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-rw-r--r--net/ax25/ax25_std_in.c443
1 files changed, 443 insertions, 0 deletions
diff --git a/net/ax25/ax25_std_in.c b/net/ax25/ax25_std_in.c
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+++ b/net/ax25/ax25_std_in.c
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+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *
+ * Copyright (C) Alan Cox GW4PTS (alan@lxorguk.ukuu.org.uk)
+ * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
+ * Copyright (C) Joerg Reuter DL1BKE (jreuter@yaina.de)
+ * Copyright (C) Hans-Joachim Hetscher DD8NE (dd8ne@bnv-bamberg.de)
+ *
+ * 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/uaccess.h>
+#include <linux/fcntl.h>
+#include <linux/mm.h>
+#include <linux/interrupt.h>
+
+/*
+ * State machine for state 1, Awaiting Connection State.
+ * The handling of the timer(s) is in file ax25_std_timer.c.
+ * Handling of state 0 and connection release is in ax25.c.
+ */
+static int ax25_std_state1_machine(ax25_cb *ax25, struct sk_buff *skb, int frametype, int pf, int type)
+{
+ switch (frametype) {
+ case AX25_SABM:
+ ax25->modulus = AX25_MODULUS;
+ ax25->window = ax25->ax25_dev->values[AX25_VALUES_WINDOW];
+ ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
+ break;
+
+ case AX25_SABME:
+ ax25->modulus = AX25_EMODULUS;
+ ax25->window = ax25->ax25_dev->values[AX25_VALUES_EWINDOW];
+ ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
+ break;
+
+ case AX25_DISC:
+ ax25_send_control(ax25, AX25_DM, pf, AX25_RESPONSE);
+ break;
+
+ case AX25_UA:
+ if (pf) {
+ ax25_calculate_rtt(ax25);
+ ax25_stop_t1timer(ax25);
+ ax25_start_t3timer(ax25);
+ ax25_start_idletimer(ax25);
+ ax25->vs = 0;
+ ax25->va = 0;
+ ax25->vr = 0;
+ ax25->state = AX25_STATE_3;
+ ax25->n2count = 0;
+ if (ax25->sk != NULL) {
+ bh_lock_sock(ax25->sk);
+ ax25->sk->sk_state = TCP_ESTABLISHED;
+ /* For WAIT_SABM connections we will produce an accept ready socket here */
+ if (!sock_flag(ax25->sk, SOCK_DEAD))
+ ax25->sk->sk_state_change(ax25->sk);
+ bh_unlock_sock(ax25->sk);
+ }
+ }
+ break;
+
+ case AX25_DM:
+ if (pf) {
+ if (ax25->modulus == AX25_MODULUS) {
+ ax25_disconnect(ax25, ECONNREFUSED);
+ } else {
+ ax25->modulus = AX25_MODULUS;
+ ax25->window = ax25->ax25_dev->values[AX25_VALUES_WINDOW];
+ }
+ }
+ break;
+
+ default:
+ break;
+ }
+
+ return 0;
+}
+
+/*
+ * State machine for state 2, Awaiting Release State.
+ * The handling of the timer(s) is in file ax25_std_timer.c
+ * Handling of state 0 and connection release is in ax25.c.
+ */
+static int ax25_std_state2_machine(ax25_cb *ax25, struct sk_buff *skb, int frametype, int pf, int type)
+{
+ switch (frametype) {
+ case AX25_SABM:
+ case AX25_SABME:
+ ax25_send_control(ax25, AX25_DM, pf, AX25_RESPONSE);
+ break;
+
+ case AX25_DISC:
+ ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
+ ax25_disconnect(ax25, 0);
+ break;
+
+ case AX25_DM:
+ case AX25_UA:
+ if (pf)
+ ax25_disconnect(ax25, 0);
+ break;
+
+ case AX25_I:
+ case AX25_REJ:
+ case AX25_RNR:
+ case AX25_RR:
+ if (pf) ax25_send_control(ax25, AX25_DM, AX25_POLLON, AX25_RESPONSE);
+ break;
+
+ default:
+ break;
+ }
+
+ return 0;
+}
+
+/*
+ * State machine for state 3, Connected State.
+ * The handling of the timer(s) is in file ax25_std_timer.c
+ * Handling of state 0 and connection release is in ax25.c.
+ */
+static int ax25_std_state3_machine(ax25_cb *ax25, struct sk_buff *skb, int frametype, int ns, int nr, int pf, int type)
+{
+ int queued = 0;
+
+ switch (frametype) {
+ case AX25_SABM:
+ case AX25_SABME:
+ if (frametype == AX25_SABM) {
+ ax25->modulus = AX25_MODULUS;
+ ax25->window = ax25->ax25_dev->values[AX25_VALUES_WINDOW];
+ } else {
+ ax25->modulus = AX25_EMODULUS;
+ ax25->window = ax25->ax25_dev->values[AX25_VALUES_EWINDOW];
+ }
+ ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
+ ax25_stop_t1timer(ax25);
+ ax25_stop_t2timer(ax25);
+ ax25_start_t3timer(ax25);
+ ax25_start_idletimer(ax25);
+ ax25->condition = 0x00;
+ ax25->vs = 0;
+ ax25->va = 0;
+ ax25->vr = 0;
+ ax25_requeue_frames(ax25);
+ break;
+
+ case AX25_DISC:
+ ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
+ ax25_disconnect(ax25, 0);
+ break;
+
+ case AX25_DM:
+ ax25_disconnect(ax25, ECONNRESET);
+ break;
+
+ case AX25_RR:
+ case AX25_RNR:
+ if (frametype == AX25_RR)
+ ax25->condition &= ~AX25_COND_PEER_RX_BUSY;
+ else
+ ax25->condition |= AX25_COND_PEER_RX_BUSY;
+ if (type == AX25_COMMAND && pf)
+ ax25_std_enquiry_response(ax25);
+ if (ax25_validate_nr(ax25, nr)) {
+ ax25_check_iframes_acked(ax25, nr);
+ } else {
+ ax25_std_nr_error_recovery(ax25);
+ ax25->state = AX25_STATE_1;
+ }
+ break;
+
+ case AX25_REJ:
+ ax25->condition &= ~AX25_COND_PEER_RX_BUSY;
+ if (type == AX25_COMMAND && pf)
+ ax25_std_enquiry_response(ax25);
+ if (ax25_validate_nr(ax25, nr)) {
+ ax25_frames_acked(ax25, nr);
+ ax25_calculate_rtt(ax25);
+ ax25_stop_t1timer(ax25);
+ ax25_start_t3timer(ax25);
+ ax25_requeue_frames(ax25);
+ } else {
+ ax25_std_nr_error_recovery(ax25);
+ ax25->state = AX25_STATE_1;
+ }
+ break;
+
+ case AX25_I:
+ if (!ax25_validate_nr(ax25, nr)) {
+ ax25_std_nr_error_recovery(ax25);
+ ax25->state = AX25_STATE_1;
+ break;
+ }
+ if (ax25->condition & AX25_COND_PEER_RX_BUSY) {
+ ax25_frames_acked(ax25, nr);
+ } else {
+ ax25_check_iframes_acked(ax25, nr);
+ }
+ if (ax25->condition & AX25_COND_OWN_RX_BUSY) {
+ if (pf) ax25_std_enquiry_response(ax25);
+ break;
+ }
+ if (ns == ax25->vr) {
+ ax25->vr = (ax25->vr + 1) % ax25->modulus;
+ queued = ax25_rx_iframe(ax25, skb);
+ if (ax25->condition & AX25_COND_OWN_RX_BUSY)
+ ax25->vr = ns; /* ax25->vr - 1 */
+ ax25->condition &= ~AX25_COND_REJECT;
+ if (pf) {
+ ax25_std_enquiry_response(ax25);
+ } else {
+ if (!(ax25->condition & AX25_COND_ACK_PENDING)) {
+ ax25->condition |= AX25_COND_ACK_PENDING;
+ ax25_start_t2timer(ax25);
+ }
+ }
+ } else {
+ if (ax25->condition & AX25_COND_REJECT) {
+ if (pf) ax25_std_enquiry_response(ax25);
+ } else {
+ ax25->condition |= AX25_COND_REJECT;
+ ax25_send_control(ax25, AX25_REJ, pf, AX25_RESPONSE);
+ ax25->condition &= ~AX25_COND_ACK_PENDING;
+ }
+ }
+ break;
+
+ case AX25_FRMR:
+ case AX25_ILLEGAL:
+ ax25_std_establish_data_link(ax25);
+ ax25->state = AX25_STATE_1;
+ break;
+
+ default:
+ break;
+ }
+
+ return queued;
+}
+
+/*
+ * State machine for state 4, Timer Recovery State.
+ * The handling of the timer(s) is in file ax25_std_timer.c
+ * Handling of state 0 and connection release is in ax25.c.
+ */
+static int ax25_std_state4_machine(ax25_cb *ax25, struct sk_buff *skb, int frametype, int ns, int nr, int pf, int type)
+{
+ int queued = 0;
+
+ switch (frametype) {
+ case AX25_SABM:
+ case AX25_SABME:
+ if (frametype == AX25_SABM) {
+ ax25->modulus = AX25_MODULUS;
+ ax25->window = ax25->ax25_dev->values[AX25_VALUES_WINDOW];
+ } else {
+ ax25->modulus = AX25_EMODULUS;
+ ax25->window = ax25->ax25_dev->values[AX25_VALUES_EWINDOW];
+ }
+ ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
+ ax25_stop_t1timer(ax25);
+ ax25_stop_t2timer(ax25);
+ ax25_start_t3timer(ax25);
+ ax25_start_idletimer(ax25);
+ ax25->condition = 0x00;
+ ax25->vs = 0;
+ ax25->va = 0;
+ ax25->vr = 0;
+ ax25->state = AX25_STATE_3;
+ ax25->n2count = 0;
+ ax25_requeue_frames(ax25);
+ break;
+
+ case AX25_DISC:
+ ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
+ ax25_disconnect(ax25, 0);
+ break;
+
+ case AX25_DM:
+ ax25_disconnect(ax25, ECONNRESET);
+ break;
+
+ case AX25_RR:
+ case AX25_RNR:
+ if (frametype == AX25_RR)
+ ax25->condition &= ~AX25_COND_PEER_RX_BUSY;
+ else
+ ax25->condition |= AX25_COND_PEER_RX_BUSY;
+ if (type == AX25_RESPONSE && pf) {
+ ax25_stop_t1timer(ax25);
+ ax25->n2count = 0;
+ if (ax25_validate_nr(ax25, nr)) {
+ ax25_frames_acked(ax25, nr);
+ if (ax25->vs == ax25->va) {
+ ax25_start_t3timer(ax25);
+ ax25->state = AX25_STATE_3;
+ } else {
+ ax25_requeue_frames(ax25);
+ }
+ } else {
+ ax25_std_nr_error_recovery(ax25);
+ ax25->state = AX25_STATE_1;
+ }
+ break;
+ }
+ if (type == AX25_COMMAND && pf)
+ ax25_std_enquiry_response(ax25);
+ if (ax25_validate_nr(ax25, nr)) {
+ ax25_frames_acked(ax25, nr);
+ } else {
+ ax25_std_nr_error_recovery(ax25);
+ ax25->state = AX25_STATE_1;
+ }
+ break;
+
+ case AX25_REJ:
+ ax25->condition &= ~AX25_COND_PEER_RX_BUSY;
+ if (pf && type == AX25_RESPONSE) {
+ ax25_stop_t1timer(ax25);
+ ax25->n2count = 0;
+ if (ax25_validate_nr(ax25, nr)) {
+ ax25_frames_acked(ax25, nr);
+ if (ax25->vs == ax25->va) {
+ ax25_start_t3timer(ax25);
+ ax25->state = AX25_STATE_3;
+ } else {
+ ax25_requeue_frames(ax25);
+ }
+ } else {
+ ax25_std_nr_error_recovery(ax25);
+ ax25->state = AX25_STATE_1;
+ }
+ break;
+ }
+ if (type == AX25_COMMAND && pf)
+ ax25_std_enquiry_response(ax25);
+ if (ax25_validate_nr(ax25, nr)) {
+ ax25_frames_acked(ax25, nr);
+ ax25_requeue_frames(ax25);
+ } else {
+ ax25_std_nr_error_recovery(ax25);
+ ax25->state = AX25_STATE_1;
+ }
+ break;
+
+ case AX25_I:
+ if (!ax25_validate_nr(ax25, nr)) {
+ ax25_std_nr_error_recovery(ax25);
+ ax25->state = AX25_STATE_1;
+ break;
+ }
+ ax25_frames_acked(ax25, nr);
+ if (ax25->condition & AX25_COND_OWN_RX_BUSY) {
+ if (pf)
+ ax25_std_enquiry_response(ax25);
+ break;
+ }
+ if (ns == ax25->vr) {
+ ax25->vr = (ax25->vr + 1) % ax25->modulus;
+ queued = ax25_rx_iframe(ax25, skb);
+ if (ax25->condition & AX25_COND_OWN_RX_BUSY)
+ ax25->vr = ns; /* ax25->vr - 1 */
+ ax25->condition &= ~AX25_COND_REJECT;
+ if (pf) {
+ ax25_std_enquiry_response(ax25);
+ } else {
+ if (!(ax25->condition & AX25_COND_ACK_PENDING)) {
+ ax25->condition |= AX25_COND_ACK_PENDING;
+ ax25_start_t2timer(ax25);
+ }
+ }
+ } else {
+ if (ax25->condition & AX25_COND_REJECT) {
+ if (pf) ax25_std_enquiry_response(ax25);
+ } else {
+ ax25->condition |= AX25_COND_REJECT;
+ ax25_send_control(ax25, AX25_REJ, pf, AX25_RESPONSE);
+ ax25->condition &= ~AX25_COND_ACK_PENDING;
+ }
+ }
+ break;
+
+ case AX25_FRMR:
+ case AX25_ILLEGAL:
+ ax25_std_establish_data_link(ax25);
+ ax25->state = AX25_STATE_1;
+ break;
+
+ default:
+ break;
+ }
+
+ return queued;
+}
+
+/*
+ * Higher level upcall for a LAPB frame
+ */
+int ax25_std_frame_in(ax25_cb *ax25, struct sk_buff *skb, int type)
+{
+ int queued = 0, frametype, ns, nr, pf;
+
+ frametype = ax25_decode(ax25, skb, &ns, &nr, &pf);
+
+ switch (ax25->state) {
+ case AX25_STATE_1:
+ queued = ax25_std_state1_machine(ax25, skb, frametype, pf, type);
+ break;
+ case AX25_STATE_2:
+ queued = ax25_std_state2_machine(ax25, skb, frametype, pf, type);
+ break;
+ case AX25_STATE_3:
+ queued = ax25_std_state3_machine(ax25, skb, frametype, ns, nr, pf, type);
+ break;
+ case AX25_STATE_4:
+ queued = ax25_std_state4_machine(ax25, skb, frametype, ns, nr, pf, type);
+ break;
+ }
+
+ ax25_kick(ax25);
+
+ return queued;
+}
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