294 lines
7.0 KiB
C
294 lines
7.0 KiB
C
/*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* Copyright (C) Alan Cox GW4PTS (alan@lxorguk.ukuu.org.uk)
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* Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
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* Copyright (C) Joerg Reuter DL1BKE (jreuter@yaina.de)
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* Copyright (C) Frederic Rible F1OAT (frible@teaser.fr)
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*/
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#include <linux/errno.h>
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#include <linux/types.h>
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#include <linux/socket.h>
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#include <linux/in.h>
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#include <linux/kernel.h>
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#include <linux/sched.h>
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#include <linux/timer.h>
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#include <linux/string.h>
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#include <linux/sockios.h>
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#include <linux/net.h>
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#include <net/ax25.h>
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#include <linux/inet.h>
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#include <linux/netdevice.h>
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#include <linux/skbuff.h>
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#include <net/sock.h>
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#include <net/tcp.h>
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#include <asm/uaccess.h>
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#include <asm/system.h>
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#include <linux/fcntl.h>
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#include <linux/mm.h>
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#include <linux/interrupt.h>
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/*
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* This routine purges all the queues of frames.
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*/
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void ax25_clear_queues(ax25_cb *ax25)
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{
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skb_queue_purge(&ax25->write_queue);
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skb_queue_purge(&ax25->ack_queue);
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skb_queue_purge(&ax25->reseq_queue);
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skb_queue_purge(&ax25->frag_queue);
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}
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/*
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* This routine purges the input queue of those frames that have been
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* acknowledged. This replaces the boxes labelled "V(a) <- N(r)" on the
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* SDL diagram.
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*/
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void ax25_frames_acked(ax25_cb *ax25, unsigned short nr)
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{
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struct sk_buff *skb;
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/*
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* Remove all the ack-ed frames from the ack queue.
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*/
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if (ax25->va != nr) {
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while (skb_peek(&ax25->ack_queue) != NULL && ax25->va != nr) {
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skb = skb_dequeue(&ax25->ack_queue);
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kfree_skb(skb);
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ax25->va = (ax25->va + 1) % ax25->modulus;
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}
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}
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}
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void ax25_requeue_frames(ax25_cb *ax25)
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{
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struct sk_buff *skb, *skb_prev = NULL;
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/*
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* Requeue all the un-ack-ed frames on the output queue to be picked
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* up by ax25_kick called from the timer. This arrangement handles the
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* possibility of an empty output queue.
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*/
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while ((skb = skb_dequeue(&ax25->ack_queue)) != NULL) {
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if (skb_prev == NULL)
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skb_queue_head(&ax25->write_queue, skb);
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else
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skb_append(skb_prev, skb);
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skb_prev = skb;
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}
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}
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/*
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* Validate that the value of nr is between va and vs. Return true or
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* false for testing.
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*/
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int ax25_validate_nr(ax25_cb *ax25, unsigned short nr)
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{
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unsigned short vc = ax25->va;
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while (vc != ax25->vs) {
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if (nr == vc) return 1;
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vc = (vc + 1) % ax25->modulus;
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}
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if (nr == ax25->vs) return 1;
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return 0;
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}
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/*
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* This routine is the centralised routine for parsing the control
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* information for the different frame formats.
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*/
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int ax25_decode(ax25_cb *ax25, struct sk_buff *skb, int *ns, int *nr, int *pf)
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{
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unsigned char *frame;
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int frametype = AX25_ILLEGAL;
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frame = skb->data;
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*ns = *nr = *pf = 0;
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if (ax25->modulus == AX25_MODULUS) {
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if ((frame[0] & AX25_S) == 0) {
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frametype = AX25_I; /* I frame - carries NR/NS/PF */
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*ns = (frame[0] >> 1) & 0x07;
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*nr = (frame[0] >> 5) & 0x07;
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*pf = frame[0] & AX25_PF;
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} else if ((frame[0] & AX25_U) == 1) { /* S frame - take out PF/NR */
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frametype = frame[0] & 0x0F;
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*nr = (frame[0] >> 5) & 0x07;
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*pf = frame[0] & AX25_PF;
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} else if ((frame[0] & AX25_U) == 3) { /* U frame - take out PF */
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frametype = frame[0] & ~AX25_PF;
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*pf = frame[0] & AX25_PF;
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}
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skb_pull(skb, 1);
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} else {
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if ((frame[0] & AX25_S) == 0) {
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frametype = AX25_I; /* I frame - carries NR/NS/PF */
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*ns = (frame[0] >> 1) & 0x7F;
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*nr = (frame[1] >> 1) & 0x7F;
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*pf = frame[1] & AX25_EPF;
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skb_pull(skb, 2);
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} else if ((frame[0] & AX25_U) == 1) { /* S frame - take out PF/NR */
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frametype = frame[0] & 0x0F;
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*nr = (frame[1] >> 1) & 0x7F;
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*pf = frame[1] & AX25_EPF;
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skb_pull(skb, 2);
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} else if ((frame[0] & AX25_U) == 3) { /* U frame - take out PF */
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frametype = frame[0] & ~AX25_PF;
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*pf = frame[0] & AX25_PF;
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skb_pull(skb, 1);
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}
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}
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return frametype;
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}
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/*
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* This routine is called when the HDLC layer internally generates a
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* command or response for the remote machine ( eg. RR, UA etc. ).
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* Only supervisory or unnumbered frames are processed.
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*/
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void ax25_send_control(ax25_cb *ax25, int frametype, int poll_bit, int type)
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{
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struct sk_buff *skb;
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unsigned char *dptr;
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if ((skb = alloc_skb(ax25->ax25_dev->dev->hard_header_len + 2, GFP_ATOMIC)) == NULL)
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return;
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skb_reserve(skb, ax25->ax25_dev->dev->hard_header_len);
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skb->nh.raw = skb->data;
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/* Assume a response - address structure for DTE */
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if (ax25->modulus == AX25_MODULUS) {
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dptr = skb_put(skb, 1);
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*dptr = frametype;
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*dptr |= (poll_bit) ? AX25_PF : 0;
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if ((frametype & AX25_U) == AX25_S) /* S frames carry NR */
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*dptr |= (ax25->vr << 5);
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} else {
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if ((frametype & AX25_U) == AX25_U) {
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dptr = skb_put(skb, 1);
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*dptr = frametype;
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*dptr |= (poll_bit) ? AX25_PF : 0;
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} else {
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dptr = skb_put(skb, 2);
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dptr[0] = frametype;
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dptr[1] = (ax25->vr << 1);
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dptr[1] |= (poll_bit) ? AX25_EPF : 0;
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}
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}
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ax25_transmit_buffer(ax25, skb, type);
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}
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/*
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* Send a 'DM' to an unknown connection attempt, or an invalid caller.
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*
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* Note: src here is the sender, thus it's the target of the DM
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*/
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void ax25_return_dm(struct net_device *dev, ax25_address *src, ax25_address *dest, ax25_digi *digi)
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{
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struct sk_buff *skb;
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char *dptr;
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ax25_digi retdigi;
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if (dev == NULL)
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return;
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if ((skb = alloc_skb(dev->hard_header_len + 1, GFP_ATOMIC)) == NULL)
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return; /* Next SABM will get DM'd */
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skb_reserve(skb, dev->hard_header_len);
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skb->nh.raw = skb->data;
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ax25_digi_invert(digi, &retdigi);
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dptr = skb_put(skb, 1);
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*dptr = AX25_DM | AX25_PF;
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/*
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* Do the address ourselves
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*/
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dptr = skb_push(skb, ax25_addr_size(digi));
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dptr += ax25_addr_build(dptr, dest, src, &retdigi, AX25_RESPONSE, AX25_MODULUS);
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ax25_queue_xmit(skb, dev);
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}
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/*
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* Exponential backoff for AX.25
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*/
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void ax25_calculate_t1(ax25_cb *ax25)
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{
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int n, t = 2;
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switch (ax25->backoff) {
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case 0:
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break;
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case 1:
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t += 2 * ax25->n2count;
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break;
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case 2:
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for (n = 0; n < ax25->n2count; n++)
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t *= 2;
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if (t > 8) t = 8;
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break;
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}
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ax25->t1 = t * ax25->rtt;
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}
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/*
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* Calculate the Round Trip Time
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*/
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void ax25_calculate_rtt(ax25_cb *ax25)
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{
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if (ax25->backoff == 0)
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return;
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if (ax25_t1timer_running(ax25) && ax25->n2count == 0)
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ax25->rtt = (9 * ax25->rtt + ax25->t1 - ax25_display_timer(&ax25->t1timer)) / 10;
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if (ax25->rtt < AX25_T1CLAMPLO)
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ax25->rtt = AX25_T1CLAMPLO;
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if (ax25->rtt > AX25_T1CLAMPHI)
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ax25->rtt = AX25_T1CLAMPHI;
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}
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void ax25_disconnect(ax25_cb *ax25, int reason)
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{
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ax25_clear_queues(ax25);
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ax25_stop_t1timer(ax25);
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ax25_stop_t2timer(ax25);
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ax25_stop_t3timer(ax25);
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ax25_stop_idletimer(ax25);
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ax25->state = AX25_STATE_0;
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ax25_link_failed(ax25, reason);
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if (ax25->sk != NULL) {
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bh_lock_sock(ax25->sk);
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ax25->sk->sk_state = TCP_CLOSE;
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ax25->sk->sk_err = reason;
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ax25->sk->sk_shutdown |= SEND_SHUTDOWN;
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if (!sock_flag(ax25->sk, SOCK_DEAD)) {
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ax25->sk->sk_state_change(ax25->sk);
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sock_set_flag(ax25->sk, SOCK_DEAD);
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}
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bh_unlock_sock(ax25->sk);
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}
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}
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