rose_out.c 2.8 KB

123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125
  1. /*
  2. * This program is free software; you can redistribute it and/or modify
  3. * it under the terms of the GNU General Public License as published by
  4. * the Free Software Foundation; either version 2 of the License, or
  5. * (at your option) any later version.
  6. *
  7. * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
  8. */
  9. #include <linux/errno.h>
  10. #include <linux/types.h>
  11. #include <linux/socket.h>
  12. #include <linux/in.h>
  13. #include <linux/kernel.h>
  14. #include <linux/timer.h>
  15. #include <linux/string.h>
  16. #include <linux/sockios.h>
  17. #include <linux/net.h>
  18. #include <net/ax25.h>
  19. #include <linux/inet.h>
  20. #include <linux/netdevice.h>
  21. #include <linux/skbuff.h>
  22. #include <net/sock.h>
  23. #include <asm/system.h>
  24. #include <linux/fcntl.h>
  25. #include <linux/mm.h>
  26. #include <linux/interrupt.h>
  27. #include <net/rose.h>
  28. /*
  29. * This procedure is passed a buffer descriptor for an iframe. It builds
  30. * the rest of the control part of the frame and then writes it out.
  31. */
  32. static void rose_send_iframe(struct sock *sk, struct sk_buff *skb)
  33. {
  34. struct rose_sock *rose = rose_sk(sk);
  35. if (skb == NULL)
  36. return;
  37. skb->data[2] |= (rose->vr << 5) & 0xE0;
  38. skb->data[2] |= (rose->vs << 1) & 0x0E;
  39. rose_start_idletimer(sk);
  40. rose_transmit_link(skb, rose->neighbour);
  41. }
  42. void rose_kick(struct sock *sk)
  43. {
  44. struct rose_sock *rose = rose_sk(sk);
  45. struct sk_buff *skb, *skbn;
  46. unsigned short start, end;
  47. if (rose->state != ROSE_STATE_3)
  48. return;
  49. if (rose->condition & ROSE_COND_PEER_RX_BUSY)
  50. return;
  51. if (!skb_peek(&sk->sk_write_queue))
  52. return;
  53. start = (skb_peek(&rose->ack_queue) == NULL) ? rose->va : rose->vs;
  54. end = (rose->va + sysctl_rose_window_size) % ROSE_MODULUS;
  55. if (start == end)
  56. return;
  57. rose->vs = start;
  58. /*
  59. * Transmit data until either we're out of data to send or
  60. * the window is full.
  61. */
  62. skb = skb_dequeue(&sk->sk_write_queue);
  63. do {
  64. if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
  65. skb_queue_head(&sk->sk_write_queue, skb);
  66. break;
  67. }
  68. skb_set_owner_w(skbn, sk);
  69. /*
  70. * Transmit the frame copy.
  71. */
  72. rose_send_iframe(sk, skbn);
  73. rose->vs = (rose->vs + 1) % ROSE_MODULUS;
  74. /*
  75. * Requeue the original data frame.
  76. */
  77. skb_queue_tail(&rose->ack_queue, skb);
  78. } while (rose->vs != end &&
  79. (skb = skb_dequeue(&sk->sk_write_queue)) != NULL);
  80. rose->vl = rose->vr;
  81. rose->condition &= ~ROSE_COND_ACK_PENDING;
  82. rose_stop_timer(sk);
  83. }
  84. /*
  85. * The following routines are taken from page 170 of the 7th ARRL Computer
  86. * Networking Conference paper, as is the whole state machine.
  87. */
  88. void rose_enquiry_response(struct sock *sk)
  89. {
  90. struct rose_sock *rose = rose_sk(sk);
  91. if (rose->condition & ROSE_COND_OWN_RX_BUSY)
  92. rose_write_internal(sk, ROSE_RNR);
  93. else
  94. rose_write_internal(sk, ROSE_RR);
  95. rose->vl = rose->vr;
  96. rose->condition &= ~ROSE_COND_ACK_PENDING;
  97. rose_stop_timer(sk);
  98. }