1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * 4 * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk) 5 * Copyright (C) Joerg Reuter DL1BKE (jreuter@yaina.de) 6 */ 7 #include <linux/errno.h> 8 #include <linux/types.h> 9 #include <linux/socket.h> 10 #include <linux/in.h> 11 #include <linux/kernel.h> 12 #include <linux/timer.h> 13 #include <linux/string.h> 14 #include <linux/sockios.h> 15 #include <linux/spinlock.h> 16 #include <linux/net.h> 17 #include <linux/gfp.h> 18 #include <net/ax25.h> 19 #include <linux/inet.h> 20 #include <linux/netdevice.h> 21 #include <linux/skbuff.h> 22 #include <net/sock.h> 23 #include <linux/uaccess.h> 24 #include <linux/fcntl.h> 25 #include <linux/mm.h> 26 #include <linux/interrupt.h> 27 28 void ax25_ds_nr_error_recovery(ax25_cb *ax25) 29 { 30 ax25_ds_establish_data_link(ax25); 31 } 32 33 /* 34 * dl1bke 960114: transmit I frames on DAMA poll 35 */ 36 void ax25_ds_enquiry_response(ax25_cb *ax25) 37 { 38 ax25_cb *ax25o; 39 40 /* Please note that neither DK4EG's nor DG2FEF's 41 * DAMA spec mention the following behaviour as seen 42 * with TheFirmware: 43 * 44 * DB0ACH->DL1BKE <RR C P R0> [DAMA] 45 * DL1BKE->DB0ACH <I NR=0 NS=0> 46 * DL1BKE-7->DB0PRA-6 DB0ACH <I C S3 R5> 47 * DL1BKE->DB0ACH <RR R F R0> 48 * 49 * The Flexnet DAMA Master implementation apparently 50 * insists on the "proper" AX.25 behaviour: 51 * 52 * DB0ACH->DL1BKE <RR C P R0> [DAMA] 53 * DL1BKE->DB0ACH <RR R F R0> 54 * DL1BKE->DB0ACH <I NR=0 NS=0> 55 * DL1BKE-7->DB0PRA-6 DB0ACH <I C S3 R5> 56 * 57 * Flexnet refuses to send us *any* I frame if we send 58 * a REJ in case AX25_COND_REJECT is set. It is superfluous in 59 * this mode anyway (a RR or RNR invokes the retransmission). 60 * Is this a Flexnet bug? 61 */ 62 63 ax25_std_enquiry_response(ax25); 64 65 if (!(ax25->condition & AX25_COND_PEER_RX_BUSY)) { 66 ax25_requeue_frames(ax25); 67 ax25_kick(ax25); 68 } 69 70 if (ax25->state == AX25_STATE_1 || ax25->state == AX25_STATE_2 || skb_peek(&ax25->ack_queue) != NULL) 71 ax25_ds_t1_timeout(ax25); 72 else 73 ax25->n2count = 0; 74 75 ax25_start_t3timer(ax25); 76 ax25_ds_set_timer(ax25->ax25_dev); 77 78 spin_lock(&ax25_list_lock); 79 ax25_for_each(ax25o, &ax25_list) { 80 if (ax25o == ax25) 81 continue; 82 83 if (ax25o->ax25_dev != ax25->ax25_dev) 84 continue; 85 86 if (ax25o->state == AX25_STATE_1 || ax25o->state == AX25_STATE_2) { 87 ax25_ds_t1_timeout(ax25o); 88 continue; 89 } 90 91 if (!(ax25o->condition & AX25_COND_PEER_RX_BUSY) && ax25o->state == AX25_STATE_3) { 92 ax25_requeue_frames(ax25o); 93 ax25_kick(ax25o); 94 } 95 96 if (ax25o->state == AX25_STATE_1 || ax25o->state == AX25_STATE_2 || skb_peek(&ax25o->ack_queue) != NULL) 97 ax25_ds_t1_timeout(ax25o); 98 99 /* do not start T3 for listening sockets (tnx DD8NE) */ 100 101 if (ax25o->state != AX25_STATE_0) 102 ax25_start_t3timer(ax25o); 103 } 104 spin_unlock(&ax25_list_lock); 105 } 106 107 void ax25_ds_establish_data_link(ax25_cb *ax25) 108 { 109 ax25->condition &= AX25_COND_DAMA_MODE; 110 ax25->n2count = 0; 111 ax25_calculate_t1(ax25); 112 ax25_start_t1timer(ax25); 113 ax25_stop_t2timer(ax25); 114 ax25_start_t3timer(ax25); 115 } 116 117 /* 118 * :::FIXME::: 119 * This is a kludge. Not all drivers recognize kiss commands. 120 * We need a driver level request to switch duplex mode, that does 121 * either SCC changing, PI config or KISS as required. Currently 122 * this request isn't reliable. 123 */ 124 static void ax25_kiss_cmd(ax25_dev *ax25_dev, unsigned char cmd, unsigned char param) 125 { 126 struct sk_buff *skb; 127 unsigned char *p; 128 129 if (ax25_dev->dev == NULL) 130 return; 131 132 if ((skb = alloc_skb(2, GFP_ATOMIC)) == NULL) 133 return; 134 135 skb_reset_network_header(skb); 136 p = skb_put(skb, 2); 137 138 *p++ = cmd; 139 *p++ = param; 140 141 skb->protocol = ax25_type_trans(skb, ax25_dev->dev); 142 143 dev_queue_xmit(skb); 144 } 145 146 /* 147 * A nasty problem arises if we count the number of DAMA connections 148 * wrong, especially when connections on the device already existed 149 * and our network node (or the sysop) decides to turn on DAMA Master 150 * mode. We thus flag the 'real' slave connections with 151 * ax25->dama_slave=1 and look on every disconnect if still slave 152 * connections exist. 153 */ 154 static int ax25_check_dama_slave(ax25_dev *ax25_dev) 155 { 156 ax25_cb *ax25; 157 int res = 0; 158 159 spin_lock(&ax25_list_lock); 160 ax25_for_each(ax25, &ax25_list) 161 if (ax25->ax25_dev == ax25_dev && (ax25->condition & AX25_COND_DAMA_MODE) && ax25->state > AX25_STATE_1) { 162 res = 1; 163 break; 164 } 165 spin_unlock(&ax25_list_lock); 166 167 return res; 168 } 169 170 static void ax25_dev_dama_on(ax25_dev *ax25_dev) 171 { 172 if (ax25_dev == NULL) 173 return; 174 175 if (ax25_dev->dama.slave == 0) 176 ax25_kiss_cmd(ax25_dev, 5, 1); 177 178 ax25_dev->dama.slave = 1; 179 ax25_ds_set_timer(ax25_dev); 180 } 181 182 void ax25_dev_dama_off(ax25_dev *ax25_dev) 183 { 184 if (ax25_dev == NULL) 185 return; 186 187 if (ax25_dev->dama.slave && !ax25_check_dama_slave(ax25_dev)) { 188 ax25_kiss_cmd(ax25_dev, 5, 0); 189 ax25_dev->dama.slave = 0; 190 ax25_ds_del_timer(ax25_dev); 191 } 192 } 193 194 void ax25_dama_on(ax25_cb *ax25) 195 { 196 ax25_dev_dama_on(ax25->ax25_dev); 197 ax25->condition |= AX25_COND_DAMA_MODE; 198 } 199 200 void ax25_dama_off(ax25_cb *ax25) 201 { 202 ax25->condition &= ~AX25_COND_DAMA_MODE; 203 ax25_dev_dama_off(ax25->ax25_dev); 204 } 205