patch-2.1.16 linux/net/x25/x25_out.c

• Lines: 208
• Date: Wed Dec 18 12:07:56 1996
• Orig file: v2.1.15/linux/net/x25/x25_out.c
• Orig date: Thu Jan 1 02:00:00 1970

diff -u --recursive --new-file v2.1.15/linux/net/x25/x25_out.c linux/net/x25/x25_out.c
@@ -0,0 +1,207 @@
+/*
+ *	X.25 Packet Layer release 001
+ *
+ *	This is ALPHA test software. This code may break your machine, randomly fail to work with new 
+ *	releases, misbehave and/or generally screw up. It might even work. 
+ *
+ *	This code REQUIRES 2.1.15 or higher
+ *
+ *	This module:
+ *		This module is free software; you can redistribute it and/or
+ *		modify it under the terms of the GNU General Public License
+ *		as published by the Free Software Foundation; either version
+ *		2 of the License, or (at your option) any later version.
+ *
+ *	History
+ *	X.25 001	Jonathan Naylor	Started coding.
+ */
+
+#include <linux/config.h>
+#if defined(CONFIG_X25) || defined(CONFIG_X25_MODULE)
+#include <linux/errno.h>
+#include <linux/types.h>
+#include <linux/socket.h>
+#include <linux/in.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/timer.h>
+#include <linux/string.h>
+#include <linux/sockios.h>
+#include <linux/net.h>
+#include <linux/inet.h>
+#include <linux/netdevice.h>
+#include <linux/skbuff.h>
+#include <net/sock.h>
+#include <asm/segment.h>
+#include <asm/system.h>
+#include <linux/fcntl.h>
+#include <linux/mm.h>
+#include <linux/interrupt.h>
+#include <net/x25.h>
+
+/*
+ *	This is where all X.25 information frames pass;
+ */
+void x25_output(struct sock *sk, struct sk_buff *skb)
+{
+	struct sk_buff *skbn;
+	unsigned char header[X25_EXT_MIN_LEN];
+	int err, frontlen, len, min_len;
+	
+	min_len  = (sk->protinfo.x25->neighbour->extended) ? X25_EXT_MIN_LEN : X25_STD_MIN_LEN;
+
+	if (skb->len - min_len > 128) {		/* XXX */
+		/* Save a copy of the Header */
+		memcpy(header, skb->data, min_len);
+		skb_pull(skb, min_len);
+
+		frontlen = skb_headroom(skb);
+
+		while (skb->len > 0) {
+			if ((skbn = sock_alloc_send_skb(sk, frontlen + 128, 0, 0, &err)) == NULL)	/* XXX */
+				return;
+
+			skbn->sk   = sk;
+			skbn->arp  = 1;
+
+			skb_reserve(skbn, frontlen);
+
+			len = (128 > skb->len) ? skb->len : 128;	/* XXX */
+
+			/* Copy the user data */
+			memcpy(skb_put(skbn, len), skb->data, len);
+			skb_pull(skb, len);
+
+			/* Duplicate the Header */
+			skb_push(skbn, min_len);
+			memcpy(skbn->data, header, min_len);
+
+			if (skb->len > 0) {
+				if (sk->protinfo.x25->neighbour->extended)
+					skbn->data[3] |= X25_EXT_M_BIT;
+				else
+					skbn->data[2] |= X25_STD_M_BIT;
+			}
+		
+			skb_queue_tail(&sk->write_queue, skbn); /* Throw it on the queue */
+		}
+		
+		kfree_skb(skb, FREE_WRITE);
+	} else {
+		skb_queue_tail(&sk->write_queue, skb);		/* Throw it on the queue */
+	}
+
+	if (sk->protinfo.x25->state == X25_STATE_3)
+		x25_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 x25_send_iframe(struct sock *sk, struct sk_buff *skb)
+{
+	if (skb == NULL)
+		return;
+
+	if (sk->protinfo.x25->neighbour->extended) {
+		skb->data[2] |= (sk->protinfo.x25->vs << 1) & 0xFE;
+		skb->data[3] |= (sk->protinfo.x25->vr << 1) & 0xFE;
+	} else {
+		skb->data[2] |= (sk->protinfo.x25->vs << 1) & 0x0E;
+		skb->data[2] |= (sk->protinfo.x25->vr << 5) & 0xE0;
+	}
+
+	x25_transmit_link(skb, sk->protinfo.x25->neighbour);	
+}
+
+void x25_kick(struct sock *sk)
+{
+	struct sk_buff *skb, *skbn;
+	int last = 1;
+	unsigned short start, end, next;
+	int modulus;
+	
+	modulus = (sk->protinfo.x25->neighbour->extended) ? X25_EMODULUS : X25_SMODULUS;
+
+	del_timer(&sk->timer);
+
+	start = (skb_peek(&sk->protinfo.x25->ack_queue) == NULL) ? sk->protinfo.x25->va : sk->protinfo.x25->vs;
+	end   = (sk->protinfo.x25->va + sk->protinfo.x25->facilities.window_size) % modulus;
+
+	if (!(sk->protinfo.x25->condition & X25_COND_PEER_RX_BUSY) &&
+	    start != end                                           &&
+	    skb_peek(&sk->write_queue) != NULL) {
+
+		sk->protinfo.x25->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->write_queue);
+
+		do {
+			if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
+				skb_queue_head(&sk->write_queue, skb);
+				break;
+			}
+
+			next = (sk->protinfo.x25->vs + 1) % modulus;
+			last = (next == end);
+
+			/*
+			 * Transmit the frame copy.
+			 */
+			x25_send_iframe(sk, skbn);
+
+			sk->protinfo.x25->vs = next;
+
+			/*
+			 * Requeue the original data frame.
+			 */
+			skb_queue_tail(&sk->protinfo.x25->ack_queue, skb);
+
+		} while (!last && (skb = skb_dequeue(&sk->write_queue)) != NULL);
+
+		sk->protinfo.x25->vl         = sk->protinfo.x25->vr;
+		sk->protinfo.x25->condition &= ~X25_COND_ACK_PENDING;
+		sk->protinfo.x25->timer      = 0;
+	}
+
+	x25_set_timer(sk);
+}
+
+/*
+ * The following routines are taken from page 170 of the 7th ARRL Computer
+ * Networking Conference paper, as is the whole state machine.
+ */
+
+void x25_enquiry_response(struct sock *sk)
+{
+	if (sk->protinfo.x25->condition & X25_COND_OWN_RX_BUSY)
+		x25_write_internal(sk, X25_RNR);
+	else
+		x25_write_internal(sk, X25_RR);
+
+	sk->protinfo.x25->vl         = sk->protinfo.x25->vr;
+	sk->protinfo.x25->condition &= ~X25_COND_ACK_PENDING;
+	sk->protinfo.x25->timer      = 0;
+}
+
+void x25_check_iframes_acked(struct sock *sk, unsigned short nr)
+{
+	if (sk->protinfo.x25->vs == nr) {
+		x25_frames_acked(sk, nr);
+	} else {
+		if (sk->protinfo.x25->va != nr) {
+			x25_frames_acked(sk, nr);
+		}
+	}
+}
+
+#endif