patch-2.1.20 linux/net/lapb/lapb_subr.c

• Lines: 237
• Date: Thu Jan 2 15:13:29 1997
• Orig file: v2.1.19/linux/net/lapb/lapb_subr.c
• Orig date: Thu Jan 1 02:00:00 1970

diff -u --recursive --new-file v2.1.19/linux/net/lapb/lapb_subr.c linux/net/lapb/lapb_subr.c
@@ -0,0 +1,236 @@
+/*
+ *	LAPB 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/ NET3.038
+ *
+ *	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
+ *	LAPB 001	Jonathan Naylor	Started Coding
+ */
+
+#include <linux/config.h>
+#if defined(CONFIG_LAPB) || defined(CONFIG_LAPB_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/skbuff.h>
+#include <net/sock.h>
+#include <asm/uaccess.h>
+#include <asm/system.h>
+#include <linux/fcntl.h>
+#include <linux/mm.h>
+#include <linux/interrupt.h>
+#include <net/lapb.h>
+
+/*
+ *	This routine purges all the queues of frames.
+ */
+void lapb_clear_queues(lapb_cb *lapb)
+{
+	struct sk_buff *skb;
+
+	while ((skb = skb_dequeue(&lapb->write_queue)) != NULL)
+		kfree_skb(skb, FREE_WRITE);
+
+	while ((skb = skb_dequeue(&lapb->ack_queue)) != NULL)
+		kfree_skb(skb, FREE_WRITE);
+}
+
+/*
+ * This routine purges the input queue of those frames that have been
+ * acknowledged. This replaces the boxes labelled "V(a) <- N(r)" on the
+ * SDL diagram.
+ */
+void lapb_frames_acked(lapb_cb *lapb, unsigned short nr)
+{
+	struct sk_buff *skb;
+	int modulus;
+
+	modulus = (lapb->mode & LAPB_EXTENDED) ? LAPB_EMODULUS : LAPB_SMODULUS;
+
+	/*
+	 * Remove all the ack-ed frames from the ack queue.
+	 */
+	if (lapb->va != nr) {
+		while (skb_peek(&lapb->ack_queue) != NULL && lapb->va != nr) {
+		        skb = skb_dequeue(&lapb->ack_queue);
+			kfree_skb(skb, FREE_WRITE);
+			lapb->va = (lapb->va + 1) % modulus;
+		}
+	}
+}
+
+void lapb_requeue_frames(lapb_cb *lapb)
+{
+        struct sk_buff *skb, *skb_prev = NULL;
+
+	/*
+	 * Requeue all the un-ack-ed frames on the output queue to be picked
+	 * up by lapb_kick called from the timer. This arrangement handles the
+	 * possibility of an empty output queue.
+	 */
+	while ((skb = skb_dequeue(&lapb->ack_queue)) != NULL) {
+		if (skb_prev == NULL)
+			skb_queue_head(&lapb->write_queue, skb);
+		else
+			skb_append(skb_prev, skb);
+		skb_prev = skb;
+	}
+}
+
+/*
+ *	Validate that the value of nr is between va and vs. Return true or
+ *	false for testing.
+ */
+int lapb_validate_nr(lapb_cb *lapb, unsigned short nr)
+{
+	unsigned short vc = lapb->va;
+	int modulus;
+	
+	modulus = (lapb->mode & LAPB_EXTENDED) ? LAPB_EMODULUS : LAPB_SMODULUS;
+
+	while (vc != lapb->vs) {
+		if (nr == vc) return 1;
+		vc = (vc + 1) % modulus;
+	}
+	
+	if (nr == lapb->vs) return 1;
+
+	return 0;
+}
+
+/*
+ *	This routine is the centralised routine for parsing the control
+ *	information for the different frame formats.
+ */
+int lapb_decode(lapb_cb *lapb, struct sk_buff *skb, int *ns, int *nr, int *pf, int *type)
+{
+	int frametype = LAPB_ILLEGAL;
+
+	*ns = *nr = *pf = *type = 0;
+
+#if LAPB_DEBUG > 2
+	printk(KERN_DEBUG "lapb: (%p) S%d RX %02X %02X %02X\n", lapb->token, lapb->state, skb->data[0], skb->data[1], skb->data[2]);
+#endif
+
+	if (lapb->mode & LAPB_MLP) {
+		if (lapb->mode & LAPB_DCE) {
+			if (skb->data[0] == LAPB_ADDR_C)
+				*type = LAPB_COMMAND;
+			if (skb->data[0] == LAPB_ADDR_D)
+				*type = LAPB_RESPONSE;
+		} else {
+			if (skb->data[0] == LAPB_ADDR_D)
+				*type = LAPB_COMMAND;
+			if (skb->data[0] == LAPB_ADDR_C)
+				*type = LAPB_RESPONSE;
+		}
+	} else {
+		if (lapb->mode & LAPB_DCE) {
+			if (skb->data[0] == LAPB_ADDR_A)
+				*type = LAPB_COMMAND;
+			if (skb->data[0] == LAPB_ADDR_B)
+				*type = LAPB_RESPONSE;
+		} else {
+			if (skb->data[0] == LAPB_ADDR_B)
+				*type = LAPB_COMMAND;
+			if (skb->data[0] == LAPB_ADDR_A)
+				*type = LAPB_RESPONSE;
+		}
+	}
+		
+	skb_pull(skb, 1);
+
+	if (lapb->mode & LAPB_EXTENDED) {
+		if ((skb->data[0] & LAPB_S) == 0) {
+			frametype = LAPB_I;			/* I frame - carries NR/NS/PF */
+			*ns = (skb->data[0] >> 1) & 0x7F;
+			*nr = (skb->data[1] >> 1) & 0x7F;
+			*pf = skb->data[1] & LAPB_EPF;
+			skb_pull(skb, 2);
+		} else if ((skb->data[0] & LAPB_U) == 1) { 	/* S frame - take out PF/NR */
+			frametype = skb->data[0] & 0x0F;
+			*nr = (skb->data[1] >> 1) & 0x7F;
+			*pf = skb->data[1] & LAPB_EPF;
+			skb_pull(skb, 2);
+		} else if ((skb->data[0] & LAPB_U) == 3) { 	/* U frame - take out PF */
+			frametype = skb->data[0] & ~LAPB_SPF;
+			*pf = skb->data[0] & LAPB_SPF;
+			skb_pull(skb, 1);
+		}
+	} else {
+		if ((skb->data[0] & LAPB_S) == 0) {
+			frametype = LAPB_I;			/* I frame - carries NR/NS/PF */
+			*ns = (skb->data[0] >> 1) & 0x07;
+			*nr = (skb->data[0] >> 5) & 0x07;
+			*pf = skb->data[0] & LAPB_SPF;
+		} else if ((skb->data[0] & LAPB_U) == 1) { 	/* S frame - take out PF/NR */
+			frametype = skb->data[0] & 0x0F;
+			*nr = (skb->data[0] >> 5) & 0x07;
+			*pf = skb->data[0] & LAPB_SPF;
+		} else if ((skb->data[0] & LAPB_U) == 3) { 	/* U frame - take out PF */
+			frametype = skb->data[0] & ~PF;
+			*pf = skb->data[0] & LAPB_SPF;
+		}
+
+		skb_pull(skb, 1);
+	}
+
+	return frametype;
+}
+
+/* 
+ *	This routine is called when the HDLC layer internally  generates a
+ *	command or  response  for  the remote machine ( eg. RR, UA etc. ). 
+ *	Only supervisory or unnumbered frames are processed.
+ */
+void lapb_send_control(lapb_cb *lapb, int frametype, int poll_bit, int type)
+{
+	struct sk_buff *skb;
+	unsigned char  *dptr;
+	
+	if ((skb = alloc_skb(LAPB_HEADER_LEN + 3, GFP_ATOMIC)) == NULL)
+		return;
+
+	skb_reserve(skb, LAPB_HEADER_LEN + 1);
+
+	/* Assume a response - address structure for DTE */
+	if (lapb->mode & LAPB_EXTENDED) {
+		if ((frametype & LAPB_U) == LAPB_U) {
+			dptr = skb_put(skb, 1);
+			*dptr = frametype;
+			*dptr |= (poll_bit) ? LAPB_SPF : 0;
+		} else {
+			dptr = skb_put(skb, 2);
+			dptr[0] = frametype;
+			dptr[1] = (lapb->vr << 1);
+			dptr[1] |= (poll_bit) ? LAPB_EPF : 0;
+		}
+	} else {
+		dptr = skb_put(skb, 1);
+		*dptr = frametype;
+		*dptr |= (poll_bit) ? LAPB_SPF : 0;
+		if ((frametype & LAPB_U) == LAPB_S)		/* S frames carry NR */
+			*dptr |= (lapb->vr << 5);
+	}
+
+	lapb_transmit_buffer(lapb, skb, type);
+}
+
+#endif