net/lapb/lapb_out.c

0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /*
0003  *  LAPB release 002
0004  *
0005  *  This code REQUIRES 2.1.15 or higher/ NET3.038
0006  *
0007  *  History
0008  *  LAPB 001    Jonathan Naylor Started Coding
0009  *  LAPB 002    Jonathan Naylor New timer architecture.
0010  */
0011
0012 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
0013
0014 #include <linux/errno.h>
0015 #include <linux/types.h>
0016 #include <linux/socket.h>
0017 #include <linux/in.h>
0018 #include <linux/kernel.h>
0019 #include <linux/timer.h>
0020 #include <linux/string.h>
0021 #include <linux/sockios.h>
0022 #include <linux/net.h>
0023 #include <linux/inet.h>
0024 #include <linux/skbuff.h>
0025 #include <linux/slab.h>
0026 #include <net/sock.h>
0027 #include <linux/uaccess.h>
0028 #include <linux/fcntl.h>
0029 #include <linux/mm.h>
0030 #include <linux/interrupt.h>
0031 #include <net/lapb.h>
0032
0033 /*
0034  *  This procedure is passed a buffer descriptor for an iframe. It builds
0035  *  the rest of the control part of the frame and then writes it out.
0036  */
0037 static void lapb_send_iframe(struct lapb_cb *lapb, struct sk_buff *skb, int poll_bit)
0038 {
0039     unsigned char *frame;
0040
0041     if (!skb)
0042         return;
0043
0044     if (lapb->mode & LAPB_EXTENDED) {
0045         frame = skb_push(skb, 2);
0046
0047         frame[0] = LAPB_I;
0048         frame[0] |= lapb->vs << 1;
0049         frame[1] = poll_bit ? LAPB_EPF : 0;
0050         frame[1] |= lapb->vr << 1;
0051     } else {
0052         frame = skb_push(skb, 1);
0053
0054         *frame = LAPB_I;
0055         *frame |= poll_bit ? LAPB_SPF : 0;
0056         *frame |= lapb->vr << 5;
0057         *frame |= lapb->vs << 1;
0058     }
0059
0060     lapb_dbg(1, "(%p) S%d TX I(%d) S%d R%d\n",
0061          lapb->dev, lapb->state, poll_bit, lapb->vs, lapb->vr);
0062
0063     lapb_transmit_buffer(lapb, skb, LAPB_COMMAND);
0064 }
0065
0066 void lapb_kick(struct lapb_cb *lapb)
0067 {
0068     struct sk_buff *skb, *skbn;
0069     unsigned short modulus, start, end;
0070
0071     modulus = (lapb->mode & LAPB_EXTENDED) ? LAPB_EMODULUS : LAPB_SMODULUS;
0072     start = !skb_peek(&lapb->ack_queue) ? lapb->va : lapb->vs;
0073     end   = (lapb->va + lapb->window) % modulus;
0074
0075     if (!(lapb->condition & LAPB_PEER_RX_BUSY_CONDITION) &&
0076         start != end && skb_peek(&lapb->write_queue)) {
0077         lapb->vs = start;
0078
0079         /*
0080          * Dequeue the frame and copy it.
0081          */
0082         skb = skb_dequeue(&lapb->write_queue);
0083
0084         do {
0085             skbn = skb_copy(skb, GFP_ATOMIC);
0086             if (!skbn) {
0087                 skb_queue_head(&lapb->write_queue, skb);
0088                 break;
0089             }
0090
0091             if (skb->sk)
0092                 skb_set_owner_w(skbn, skb->sk);
0093
0094             /*
0095              * Transmit the frame copy.
0096              */
0097             lapb_send_iframe(lapb, skbn, LAPB_POLLOFF);
0098
0099             lapb->vs = (lapb->vs + 1) % modulus;
0100
0101             /*
0102              * Requeue the original data frame.
0103              */
0104             skb_queue_tail(&lapb->ack_queue, skb);
0105
0106         } while (lapb->vs != end && (skb = skb_dequeue(&lapb->write_queue)) != NULL);
0107
0108         lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
0109
0110         if (!lapb_t1timer_running(lapb))
0111             lapb_start_t1timer(lapb);
0112     }
0113 }
0114
0115 void lapb_transmit_buffer(struct lapb_cb *lapb, struct sk_buff *skb, int type)
0116 {
0117     unsigned char *ptr;
0118
0119     ptr = skb_push(skb, 1);
0120
0121     if (lapb->mode & LAPB_MLP) {
0122         if (lapb->mode & LAPB_DCE) {
0123             if (type == LAPB_COMMAND)
0124                 *ptr = LAPB_ADDR_C;
0125             if (type == LAPB_RESPONSE)
0126                 *ptr = LAPB_ADDR_D;
0127         } else {
0128             if (type == LAPB_COMMAND)
0129                 *ptr = LAPB_ADDR_D;
0130             if (type == LAPB_RESPONSE)
0131                 *ptr = LAPB_ADDR_C;
0132         }
0133     } else {
0134         if (lapb->mode & LAPB_DCE) {
0135             if (type == LAPB_COMMAND)
0136                 *ptr = LAPB_ADDR_A;
0137             if (type == LAPB_RESPONSE)
0138                 *ptr = LAPB_ADDR_B;
0139         } else {
0140             if (type == LAPB_COMMAND)
0141                 *ptr = LAPB_ADDR_B;
0142             if (type == LAPB_RESPONSE)
0143                 *ptr = LAPB_ADDR_A;
0144         }
0145     }
0146
0147     lapb_dbg(2, "(%p) S%d TX %3ph\n", lapb->dev, lapb->state, skb->data);
0148
0149     if (!lapb_data_transmit(lapb, skb))
0150         kfree_skb(skb);
0151 }
0152
0153 void lapb_establish_data_link(struct lapb_cb *lapb)
0154 {
0155     lapb->condition = 0x00;
0156     lapb->n2count   = 0;
0157
0158     if (lapb->mode & LAPB_EXTENDED) {
0159         lapb_dbg(1, "(%p) S%d TX SABME(1)\n", lapb->dev, lapb->state);
0160         lapb_send_control(lapb, LAPB_SABME, LAPB_POLLON, LAPB_COMMAND);
0161     } else {
0162         lapb_dbg(1, "(%p) S%d TX SABM(1)\n", lapb->dev, lapb->state);
0163         lapb_send_control(lapb, LAPB_SABM, LAPB_POLLON, LAPB_COMMAND);
0164     }
0165
0166     lapb_start_t1timer(lapb);
0167     lapb_stop_t2timer(lapb);
0168 }
0169
0170 void lapb_enquiry_response(struct lapb_cb *lapb)
0171 {
0172     lapb_dbg(1, "(%p) S%d TX RR(1) R%d\n",
0173          lapb->dev, lapb->state, lapb->vr);
0174
0175     lapb_send_control(lapb, LAPB_RR, LAPB_POLLON, LAPB_RESPONSE);
0176
0177     lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
0178 }
0179
0180 void lapb_timeout_response(struct lapb_cb *lapb)
0181 {
0182     lapb_dbg(1, "(%p) S%d TX RR(0) R%d\n",
0183          lapb->dev, lapb->state, lapb->vr);
0184     lapb_send_control(lapb, LAPB_RR, LAPB_POLLOFF, LAPB_RESPONSE);
0185
0186     lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
0187 }
0188
0189 void lapb_check_iframes_acked(struct lapb_cb *lapb, unsigned short nr)
0190 {
0191     if (lapb->vs == nr) {
0192         lapb_frames_acked(lapb, nr);
0193         lapb_stop_t1timer(lapb);
0194         lapb->n2count = 0;
0195     } else if (lapb->va != nr) {
0196         lapb_frames_acked(lapb, nr);
0197         lapb_start_t1timer(lapb);
0198     }
0199 }
0200
0201 void lapb_check_need_response(struct lapb_cb *lapb, int type, int pf)
0202 {
0203     if (type == LAPB_COMMAND && pf)
0204         lapb_enquiry_response(lapb);
0205 }