1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * X.25 Packet Layer release 002 4 * 5 * This is ALPHA test software. This code may break your machine, 6 * randomly fail to work with new releases, misbehave and/or generally 7 * screw up. It might even work. 8 * 9 * This code REQUIRES 2.1.15 or higher 10 * 11 * History 12 * X.25 001 Jonathan Naylor Started coding. 13 * X.25 002 Jonathan Naylor New timer architecture. 14 * Centralised disconnection processing. 15 */ 16 17 #include <linux/errno.h> 18 #include <linux/jiffies.h> 19 #include <linux/timer.h> 20 #include <net/sock.h> 21 #include <net/tcp_states.h> 22 #include <net/x25.h> 23 24 static void x25_heartbeat_expiry(struct timer_list *t); 25 static void x25_timer_expiry(struct timer_list *t); 26 27 void x25_init_timers(struct sock *sk) 28 { 29 struct x25_sock *x25 = x25_sk(sk); 30 31 timer_setup(&x25->timer, x25_timer_expiry, 0); 32 33 /* initialized by sock_init_data */ 34 sk->sk_timer.function = x25_heartbeat_expiry; 35 } 36 37 void x25_start_heartbeat(struct sock *sk) 38 { 39 sk_reset_timer(sk, &sk->sk_timer, jiffies + 5 * HZ); 40 } 41 42 void x25_stop_heartbeat(struct sock *sk) 43 { 44 sk_stop_timer(sk, &sk->sk_timer); 45 } 46 47 void x25_start_t2timer(struct sock *sk) 48 { 49 struct x25_sock *x25 = x25_sk(sk); 50 51 sk_reset_timer(sk, &x25->timer, jiffies + x25->t2); 52 } 53 54 void x25_start_t21timer(struct sock *sk) 55 { 56 struct x25_sock *x25 = x25_sk(sk); 57 58 sk_reset_timer(sk, &x25->timer, jiffies + x25->t21); 59 } 60 61 void x25_start_t22timer(struct sock *sk) 62 { 63 struct x25_sock *x25 = x25_sk(sk); 64 65 sk_reset_timer(sk, &x25->timer, jiffies + x25->t22); 66 } 67 68 void x25_start_t23timer(struct sock *sk) 69 { 70 struct x25_sock *x25 = x25_sk(sk); 71 72 sk_reset_timer(sk, &x25->timer, jiffies + x25->t23); 73 } 74 75 void x25_stop_timer(struct sock *sk) 76 { 77 sk_stop_timer(sk, &x25_sk(sk)->timer); 78 } 79 80 unsigned long x25_display_timer(struct sock *sk) 81 { 82 struct x25_sock *x25 = x25_sk(sk); 83 84 if (!timer_pending(&x25->timer)) 85 return 0; 86 87 return x25->timer.expires - jiffies; 88 } 89 90 static void x25_heartbeat_expiry(struct timer_list *t) 91 { 92 struct sock *sk = timer_container_of(sk, t, sk_timer); 93 94 bh_lock_sock(sk); 95 if (sock_owned_by_user(sk)) /* can currently only occur in state 3 */ 96 goto restart_heartbeat; 97 98 switch (x25_sk(sk)->state) { 99 100 case X25_STATE_0: 101 /* 102 * Magic here: If we listen() and a new link dies 103 * before it is accepted() it isn't 'dead' so doesn't 104 * get removed. 105 */ 106 if (sock_flag(sk, SOCK_DESTROY) || 107 (sk->sk_state == TCP_LISTEN && 108 sock_flag(sk, SOCK_DEAD))) { 109 bh_unlock_sock(sk); 110 x25_destroy_socket_from_timer(sk); 111 goto out; 112 } 113 break; 114 115 case X25_STATE_3: 116 /* 117 * Check for the state of the receive buffer. 118 */ 119 x25_check_rbuf(sk); 120 break; 121 } 122 restart_heartbeat: 123 /* Do not rearm once __x25_destroy_socket() has unlinked the socket: 124 * it is past its cancel point and owns the teardown from there on. 125 */ 126 if (sk_hashed(sk)) 127 x25_start_heartbeat(sk); 128 bh_unlock_sock(sk); 129 out: 130 sock_put(sk); 131 } 132 133 /* 134 * Timer has expired, it may have been T2, T21, T22, or T23. We can tell 135 * by the state machine state. 136 */ 137 static inline void x25_do_timer_expiry(struct sock * sk) 138 { 139 struct x25_sock *x25 = x25_sk(sk); 140 141 switch (x25->state) { 142 143 case X25_STATE_3: /* T2 */ 144 if (x25->condition & X25_COND_ACK_PENDING) { 145 x25->condition &= ~X25_COND_ACK_PENDING; 146 x25_enquiry_response(sk); 147 } 148 break; 149 150 case X25_STATE_1: /* T21 */ 151 case X25_STATE_4: /* T22 */ 152 x25_write_internal(sk, X25_CLEAR_REQUEST); 153 x25->state = X25_STATE_2; 154 x25_start_t23timer(sk); 155 break; 156 157 case X25_STATE_2: /* T23 */ 158 x25_disconnect(sk, ETIMEDOUT, 0, 0); 159 break; 160 } 161 } 162 163 static void x25_timer_expiry(struct timer_list *t) 164 { 165 struct x25_sock *x25 = timer_container_of(x25, t, timer); 166 struct sock *sk = &x25->sk; 167 168 bh_lock_sock(sk); 169 if (sock_owned_by_user(sk)) { /* can currently only occur in state 3 */ 170 if (x25_sk(sk)->state == X25_STATE_3) 171 x25_start_t2timer(sk); 172 } else 173 x25_do_timer_expiry(sk); 174 bh_unlock_sock(sk); 175 sock_put(sk); 176 } 177