/* * AX.25 release 037 * * 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. * * 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.25 029 Alan(GW4PTS) Switched to KA9Q constant names. Removed * old BSD code. * AX.25 030 Jonathan(G4KLX) Added support for extended AX.25. * Added fragmentation support. * Darryl(G7LED) Added function ax25_requeue_frames() to split * it up from ax25_frames_acked(). * AX.25 031 Joerg(DL1BKE) DAMA needs KISS Fullduplex ON/OFF. * Thus we have ax25_kiss_cmd() now... ;-) * Dave Brown(N2RJT) * Killed a silly bug in the DAMA code. * Joerg(DL1BKE) Found the real bug in ax25.h, sri. * AX.25 032 Joerg(DL1BKE) Added ax25_queue_length to count the number of * enqueued buffers of a socket.. * AX.25 035 Frederic(F1OAT) Support for pseudo-digipeating. * AX.25 037 Jonathan(G4KLX) New timer architecture. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * This routine purges all the queues of frames. */ void ax25_clear_queues(ax25_cb *ax25) { struct sk_buff *skb; while ((skb = skb_dequeue(&ax25->write_queue)) != NULL) kfree_skb(skb); while ((skb = skb_dequeue(&ax25->ack_queue)) != NULL) kfree_skb(skb); while ((skb = skb_dequeue(&ax25->reseq_queue)) != NULL) kfree_skb(skb); while ((skb = skb_dequeue(&ax25->frag_queue)) != NULL) kfree_skb(skb); } /* * 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 ax25_frames_acked(ax25_cb *ax25, unsigned short nr) { struct sk_buff *skb; /* * Remove all the ack-ed frames from the ack queue. */ if (ax25->va != nr) { while (skb_peek(&ax25->ack_queue) != NULL && ax25->va != nr) { skb = skb_dequeue(&ax25->ack_queue); kfree_skb(skb); ax25->va = (ax25->va + 1) % ax25->modulus; } } } void ax25_requeue_frames(ax25_cb *ax25) { struct sk_buff *skb, *skb_prev = NULL; /* * Requeue all the un-ack-ed frames on the output queue to be picked * up by ax25_kick called from the timer. This arrangement handles the * possibility of an empty output queue. */ while ((skb = skb_dequeue(&ax25->ack_queue)) != NULL) { if (skb_prev == NULL) skb_queue_head(&ax25->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 ax25_validate_nr(ax25_cb *ax25, unsigned short nr) { unsigned short vc = ax25->va; while (vc != ax25->vs) { if (nr == vc) return 1; vc = (vc + 1) % ax25->modulus; } if (nr == ax25->vs) return 1; return 0; } /* * This routine is the centralised routine for parsing the control * information for the different frame formats. */ int ax25_decode(ax25_cb *ax25, struct sk_buff *skb, int *ns, int *nr, int *pf) { unsigned char *frame; int frametype = AX25_ILLEGAL; frame = skb->data; *ns = *nr = *pf = 0; if (ax25->modulus == AX25_MODULUS) { if ((frame[0] & AX25_S) == 0) { frametype = AX25_I; /* I frame - carries NR/NS/PF */ *ns = (frame[0] >> 1) & 0x07; *nr = (frame[0] >> 5) & 0x07; *pf = frame[0] & AX25_PF; } else if ((frame[0] & AX25_U) == 1) { /* S frame - take out PF/NR */ frametype = frame[0] & 0x0F; *nr = (frame[0] >> 5) & 0x07; *pf = frame[0] & AX25_PF; } else if ((frame[0] & AX25_U) == 3) { /* U frame - take out PF */ frametype = frame[0] & ~AX25_PF; *pf = frame[0] & AX25_PF; } skb_pull(skb, 1); } else { if ((frame[0] & AX25_S) == 0) { frametype = AX25_I; /* I frame - carries NR/NS/PF */ *ns = (frame[0] >> 1) & 0x7F; *nr = (frame[1] >> 1) & 0x7F; *pf = frame[1] & AX25_EPF; skb_pull(skb, 2); } else if ((frame[0] & AX25_U) == 1) { /* S frame - take out PF/NR */ frametype = frame[0] & 0x0F; *nr = (frame[1] >> 1) & 0x7F; *pf = frame[1] & AX25_EPF; skb_pull(skb, 2); } else if ((frame[0] & AX25_U) == 3) { /* U frame - take out PF */ frametype = frame[0] & ~AX25_PF; *pf = frame[0] & AX25_PF; 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 ax25_send_control(ax25_cb *ax25, int frametype, int poll_bit, int type) { struct sk_buff *skb; unsigned char *dptr; if ((skb = alloc_skb(AX25_BPQ_HEADER_LEN + ax25_addr_size(ax25->digipeat) + 2, GFP_ATOMIC)) == NULL) return; skb_reserve(skb, AX25_BPQ_HEADER_LEN + ax25_addr_size(ax25->digipeat)); skb->nh.raw = skb->data; /* Assume a response - address structure for DTE */ if (ax25->modulus == AX25_MODULUS) { dptr = skb_put(skb, 1); *dptr = frametype; *dptr |= (poll_bit) ? AX25_PF : 0; if ((frametype & AX25_U) == AX25_S) /* S frames carry NR */ *dptr |= (ax25->vr << 5); } else { if ((frametype & AX25_U) == AX25_U) { dptr = skb_put(skb, 1); *dptr = frametype; *dptr |= (poll_bit) ? AX25_PF : 0; } else { dptr = skb_put(skb, 2); dptr[0] = frametype; dptr[1] = (ax25->vr << 1); dptr[1] |= (poll_bit) ? AX25_EPF : 0; } } ax25_transmit_buffer(ax25, skb, type); } /* * Send a 'DM' to an unknown connection attempt, or an invalid caller. * * Note: src here is the sender, thus it's the target of the DM */ void ax25_return_dm(struct net_device *dev, ax25_address *src, ax25_address *dest, ax25_digi *digi) { struct sk_buff *skb; char *dptr; ax25_digi retdigi; if (dev == NULL) return; if ((skb = alloc_skb(AX25_BPQ_HEADER_LEN + ax25_addr_size(digi) + 1, GFP_ATOMIC)) == NULL) return; /* Next SABM will get DM'd */ skb_reserve(skb, AX25_BPQ_HEADER_LEN + ax25_addr_size(digi)); skb->nh.raw = skb->data; ax25_digi_invert(digi, &retdigi); dptr = skb_put(skb, 1); *dptr = AX25_DM | AX25_PF; /* * Do the address ourselves */ dptr = skb_push(skb, ax25_addr_size(digi)); dptr += ax25_addr_build(dptr, dest, src, &retdigi, AX25_RESPONSE, AX25_MODULUS); skb->dev = dev; ax25_queue_xmit(skb); } /* * Exponential backoff for AX.25 */ void ax25_calculate_t1(ax25_cb *ax25) { int n, t = 2; switch (ax25->backoff) { case 0: break; case 1: t += 2 * ax25->n2count; break; case 2: for (n = 0; n < ax25->n2count; n++) t *= 2; if (t > 8) t = 8; break; } ax25->t1 = t * ax25->rtt; } /* * Calculate the Round Trip Time */ void ax25_calculate_rtt(ax25_cb *ax25) { if (ax25->backoff == 0) return; if (ax25_t1timer_running(ax25) && ax25->n2count == 0) ax25->rtt = (9 * ax25->rtt + ax25->t1 - ax25_display_timer(&ax25->t1timer)) / 10; if (ax25->rtt < AX25_T1CLAMPLO) ax25->rtt = AX25_T1CLAMPLO; if (ax25->rtt > AX25_T1CLAMPHI) ax25->rtt = AX25_T1CLAMPHI; } void ax25_disconnect(ax25_cb *ax25, int reason) { ax25_clear_queues(ax25); ax25_stop_t1timer(ax25); ax25_stop_t2timer(ax25); ax25_stop_t3timer(ax25); ax25_stop_idletimer(ax25); ax25->state = AX25_STATE_0; ax25_link_failed(ax25, reason); if (ax25->sk != NULL) { ax25->sk->state = TCP_CLOSE; ax25->sk->err = reason; ax25->sk->shutdown |= SEND_SHUTDOWN; if (!ax25->sk->dead) ax25->sk->state_change(ax25->sk); ax25->sk->dead = 1; } }