diff options
Diffstat (limited to 'net/x25/x25_out.c')
| -rw-r--r-- | net/x25/x25_out.c | 226 |
1 files changed, 226 insertions, 0 deletions
diff --git a/net/x25/x25_out.c b/net/x25/x25_out.c new file mode 100644 index 0000000000..dbc0940bf3 --- /dev/null +++ b/net/x25/x25_out.c @@ -0,0 +1,226 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * 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 + * + * 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/slab.h> +#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 */ + skb_copy_from_linear_data(skb, header, header_len); + skb_pull(skb, header_len); + + frontlen = skb_headroom(skb); + + while (skb->len > 0) { + release_sock(sk); + skbn = sock_alloc_send_skb(sk, frontlen + max_len, + noblock, &err); + lock_sock(sk); + if (!skbn) { + 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 */ + skb_copy_from_linear_data(skb, skb_put(skbn, len), len); + skb_pull(skb, len); + + /* Duplicate the Header */ + skb_push(skbn, header_len); + skb_copy_to_linear_data(skbn, 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 (skb_peek(&x25->interrupt_out_queue) != NULL && + !test_and_set_bit(X25_INTERRUPT_FLAG, &x25->flags)) { + + 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); +} |