net/ax25/ax25_out.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  *
  * Copyright (C) Alan Cox GW4PTS (alan@lxorguk.ukuu.org.uk)
  * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
  * Copyright (C) Joerg Reuter DL1BKE (jreuter@yaina.de)
  */
 #include <linux/errno.h>
 #include <linux/types.h>
 #include <linux/socket.h>
 #include <linux/in.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/timer.h>
 #include <linux/string.h>
 #include <linux/sockios.h>
 #include <linux/spinlock.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 <linux/uaccess.h>
 #include <linux/fcntl.h>
 #include <linux/mm.h>
 #include <linux/interrupt.h>

 static DEFINE_SPINLOCK(ax25_frag_lock);

 ax25_cb *ax25_send_frame(struct sk_buff *skb, int paclen, ax25_address *src, ax25_address *dest, ax25_digi *digi, struct net_device *dev)
 {
 	ax25_dev *ax25_dev;
 	ax25_cb *ax25;

 	/*
 	 * Take the default packet length for the device if zero is
 	 * specified.
 	 */
 	if (paclen == 0) {
 		if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL)
 			return NULL;

 		paclen = ax25_dev->values[AX25_VALUES_PACLEN];
 	}

 	/*
 	 * Look for an existing connection.
 	 */
 	if ((ax25 = ax25_find_cb(src, dest, digi, dev)) != NULL) {
 		ax25_output(ax25, paclen, skb);
 		return ax25;		/* It already existed */
 	}

 	if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL)
 		return NULL;

 	if ((ax25 = ax25_create_cb()) == NULL)
 		return NULL;

 	ax25_fillin_cb(ax25, ax25_dev);

 	ax25->source_addr = *src;
 	ax25->dest_addr   = *dest;

 	if (digi != NULL) {
 		ax25->digipeat = kmemdup(digi, sizeof(*digi), GFP_ATOMIC);
 		if (ax25->digipeat == NULL) {
 			ax25_cb_put(ax25);
 			return NULL;
 		}
 	}

 	switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) {
 	case AX25_PROTO_STD_SIMPLEX:
 	case AX25_PROTO_STD_DUPLEX:
 		ax25_std_establish_data_link(ax25);
 		break;

 #ifdef CONFIG_AX25_DAMA_SLAVE
 	case AX25_PROTO_DAMA_SLAVE:
 		if (ax25_dev->dama.slave)
 			ax25_ds_establish_data_link(ax25);
 		else
 			ax25_std_establish_data_link(ax25);
 		break;
 #endif
 	}

 	/*
 	 * There is one ref for the state machine; a caller needs
 	 * one more to put it back, just like with the existing one.
 	 */
 	ax25_cb_hold(ax25);

 	ax25_cb_add(ax25);

 	ax25->state = AX25_STATE_1;

 	ax25_start_heartbeat(ax25);

 	ax25_output(ax25, paclen, skb);

 	return ax25;			/* We had to create it */
 }

 EXPORT_SYMBOL(ax25_send_frame);

 /*
  *	All outgoing AX.25 I frames pass via this routine. Therefore this is
  *	where the fragmentation of frames takes place. If fragment is set to
  *	zero then we are not allowed to do fragmentation, even if the frame
  *	is too large.
  */
 void ax25_output(ax25_cb *ax25, int paclen, struct sk_buff *skb)
 {
 	struct sk_buff *skbn;
 	unsigned char *p;
 	int frontlen, len, fragno, ka9qfrag, first = 1;

 	if (paclen < 16) {
 		WARN_ON_ONCE(1);
 		kfree_skb(skb);
 		return;
 	}

 	if ((skb->len - 1) > paclen) {
 		if (*skb->data == AX25_P_TEXT) {
 			skb_pull(skb, 1); /* skip PID */
 			ka9qfrag = 0;
 		} else {
 			paclen -= 2;	/* Allow for fragment control info */
 			ka9qfrag = 1;
 		}

 		fragno = skb->len / paclen;
 		if (skb->len % paclen == 0) fragno--;

 		frontlen = skb_headroom(skb);	/* Address space + CTRL */

 		while (skb->len > 0) {
 			spin_lock_bh(&ax25_frag_lock);
 			if ((skbn = alloc_skb(paclen + 2 + frontlen, GFP_ATOMIC)) == NULL) {
 				spin_unlock_bh(&ax25_frag_lock);
 				printk(KERN_CRIT "AX.25: ax25_output - out of memory\n");
 				return;
 			}

 			if (skb->sk != NULL)
 				skb_set_owner_w(skbn, skb->sk);

 			spin_unlock_bh(&ax25_frag_lock);

 			len = (paclen > skb->len) ? skb->len : paclen;

 			if (ka9qfrag == 1) {
 				skb_reserve(skbn, frontlen + 2);
 				skb_set_network_header(skbn,
 						      skb_network_offset(skb));
 				skb_copy_from_linear_data(skb, skb_put(skbn, len), len);
 				p = skb_push(skbn, 2);

 				*p++ = AX25_P_SEGMENT;

 				*p = fragno--;
 				if (first) {
 					*p |= AX25_SEG_FIRST;
 					first = 0;
 				}
 			} else {
 				skb_reserve(skbn, frontlen + 1);
 				skb_set_network_header(skbn,
 						      skb_network_offset(skb));
 				skb_copy_from_linear_data(skb, skb_put(skbn, len), len);
 				p = skb_push(skbn, 1);
 				*p = AX25_P_TEXT;
 			}

 			skb_pull(skb, len);
 			skb_queue_tail(&ax25->write_queue, skbn); /* Throw it on the queue */
 		}

 		kfree_skb(skb);
 	} else {
 		skb_queue_tail(&ax25->write_queue, skb);	  /* Throw it on the queue */
 	}

 	switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) {
 	case AX25_PROTO_STD_SIMPLEX:
 	case AX25_PROTO_STD_DUPLEX:
 		ax25_kick(ax25);
 		break;

 #ifdef CONFIG_AX25_DAMA_SLAVE
 	/*
 	 * A DAMA slave is _required_ to work as normal AX.25L2V2
 	 * if no DAMA master is available.
 	 */
 	case AX25_PROTO_DAMA_SLAVE:
 		if (!ax25->ax25_dev->dama.slave) ax25_kick(ax25);
 		break;
 #endif
 	}
 }

 /*
  *  This procedure is passed a buffer descriptor for an iframe. It builds
  *  the rest of the control part of the frame and then writes it out.
  */
 static void ax25_send_iframe(ax25_cb *ax25, struct sk_buff *skb, int poll_bit)
 {
 	unsigned char *frame;

 	if (skb == NULL)
 		return;

 	skb_reset_network_header(skb);

 	if (ax25->modulus == AX25_MODULUS) {
 		frame = skb_push(skb, 1);

 		*frame = AX25_I;
 		*frame |= (poll_bit) ? AX25_PF : 0;
 		*frame |= (ax25->vr << 5);
 		*frame |= (ax25->vs << 1);
 	} else {
 		frame = skb_push(skb, 2);

 		frame[0] = AX25_I;
 		frame[0] |= (ax25->vs << 1);
 		frame[1] = (poll_bit) ? AX25_EPF : 0;
 		frame[1] |= (ax25->vr << 1);
 	}

 	ax25_start_idletimer(ax25);

 	ax25_transmit_buffer(ax25, skb, AX25_COMMAND);
 }

 void ax25_kick(ax25_cb *ax25)
 {
 	struct sk_buff *skb, *skbn;
 	int last = 1;
 	unsigned short start, end, next;

 	if (ax25->state != AX25_STATE_3 && ax25->state != AX25_STATE_4)
 		return;

 	if (ax25->condition & AX25_COND_PEER_RX_BUSY)
 		return;

 	if (skb_peek(&ax25->write_queue) == NULL)
 		return;

 	start = (skb_peek(&ax25->ack_queue) == NULL) ? ax25->va : ax25->vs;
 	end   = (ax25->va + ax25->window) % ax25->modulus;

 	if (start == end)
 		return;

 	/*
 	 * Transmit data until either we're out of data to send or
 	 * the window is full. Send a poll on the final I frame if
 	 * the window is filled.
 	 */

 	/*
 	 * Dequeue the frame and copy it.
 	 * Check for race with ax25_clear_queues().
 	 */
 	skb  = skb_dequeue(&ax25->write_queue);
 	if (!skb)
 		return;

 	ax25->vs = start;

 	do {
 		if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
 			skb_queue_head(&ax25->write_queue, skb);
 			break;
 		}

 		if (skb->sk != NULL)
 			skb_set_owner_w(skbn, skb->sk);

 		next = (ax25->vs + 1) % ax25->modulus;
 		last = (next == end);

 		/*
 		 * Transmit the frame copy.
 		 * bke 960114: do not set the Poll bit on the last frame
 		 * in DAMA mode.
 		 */
 		switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) {
 		case AX25_PROTO_STD_SIMPLEX:
 		case AX25_PROTO_STD_DUPLEX:
 			ax25_send_iframe(ax25, skbn, (last) ? AX25_POLLON : AX25_POLLOFF);
 			break;

 #ifdef CONFIG_AX25_DAMA_SLAVE
 		case AX25_PROTO_DAMA_SLAVE:
 			ax25_send_iframe(ax25, skbn, AX25_POLLOFF);
 			break;
 #endif
 		}

 		ax25->vs = next;

 		/*
 		 * Requeue the original data frame.
 		 */
 		skb_queue_tail(&ax25->ack_queue, skb);

 	} while (!last && (skb = skb_dequeue(&ax25->write_queue)) != NULL);

 	ax25->condition &= ~AX25_COND_ACK_PENDING;

 	if (!ax25_t1timer_running(ax25)) {
 		ax25_stop_t3timer(ax25);
 		ax25_calculate_t1(ax25);
 		ax25_start_t1timer(ax25);
 	}
 }

 void ax25_transmit_buffer(ax25_cb *ax25, struct sk_buff *skb, int type)
 {
 	struct sk_buff *skbn;
 	unsigned char *ptr;
 	int headroom;

 	if (ax25->ax25_dev == NULL) {
 		ax25_disconnect(ax25, ENETUNREACH);
 		return;
 	}

 	headroom = ax25_addr_size(ax25->digipeat);

 	if (skb_headroom(skb) < headroom) {
 		if ((skbn = skb_realloc_headroom(skb, headroom)) == NULL) {
 			printk(KERN_CRIT "AX.25: ax25_transmit_buffer - out of memory\n");
 			kfree_skb(skb);
 			return;
 		}

 		if (skb->sk != NULL)
 			skb_set_owner_w(skbn, skb->sk);

 		consume_skb(skb);
 		skb = skbn;
 	}

 	ptr = skb_push(skb, headroom);

 	ax25_addr_build(ptr, &ax25->source_addr, &ax25->dest_addr, ax25->digipeat, type, ax25->modulus);

 	ax25_queue_xmit(skb, ax25->ax25_dev->dev);
 }

 /*
  *	A small shim to dev_queue_xmit to add the KISS control byte, and do
  *	any packet forwarding in operation.
  */
 void ax25_queue_xmit(struct sk_buff *skb, struct net_device *dev)
 {
 	unsigned char *ptr;

 	skb->protocol = ax25_type_trans(skb, ax25_fwd_dev(dev));

 	ptr  = skb_push(skb, 1);
 	*ptr = 0x00;			/* KISS */

 	dev_queue_xmit(skb);
 }

 int ax25_check_iframes_acked(ax25_cb *ax25, unsigned short nr)
 {
 	if (ax25->vs == nr) {
 		ax25_frames_acked(ax25, nr);
 		ax25_calculate_rtt(ax25);
 		ax25_stop_t1timer(ax25);
 		ax25_start_t3timer(ax25);
 		return 1;
 	} else {
 		if (ax25->va != nr) {
 			ax25_frames_acked(ax25, nr);
 			ax25_calculate_t1(ax25);
 			ax25_start_t1timer(ax25);
 			return 1;
 		}
 	}
 	return 0;
 }
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	*
	* Copyright (C) Alan Cox GW4PTS (alan@lxorguk.ukuu.org.uk)
	* Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
	* Copyright (C) Joerg Reuter DL1BKE (jreuter@yaina.de)
	*/
	#include <linux/errno.h>
	#include <linux/types.h>
	#include <linux/socket.h>
	#include <linux/in.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/timer.h>
	#include <linux/string.h>
	#include <linux/sockios.h>
	#include <linux/spinlock.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 <linux/uaccess.h>
	#include <linux/fcntl.h>
	#include <linux/mm.h>
	#include <linux/interrupt.h>

	static DEFINE_SPINLOCK(ax25_frag_lock);

	ax25_cb ax25_send_frame(struct sk_buff skb, int paclen, ax25_address src, ax25_address dest, ax25_digi digi, struct net_device dev)
	{
	ax25_dev *ax25_dev;
	ax25_cb *ax25;

	/*
	* Take the default packet length for the device if zero is
	* specified.
	*/
	if (paclen == 0) {
	if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL)
	return NULL;

	paclen = ax25_dev->values[AX25_VALUES_PACLEN];
	}

	/*
	* Look for an existing connection.
	*/
	if ((ax25 = ax25_find_cb(src, dest, digi, dev)) != NULL) {
	ax25_output(ax25, paclen, skb);
	return ax25; /* It already existed */
	}

	if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL)
	return NULL;

	if ((ax25 = ax25_create_cb()) == NULL)
	return NULL;

	ax25_fillin_cb(ax25, ax25_dev);

	ax25->source_addr = *src;
	ax25->dest_addr = *dest;

	if (digi != NULL) {
	ax25->digipeat = kmemdup(digi, sizeof(*digi), GFP_ATOMIC);
	if (ax25->digipeat == NULL) {
	ax25_cb_put(ax25);
	return NULL;
	}
	}

	switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) {
	case AX25_PROTO_STD_SIMPLEX:
	case AX25_PROTO_STD_DUPLEX:
	ax25_std_establish_data_link(ax25);
	break;

	#ifdef CONFIG_AX25_DAMA_SLAVE
	case AX25_PROTO_DAMA_SLAVE:
	if (ax25_dev->dama.slave)
	ax25_ds_establish_data_link(ax25);
	else
	ax25_std_establish_data_link(ax25);
	break;
	#endif
	}

	/*
	* There is one ref for the state machine; a caller needs
	* one more to put it back, just like with the existing one.
	*/
	ax25_cb_hold(ax25);

	ax25_cb_add(ax25);

	ax25->state = AX25_STATE_1;

	ax25_start_heartbeat(ax25);

	ax25_output(ax25, paclen, skb);

	return ax25; /* We had to create it */
	}

	EXPORT_SYMBOL(ax25_send_frame);

	/*
	* All outgoing AX.25 I frames pass via this routine. Therefore this is
	* where the fragmentation of frames takes place. If fragment is set to
	* zero then we are not allowed to do fragmentation, even if the frame
	* is too large.
	*/
	void ax25_output(ax25_cb ax25, int paclen, struct sk_buff skb)
	{
	struct sk_buff *skbn;
	unsigned char *p;
	int frontlen, len, fragno, ka9qfrag, first = 1;

	if (paclen < 16) {
	WARN_ON_ONCE(1);
	kfree_skb(skb);
	return;
	}

	if ((skb->len - 1) > paclen) {
	if (*skb->data == AX25_P_TEXT) {
	skb_pull(skb, 1); /* skip PID */
	ka9qfrag = 0;
	} else {
	paclen -= 2; /* Allow for fragment control info */
	ka9qfrag = 1;
	}

	fragno = skb->len / paclen;
	if (skb->len % paclen == 0) fragno--;

	frontlen = skb_headroom(skb); /* Address space + CTRL */

	while (skb->len > 0) {
	spin_lock_bh(&ax25_frag_lock);
	if ((skbn = alloc_skb(paclen + 2 + frontlen, GFP_ATOMIC)) == NULL) {
	spin_unlock_bh(&ax25_frag_lock);
	printk(KERN_CRIT "AX.25: ax25_output - out of memory\n");
	return;
	}

	if (skb->sk != NULL)
	skb_set_owner_w(skbn, skb->sk);

	spin_unlock_bh(&ax25_frag_lock);

	len = (paclen > skb->len) ? skb->len : paclen;

	if (ka9qfrag == 1) {
	skb_reserve(skbn, frontlen + 2);
	skb_set_network_header(skbn,
	skb_network_offset(skb));
	skb_copy_from_linear_data(skb, skb_put(skbn, len), len);
	p = skb_push(skbn, 2);

	*p++ = AX25_P_SEGMENT;

	*p = fragno--;
	if (first) {
	*p \|= AX25_SEG_FIRST;
	first = 0;
	}
	} else {
	skb_reserve(skbn, frontlen + 1);
	skb_set_network_header(skbn,
	skb_network_offset(skb));
	skb_copy_from_linear_data(skb, skb_put(skbn, len), len);
	p = skb_push(skbn, 1);
	*p = AX25_P_TEXT;
	}

	skb_pull(skb, len);
	skb_queue_tail(&ax25->write_queue, skbn); /* Throw it on the queue */
	}

	kfree_skb(skb);
	} else {
	skb_queue_tail(&ax25->write_queue, skb); /* Throw it on the queue */
	}

	switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) {
	case AX25_PROTO_STD_SIMPLEX:
	case AX25_PROTO_STD_DUPLEX:
	ax25_kick(ax25);
	break;

	#ifdef CONFIG_AX25_DAMA_SLAVE
	/*
	* A DAMA slave is _required_ to work as normal AX.25L2V2
	* if no DAMA master is available.
	*/
	case AX25_PROTO_DAMA_SLAVE:
	if (!ax25->ax25_dev->dama.slave) ax25_kick(ax25);
	break;
	#endif
	}
	}

	/*
	* This procedure is passed a buffer descriptor for an iframe. It builds
	* the rest of the control part of the frame and then writes it out.
	*/
	static void ax25_send_iframe(ax25_cb ax25, struct sk_buff skb, int poll_bit)
	{
	unsigned char *frame;

	if (skb == NULL)
	return;

	skb_reset_network_header(skb);

	if (ax25->modulus == AX25_MODULUS) {
	frame = skb_push(skb, 1);

	*frame = AX25_I;
	*frame \|= (poll_bit) ? AX25_PF : 0;
	*frame \|= (ax25->vr << 5);
	*frame \|= (ax25->vs << 1);
	} else {
	frame = skb_push(skb, 2);

	frame[0] = AX25_I;
	frame[0] \|= (ax25->vs << 1);
	frame[1] = (poll_bit) ? AX25_EPF : 0;
	frame[1] \|= (ax25->vr << 1);
	}

	ax25_start_idletimer(ax25);

	ax25_transmit_buffer(ax25, skb, AX25_COMMAND);
	}

	void ax25_kick(ax25_cb *ax25)
	{
	struct sk_buff skb, skbn;
	int last = 1;
	unsigned short start, end, next;

	if (ax25->state != AX25_STATE_3 && ax25->state != AX25_STATE_4)
	return;

	if (ax25->condition & AX25_COND_PEER_RX_BUSY)
	return;

	if (skb_peek(&ax25->write_queue) == NULL)
	return;

	start = (skb_peek(&ax25->ack_queue) == NULL) ? ax25->va : ax25->vs;
	end = (ax25->va + ax25->window) % ax25->modulus;

	if (start == end)
	return;

	/*
	* Transmit data until either we're out of data to send or
	* the window is full. Send a poll on the final I frame if
	* the window is filled.
	*/

	/*
	* Dequeue the frame and copy it.
	* Check for race with ax25_clear_queues().
	*/
	skb = skb_dequeue(&ax25->write_queue);
	if (!skb)
	return;

	ax25->vs = start;

	do {
	if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
	skb_queue_head(&ax25->write_queue, skb);
	break;
	}

	if (skb->sk != NULL)
	skb_set_owner_w(skbn, skb->sk);

	next = (ax25->vs + 1) % ax25->modulus;
	last = (next == end);

	/*
	* Transmit the frame copy.
	* bke 960114: do not set the Poll bit on the last frame
	* in DAMA mode.
	*/
	switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) {
	case AX25_PROTO_STD_SIMPLEX:
	case AX25_PROTO_STD_DUPLEX:
	ax25_send_iframe(ax25, skbn, (last) ? AX25_POLLON : AX25_POLLOFF);
	break;

	#ifdef CONFIG_AX25_DAMA_SLAVE
	case AX25_PROTO_DAMA_SLAVE:
	ax25_send_iframe(ax25, skbn, AX25_POLLOFF);
	break;
	#endif
	}

	ax25->vs = next;

	/*
	* Requeue the original data frame.
	*/
	skb_queue_tail(&ax25->ack_queue, skb);

	} while (!last && (skb = skb_dequeue(&ax25->write_queue)) != NULL);

	ax25->condition &= ~AX25_COND_ACK_PENDING;

	if (!ax25_t1timer_running(ax25)) {
	ax25_stop_t3timer(ax25);
	ax25_calculate_t1(ax25);
	ax25_start_t1timer(ax25);
	}
	}

	void ax25_transmit_buffer(ax25_cb ax25, struct sk_buff skb, int type)
	{
	struct sk_buff *skbn;
	unsigned char *ptr;
	int headroom;

	if (ax25->ax25_dev == NULL) {
	ax25_disconnect(ax25, ENETUNREACH);
	return;
	}

	headroom = ax25_addr_size(ax25->digipeat);

	if (skb_headroom(skb) < headroom) {
	if ((skbn = skb_realloc_headroom(skb, headroom)) == NULL) {
	printk(KERN_CRIT "AX.25: ax25_transmit_buffer - out of memory\n");
	kfree_skb(skb);
	return;
	}

	if (skb->sk != NULL)
	skb_set_owner_w(skbn, skb->sk);

	consume_skb(skb);
	skb = skbn;
	}

	ptr = skb_push(skb, headroom);

	ax25_addr_build(ptr, &ax25->source_addr, &ax25->dest_addr, ax25->digipeat, type, ax25->modulus);

	ax25_queue_xmit(skb, ax25->ax25_dev->dev);
	}

	/*
	* A small shim to dev_queue_xmit to add the KISS control byte, and do
	* any packet forwarding in operation.
	*/
	void ax25_queue_xmit(struct sk_buff skb, struct net_device dev)
	{
	unsigned char *ptr;

	skb->protocol = ax25_type_trans(skb, ax25_fwd_dev(dev));

	ptr = skb_push(skb, 1);
	ptr = 0x00; / KISS */

	dev_queue_xmit(skb);
	}

	int ax25_check_iframes_acked(ax25_cb *ax25, unsigned short nr)
	{
	if (ax25->vs == nr) {
	ax25_frames_acked(ax25, nr);
	ax25_calculate_rtt(ax25);
	ax25_stop_t1timer(ax25);
	ax25_start_t3timer(ax25);
	return 1;
	} else {
	if (ax25->va != nr) {
	ax25_frames_acked(ax25, nr);
	ax25_calculate_t1(ax25);
	ax25_start_t1timer(ax25);
	return 1;
	}
	}
	return 0;
	}