/* * 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/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, &lapb->write_queue); 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); }