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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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* Copyright Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
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* Copyright Darryl Miles G7LED (dlm@g7led.demon.co.uk)
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#include <linux/errno.h>
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#include <linux/types.h>
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#include <linux/socket.h>
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#include <linux/kernel.h>
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#include <linux/timer.h>
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#include <linux/string.h>
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#include <linux/sockios.h>
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#include <linux/net.h>
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#include <linux/inet.h>
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#include <linux/netdevice.h>
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#include <linux/skbuff.h>
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#include <asm/uaccess.h>
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#include <asm/system.h>
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#include <linux/fcntl.h>
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#include <linux/interrupt.h>
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#include <net/netrom.h>
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* This is where all NET/ROM frames pass, except for IP-over-NET/ROM which
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* cannot be fragmented in this manner.
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void nr_output(struct sock *sk, struct sk_buff *skb)
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unsigned char transport[NR_TRANSPORT_LEN];
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int err, frontlen, len;
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if (skb->len - NR_TRANSPORT_LEN > NR_MAX_PACKET_SIZE) {
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/* Save a copy of the Transport Header */
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skb_copy_from_linear_data(skb, transport, NR_TRANSPORT_LEN);
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skb_pull(skb, NR_TRANSPORT_LEN);
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frontlen = skb_headroom(skb);
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while (skb->len > 0) {
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if ((skbn = sock_alloc_send_skb(sk, frontlen + NR_MAX_PACKET_SIZE, 0, &err)) == NULL)
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skb_reserve(skbn, frontlen);
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len = (NR_MAX_PACKET_SIZE > skb->len) ? skb->len : NR_MAX_PACKET_SIZE;
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/* Copy the user data */
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skb_copy_from_linear_data(skb, skb_put(skbn, len), len);
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/* Duplicate the Transport Header */
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skb_push(skbn, NR_TRANSPORT_LEN);
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skb_copy_to_linear_data(skbn, transport,
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skbn->data[4] |= NR_MORE_FLAG;
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skb_queue_tail(&sk->sk_write_queue, skbn); /* Throw it on the queue */
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skb_queue_tail(&sk->sk_write_queue, skb); /* Throw it on the queue */
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* This procedure is passed a buffer descriptor for an iframe. It builds
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* the rest of the control part of the frame and then writes it out.
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static void nr_send_iframe(struct sock *sk, struct sk_buff *skb)
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struct nr_sock *nr = nr_sk(sk);
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skb->data[2] = nr->vs;
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skb->data[3] = nr->vr;
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if (nr->condition & NR_COND_OWN_RX_BUSY)
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skb->data[4] |= NR_CHOKE_FLAG;
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nr_start_idletimer(sk);
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nr_transmit_buffer(sk, skb);
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void nr_send_nak_frame(struct sock *sk)
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struct sk_buff *skb, *skbn;
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struct nr_sock *nr = nr_sk(sk);
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if ((skb = skb_peek(&nr->ack_queue)) == NULL)
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if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL)
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skbn->data[2] = nr->va;
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skbn->data[3] = nr->vr;
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if (nr->condition & NR_COND_OWN_RX_BUSY)
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skbn->data[4] |= NR_CHOKE_FLAG;
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nr_transmit_buffer(sk, skbn);
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nr->condition &= ~NR_COND_ACK_PENDING;
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void nr_kick(struct sock *sk)
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struct nr_sock *nr = nr_sk(sk);
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struct sk_buff *skb, *skbn;
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unsigned short start, end;
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if (nr->state != NR_STATE_3)
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if (nr->condition & NR_COND_PEER_RX_BUSY)
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if (!skb_peek(&sk->sk_write_queue))
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start = (skb_peek(&nr->ack_queue) == NULL) ? nr->va : nr->vs;
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end = (nr->va + nr->window) % NR_MODULUS;
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* Transmit data until either we're out of data to send or
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* the window is full.
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* Dequeue the frame and copy it.
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skb = skb_dequeue(&sk->sk_write_queue);
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if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
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skb_queue_head(&sk->sk_write_queue, skb);
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skb_set_owner_w(skbn, sk);
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* Transmit the frame copy.
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nr_send_iframe(sk, skbn);
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nr->vs = (nr->vs + 1) % NR_MODULUS;
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* Requeue the original data frame.
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skb_queue_tail(&nr->ack_queue, skb);
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} while (nr->vs != end &&
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(skb = skb_dequeue(&sk->sk_write_queue)) != NULL);
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nr->condition &= ~NR_COND_ACK_PENDING;
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if (!nr_t1timer_running(sk))
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nr_start_t1timer(sk);
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void nr_transmit_buffer(struct sock *sk, struct sk_buff *skb)
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struct nr_sock *nr = nr_sk(sk);
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* Add the protocol byte and network header.
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dptr = skb_push(skb, NR_NETWORK_LEN);
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memcpy(dptr, &nr->source_addr, AX25_ADDR_LEN);
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dptr[6] &= ~AX25_CBIT;
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dptr[6] &= ~AX25_EBIT;
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dptr[6] |= AX25_SSSID_SPARE;
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dptr += AX25_ADDR_LEN;
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memcpy(dptr, &nr->dest_addr, AX25_ADDR_LEN);
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dptr[6] &= ~AX25_CBIT;
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dptr[6] |= AX25_EBIT;
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dptr[6] |= AX25_SSSID_SPARE;
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dptr += AX25_ADDR_LEN;
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*dptr++ = sysctl_netrom_network_ttl_initialiser;
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if (!nr_route_frame(skb, NULL)) {
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nr_disconnect(sk, ENETUNREACH);
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* The following routines are taken from page 170 of the 7th ARRL Computer
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* Networking Conference paper, as is the whole state machine.
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void nr_establish_data_link(struct sock *sk)
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struct nr_sock *nr = nr_sk(sk);
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nr->condition = 0x00;
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nr_write_internal(sk, NR_CONNREQ);
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nr_stop_idletimer(sk);
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nr_start_t1timer(sk);
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* Never send a NAK when we are CHOKEd.
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void nr_enquiry_response(struct sock *sk)
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struct nr_sock *nr = nr_sk(sk);
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int frametype = NR_INFOACK;
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if (nr->condition & NR_COND_OWN_RX_BUSY) {
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frametype |= NR_CHOKE_FLAG;
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if (skb_peek(&nr->reseq_queue) != NULL)
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frametype |= NR_NAK_FLAG;
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nr_write_internal(sk, frametype);
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nr->condition &= ~NR_COND_ACK_PENDING;
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void nr_check_iframes_acked(struct sock *sk, unsigned short nr)
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struct nr_sock *nrom = nr_sk(sk);
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if (nrom->vs == nr) {
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nr_frames_acked(sk, nr);
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if (nrom->va != nr) {
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nr_frames_acked(sk, nr);
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nr_start_t1timer(sk);