From 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sat, 16 Apr 2005 15:20:36 -0700 Subject: Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip! --- net/ax25/ax25_subr.c | 295 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 295 insertions(+) create mode 100644 net/ax25/ax25_subr.c (limited to 'net/ax25/ax25_subr.c') diff --git a/net/ax25/ax25_subr.c b/net/ax25/ax25_subr.c new file mode 100644 index 000000000000..8cf72707af8b --- /dev/null +++ b/net/ax25/ax25_subr.c @@ -0,0 +1,295 @@ +/* + * 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 (C) Alan Cox GW4PTS (alan@lxorguk.ukuu.org.uk) + * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk) + * Copyright (C) Joerg Reuter DL1BKE (jreuter@yaina.de) + * Copyright (C) Frederic Rible F1OAT (frible@teaser.fr) + */ +#include +#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) +{ + skb_queue_purge(&ax25->write_queue); + skb_queue_purge(&ax25->ack_queue); + skb_queue_purge(&ax25->reseq_queue); + skb_queue_purge(&ax25->frag_queue); +} + +/* + * 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->ax25_dev->dev->hard_header_len + 2, GFP_ATOMIC)) == NULL) + return; + + skb_reserve(skb, ax25->ax25_dev->dev->hard_header_len); + + 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(dev->hard_header_len + 1, GFP_ATOMIC)) == NULL) + return; /* Next SABM will get DM'd */ + + skb_reserve(skb, dev->hard_header_len); + 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) { + bh_lock_sock(ax25->sk); + ax25->sk->sk_state = TCP_CLOSE; + ax25->sk->sk_err = reason; + ax25->sk->sk_shutdown |= SEND_SHUTDOWN; + if (!sock_flag(ax25->sk, SOCK_DEAD)) { + ax25->sk->sk_state_change(ax25->sk); + sock_set_flag(ax25->sk, SOCK_DEAD); + } + bh_unlock_sock(ax25->sk); + } +} -- cgit v1.2.3