/* * X.25 Packet Layer release 002 * * This is ALPHA test software. This code may break your machine, * randomly fail to work with new releases, misbehave and/or generally * screw up. It might even work. * * This code REQUIRES 2.1.15 or higher * * 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. * * History * X.25 001 Jonathan Naylor Started coding. * X.25 002 Jonathan Naylor New timer architecture. * 2000-09-04 Henner Eisen Prevented x25_output() skb leakage. * 2000-10-27 Henner Eisen MSG_DONTWAIT for fragment allocation. * 2000-11-10 Henner Eisen x25_send_iframe(): re-queued frames * needed cleaned seq-number fields. */ #include <linux/socket.h> #include <linux/kernel.h> #include <linux/string.h> #include <linux/skbuff.h> #include <net/sock.h> #include <net/x25.h> static int x25_pacsize_to_bytes(unsigned int pacsize) { int bytes = 1; if (!pacsize) return 128; while (pacsize-- > 0) bytes *= 2; return bytes; } /* * This is where all X.25 information frames pass. * * Returns the amount of user data bytes sent on success * or a negative error code on failure. */ int x25_output(struct sock *sk, struct sk_buff *skb) { struct sk_buff *skbn; unsigned char header[X25_EXT_MIN_LEN]; int err, frontlen, len; int sent=0, noblock = X25_SKB_CB(skb)->flags & MSG_DONTWAIT; struct x25_sock *x25 = x25_sk(sk); int header_len = x25->neighbour->extended ? X25_EXT_MIN_LEN : X25_STD_MIN_LEN; int max_len = x25_pacsize_to_bytes(x25->facilities.pacsize_out); if (skb->len - header_len > max_len) { /* Save a copy of the Header */ memcpy(header, skb->data, header_len); skb_pull(skb, header_len); frontlen = skb_headroom(skb); while (skb->len > 0) { if ((skbn = sock_alloc_send_skb(sk, frontlen + max_len, noblock, &err)) == NULL){ if (err == -EWOULDBLOCK && noblock){ kfree_skb(skb); return sent; } SOCK_DEBUG(sk, "x25_output: fragment alloc" " failed, err=%d, %d bytes " "sent\n", err, sent); return err; } skb_reserve(skbn, frontlen); len = max_len > skb->len ? skb->len : max_len; /* Copy the user data */ memcpy(skb_put(skbn, len), skb->data, len); skb_pull(skb, len); /* Duplicate the Header */ skb_push(skbn, header_len); memcpy(skbn->data, header, header_len); if (skb->len > 0) { if (x25->neighbour->extended) skbn->data[3] |= X25_EXT_M_BIT; else skbn->data[2] |= X25_STD_M_BIT; } skb_queue_tail(&sk->sk_write_queue, skbn); sent += len; } kfree_skb(skb); } else { skb_queue_tail(&sk->sk_write_queue, skb); sent = skb->len - header_len; } return sent; } /* * 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 x25_send_iframe(struct sock *sk, struct sk_buff *skb) { struct x25_sock *x25 = x25_sk(sk); if (!skb) return; if (x25->neighbour->extended) { skb->data[2] = (x25->vs << 1) & 0xFE; skb->data[3] &= X25_EXT_M_BIT; skb->data[3] |= (x25->vr << 1) & 0xFE; } else { skb->data[2] &= X25_STD_M_BIT; skb->data[2] |= (x25->vs << 1) & 0x0E; skb->data[2] |= (x25->vr << 5) & 0xE0; } x25_transmit_link(skb, x25->neighbour); } void x25_kick(struct sock *sk) { struct sk_buff *skb, *skbn; unsigned short start, end; int modulus; struct x25_sock *x25 = x25_sk(sk); if (x25->state != X25_STATE_3) return; /* * Transmit interrupt data. */ if (!x25->intflag && skb_peek(&x25->interrupt_out_queue) != NULL) { x25->intflag = 1; skb = skb_dequeue(&x25->interrupt_out_queue); x25_transmit_link(skb, x25->neighbour); } if (x25->condition & X25_COND_PEER_RX_BUSY) return; if (!skb_peek(&sk->sk_write_queue)) return; modulus = x25->neighbour->extended ? X25_EMODULUS : X25_SMODULUS; start = skb_peek(&x25->ack_queue) ? x25->vs : x25->va; end = (x25->va + x25->facilities.winsize_out) % modulus; if (start == end) return; x25->vs = start; /* * Transmit data until either we're out of data to send or * the window is full. */ 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. */ x25_send_iframe(sk, skbn); x25->vs = (x25->vs + 1) % modulus; /* * Requeue the original data frame. */ skb_queue_tail(&x25->ack_queue, skb); } while (x25->vs != end && (skb = skb_dequeue(&sk->sk_write_queue)) != NULL); x25->vl = x25->vr; x25->condition &= ~X25_COND_ACK_PENDING; x25_stop_timer(sk); } /* * The following routines are taken from page 170 of the 7th ARRL Computer * Networking Conference paper, as is the whole state machine. */ void x25_enquiry_response(struct sock *sk) { struct x25_sock *x25 = x25_sk(sk); if (x25->condition & X25_COND_OWN_RX_BUSY) x25_write_internal(sk, X25_RNR); else x25_write_internal(sk, X25_RR); x25->vl = x25->vr; x25->condition &= ~X25_COND_ACK_PENDING; x25_stop_timer(sk); }