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-rw-r--r--net/rose/rose_in.c293
1 files changed, 293 insertions, 0 deletions
diff --git a/net/rose/rose_in.c b/net/rose/rose_in.c
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+++ b/net/rose/rose_in.c
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+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *
+ * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
+ *
+ * Most of this code is based on the SDL diagrams published in the 7th ARRL
+ * Computer Networking Conference papers. The diagrams have mistakes in them,
+ * but are mostly correct. Before you modify the code could you read the SDL
+ * diagrams as the code is not obvious and probably very easy to break.
+ */
+#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 <net/ax25.h>
+#include <linux/inet.h>
+#include <linux/netdevice.h>
+#include <linux/skbuff.h>
+#include <net/sock.h>
+#include <net/tcp_states.h>
+#include <linux/fcntl.h>
+#include <linux/mm.h>
+#include <linux/interrupt.h>
+#include <net/rose.h>
+
+/*
+ * State machine for state 1, Awaiting Call Accepted State.
+ * The handling of the timer(s) is in file rose_timer.c.
+ * Handling of state 0 and connection release is in af_rose.c.
+ */
+static int rose_state1_machine(struct sock *sk, struct sk_buff *skb, int frametype)
+{
+ struct rose_sock *rose = rose_sk(sk);
+
+ switch (frametype) {
+ case ROSE_CALL_ACCEPTED:
+ rose_stop_timer(sk);
+ rose_start_idletimer(sk);
+ rose->condition = 0x00;
+ rose->vs = 0;
+ rose->va = 0;
+ rose->vr = 0;
+ rose->vl = 0;
+ rose->state = ROSE_STATE_3;
+ sk->sk_state = TCP_ESTABLISHED;
+ if (!sock_flag(sk, SOCK_DEAD))
+ sk->sk_state_change(sk);
+ break;
+
+ case ROSE_CLEAR_REQUEST:
+ rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
+ rose_disconnect(sk, ECONNREFUSED, skb->data[3], skb->data[4]);
+ rose->neighbour->use--;
+ break;
+
+ default:
+ break;
+ }
+
+ return 0;
+}
+
+/*
+ * State machine for state 2, Awaiting Clear Confirmation State.
+ * The handling of the timer(s) is in file rose_timer.c
+ * Handling of state 0 and connection release is in af_rose.c.
+ */
+static int rose_state2_machine(struct sock *sk, struct sk_buff *skb, int frametype)
+{
+ struct rose_sock *rose = rose_sk(sk);
+
+ switch (frametype) {
+ case ROSE_CLEAR_REQUEST:
+ rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
+ rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
+ rose->neighbour->use--;
+ break;
+
+ case ROSE_CLEAR_CONFIRMATION:
+ rose_disconnect(sk, 0, -1, -1);
+ rose->neighbour->use--;
+ break;
+
+ default:
+ break;
+ }
+
+ return 0;
+}
+
+/*
+ * State machine for state 3, Connected State.
+ * The handling of the timer(s) is in file rose_timer.c
+ * Handling of state 0 and connection release is in af_rose.c.
+ */
+static int rose_state3_machine(struct sock *sk, struct sk_buff *skb, int frametype, int ns, int nr, int q, int d, int m)
+{
+ struct rose_sock *rose = rose_sk(sk);
+ int queued = 0;
+
+ switch (frametype) {
+ case ROSE_RESET_REQUEST:
+ rose_stop_timer(sk);
+ rose_start_idletimer(sk);
+ rose_write_internal(sk, ROSE_RESET_CONFIRMATION);
+ rose->condition = 0x00;
+ rose->vs = 0;
+ rose->vr = 0;
+ rose->va = 0;
+ rose->vl = 0;
+ rose_requeue_frames(sk);
+ break;
+
+ case ROSE_CLEAR_REQUEST:
+ rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
+ rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
+ rose->neighbour->use--;
+ break;
+
+ case ROSE_RR:
+ case ROSE_RNR:
+ if (!rose_validate_nr(sk, nr)) {
+ rose_write_internal(sk, ROSE_RESET_REQUEST);
+ rose->condition = 0x00;
+ rose->vs = 0;
+ rose->vr = 0;
+ rose->va = 0;
+ rose->vl = 0;
+ rose->state = ROSE_STATE_4;
+ rose_start_t2timer(sk);
+ rose_stop_idletimer(sk);
+ } else {
+ rose_frames_acked(sk, nr);
+ if (frametype == ROSE_RNR) {
+ rose->condition |= ROSE_COND_PEER_RX_BUSY;
+ } else {
+ rose->condition &= ~ROSE_COND_PEER_RX_BUSY;
+ }
+ }
+ break;
+
+ case ROSE_DATA: /* XXX */
+ rose->condition &= ~ROSE_COND_PEER_RX_BUSY;
+ if (!rose_validate_nr(sk, nr)) {
+ rose_write_internal(sk, ROSE_RESET_REQUEST);
+ rose->condition = 0x00;
+ rose->vs = 0;
+ rose->vr = 0;
+ rose->va = 0;
+ rose->vl = 0;
+ rose->state = ROSE_STATE_4;
+ rose_start_t2timer(sk);
+ rose_stop_idletimer(sk);
+ break;
+ }
+ rose_frames_acked(sk, nr);
+ if (ns == rose->vr) {
+ rose_start_idletimer(sk);
+ if (sk_filter_trim_cap(sk, skb, ROSE_MIN_LEN) == 0 &&
+ __sock_queue_rcv_skb(sk, skb) == 0) {
+ rose->vr = (rose->vr + 1) % ROSE_MODULUS;
+ queued = 1;
+ } else {
+ /* Should never happen ! */
+ rose_write_internal(sk, ROSE_RESET_REQUEST);
+ rose->condition = 0x00;
+ rose->vs = 0;
+ rose->vr = 0;
+ rose->va = 0;
+ rose->vl = 0;
+ rose->state = ROSE_STATE_4;
+ rose_start_t2timer(sk);
+ rose_stop_idletimer(sk);
+ break;
+ }
+ if (atomic_read(&sk->sk_rmem_alloc) >
+ (sk->sk_rcvbuf >> 1))
+ rose->condition |= ROSE_COND_OWN_RX_BUSY;
+ }
+ /*
+ * If the window is full, ack the frame, else start the
+ * acknowledge hold back timer.
+ */
+ if (((rose->vl + sysctl_rose_window_size) % ROSE_MODULUS) == rose->vr) {
+ rose->condition &= ~ROSE_COND_ACK_PENDING;
+ rose_stop_timer(sk);
+ rose_enquiry_response(sk);
+ } else {
+ rose->condition |= ROSE_COND_ACK_PENDING;
+ rose_start_hbtimer(sk);
+ }
+ break;
+
+ default:
+ printk(KERN_WARNING "ROSE: unknown %02X in state 3\n", frametype);
+ break;
+ }
+
+ return queued;
+}
+
+/*
+ * State machine for state 4, Awaiting Reset Confirmation State.
+ * The handling of the timer(s) is in file rose_timer.c
+ * Handling of state 0 and connection release is in af_rose.c.
+ */
+static int rose_state4_machine(struct sock *sk, struct sk_buff *skb, int frametype)
+{
+ struct rose_sock *rose = rose_sk(sk);
+
+ switch (frametype) {
+ case ROSE_RESET_REQUEST:
+ rose_write_internal(sk, ROSE_RESET_CONFIRMATION);
+ fallthrough;
+ case ROSE_RESET_CONFIRMATION:
+ rose_stop_timer(sk);
+ rose_start_idletimer(sk);
+ rose->condition = 0x00;
+ rose->va = 0;
+ rose->vr = 0;
+ rose->vs = 0;
+ rose->vl = 0;
+ rose->state = ROSE_STATE_3;
+ rose_requeue_frames(sk);
+ break;
+
+ case ROSE_CLEAR_REQUEST:
+ rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
+ rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
+ rose->neighbour->use--;
+ break;
+
+ default:
+ break;
+ }
+
+ return 0;
+}
+
+/*
+ * State machine for state 5, Awaiting Call Acceptance State.
+ * The handling of the timer(s) is in file rose_timer.c
+ * Handling of state 0 and connection release is in af_rose.c.
+ */
+static int rose_state5_machine(struct sock *sk, struct sk_buff *skb, int frametype)
+{
+ if (frametype == ROSE_CLEAR_REQUEST) {
+ rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
+ rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
+ rose_sk(sk)->neighbour->use--;
+ }
+
+ return 0;
+}
+
+/* Higher level upcall for a LAPB frame */
+int rose_process_rx_frame(struct sock *sk, struct sk_buff *skb)
+{
+ struct rose_sock *rose = rose_sk(sk);
+ int queued = 0, frametype, ns, nr, q, d, m;
+
+ if (rose->state == ROSE_STATE_0)
+ return 0;
+
+ frametype = rose_decode(skb, &ns, &nr, &q, &d, &m);
+
+ switch (rose->state) {
+ case ROSE_STATE_1:
+ queued = rose_state1_machine(sk, skb, frametype);
+ break;
+ case ROSE_STATE_2:
+ queued = rose_state2_machine(sk, skb, frametype);
+ break;
+ case ROSE_STATE_3:
+ queued = rose_state3_machine(sk, skb, frametype, ns, nr, q, d, m);
+ break;
+ case ROSE_STATE_4:
+ queued = rose_state4_machine(sk, skb, frametype);
+ break;
+ case ROSE_STATE_5:
+ queued = rose_state5_machine(sk, skb, frametype);
+ break;
+ }
+
+ rose_kick(sk);
+
+ return queued;
+}
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