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[/] [or1k/] [trunk/] [rc203soc/] [sw/] [uClinux/] [net/] [ax25/] [ax25_out.c] - Rev 1772
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/* * AX.25 release 035 * * This code REQUIRES 1.2.1 or higher/ NET3.029 * * 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. * * Most of this code is based on the SDL diagrams published in the 7th * ARRL Computer Networking Conference papers. The diagrams have mistakes * in them, but are mostly correct. Before you modify the code could you * read the SDL diagrams as the code is not obvious and probably very * easy to break; * * History * AX.25 028a Jonathan(G4KLX) New state machine based on SDL diagrams. * AX.25 029 Alan(GW4PTS) Switched to KA9Q constant names. * Jonathan(G4KLX) Only poll when window is full. * AX.25 030 Jonathan(G4KLX) Added fragmentation to ax25_output. * Added support for extended AX.25. * AX.25 031 Joerg(DL1BKE) Added DAMA support * Joerg(DL1BKE) Modified fragmenter to fragment vanilla * AX.25 I-Frames. Added PACLEN parameter. * Joerg(DL1BKE) Fixed a problem with buffer allocation * for fragments. */ #include <linux/config.h> #if defined(CONFIG_AX25) || defined(CONFIG_AX25_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 <net/ax25.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> /* * All outgoing AX.25 I frames pass via this routine. Therefore this is * where the fragmentation of frames takes place. If fragment is set to * zero then we are not allowed to do fragmentation, even if the frame * is too large. */ void ax25_output(ax25_cb *ax25, int paclen, struct sk_buff *skb) { struct sk_buff *skbn; unsigned char *p; int frontlen, len, fragno, ka9qfrag, first = 1; long flags; if ((skb->len - 1) > paclen) { if (*skb->data == AX25_P_TEXT) { skb_pull(skb, 1); /* skip PID */ ka9qfrag = 0; } else { paclen -= 2; /* Allow for fragment control info */ ka9qfrag = 1; } fragno = skb->len / paclen; if (skb->len % paclen == 0) fragno--; frontlen = skb_headroom(skb); /* Address space + CTRL */ while (skb->len > 0) { save_flags(flags); cli(); if ((skbn = alloc_skb(paclen + 2 + frontlen, GFP_ATOMIC)) == NULL) { restore_flags(flags); printk(KERN_DEBUG "ax25_output: alloc_skb returned NULL\n"); if (skb_device_locked(skb)) skb_device_unlock(skb); return; } skbn->sk = skb->sk; skbn->free = 1; if (skbn->sk != NULL) atomic_add(skbn->truesize, &skbn->sk->wmem_alloc); restore_flags(flags); len = (paclen > skb->len) ? skb->len : paclen; if (ka9qfrag == 1) { skb_reserve(skbn, frontlen + 2); memcpy(skb_put(skbn, len), skb->data, len); p = skb_push(skbn, 2); *p++ = AX25_P_SEGMENT; *p = fragno--; if (first) { *p |= AX25_SEG_FIRST; first = 0; } } else { skb_reserve(skbn, frontlen + 1); memcpy(skb_put(skbn, len), skb->data, len); p = skb_push(skbn, 1); *p = AX25_P_TEXT; } skb_pull(skb, len); skb_queue_tail(&ax25->write_queue, skbn); /* Throw it on the queue */ } kfree_skb(skb, FREE_WRITE); } else { skb_queue_tail(&ax25->write_queue, skb); /* Throw it on the queue */ } if (ax25->state == AX25_STATE_3 || ax25->state == AX25_STATE_4) { if (!ax25->dama_slave) /* bke 960114: we aren't allowed to transmit */ ax25_kick(ax25); /* in DAMA mode unless we received a Poll */ } } /* * 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 ax25_send_iframe(ax25_cb *ax25, struct sk_buff *skb, int poll_bit) { unsigned char *frame; if (skb == NULL) return; if (ax25->modulus == AX25_MODULUS) { frame = skb_push(skb, 1); *frame = AX25_I; *frame |= (poll_bit) ? AX25_PF : 0; *frame |= (ax25->vr << 5); *frame |= (ax25->vs << 1); } else { frame = skb_push(skb, 2); frame[0] = AX25_I; frame[0] |= (ax25->vs << 1); frame[1] = (poll_bit) ? AX25_EPF : 0; frame[1] |= (ax25->vr << 1); } ax25->idletimer = ax25->idle; ax25_transmit_buffer(ax25, skb, AX25_COMMAND); } void ax25_kick(ax25_cb *ax25) { struct sk_buff *skb, *skbn; int last = 1; unsigned short start, end, next; del_timer(&ax25->timer); start = (skb_peek(&ax25->ack_queue) == NULL) ? ax25->va : ax25->vs; end = (ax25->va + ax25->window) % ax25->modulus; if (!(ax25->condition & AX25_COND_PEER_RX_BUSY) && start != end && skb_peek(&ax25->write_queue) != NULL) { ax25->vs = start; /* * Transmit data until either we're out of data to send or * the window is full. Send a poll on the final I frame if * the window is filled. */ /* * Dequeue the frame and copy it. */ skb = skb_dequeue(&ax25->write_queue); do { if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) { skb_queue_head(&ax25->write_queue, skb); break; } skbn->sk = skb->sk; if (skbn->sk != NULL) atomic_add(skbn->truesize, &skbn->sk->wmem_alloc); next = (ax25->vs + 1) % ax25->modulus; last = (next == end); /* * Transmit the frame copy. * bke 960114: do not set the Poll bit on the last frame * in DAMA mode. */ ax25_send_iframe(ax25, skbn, (last && !ax25->dama_slave) ? AX25_POLLON : AX25_POLLOFF); ax25->vs = next; /* * Requeue the original data frame. */ skb_queue_tail(&ax25->ack_queue, skb); } while (!last && (skb = skb_dequeue(&ax25->write_queue)) != NULL); ax25->condition &= ~AX25_COND_ACK_PENDING; if (ax25->t1timer == 0) { ax25->t3timer = 0; ax25->t1timer = ax25->t1 = ax25_calculate_t1(ax25); } } ax25_set_timer(ax25); } void ax25_transmit_buffer(ax25_cb *ax25, struct sk_buff *skb, int type) { unsigned char *ptr; if (ax25->device == NULL) { ax25_disconnect(ax25, ENETUNREACH); return; } if (skb_headroom(skb) < size_ax25_addr(ax25->digipeat)) { printk(KERN_CRIT "ax25_transmit_buffer: not enough room for digi-peaters\n"); skb->free = 1; kfree_skb(skb, FREE_WRITE); return; } ptr = skb_push(skb, size_ax25_addr(ax25->digipeat)); build_ax25_addr(ptr, &ax25->source_addr, &ax25->dest_addr, ax25->digipeat, type, ax25->modulus); ax25_queue_xmit(skb, ax25->device, SOPRI_NORMAL); } /* * The following routines are taken from page 170 of the 7th ARRL Computer * Networking Conference paper, as is the whole state machine. */ void ax25_nr_error_recovery(ax25_cb *ax25) { ax25_establish_data_link(ax25); } void ax25_establish_data_link(ax25_cb *ax25) { ax25->condition = 0x00; ax25->n2count = 0; if (ax25->modulus == AX25_MODULUS) ax25_send_control(ax25, AX25_SABM, AX25_POLLON, AX25_COMMAND); else ax25_send_control(ax25, AX25_SABME, AX25_POLLON, AX25_COMMAND); ax25->t3timer = 0; ax25->t2timer = 0; ax25->t1timer = ax25->t1 = ax25_calculate_t1(ax25); } void ax25_transmit_enquiry(ax25_cb *ax25) { if (ax25->condition & AX25_COND_OWN_RX_BUSY) ax25_send_control(ax25, AX25_RNR, AX25_POLLON, AX25_COMMAND); else ax25_send_control(ax25, AX25_RR, AX25_POLLON, AX25_COMMAND); ax25->condition &= ~AX25_COND_ACK_PENDING; ax25->t1timer = ax25->t1 = ax25_calculate_t1(ax25); } void ax25_enquiry_response(ax25_cb *ax25) { if (ax25->condition & AX25_COND_OWN_RX_BUSY) ax25_send_control(ax25, AX25_RNR, AX25_POLLON, AX25_RESPONSE); else ax25_send_control(ax25, AX25_RR, AX25_POLLON, AX25_RESPONSE); ax25->condition &= ~AX25_COND_ACK_PENDING; } void ax25_timeout_response(ax25_cb *ax25) { if (ax25->condition & AX25_COND_OWN_RX_BUSY) ax25_send_control(ax25, AX25_RNR, AX25_POLLOFF, AX25_RESPONSE); else ax25_send_control(ax25, AX25_RR, AX25_POLLOFF, AX25_RESPONSE); ax25->condition &= ~AX25_COND_ACK_PENDING; } void ax25_check_iframes_acked(ax25_cb *ax25, unsigned short nr) { if (ax25->vs == nr) { ax25_frames_acked(ax25, nr); ax25_calculate_rtt(ax25); ax25->t1timer = 0; ax25->t3timer = ax25->t3; } else { if (ax25->va != nr) { ax25_frames_acked(ax25, nr); ax25->t1timer = ax25->t1 = ax25_calculate_t1(ax25); } } } /* * dl1bke 960114: transmit I frames on DAMA poll */ void dama_enquiry_response(ax25_cb *ax25) { ax25_cb *ax25o; if (!(ax25->condition & AX25_COND_PEER_RX_BUSY)) { ax25_requeue_frames(ax25); ax25_kick(ax25); } if (ax25->state == AX25_STATE_1 || ax25->state == AX25_STATE_2 || skb_peek(&ax25->ack_queue) != NULL) ax25_t1_timeout(ax25); else ax25->n2count = 0; ax25->t3timer = ax25->t3; /* The FLEXNET DAMA master implementation refuses to send us ANY */ /* I frame for this connection if we send a REJ here, probably */ /* due to its frame collector scheme? A simple RR or RNR will */ /* invoke the retransmission, and in fact REJs are superfluous */ /* in DAMA mode anyway... */ #if 0 if (ax25->condition & AX25_COND_REJECT) ax25_send_control(ax25, AX25_REJ, AX25_POLLOFF, AX25_RESPONSE); else #endif ax25_enquiry_response(ax25); /* Note that above response to the poll could be sent behind the */ /* transmissions of the other channels as well... This version */ /* gives better performance on FLEXNET nodes. (Why, Gunter?) */ for (ax25o = ax25_list; ax25o != NULL; ax25o = ax25o->next) { if (ax25o == ax25) continue; if (ax25o->device != ax25->device) continue; if (ax25o->state == AX25_STATE_1 || ax25o->state == AX25_STATE_2) { ax25_t1_timeout(ax25o); continue; } if (!ax25o->dama_slave) continue; if (!(ax25o->condition & AX25_COND_PEER_RX_BUSY) && (ax25o->state == AX25_STATE_3 || (ax25o->state == AX25_STATE_4 && ax25o->t1timer == 0))) { ax25_requeue_frames(ax25o); ax25_kick(ax25o); } if (ax25o->state == AX25_STATE_1 || ax25o->state == AX25_STATE_2 || skb_peek(&ax25o->ack_queue) != NULL) ax25_t1_timeout(ax25o); ax25o->t3timer = ax25o->t3; } } void dama_establish_data_link(ax25_cb *ax25) { ax25->condition = 0x00; ax25->n2count = 0; ax25->t3timer = ax25->t3; ax25->t2timer = 0; ax25->t1timer = ax25->t1 = ax25_calculate_t1(ax25); } #endif
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