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299 lines
7.3 KiB
299 lines
7.3 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* LAPB release 002 |
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* |
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* This code REQUIRES 2.1.15 or higher/ NET3.038 |
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* |
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* History |
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* LAPB 001 Jonathan Naylor Started Coding |
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*/ |
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
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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/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 <linux/inet.h> |
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#include <linux/skbuff.h> |
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#include <linux/slab.h> |
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#include <net/sock.h> |
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#include <linux/uaccess.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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#include <net/lapb.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 lapb_clear_queues(struct lapb_cb *lapb) |
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{ |
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skb_queue_purge(&lapb->write_queue); |
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skb_queue_purge(&lapb->ack_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 lapb_frames_acked(struct lapb_cb *lapb, unsigned short nr) |
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{ |
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struct sk_buff *skb; |
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int modulus; |
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modulus = (lapb->mode & LAPB_EXTENDED) ? LAPB_EMODULUS : LAPB_SMODULUS; |
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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 (lapb->va != nr) |
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while (skb_peek(&lapb->ack_queue) && lapb->va != nr) { |
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skb = skb_dequeue(&lapb->ack_queue); |
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kfree_skb(skb); |
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lapb->va = (lapb->va + 1) % modulus; |
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} |
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} |
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void lapb_requeue_frames(struct lapb_cb *lapb) |
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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 lapb_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(&lapb->ack_queue)) != NULL) { |
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if (!skb_prev) |
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skb_queue_head(&lapb->write_queue, skb); |
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else |
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skb_append(skb_prev, skb, &lapb->write_queue); |
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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 lapb_validate_nr(struct lapb_cb *lapb, unsigned short nr) |
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{ |
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unsigned short vc = lapb->va; |
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int modulus; |
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modulus = (lapb->mode & LAPB_EXTENDED) ? LAPB_EMODULUS : LAPB_SMODULUS; |
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while (vc != lapb->vs) { |
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if (nr == vc) |
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return 1; |
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vc = (vc + 1) % modulus; |
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} |
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return nr == lapb->vs; |
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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 lapb_decode(struct lapb_cb *lapb, struct sk_buff *skb, |
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struct lapb_frame *frame) |
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{ |
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frame->type = LAPB_ILLEGAL; |
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lapb_dbg(2, "(%p) S%d RX %3ph\n", lapb->dev, lapb->state, skb->data); |
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/* We always need to look at 2 bytes, sometimes we need |
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* to look at 3 and those cases are handled below. |
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*/ |
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if (!pskb_may_pull(skb, 2)) |
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return -1; |
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if (lapb->mode & LAPB_MLP) { |
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if (lapb->mode & LAPB_DCE) { |
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if (skb->data[0] == LAPB_ADDR_D) |
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frame->cr = LAPB_COMMAND; |
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if (skb->data[0] == LAPB_ADDR_C) |
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frame->cr = LAPB_RESPONSE; |
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} else { |
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if (skb->data[0] == LAPB_ADDR_C) |
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frame->cr = LAPB_COMMAND; |
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if (skb->data[0] == LAPB_ADDR_D) |
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frame->cr = LAPB_RESPONSE; |
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} |
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} else { |
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if (lapb->mode & LAPB_DCE) { |
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if (skb->data[0] == LAPB_ADDR_B) |
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frame->cr = LAPB_COMMAND; |
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if (skb->data[0] == LAPB_ADDR_A) |
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frame->cr = LAPB_RESPONSE; |
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} else { |
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if (skb->data[0] == LAPB_ADDR_A) |
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frame->cr = LAPB_COMMAND; |
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if (skb->data[0] == LAPB_ADDR_B) |
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frame->cr = LAPB_RESPONSE; |
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} |
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} |
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skb_pull(skb, 1); |
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if (lapb->mode & LAPB_EXTENDED) { |
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if (!(skb->data[0] & LAPB_S)) { |
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if (!pskb_may_pull(skb, 2)) |
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return -1; |
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/* |
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* I frame - carries NR/NS/PF |
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*/ |
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frame->type = LAPB_I; |
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frame->ns = (skb->data[0] >> 1) & 0x7F; |
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frame->nr = (skb->data[1] >> 1) & 0x7F; |
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frame->pf = skb->data[1] & LAPB_EPF; |
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frame->control[0] = skb->data[0]; |
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frame->control[1] = skb->data[1]; |
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skb_pull(skb, 2); |
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} else if ((skb->data[0] & LAPB_U) == 1) { |
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if (!pskb_may_pull(skb, 2)) |
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return -1; |
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/* |
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* S frame - take out PF/NR |
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*/ |
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frame->type = skb->data[0] & 0x0F; |
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frame->nr = (skb->data[1] >> 1) & 0x7F; |
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frame->pf = skb->data[1] & LAPB_EPF; |
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frame->control[0] = skb->data[0]; |
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frame->control[1] = skb->data[1]; |
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skb_pull(skb, 2); |
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} else if ((skb->data[0] & LAPB_U) == 3) { |
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/* |
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* U frame - take out PF |
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*/ |
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frame->type = skb->data[0] & ~LAPB_SPF; |
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frame->pf = skb->data[0] & LAPB_SPF; |
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frame->control[0] = skb->data[0]; |
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frame->control[1] = 0x00; |
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skb_pull(skb, 1); |
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} |
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} else { |
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if (!(skb->data[0] & LAPB_S)) { |
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/* |
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* I frame - carries NR/NS/PF |
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*/ |
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frame->type = LAPB_I; |
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frame->ns = (skb->data[0] >> 1) & 0x07; |
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frame->nr = (skb->data[0] >> 5) & 0x07; |
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frame->pf = skb->data[0] & LAPB_SPF; |
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} else if ((skb->data[0] & LAPB_U) == 1) { |
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/* |
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* S frame - take out PF/NR |
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*/ |
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frame->type = skb->data[0] & 0x0F; |
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frame->nr = (skb->data[0] >> 5) & 0x07; |
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frame->pf = skb->data[0] & LAPB_SPF; |
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} else if ((skb->data[0] & LAPB_U) == 3) { |
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/* |
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* U frame - take out PF |
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*/ |
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frame->type = skb->data[0] & ~LAPB_SPF; |
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frame->pf = skb->data[0] & LAPB_SPF; |
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} |
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frame->control[0] = skb->data[0]; |
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skb_pull(skb, 1); |
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} |
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return 0; |
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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, FRMRs are handled |
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* by lapb_transmit_frmr below. |
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*/ |
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void lapb_send_control(struct lapb_cb *lapb, int frametype, |
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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(LAPB_HEADER_LEN + 3, GFP_ATOMIC)) == NULL) |
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return; |
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skb_reserve(skb, LAPB_HEADER_LEN + 1); |
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if (lapb->mode & LAPB_EXTENDED) { |
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if ((frametype & LAPB_U) == LAPB_U) { |
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dptr = skb_put(skb, 1); |
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*dptr = frametype; |
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*dptr |= poll_bit ? LAPB_SPF : 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] = (lapb->vr << 1); |
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dptr[1] |= poll_bit ? LAPB_EPF : 0; |
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} |
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} else { |
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dptr = skb_put(skb, 1); |
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*dptr = frametype; |
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*dptr |= poll_bit ? LAPB_SPF : 0; |
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if ((frametype & LAPB_U) == LAPB_S) /* S frames carry NR */ |
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*dptr |= (lapb->vr << 5); |
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} |
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lapb_transmit_buffer(lapb, skb, type); |
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} |
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/* |
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* This routine generates FRMRs based on information previously stored in |
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* the LAPB control block. |
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*/ |
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void lapb_transmit_frmr(struct lapb_cb *lapb) |
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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(LAPB_HEADER_LEN + 7, GFP_ATOMIC)) == NULL) |
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return; |
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skb_reserve(skb, LAPB_HEADER_LEN + 1); |
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if (lapb->mode & LAPB_EXTENDED) { |
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dptr = skb_put(skb, 6); |
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*dptr++ = LAPB_FRMR; |
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*dptr++ = lapb->frmr_data.control[0]; |
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*dptr++ = lapb->frmr_data.control[1]; |
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*dptr++ = (lapb->vs << 1) & 0xFE; |
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*dptr = (lapb->vr << 1) & 0xFE; |
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if (lapb->frmr_data.cr == LAPB_RESPONSE) |
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*dptr |= 0x01; |
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dptr++; |
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*dptr++ = lapb->frmr_type; |
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lapb_dbg(1, "(%p) S%d TX FRMR %5ph\n", |
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lapb->dev, lapb->state, |
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&skb->data[1]); |
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} else { |
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dptr = skb_put(skb, 4); |
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*dptr++ = LAPB_FRMR; |
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*dptr++ = lapb->frmr_data.control[0]; |
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*dptr = (lapb->vs << 1) & 0x0E; |
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*dptr |= (lapb->vr << 5) & 0xE0; |
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if (lapb->frmr_data.cr == LAPB_RESPONSE) |
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*dptr |= 0x10; |
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dptr++; |
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*dptr++ = lapb->frmr_type; |
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lapb_dbg(1, "(%p) S%d TX FRMR %3ph\n", |
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lapb->dev, lapb->state, &skb->data[1]); |
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} |
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lapb_transmit_buffer(lapb, skb, LAPB_RESPONSE); |
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}
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