/* * This program 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. * * 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 <net/ax25.h> #include <linux/inet.h> #include <linux/netdevice.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/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); } } }