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-rw-r--r--net/lapb/lapb_subr.c313
1 files changed, 313 insertions, 0 deletions
diff --git a/net/lapb/lapb_subr.c b/net/lapb/lapb_subr.c
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--- /dev/null
+++ b/net/lapb/lapb_subr.c
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+/*
+ * LAPB release 002
+ *
+ * This code REQUIRES 2.1.15 or higher/ NET3.038
+ *
+ * This module:
+ * This module 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.
+ *
+ * History
+ * LAPB 001 Jonathan Naylor Started Coding
+ */
+
+#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 <linux/inet.h>
+#include <linux/skbuff.h>
+#include <net/sock.h>
+#include <asm/uaccess.h>
+#include <asm/system.h>
+#include <linux/fcntl.h>
+#include <linux/mm.h>
+#include <linux/interrupt.h>
+#include <net/lapb.h>
+
+/*
+ * This routine purges all the queues of frames.
+ */
+void lapb_clear_queues(struct lapb_cb *lapb)
+{
+ skb_queue_purge(&lapb->write_queue);
+ skb_queue_purge(&lapb->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 lapb_frames_acked(struct lapb_cb *lapb, unsigned short nr)
+{
+ struct sk_buff *skb;
+ int modulus;
+
+ modulus = (lapb->mode & LAPB_EXTENDED) ? LAPB_EMODULUS : LAPB_SMODULUS;
+
+ /*
+ * Remove all the ack-ed frames from the ack queue.
+ */
+ if (lapb->va != nr)
+ while (skb_peek(&lapb->ack_queue) && lapb->va != nr) {
+ skb = skb_dequeue(&lapb->ack_queue);
+ kfree_skb(skb);
+ lapb->va = (lapb->va + 1) % modulus;
+ }
+}
+
+void lapb_requeue_frames(struct lapb_cb *lapb)
+{
+ struct sk_buff *skb, *skb_prev = NULL;
+
+ /*
+ * Requeue all the un-ack-ed frames on the output queue to be picked
+ * up by lapb_kick called from the timer. This arrangement handles the
+ * possibility of an empty output queue.
+ */
+ while ((skb = skb_dequeue(&lapb->ack_queue)) != NULL) {
+ if (!skb_prev)
+ skb_queue_head(&lapb->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 lapb_validate_nr(struct lapb_cb *lapb, unsigned short nr)
+{
+ unsigned short vc = lapb->va;
+ int modulus;
+
+ modulus = (lapb->mode & LAPB_EXTENDED) ? LAPB_EMODULUS : LAPB_SMODULUS;
+
+ while (vc != lapb->vs) {
+ if (nr == vc)
+ return 1;
+ vc = (vc + 1) % modulus;
+ }
+
+ return nr == lapb->vs;
+}
+
+/*
+ * This routine is the centralised routine for parsing the control
+ * information for the different frame formats.
+ */
+int lapb_decode(struct lapb_cb *lapb, struct sk_buff *skb,
+ struct lapb_frame *frame)
+{
+ frame->type = LAPB_ILLEGAL;
+
+#if LAPB_DEBUG > 2
+ printk(KERN_DEBUG "lapb: (%p) S%d RX %02X %02X %02X\n",
+ lapb->dev, lapb->state,
+ skb->data[0], skb->data[1], skb->data[2]);
+#endif
+
+ /* We always need to look at 2 bytes, sometimes we need
+ * to look at 3 and those cases are handled below.
+ */
+ if (!pskb_may_pull(skb, 2))
+ return -1;
+
+ if (lapb->mode & LAPB_MLP) {
+ if (lapb->mode & LAPB_DCE) {
+ if (skb->data[0] == LAPB_ADDR_D)
+ frame->cr = LAPB_COMMAND;
+ if (skb->data[0] == LAPB_ADDR_C)
+ frame->cr = LAPB_RESPONSE;
+ } else {
+ if (skb->data[0] == LAPB_ADDR_C)
+ frame->cr = LAPB_COMMAND;
+ if (skb->data[0] == LAPB_ADDR_D)
+ frame->cr = LAPB_RESPONSE;
+ }
+ } else {
+ if (lapb->mode & LAPB_DCE) {
+ if (skb->data[0] == LAPB_ADDR_B)
+ frame->cr = LAPB_COMMAND;
+ if (skb->data[0] == LAPB_ADDR_A)
+ frame->cr = LAPB_RESPONSE;
+ } else {
+ if (skb->data[0] == LAPB_ADDR_A)
+ frame->cr = LAPB_COMMAND;
+ if (skb->data[0] == LAPB_ADDR_B)
+ frame->cr = LAPB_RESPONSE;
+ }
+ }
+
+ skb_pull(skb, 1);
+
+ if (lapb->mode & LAPB_EXTENDED) {
+ if (!(skb->data[0] & LAPB_S)) {
+ if (!pskb_may_pull(skb, 2))
+ return -1;
+ /*
+ * I frame - carries NR/NS/PF
+ */
+ frame->type = LAPB_I;
+ frame->ns = (skb->data[0] >> 1) & 0x7F;
+ frame->nr = (skb->data[1] >> 1) & 0x7F;
+ frame->pf = skb->data[1] & LAPB_EPF;
+ frame->control[0] = skb->data[0];
+ frame->control[1] = skb->data[1];
+ skb_pull(skb, 2);
+ } else if ((skb->data[0] & LAPB_U) == 1) {
+ if (!pskb_may_pull(skb, 2))
+ return -1;
+ /*
+ * S frame - take out PF/NR
+ */
+ frame->type = skb->data[0] & 0x0F;
+ frame->nr = (skb->data[1] >> 1) & 0x7F;
+ frame->pf = skb->data[1] & LAPB_EPF;
+ frame->control[0] = skb->data[0];
+ frame->control[1] = skb->data[1];
+ skb_pull(skb, 2);
+ } else if ((skb->data[0] & LAPB_U) == 3) {
+ /*
+ * U frame - take out PF
+ */
+ frame->type = skb->data[0] & ~LAPB_SPF;
+ frame->pf = skb->data[0] & LAPB_SPF;
+ frame->control[0] = skb->data[0];
+ frame->control[1] = 0x00;
+ skb_pull(skb, 1);
+ }
+ } else {
+ if (!(skb->data[0] & LAPB_S)) {
+ /*
+ * I frame - carries NR/NS/PF
+ */
+ frame->type = LAPB_I;
+ frame->ns = (skb->data[0] >> 1) & 0x07;
+ frame->nr = (skb->data[0] >> 5) & 0x07;
+ frame->pf = skb->data[0] & LAPB_SPF;
+ } else if ((skb->data[0] & LAPB_U) == 1) {
+ /*
+ * S frame - take out PF/NR
+ */
+ frame->type = skb->data[0] & 0x0F;
+ frame->nr = (skb->data[0] >> 5) & 0x07;
+ frame->pf = skb->data[0] & LAPB_SPF;
+ } else if ((skb->data[0] & LAPB_U) == 3) {
+ /*
+ * U frame - take out PF
+ */
+ frame->type = skb->data[0] & ~LAPB_SPF;
+ frame->pf = skb->data[0] & LAPB_SPF;
+ }
+
+ frame->control[0] = skb->data[0];
+
+ skb_pull(skb, 1);
+ }
+
+ return 0;
+}
+
+/*
+ * 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, FRMRs are handled
+ * by lapb_transmit_frmr below.
+ */
+void lapb_send_control(struct lapb_cb *lapb, int frametype,
+ int poll_bit, int type)
+{
+ struct sk_buff *skb;
+ unsigned char *dptr;
+
+ if ((skb = alloc_skb(LAPB_HEADER_LEN + 3, GFP_ATOMIC)) == NULL)
+ return;
+
+ skb_reserve(skb, LAPB_HEADER_LEN + 1);
+
+ if (lapb->mode & LAPB_EXTENDED) {
+ if ((frametype & LAPB_U) == LAPB_U) {
+ dptr = skb_put(skb, 1);
+ *dptr = frametype;
+ *dptr |= poll_bit ? LAPB_SPF : 0;
+ } else {
+ dptr = skb_put(skb, 2);
+ dptr[0] = frametype;
+ dptr[1] = (lapb->vr << 1);
+ dptr[1] |= poll_bit ? LAPB_EPF : 0;
+ }
+ } else {
+ dptr = skb_put(skb, 1);
+ *dptr = frametype;
+ *dptr |= poll_bit ? LAPB_SPF : 0;
+ if ((frametype & LAPB_U) == LAPB_S) /* S frames carry NR */
+ *dptr |= (lapb->vr << 5);
+ }
+
+ lapb_transmit_buffer(lapb, skb, type);
+}
+
+/*
+ * This routine generates FRMRs based on information previously stored in
+ * the LAPB control block.
+ */
+void lapb_transmit_frmr(struct lapb_cb *lapb)
+{
+ struct sk_buff *skb;
+ unsigned char *dptr;
+
+ if ((skb = alloc_skb(LAPB_HEADER_LEN + 7, GFP_ATOMIC)) == NULL)
+ return;
+
+ skb_reserve(skb, LAPB_HEADER_LEN + 1);
+
+ if (lapb->mode & LAPB_EXTENDED) {
+ dptr = skb_put(skb, 6);
+ *dptr++ = LAPB_FRMR;
+ *dptr++ = lapb->frmr_data.control[0];
+ *dptr++ = lapb->frmr_data.control[1];
+ *dptr++ = (lapb->vs << 1) & 0xFE;
+ *dptr = (lapb->vr << 1) & 0xFE;
+ if (lapb->frmr_data.cr == LAPB_RESPONSE)
+ *dptr |= 0x01;
+ dptr++;
+ *dptr++ = lapb->frmr_type;
+
+#if LAPB_DEBUG > 1
+ printk(KERN_DEBUG "lapb: (%p) S%d TX FRMR %02X %02X %02X %02X %02X\n",
+ lapb->dev, lapb->state,
+ skb->data[1], skb->data[2], skb->data[3],
+ skb->data[4], skb->data[5]);
+#endif
+ } else {
+ dptr = skb_put(skb, 4);
+ *dptr++ = LAPB_FRMR;
+ *dptr++ = lapb->frmr_data.control[0];
+ *dptr = (lapb->vs << 1) & 0x0E;
+ *dptr |= (lapb->vr << 5) & 0xE0;
+ if (lapb->frmr_data.cr == LAPB_RESPONSE)
+ *dptr |= 0x10;
+ dptr++;
+ *dptr++ = lapb->frmr_type;
+
+#if LAPB_DEBUG > 1
+ printk(KERN_DEBUG "lapb: (%p) S%d TX FRMR %02X %02X %02X\n",
+ lapb->dev, lapb->state, skb->data[1],
+ skb->data[2], skb->data[3]);
+#endif
+ }
+
+ lapb_transmit_buffer(lapb, skb, LAPB_RESPONSE);
+}
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