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-rw-r--r--net/ax25/ax25_subr.c295
1 files changed, 295 insertions, 0 deletions
diff --git a/net/ax25/ax25_subr.c b/net/ax25/ax25_subr.c
new file mode 100644
index 00000000000..8cf72707af8
--- /dev/null
+++ b/net/ax25/ax25_subr.c
@@ -0,0 +1,295 @@
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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)
+ * Copyright (C) Frederic Rible F1OAT (frible@teaser.fr)
+ */
+#include <linux/errno.h>
+#include <linux/types.h>
+#include <linux/socket.h>
+#include <linux/in.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/timer.h>
+#include <linux/string.h>
+#include <linux/sockios.h>
+#include <linux/net.h>
+#include <net/ax25.h>
+#include <linux/inet.h>
+#include <linux/netdevice.h>
+#include <linux/skbuff.h>
+#include <net/sock.h>
+#include <net/tcp.h>
+#include <asm/uaccess.h>
+#include <asm/system.h>
+#include <linux/fcntl.h>
+#include <linux/mm.h>
+#include <linux/interrupt.h>
+
+/*
+ * This routine purges all the queues of frames.
+ */
+void ax25_clear_queues(ax25_cb *ax25)
+{
+ skb_queue_purge(&ax25->write_queue);
+ skb_queue_purge(&ax25->ack_queue);
+ skb_queue_purge(&ax25->reseq_queue);
+ skb_queue_purge(&ax25->frag_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 ax25_frames_acked(ax25_cb *ax25, unsigned short nr)
+{
+ struct sk_buff *skb;
+
+ /*
+ * Remove all the ack-ed frames from the ack queue.
+ */
+ if (ax25->va != nr) {
+ while (skb_peek(&ax25->ack_queue) != NULL && ax25->va != nr) {
+ skb = skb_dequeue(&ax25->ack_queue);
+ kfree_skb(skb);
+ ax25->va = (ax25->va + 1) % ax25->modulus;
+ }
+ }
+}
+
+void ax25_requeue_frames(ax25_cb *ax25)
+{
+ struct sk_buff *skb, *skb_prev = NULL;
+
+ /*
+ * Requeue all the un-ack-ed frames on the output queue to be picked
+ * up by ax25_kick called from the timer. This arrangement handles the
+ * possibility of an empty output queue.
+ */
+ while ((skb = skb_dequeue(&ax25->ack_queue)) != NULL) {
+ if (skb_prev == NULL)
+ skb_queue_head(&ax25->write_queue, skb);
+ else
+ skb_append(skb_prev, skb);
+ skb_prev = skb;
+ }
+}
+
+/*
+ * Validate that the value of nr is between va and vs. Return true or
+ * false for testing.
+ */
+int ax25_validate_nr(ax25_cb *ax25, unsigned short nr)
+{
+ unsigned short vc = ax25->va;
+
+ while (vc != ax25->vs) {
+ if (nr == vc) return 1;
+ vc = (vc + 1) % ax25->modulus;
+ }
+
+ if (nr == ax25->vs) return 1;
+
+ return 0;
+}
+
+/*
+ * This routine is the centralised routine for parsing the control
+ * information for the different frame formats.
+ */
+int ax25_decode(ax25_cb *ax25, struct sk_buff *skb, int *ns, int *nr, int *pf)
+{
+ unsigned char *frame;
+ int frametype = AX25_ILLEGAL;
+
+ frame = skb->data;
+ *ns = *nr = *pf = 0;
+
+ if (ax25->modulus == AX25_MODULUS) {
+ if ((frame[0] & AX25_S) == 0) {
+ frametype = AX25_I; /* I frame - carries NR/NS/PF */
+ *ns = (frame[0] >> 1) & 0x07;
+ *nr = (frame[0] >> 5) & 0x07;
+ *pf = frame[0] & AX25_PF;
+ } else if ((frame[0] & AX25_U) == 1) { /* S frame - take out PF/NR */
+ frametype = frame[0] & 0x0F;
+ *nr = (frame[0] >> 5) & 0x07;
+ *pf = frame[0] & AX25_PF;
+ } else if ((frame[0] & AX25_U) == 3) { /* U frame - take out PF */
+ frametype = frame[0] & ~AX25_PF;
+ *pf = frame[0] & AX25_PF;
+ }
+ skb_pull(skb, 1);
+ } else {
+ if ((frame[0] & AX25_S) == 0) {
+ frametype = AX25_I; /* I frame - carries NR/NS/PF */
+ *ns = (frame[0] >> 1) & 0x7F;
+ *nr = (frame[1] >> 1) & 0x7F;
+ *pf = frame[1] & AX25_EPF;
+ skb_pull(skb, 2);
+ } else if ((frame[0] & AX25_U) == 1) { /* S frame - take out PF/NR */
+ frametype = frame[0] & 0x0F;
+ *nr = (frame[1] >> 1) & 0x7F;
+ *pf = frame[1] & AX25_EPF;
+ skb_pull(skb, 2);
+ } else if ((frame[0] & AX25_U) == 3) { /* U frame - take out PF */
+ frametype = frame[0] & ~AX25_PF;
+ *pf = frame[0] & AX25_PF;
+ skb_pull(skb, 1);
+ }
+ }
+
+ return frametype;
+}
+
+/*
+ * This routine is called when the HDLC layer internally generates a
+ * command or response for the remote machine ( eg. RR, UA etc. ).
+ * Only supervisory or unnumbered frames are processed.
+ */
+void ax25_send_control(ax25_cb *ax25, int frametype, int poll_bit, int type)
+{
+ struct sk_buff *skb;
+ unsigned char *dptr;
+
+ if ((skb = alloc_skb(ax25->ax25_dev->dev->hard_header_len + 2, GFP_ATOMIC)) == NULL)
+ return;
+
+ skb_reserve(skb, ax25->ax25_dev->dev->hard_header_len);
+
+ skb->nh.raw = skb->data;
+
+ /* Assume a response - address structure for DTE */
+ if (ax25->modulus == AX25_MODULUS) {
+ dptr = skb_put(skb, 1);
+ *dptr = frametype;
+ *dptr |= (poll_bit) ? AX25_PF : 0;
+ if ((frametype & AX25_U) == AX25_S) /* S frames carry NR */
+ *dptr |= (ax25->vr << 5);
+ } else {
+ if ((frametype & AX25_U) == AX25_U) {
+ dptr = skb_put(skb, 1);
+ *dptr = frametype;
+ *dptr |= (poll_bit) ? AX25_PF : 0;
+ } else {
+ dptr = skb_put(skb, 2);
+ dptr[0] = frametype;
+ dptr[1] = (ax25->vr << 1);
+ dptr[1] |= (poll_bit) ? AX25_EPF : 0;
+ }
+ }
+
+ ax25_transmit_buffer(ax25, skb, type);
+}
+
+/*
+ * Send a 'DM' to an unknown connection attempt, or an invalid caller.
+ *
+ * Note: src here is the sender, thus it's the target of the DM
+ */
+void ax25_return_dm(struct net_device *dev, ax25_address *src, ax25_address *dest, ax25_digi *digi)
+{
+ struct sk_buff *skb;
+ char *dptr;
+ ax25_digi retdigi;
+
+ if (dev == NULL)
+ return;
+
+ if ((skb = alloc_skb(dev->hard_header_len + 1, GFP_ATOMIC)) == NULL)
+ return; /* Next SABM will get DM'd */
+
+ skb_reserve(skb, dev->hard_header_len);
+ skb->nh.raw = skb->data;
+
+ ax25_digi_invert(digi, &retdigi);
+
+ dptr = skb_put(skb, 1);
+
+ *dptr = AX25_DM | AX25_PF;
+
+ /*
+ * Do the address ourselves
+ */
+ dptr = skb_push(skb, ax25_addr_size(digi));
+ dptr += ax25_addr_build(dptr, dest, src, &retdigi, AX25_RESPONSE, AX25_MODULUS);
+
+ skb->dev = dev;
+
+ ax25_queue_xmit(skb);
+}
+
+/*
+ * Exponential backoff for AX.25
+ */
+void ax25_calculate_t1(ax25_cb *ax25)
+{
+ int n, t = 2;
+
+ switch (ax25->backoff) {
+ case 0:
+ break;
+
+ case 1:
+ t += 2 * ax25->n2count;
+ break;
+
+ case 2:
+ for (n = 0; n < ax25->n2count; n++)
+ t *= 2;
+ if (t > 8) t = 8;
+ break;
+ }
+
+ ax25->t1 = t * ax25->rtt;
+}
+
+/*
+ * Calculate the Round Trip Time
+ */
+void ax25_calculate_rtt(ax25_cb *ax25)
+{
+ if (ax25->backoff == 0)
+ return;
+
+ if (ax25_t1timer_running(ax25) && ax25->n2count == 0)
+ ax25->rtt = (9 * ax25->rtt + ax25->t1 - ax25_display_timer(&ax25->t1timer)) / 10;
+
+ if (ax25->rtt < AX25_T1CLAMPLO)
+ ax25->rtt = AX25_T1CLAMPLO;
+
+ if (ax25->rtt > AX25_T1CLAMPHI)
+ ax25->rtt = AX25_T1CLAMPHI;
+}
+
+void ax25_disconnect(ax25_cb *ax25, int reason)
+{
+ ax25_clear_queues(ax25);
+
+ ax25_stop_t1timer(ax25);
+ ax25_stop_t2timer(ax25);
+ ax25_stop_t3timer(ax25);
+ ax25_stop_idletimer(ax25);
+
+ ax25->state = AX25_STATE_0;
+
+ ax25_link_failed(ax25, reason);
+
+ if (ax25->sk != NULL) {
+ bh_lock_sock(ax25->sk);
+ ax25->sk->sk_state = TCP_CLOSE;
+ ax25->sk->sk_err = reason;
+ ax25->sk->sk_shutdown |= SEND_SHUTDOWN;
+ if (!sock_flag(ax25->sk, SOCK_DEAD)) {
+ ax25->sk->sk_state_change(ax25->sk);
+ sock_set_flag(ax25->sk, SOCK_DEAD);
+ }
+ bh_unlock_sock(ax25->sk);
+ }
+}
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