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226 lines
5.1 KiB
226 lines
5.1 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* X.25 Packet Layer release 002 |
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* |
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* This is ALPHA test software. This code may break your machine, |
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* randomly fail to work with new releases, misbehave and/or generally |
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* screw up. It might even work. |
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* |
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* This code REQUIRES 2.1.15 or higher |
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* |
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* History |
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* X.25 001 Jonathan Naylor Started coding. |
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* X.25 002 Jonathan Naylor New timer architecture. |
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* 2000-09-04 Henner Eisen Prevented x25_output() skb leakage. |
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* 2000-10-27 Henner Eisen MSG_DONTWAIT for fragment allocation. |
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* 2000-11-10 Henner Eisen x25_send_iframe(): re-queued frames |
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* needed cleaned seq-number fields. |
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*/ |
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#include <linux/slab.h> |
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#include <linux/socket.h> |
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#include <linux/kernel.h> |
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#include <linux/string.h> |
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#include <linux/skbuff.h> |
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#include <net/sock.h> |
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#include <net/x25.h> |
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static int x25_pacsize_to_bytes(unsigned int pacsize) |
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{ |
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int bytes = 1; |
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if (!pacsize) |
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return 128; |
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while (pacsize-- > 0) |
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bytes *= 2; |
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return bytes; |
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} |
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/* |
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* This is where all X.25 information frames pass. |
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* |
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* Returns the amount of user data bytes sent on success |
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* or a negative error code on failure. |
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*/ |
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int x25_output(struct sock *sk, struct sk_buff *skb) |
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{ |
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struct sk_buff *skbn; |
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unsigned char header[X25_EXT_MIN_LEN]; |
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int err, frontlen, len; |
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int sent=0, noblock = X25_SKB_CB(skb)->flags & MSG_DONTWAIT; |
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struct x25_sock *x25 = x25_sk(sk); |
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int header_len = x25->neighbour->extended ? X25_EXT_MIN_LEN : |
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X25_STD_MIN_LEN; |
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int max_len = x25_pacsize_to_bytes(x25->facilities.pacsize_out); |
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if (skb->len - header_len > max_len) { |
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/* Save a copy of the Header */ |
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skb_copy_from_linear_data(skb, header, header_len); |
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skb_pull(skb, header_len); |
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frontlen = skb_headroom(skb); |
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while (skb->len > 0) { |
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release_sock(sk); |
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skbn = sock_alloc_send_skb(sk, frontlen + max_len, |
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noblock, &err); |
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lock_sock(sk); |
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if (!skbn) { |
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if (err == -EWOULDBLOCK && noblock){ |
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kfree_skb(skb); |
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return sent; |
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} |
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SOCK_DEBUG(sk, "x25_output: fragment alloc" |
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" failed, err=%d, %d bytes " |
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"sent\n", err, sent); |
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return err; |
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} |
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skb_reserve(skbn, frontlen); |
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len = max_len > skb->len ? skb->len : max_len; |
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/* Copy the user data */ |
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skb_copy_from_linear_data(skb, skb_put(skbn, len), len); |
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skb_pull(skb, len); |
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/* Duplicate the Header */ |
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skb_push(skbn, header_len); |
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skb_copy_to_linear_data(skbn, header, header_len); |
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if (skb->len > 0) { |
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if (x25->neighbour->extended) |
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skbn->data[3] |= X25_EXT_M_BIT; |
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else |
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skbn->data[2] |= X25_STD_M_BIT; |
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} |
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skb_queue_tail(&sk->sk_write_queue, skbn); |
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sent += len; |
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} |
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kfree_skb(skb); |
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} else { |
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skb_queue_tail(&sk->sk_write_queue, skb); |
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sent = skb->len - header_len; |
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} |
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return sent; |
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} |
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/* |
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* This procedure is passed a buffer descriptor for an iframe. It builds |
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* the rest of the control part of the frame and then writes it out. |
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*/ |
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static void x25_send_iframe(struct sock *sk, struct sk_buff *skb) |
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{ |
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struct x25_sock *x25 = x25_sk(sk); |
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if (!skb) |
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return; |
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if (x25->neighbour->extended) { |
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skb->data[2] = (x25->vs << 1) & 0xFE; |
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skb->data[3] &= X25_EXT_M_BIT; |
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skb->data[3] |= (x25->vr << 1) & 0xFE; |
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} else { |
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skb->data[2] &= X25_STD_M_BIT; |
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skb->data[2] |= (x25->vs << 1) & 0x0E; |
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skb->data[2] |= (x25->vr << 5) & 0xE0; |
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} |
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x25_transmit_link(skb, x25->neighbour); |
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} |
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void x25_kick(struct sock *sk) |
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{ |
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struct sk_buff *skb, *skbn; |
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unsigned short start, end; |
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int modulus; |
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struct x25_sock *x25 = x25_sk(sk); |
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if (x25->state != X25_STATE_3) |
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return; |
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/* |
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* Transmit interrupt data. |
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*/ |
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if (skb_peek(&x25->interrupt_out_queue) != NULL && |
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!test_and_set_bit(X25_INTERRUPT_FLAG, &x25->flags)) { |
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skb = skb_dequeue(&x25->interrupt_out_queue); |
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x25_transmit_link(skb, x25->neighbour); |
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} |
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if (x25->condition & X25_COND_PEER_RX_BUSY) |
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return; |
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if (!skb_peek(&sk->sk_write_queue)) |
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return; |
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modulus = x25->neighbour->extended ? X25_EMODULUS : X25_SMODULUS; |
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start = skb_peek(&x25->ack_queue) ? x25->vs : x25->va; |
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end = (x25->va + x25->facilities.winsize_out) % modulus; |
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if (start == end) |
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return; |
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x25->vs = start; |
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/* |
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* Transmit data until either we're out of data to send or |
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* the window is full. |
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*/ |
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skb = skb_dequeue(&sk->sk_write_queue); |
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do { |
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if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) { |
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skb_queue_head(&sk->sk_write_queue, skb); |
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break; |
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} |
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skb_set_owner_w(skbn, sk); |
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/* |
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* Transmit the frame copy. |
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*/ |
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x25_send_iframe(sk, skbn); |
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x25->vs = (x25->vs + 1) % modulus; |
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/* |
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* Requeue the original data frame. |
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*/ |
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skb_queue_tail(&x25->ack_queue, skb); |
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} while (x25->vs != end && |
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(skb = skb_dequeue(&sk->sk_write_queue)) != NULL); |
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x25->vl = x25->vr; |
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x25->condition &= ~X25_COND_ACK_PENDING; |
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x25_stop_timer(sk); |
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} |
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/* |
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* The following routines are taken from page 170 of the 7th ARRL Computer |
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* Networking Conference paper, as is the whole state machine. |
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*/ |
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void x25_enquiry_response(struct sock *sk) |
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{ |
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struct x25_sock *x25 = x25_sk(sk); |
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if (x25->condition & X25_COND_OWN_RX_BUSY) |
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x25_write_internal(sk, X25_RNR); |
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else |
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x25_write_internal(sk, X25_RR); |
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x25->vl = x25->vr; |
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x25->condition &= ~X25_COND_ACK_PENDING; |
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x25_stop_timer(sk); |
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}
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