- N(r)" on the
   * SDL diagram.
   */
  void rose_frames_acked(struct sock *sk, unsigned short nr)
  {
  	struct sk_buff *skb;
  	struct rose_sock *rose = rose_sk(sk);
  
  	/*
  	 * Remove all the ack-ed frames from the ack queue.
  	 */
  	if (rose->va != nr) {
  		while (skb_peek(&rose->ack_queue) != NULL && rose->va != nr) {
  			skb = skb_dequeue(&rose->ack_queue);
  			kfree_skb(skb);
  			rose->va = (rose->va + 1) % ROSE_MODULUS;
  		}
  	}
  }
  
  void rose_requeue_frames(struct sock *sk)
  {
  	struct sk_buff *skb, *skb_prev = NULL;
  
  	/*
  	 * Requeue all the un-ack-ed frames on the output queue to be picked
  	 * up by rose_kick. This arrangement handles the possibility of an
  	 * empty output queue.
  	 */
  	while ((skb = skb_dequeue(&rose_sk(sk)->ack_queue)) != NULL) {
  		if (skb_prev == NULL)
  			skb_queue_head(&sk->sk_write_queue, skb);
  		else

  			skb_append(skb_prev, skb, &sk->sk_write_queue);

  		skb_prev = skb;
  	}
  }
  
  /*
   *	Validate that the value of nr is between va and vs. Return true or
   *	false for testing.
   */
  int rose_validate_nr(struct sock *sk, unsigned short nr)
  {
  	struct rose_sock *rose = rose_sk(sk);
  	unsigned short vc = rose->va;
  
  	while (vc != rose->vs) {
  		if (nr == vc) return 1;
  		vc = (vc + 1) % ROSE_MODULUS;
  	}
  
  	return nr == rose->vs;
  }
  
  /*
   *  This routine is called when the packet layer internally generates a
   *  control frame.
   */
  void rose_write_internal(struct sock *sk, int frametype)
  {
  	struct rose_sock *rose = rose_sk(sk);
  	struct sk_buff *skb;
  	unsigned char  *dptr;
  	unsigned char  lci1, lci2;

  	int maxfaclen = 0;
  	int len, faclen;
  	int reserve;

  	reserve = AX25_BPQ_HEADER_LEN + AX25_MAX_HEADER_LEN + 1;
  	len = ROSE_MIN_LEN;

  
  	switch (frametype) {
  	case ROSE_CALL_REQUEST:
  		len   += 1 + ROSE_ADDR_LEN + ROSE_ADDR_LEN;

  		maxfaclen = 256;

  		break;
  	case ROSE_CALL_ACCEPTED:
  	case ROSE_CLEAR_REQUEST:
  	case ROSE_RESET_REQUEST:
  		len   += 2;
  		break;
  	}

  	skb = alloc_skb(reserve + len + maxfaclen, GFP_ATOMIC);
  	if (!skb)

  		return;
  
  	/*
  	 *	Space for AX.25 header and PID.
  	 */

  	skb_reserve(skb, reserve);

  	dptr = skb_put(skb, len);

  
  	lci1 = (rose->lci >> 8) & 0x0F;
  	lci2 = (rose->lci >> 0) & 0xFF;
  
  	switch (frametype) {
  	case ROSE_CALL_REQUEST:
  		*dptr++ = ROSE_GFI | lci1;
  		*dptr++ = lci2;
  		*dptr++ = frametype;

  		*dptr++ = ROSE_CALL_REQ_ADDR_LEN_VAL;

  		memcpy(dptr, &rose->dest_addr,  ROSE_ADDR_LEN);
  		dptr   += ROSE_ADDR_LEN;
  		memcpy(dptr, &rose->source_addr, ROSE_ADDR_LEN);
  		dptr   += ROSE_ADDR_LEN;

  		faclen = rose_create_facilities(dptr, rose);
  		skb_put(skb, faclen);

  		dptr   += faclen;
  		break;
  
  	case ROSE_CALL_ACCEPTED:
  		*dptr++ = ROSE_GFI | lci1;
  		*dptr++ = lci2;
  		*dptr++ = frametype;
  		*dptr++ = 0x00;		/* Address length */
  		*dptr++ = 0;		/* Facilities length */
  		break;
  
  	case ROSE_CLEAR_REQUEST:
  		*dptr++ = ROSE_GFI | lci1;
  		*dptr++ = lci2;
  		*dptr++ = frametype;
  		*dptr++ = rose->cause;
  		*dptr++ = rose->diagnostic;
  		break;
  
  	case ROSE_RESET_REQUEST:
  		*dptr++ = ROSE_GFI | lci1;
  		*dptr++ = lci2;
  		*dptr++ = frametype;
  		*dptr++ = ROSE_DTE_ORIGINATED;
  		*dptr++ = 0;
  		break;
  
  	case ROSE_RR:
  	case ROSE_RNR:
  		*dptr++ = ROSE_GFI | lci1;
  		*dptr++ = lci2;
  		*dptr   = frametype;
  		*dptr++ |= (rose->vr << 5) & 0xE0;
  		break;
  
  	case ROSE_CLEAR_CONFIRMATION:
  	case ROSE_RESET_CONFIRMATION:
  		*dptr++ = ROSE_GFI | lci1;
  		*dptr++ = lci2;
  		*dptr++  = frametype;
  		break;
  
  	default:
  		printk(KERN_ERR "ROSE: rose_write_internal - invalid frametype %02X
  ", frametype);
  		kfree_skb(skb);
  		return;
  	}
  
  	rose_transmit_link(skb, rose->neighbour);
  }
  
  int rose_decode(struct sk_buff *skb, int *ns, int *nr, int *q, int *d, int *m)
  {
  	unsigned char *frame;
  
  	frame = skb->data;
  
  	*ns = *nr = *q = *d = *m = 0;
  
  	switch (frame[2]) {
  	case ROSE_CALL_REQUEST:
  	case ROSE_CALL_ACCEPTED:
  	case ROSE_CLEAR_REQUEST:
  	case ROSE_CLEAR_CONFIRMATION:
  	case ROSE_RESET_REQUEST:
  	case ROSE_RESET_CONFIRMATION:
  		return frame[2];
  	default:
  		break;
  	}
  
  	if ((frame[2] & 0x1F) == ROSE_RR  ||
  	    (frame[2] & 0x1F) == ROSE_RNR) {
  		*nr = (frame[2] >> 5) & 0x07;
  		return frame[2] & 0x1F;
  	}
  
  	if ((frame[2] & 0x01) == ROSE_DATA) {
  		*q  = (frame[0] & ROSE_Q_BIT) == ROSE_Q_BIT;
  		*d  = (frame[0] & ROSE_D_BIT) == ROSE_D_BIT;
  		*m  = (frame[2] & ROSE_M_BIT) == ROSE_M_BIT;
  		*nr = (frame[2] >> 5) & 0x07;
  		*ns = (frame[2] >> 1) & 0x07;
  		return ROSE_DATA;
  	}
  
  	return ROSE_ILLEGAL;
  }
  
  static int rose_parse_national(unsigned char *p, struct rose_facilities_struct *facilities, int len)
  {
  	unsigned char *pt;
  	unsigned char l, lg, n = 0;
  	int fac_national_digis_received = 0;
  
  	do {
  		switch (*p & 0xC0) {
  		case 0x00:

  			if (len < 2)
  				return -1;

  			p   += 2;
  			n   += 2;
  			len -= 2;
  			break;
  
  		case 0x40:

  			if (len < 3)
  				return -1;

  			if (*p == FAC_NATIONAL_RAND)
  				facilities->rand = ((p[1] << 8) & 0xFF00) + ((p[2] << 0) & 0x00FF);
  			p   += 3;
  			n   += 3;
  			len -= 3;
  			break;
  
  		case 0x80:

  			if (len < 4)
  				return -1;

  			p   += 4;
  			n   += 4;
  			len -= 4;
  			break;
  
  		case 0xC0:

  			if (len < 2)
  				return -1;

  			l = p[1];

  			if (len < 2 + l)
  				return -1;

  			if (*p == FAC_NATIONAL_DEST_DIGI) {
  				if (!fac_national_digis_received) {

  					if (l < AX25_ADDR_LEN)
  						return -1;

  					memcpy(&facilities->source_digis[0], p + 2, AX25_ADDR_LEN);
  					facilities->source_ndigis = 1;
  				}
  			}
  			else if (*p == FAC_NATIONAL_SRC_DIGI) {
  				if (!fac_national_digis_received) {

  					if (l < AX25_ADDR_LEN)
  						return -1;

  					memcpy(&facilities->dest_digis[0], p + 2, AX25_ADDR_LEN);
  					facilities->dest_ndigis = 1;
  				}
  			}
  			else if (*p == FAC_NATIONAL_FAIL_CALL) {

  				if (l < AX25_ADDR_LEN)
  					return -1;

  				memcpy(&facilities->fail_call, p + 2, AX25_ADDR_LEN);
  			}
  			else if (*p == FAC_NATIONAL_FAIL_ADD) {

  				if (l < 1 + ROSE_ADDR_LEN)
  					return -1;

  				memcpy(&facilities->fail_addr, p + 3, ROSE_ADDR_LEN);
  			}
  			else if (*p == FAC_NATIONAL_DIGIS) {

  				if (l % AX25_ADDR_LEN)
  					return -1;

  				fac_national_digis_received = 1;
  				facilities->source_ndigis = 0;
  				facilities->dest_ndigis   = 0;
  				for (pt = p + 2, lg = 0 ; lg < l ; pt += AX25_ADDR_LEN, lg += AX25_ADDR_LEN) {

  					if (pt[6] & AX25_HBIT) {
  						if (facilities->dest_ndigis >= ROSE_MAX_DIGIS)
  							return -1;

  						memcpy(&facilities->dest_digis[facilities->dest_ndigis++], pt, AX25_ADDR_LEN);

  					} else {
  						if (facilities->source_ndigis >= ROSE_MAX_DIGIS)
  							return -1;

  						memcpy(&facilities->source_digis[facilities->source_ndigis++], pt, AX25_ADDR_LEN);

  					}

  				}
  			}
  			p   += l + 2;
  			n   += l + 2;
  			len -= l + 2;
  			break;
  		}
  	} while (*p != 0x00 && len > 0);
  
  	return n;
  }
  
  static int rose_parse_ccitt(unsigned char *p, struct rose_facilities_struct *facilities, int len)
  {
  	unsigned char l, n = 0;
  	char callsign[11];
  
  	do {
  		switch (*p & 0xC0) {
  		case 0x00:

  			if (len < 2)
  				return -1;

  			p   += 2;
  			n   += 2;
  			len -= 2;
  			break;
  
  		case 0x40:

  			if (len < 3)
  				return -1;

  			p   += 3;
  			n   += 3;
  			len -= 3;
  			break;
  
  		case 0x80:

  			if (len < 4)
  				return -1;

  			p   += 4;
  			n   += 4;
  			len -= 4;
  			break;
  
  		case 0xC0:

  			if (len < 2)
  				return -1;

  			l = p[1];

  
  			/* Prevent overflows*/
  			if (l < 10 || l > 20)
  				return -1;

  			if (*p == FAC_CCITT_DEST_NSAP) {
  				memcpy(&facilities->source_addr, p + 7, ROSE_ADDR_LEN);
  				memcpy(callsign, p + 12,   l - 10);
  				callsign[l - 10] = '\0';

  				asc2ax(&facilities->source_call, callsign);

  			}
  			if (*p == FAC_CCITT_SRC_NSAP) {
  				memcpy(&facilities->dest_addr, p + 7, ROSE_ADDR_LEN);
  				memcpy(callsign, p + 12, l - 10);
  				callsign[l - 10] = '\0';

  				asc2ax(&facilities->dest_call, callsign);

  			}
  			p   += l + 2;
  			n   += l + 2;
  			len -= l + 2;
  			break;
  		}
  	} while (*p != 0x00 && len > 0);
  
  	return n;
  }

  int rose_parse_facilities(unsigned char *p, unsigned packet_len,

  	struct rose_facilities_struct *facilities)
  {
  	int facilities_len, len;
  
  	facilities_len = *p++;

  	if (facilities_len == 0 || (unsigned int)facilities_len > packet_len)

  		return 0;

  	while (facilities_len >= 3 && *p == 0x00) {
  		facilities_len--;
  		p++;
  
  		switch (*p) {
  		case FAC_NATIONAL:		/* National */
  			len = rose_parse_national(p + 1, facilities, facilities_len - 1);
  			break;
  
  		case FAC_CCITT:		/* CCITT */
  			len = rose_parse_ccitt(p + 1, facilities, facilities_len - 1);
  			break;
  
  		default:
  			printk(KERN_DEBUG "ROSE: rose_parse_facilities - unknown facilities family %02X
  ", *p);
  			len = 1;
  			break;
  		}
  
  		if (len < 0)
  			return 0;
  		if (WARN_ON(len >= facilities_len))
  			return 0;
  		facilities_len -= len + 1;
  		p += len + 1;

  	}

  	return facilities_len == 0;

  }
  
  static int rose_create_facilities(unsigned char *buffer, struct rose_sock *rose)
  {
  	unsigned char *p = buffer + 1;
  	char *callsign;

  	char buf[11];

  	int len, nb;
  
  	/* National Facilities */
  	if (rose->rand != 0 || rose->source_ndigis == 1 || rose->dest_ndigis == 1) {
  		*p++ = 0x00;
  		*p++ = FAC_NATIONAL;
  
  		if (rose->rand != 0) {
  			*p++ = FAC_NATIONAL_RAND;
  			*p++ = (rose->rand >> 8) & 0xFF;
  			*p++ = (rose->rand >> 0) & 0xFF;
  		}
  
  		/* Sent before older facilities */
  		if ((rose->source_ndigis > 0) || (rose->dest_ndigis > 0)) {
  			int maxdigi = 0;
  			*p++ = FAC_NATIONAL_DIGIS;
  			*p++ = AX25_ADDR_LEN * (rose->source_ndigis + rose->dest_ndigis);
  			for (nb = 0 ; nb < rose->source_ndigis ; nb++) {
  				if (++maxdigi >= ROSE_MAX_DIGIS)
  					break;
  				memcpy(p, &rose->source_digis[nb], AX25_ADDR_LEN);
  				p[6] |= AX25_HBIT;
  				p += AX25_ADDR_LEN;
  			}
  			for (nb = 0 ; nb < rose->dest_ndigis ; nb++) {
  				if (++maxdigi >= ROSE_MAX_DIGIS)
  					break;
  				memcpy(p, &rose->dest_digis[nb], AX25_ADDR_LEN);
  				p[6] &= ~AX25_HBIT;
  				p += AX25_ADDR_LEN;
  			}
  		}
  
  		/* For compatibility */
  		if (rose->source_ndigis > 0) {
  			*p++ = FAC_NATIONAL_SRC_DIGI;
  			*p++ = AX25_ADDR_LEN;
  			memcpy(p, &rose->source_digis[0], AX25_ADDR_LEN);
  			p   += AX25_ADDR_LEN;
  		}
  
  		/* For compatibility */
  		if (rose->dest_ndigis > 0) {
  			*p++ = FAC_NATIONAL_DEST_DIGI;
  			*p++ = AX25_ADDR_LEN;
  			memcpy(p, &rose->dest_digis[0], AX25_ADDR_LEN);
  			p   += AX25_ADDR_LEN;
  		}
  	}
  
  	*p++ = 0x00;
  	*p++ = FAC_CCITT;
  
  	*p++ = FAC_CCITT_DEST_NSAP;

  	callsign = ax2asc(buf, &rose->dest_call);

  
  	*p++ = strlen(callsign) + 10;
  	*p++ = (strlen(callsign) + 9) * 2;		/* ??? */
  
  	*p++ = 0x47; *p++ = 0x00; *p++ = 0x11;
  	*p++ = ROSE_ADDR_LEN * 2;
  	memcpy(p, &rose->dest_addr, ROSE_ADDR_LEN);
  	p   += ROSE_ADDR_LEN;
  
  	memcpy(p, callsign, strlen(callsign));
  	p   += strlen(callsign);
  
  	*p++ = FAC_CCITT_SRC_NSAP;

  	callsign = ax2asc(buf, &rose->source_call);

  
  	*p++ = strlen(callsign) + 10;
  	*p++ = (strlen(callsign) + 9) * 2;		/* ??? */
  
  	*p++ = 0x47; *p++ = 0x00; *p++ = 0x11;
  	*p++ = ROSE_ADDR_LEN * 2;
  	memcpy(p, &rose->source_addr, ROSE_ADDR_LEN);
  	p   += ROSE_ADDR_LEN;
  
  	memcpy(p, callsign, strlen(callsign));
  	p   += strlen(callsign);
  
  	len       = p - buffer;
  	buffer[0] = len - 1;
  
  	return len;
  }
  
  void rose_disconnect(struct sock *sk, int reason, int cause, int diagnostic)
  {
  	struct rose_sock *rose = rose_sk(sk);
  
  	rose_stop_timer(sk);
  	rose_stop_idletimer(sk);
  
  	rose_clear_queues(sk);
  
  	rose->lci   = 0;
  	rose->state = ROSE_STATE_0;
  
  	if (cause != -1)
  		rose->cause = cause;
  
  	if (diagnostic != -1)
  		rose->diagnostic = diagnostic;
  
  	sk->sk_state     = TCP_CLOSE;
  	sk->sk_err       = reason;
  	sk->sk_shutdown |= SEND_SHUTDOWN;
  
  	if (!sock_flag(sk, SOCK_DEAD)) {
  		sk->sk_state_change(sk);
  		sock_set_flag(sk, SOCK_DEAD);
  	}
  }