1 files changed, 270 insertions, 0 deletions
diff --git a/net/netrom/nr_out.c b/net/netrom/nr_out.c
new file mode 100644
index 000000000..44929657f
--- /dev/null
+++ b/net/netrom/nr_out.c
@@ -0,0 +1,270 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *
+ * Copyright Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
+ * Copyright Darryl Miles G7LED (dlm@g7led.demon.co.uk)
+ */
+#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 <linux/slab.h>
+#include <net/ax25.h>
+#include <linux/inet.h>
+#include <linux/netdevice.h>
+#include <linux/skbuff.h>
+#include <net/sock.h>
+#include <linux/uaccess.h>
+#include <linux/fcntl.h>
+#include <linux/mm.h>
+#include <linux/interrupt.h>
+#include <net/netrom.h>
+
+/*
+ *	This is where all NET/ROM frames pass, except for IP-over-NET/ROM which
+ *	cannot be fragmented in this manner.
+ */
+void nr_output(struct sock *sk, struct sk_buff *skb)
+{
+	struct sk_buff *skbn;
+	unsigned char transport[NR_TRANSPORT_LEN];
+	int err, frontlen, len;
+
+	if (skb->len - NR_TRANSPORT_LEN > NR_MAX_PACKET_SIZE) {
+		/* Save a copy of the Transport Header */
+		skb_copy_from_linear_data(skb, transport, NR_TRANSPORT_LEN);
+		skb_pull(skb, NR_TRANSPORT_LEN);
+
+		frontlen = skb_headroom(skb);
+
+		while (skb->len > 0) {
+			if ((skbn = sock_alloc_send_skb(sk, frontlen + NR_MAX_PACKET_SIZE, 0, &err)) == NULL)
+				return;
+
+			skb_reserve(skbn, frontlen);
+
+			len = (NR_MAX_PACKET_SIZE > skb->len) ? skb->len : NR_MAX_PACKET_SIZE;
+
+			/* Copy the user data */
+			skb_copy_from_linear_data(skb, skb_put(skbn, len), len);
+			skb_pull(skb, len);
+
+			/* Duplicate the Transport Header */
+			skb_push(skbn, NR_TRANSPORT_LEN);
+			skb_copy_to_linear_data(skbn, transport,
+						NR_TRANSPORT_LEN);
+			if (skb->len > 0)
+				skbn->data[4] |= NR_MORE_FLAG;
+
+			skb_queue_tail(&sk->sk_write_queue, skbn); /* Throw it on the queue */
+		}
+
+		kfree_skb(skb);
+	} else {
+		skb_queue_tail(&sk->sk_write_queue, skb);		/* Throw it on the queue */
+	}
+
+	nr_kick(sk);
+}
+
+/*
+ *	This procedure is passed a buffer descriptor for an iframe. It builds
+ *	the rest of the control part of the frame and then writes it out.
+ */
+static void nr_send_iframe(struct sock *sk, struct sk_buff *skb)
+{
+	struct nr_sock *nr = nr_sk(sk);
+
+	if (skb == NULL)
+		return;
+
+	skb->data[2] = nr->vs;
+	skb->data[3] = nr->vr;
+
+	if (nr->condition & NR_COND_OWN_RX_BUSY)
+		skb->data[4] |= NR_CHOKE_FLAG;
+
+	nr_start_idletimer(sk);
+
+	nr_transmit_buffer(sk, skb);
+}
+
+void nr_send_nak_frame(struct sock *sk)
+{
+	struct sk_buff *skb, *skbn;
+	struct nr_sock *nr = nr_sk(sk);
+
+	if ((skb = skb_peek(&nr->ack_queue)) == NULL)
+		return;
+
+	if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL)
+		return;
+
+	skbn->data[2] = nr->va;
+	skbn->data[3] = nr->vr;
+
+	if (nr->condition & NR_COND_OWN_RX_BUSY)
+		skbn->data[4] |= NR_CHOKE_FLAG;
+
+	nr_transmit_buffer(sk, skbn);
+
+	nr->condition &= ~NR_COND_ACK_PENDING;
+	nr->vl         = nr->vr;
+
+	nr_stop_t1timer(sk);
+}
+
+void nr_kick(struct sock *sk)
+{
+	struct nr_sock *nr = nr_sk(sk);
+	struct sk_buff *skb, *skbn;
+	unsigned short start, end;
+
+	if (nr->state != NR_STATE_3)
+		return;
+
+	if (nr->condition & NR_COND_PEER_RX_BUSY)
+		return;
+
+	if (!skb_peek(&sk->sk_write_queue))
+		return;
+
+	start = (skb_peek(&nr->ack_queue) == NULL) ? nr->va : nr->vs;
+	end   = (nr->va + nr->window) % NR_MODULUS;
+
+	if (start == end)
+		return;
+
+	nr->vs = start;
+
+	/*
+	 * Transmit data until either we're out of data to send or
+	 * the window is full.
+	 */
+
+	/*
+	 * Dequeue the frame and copy it.
+	 */
+	skb = skb_dequeue(&sk->sk_write_queue);
+
+	do {
+		if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
+			skb_queue_head(&sk->sk_write_queue, skb);
+			break;
+		}
+
+		skb_set_owner_w(skbn, sk);
+
+		/*
+		 * Transmit the frame copy.
+		 */
+		nr_send_iframe(sk, skbn);
+
+		nr->vs = (nr->vs + 1) % NR_MODULUS;
+
+		/*
+		 * Requeue the original data frame.
+		 */
+		skb_queue_tail(&nr->ack_queue, skb);
+
+	} while (nr->vs != end &&
+		 (skb = skb_dequeue(&sk->sk_write_queue)) != NULL);
+
+	nr->vl         = nr->vr;
+	nr->condition &= ~NR_COND_ACK_PENDING;
+
+	if (!nr_t1timer_running(sk))
+		nr_start_t1timer(sk);
+}
+
+void nr_transmit_buffer(struct sock *sk, struct sk_buff *skb)
+{
+	struct nr_sock *nr = nr_sk(sk);
+	unsigned char *dptr;
+
+	/*
+	 *	Add the protocol byte and network header.
+	 */
+	dptr = skb_push(skb, NR_NETWORK_LEN);
+
+	memcpy(dptr, &nr->source_addr, AX25_ADDR_LEN);
+	dptr[6] &= ~AX25_CBIT;
+	dptr[6] &= ~AX25_EBIT;
+	dptr[6] |= AX25_SSSID_SPARE;
+	dptr += AX25_ADDR_LEN;
+
+	memcpy(dptr, &nr->dest_addr, AX25_ADDR_LEN);
+	dptr[6] &= ~AX25_CBIT;
+	dptr[6] |= AX25_EBIT;
+	dptr[6] |= AX25_SSSID_SPARE;
+	dptr += AX25_ADDR_LEN;
+
+	*dptr++ = sysctl_netrom_network_ttl_initialiser;
+
+	if (!nr_route_frame(skb, NULL)) {
+		kfree_skb(skb);
+		nr_disconnect(sk, ENETUNREACH);
+	}
+}
+
+/*
+ * The following routines are taken from page 170 of the 7th ARRL Computer
+ * Networking Conference paper, as is the whole state machine.
+ */
+
+void nr_establish_data_link(struct sock *sk)
+{
+	struct nr_sock *nr = nr_sk(sk);
+
+	nr->condition = 0x00;
+	nr->n2count   = 0;
+
+	nr_write_internal(sk, NR_CONNREQ);
+
+	nr_stop_t2timer(sk);
+	nr_stop_t4timer(sk);
+	nr_stop_idletimer(sk);
+	nr_start_t1timer(sk);
+}
+
+/*
+ * Never send a NAK when we are CHOKEd.
+ */
+void nr_enquiry_response(struct sock *sk)
+{
+	struct nr_sock *nr = nr_sk(sk);
+	int frametype = NR_INFOACK;
+
+	if (nr->condition & NR_COND_OWN_RX_BUSY) {
+		frametype |= NR_CHOKE_FLAG;
+	} else {
+		if (skb_peek(&nr->reseq_queue) != NULL)
+			frametype |= NR_NAK_FLAG;
+	}
+
+	nr_write_internal(sk, frametype);
+
+	nr->vl         = nr->vr;
+	nr->condition &= ~NR_COND_ACK_PENDING;
+}
+
+void nr_check_iframes_acked(struct sock *sk, unsigned short nr)
+{
+	struct nr_sock *nrom = nr_sk(sk);
+
+	if (nrom->vs == nr) {
+		nr_frames_acked(sk, nr);
+		nr_stop_t1timer(sk);
+		nrom->n2count = 0;
+	} else {
+		if (nrom->va != nr) {
+			nr_frames_acked(sk, nr);
+			nr_start_t1timer(sk);
+		}
+	}
+}