1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * LAPB release 002 4 * 5 * This code REQUIRES 2.1.15 or higher/ NET3.038 6 * 7 * History 8 * LAPB 001 Jonathan Naylor Started Coding 9 * LAPB 002 Jonathan Naylor New timer architecture. 10 */ 11 12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 13 14 #include <linux/errno.h> 15 #include <linux/types.h> 16 #include <linux/socket.h> 17 #include <linux/in.h> 18 #include <linux/kernel.h> 19 #include <linux/jiffies.h> 20 #include <linux/timer.h> 21 #include <linux/string.h> 22 #include <linux/sockios.h> 23 #include <linux/net.h> 24 #include <linux/inet.h> 25 #include <linux/skbuff.h> 26 #include <net/sock.h> 27 #include <linux/uaccess.h> 28 #include <linux/fcntl.h> 29 #include <linux/mm.h> 30 #include <linux/interrupt.h> 31 #include <net/lapb.h> 32 33 static void lapb_t1timer_expiry(struct timer_list *); 34 static void lapb_t2timer_expiry(struct timer_list *); 35 36 void lapb_start_t1timer(struct lapb_cb *lapb) 37 { 38 del_timer(&lapb->t1timer); 39 40 lapb->t1timer.function = lapb_t1timer_expiry; 41 lapb->t1timer.expires = jiffies + lapb->t1; 42 43 add_timer(&lapb->t1timer); 44 } 45 46 void lapb_start_t2timer(struct lapb_cb *lapb) 47 { 48 del_timer(&lapb->t2timer); 49 50 lapb->t2timer.function = lapb_t2timer_expiry; 51 lapb->t2timer.expires = jiffies + lapb->t2; 52 53 add_timer(&lapb->t2timer); 54 } 55 56 void lapb_stop_t1timer(struct lapb_cb *lapb) 57 { 58 del_timer(&lapb->t1timer); 59 } 60 61 void lapb_stop_t2timer(struct lapb_cb *lapb) 62 { 63 del_timer(&lapb->t2timer); 64 } 65 66 int lapb_t1timer_running(struct lapb_cb *lapb) 67 { 68 return timer_pending(&lapb->t1timer); 69 } 70 71 static void lapb_t2timer_expiry(struct timer_list *t) 72 { 73 struct lapb_cb *lapb = from_timer(lapb, t, t2timer); 74 75 if (lapb->condition & LAPB_ACK_PENDING_CONDITION) { 76 lapb->condition &= ~LAPB_ACK_PENDING_CONDITION; 77 lapb_timeout_response(lapb); 78 } 79 } 80 81 static void lapb_t1timer_expiry(struct timer_list *t) 82 { 83 struct lapb_cb *lapb = from_timer(lapb, t, t1timer); 84 85 switch (lapb->state) { 86 87 /* 88 * If we are a DCE, send DM up to N2 times, then switch to 89 * STATE_1 and send SABM(E). 90 */ 91 case LAPB_STATE_0: 92 if (lapb->mode & LAPB_DCE && 93 lapb->n2count != lapb->n2) { 94 lapb->n2count++; 95 lapb_send_control(lapb, LAPB_DM, LAPB_POLLOFF, LAPB_RESPONSE); 96 } else { 97 lapb->state = LAPB_STATE_1; 98 lapb_establish_data_link(lapb); 99 } 100 break; 101 102 /* 103 * Awaiting connection state, send SABM(E), up to N2 times. 104 */ 105 case LAPB_STATE_1: 106 if (lapb->n2count == lapb->n2) { 107 lapb_clear_queues(lapb); 108 lapb->state = LAPB_STATE_0; 109 lapb_disconnect_indication(lapb, LAPB_TIMEDOUT); 110 lapb_dbg(0, "(%p) S1 -> S0\n", lapb->dev); 111 return; 112 } else { 113 lapb->n2count++; 114 if (lapb->mode & LAPB_EXTENDED) { 115 lapb_dbg(1, "(%p) S1 TX SABME(1)\n", 116 lapb->dev); 117 lapb_send_control(lapb, LAPB_SABME, LAPB_POLLON, LAPB_COMMAND); 118 } else { 119 lapb_dbg(1, "(%p) S1 TX SABM(1)\n", 120 lapb->dev); 121 lapb_send_control(lapb, LAPB_SABM, LAPB_POLLON, LAPB_COMMAND); 122 } 123 } 124 break; 125 126 /* 127 * Awaiting disconnection state, send DISC, up to N2 times. 128 */ 129 case LAPB_STATE_2: 130 if (lapb->n2count == lapb->n2) { 131 lapb_clear_queues(lapb); 132 lapb->state = LAPB_STATE_0; 133 lapb_disconnect_confirmation(lapb, LAPB_TIMEDOUT); 134 lapb_dbg(0, "(%p) S2 -> S0\n", lapb->dev); 135 return; 136 } else { 137 lapb->n2count++; 138 lapb_dbg(1, "(%p) S2 TX DISC(1)\n", lapb->dev); 139 lapb_send_control(lapb, LAPB_DISC, LAPB_POLLON, LAPB_COMMAND); 140 } 141 break; 142 143 /* 144 * Data transfer state, restransmit I frames, up to N2 times. 145 */ 146 case LAPB_STATE_3: 147 if (lapb->n2count == lapb->n2) { 148 lapb_clear_queues(lapb); 149 lapb->state = LAPB_STATE_0; 150 lapb_stop_t2timer(lapb); 151 lapb_disconnect_indication(lapb, LAPB_TIMEDOUT); 152 lapb_dbg(0, "(%p) S3 -> S0\n", lapb->dev); 153 return; 154 } else { 155 lapb->n2count++; 156 lapb_requeue_frames(lapb); 157 lapb_kick(lapb); 158 } 159 break; 160 161 /* 162 * Frame reject state, restransmit FRMR frames, up to N2 times. 163 */ 164 case LAPB_STATE_4: 165 if (lapb->n2count == lapb->n2) { 166 lapb_clear_queues(lapb); 167 lapb->state = LAPB_STATE_0; 168 lapb_disconnect_indication(lapb, LAPB_TIMEDOUT); 169 lapb_dbg(0, "(%p) S4 -> S0\n", lapb->dev); 170 return; 171 } else { 172 lapb->n2count++; 173 lapb_transmit_frmr(lapb); 174 } 175 break; 176 } 177 178 lapb_start_t1timer(lapb); 179 } 180