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456 lines
11 KiB
456 lines
11 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 Centralised disconnection code. |
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* New timer architecture. |
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* 2000-03-20 Daniela Squassoni Disabling/enabling of facilities |
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* negotiation. |
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* 2000-11-10 Henner Eisen Check and reset for out-of-sequence |
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* i-frames. |
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*/ |
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#define pr_fmt(fmt) "X25: " fmt |
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#include <linux/slab.h> |
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#include <linux/errno.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/tcp_states.h> |
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#include <net/x25.h> |
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static int x25_queue_rx_frame(struct sock *sk, struct sk_buff *skb, int more) |
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{ |
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struct sk_buff *skbo, *skbn = skb; |
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struct x25_sock *x25 = x25_sk(sk); |
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if (more) { |
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x25->fraglen += skb->len; |
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skb_queue_tail(&x25->fragment_queue, skb); |
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skb_set_owner_r(skb, sk); |
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return 0; |
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} |
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if (!more && x25->fraglen > 0) { /* End of fragment */ |
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int len = x25->fraglen + skb->len; |
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if ((skbn = alloc_skb(len, GFP_ATOMIC)) == NULL){ |
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kfree_skb(skb); |
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return 1; |
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} |
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skb_queue_tail(&x25->fragment_queue, skb); |
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skb_reset_transport_header(skbn); |
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skbo = skb_dequeue(&x25->fragment_queue); |
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skb_copy_from_linear_data(skbo, skb_put(skbn, skbo->len), |
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skbo->len); |
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kfree_skb(skbo); |
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while ((skbo = |
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skb_dequeue(&x25->fragment_queue)) != NULL) { |
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skb_pull(skbo, (x25->neighbour->extended) ? |
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X25_EXT_MIN_LEN : X25_STD_MIN_LEN); |
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skb_copy_from_linear_data(skbo, |
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skb_put(skbn, skbo->len), |
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skbo->len); |
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kfree_skb(skbo); |
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} |
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x25->fraglen = 0; |
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} |
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skb_set_owner_r(skbn, sk); |
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skb_queue_tail(&sk->sk_receive_queue, skbn); |
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if (!sock_flag(sk, SOCK_DEAD)) |
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sk->sk_data_ready(sk); |
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return 0; |
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} |
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/* |
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* State machine for state 1, Awaiting Call Accepted State. |
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* The handling of the timer(s) is in file x25_timer.c. |
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* Handling of state 0 and connection release is in af_x25.c. |
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*/ |
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static int x25_state1_machine(struct sock *sk, struct sk_buff *skb, int frametype) |
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{ |
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struct x25_address source_addr, dest_addr; |
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int len; |
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struct x25_sock *x25 = x25_sk(sk); |
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switch (frametype) { |
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case X25_CALL_ACCEPTED: { |
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x25_stop_timer(sk); |
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x25->condition = 0x00; |
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x25->vs = 0; |
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x25->va = 0; |
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x25->vr = 0; |
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x25->vl = 0; |
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x25->state = X25_STATE_3; |
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sk->sk_state = TCP_ESTABLISHED; |
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/* |
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* Parse the data in the frame. |
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*/ |
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if (!pskb_may_pull(skb, X25_STD_MIN_LEN)) |
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goto out_clear; |
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skb_pull(skb, X25_STD_MIN_LEN); |
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len = x25_parse_address_block(skb, &source_addr, |
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&dest_addr); |
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if (len > 0) |
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skb_pull(skb, len); |
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else if (len < 0) |
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goto out_clear; |
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len = x25_parse_facilities(skb, &x25->facilities, |
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&x25->dte_facilities, |
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&x25->vc_facil_mask); |
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if (len > 0) |
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skb_pull(skb, len); |
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else if (len < 0) |
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goto out_clear; |
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/* |
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* Copy any Call User Data. |
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*/ |
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if (skb->len > 0) { |
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if (skb->len > X25_MAX_CUD_LEN) |
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goto out_clear; |
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skb_copy_bits(skb, 0, x25->calluserdata.cuddata, |
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skb->len); |
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x25->calluserdata.cudlength = skb->len; |
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} |
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if (!sock_flag(sk, SOCK_DEAD)) |
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sk->sk_state_change(sk); |
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break; |
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} |
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case X25_CALL_REQUEST: |
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/* call collision */ |
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x25->causediag.cause = 0x01; |
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x25->causediag.diagnostic = 0x48; |
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x25_write_internal(sk, X25_CLEAR_REQUEST); |
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x25_disconnect(sk, EISCONN, 0x01, 0x48); |
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break; |
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case X25_CLEAR_REQUEST: |
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if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2)) |
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goto out_clear; |
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x25_write_internal(sk, X25_CLEAR_CONFIRMATION); |
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x25_disconnect(sk, ECONNREFUSED, skb->data[3], skb->data[4]); |
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break; |
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default: |
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break; |
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} |
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return 0; |
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out_clear: |
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x25_write_internal(sk, X25_CLEAR_REQUEST); |
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x25->state = X25_STATE_2; |
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x25_start_t23timer(sk); |
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return 0; |
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} |
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/* |
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* State machine for state 2, Awaiting Clear Confirmation State. |
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* The handling of the timer(s) is in file x25_timer.c |
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* Handling of state 0 and connection release is in af_x25.c. |
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*/ |
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static int x25_state2_machine(struct sock *sk, struct sk_buff *skb, int frametype) |
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{ |
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switch (frametype) { |
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case X25_CLEAR_REQUEST: |
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if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2)) |
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goto out_clear; |
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x25_write_internal(sk, X25_CLEAR_CONFIRMATION); |
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x25_disconnect(sk, 0, skb->data[3], skb->data[4]); |
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break; |
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case X25_CLEAR_CONFIRMATION: |
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x25_disconnect(sk, 0, 0, 0); |
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break; |
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default: |
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break; |
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} |
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return 0; |
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out_clear: |
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x25_write_internal(sk, X25_CLEAR_REQUEST); |
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x25_start_t23timer(sk); |
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return 0; |
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} |
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/* |
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* State machine for state 3, Connected State. |
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* The handling of the timer(s) is in file x25_timer.c |
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* Handling of state 0 and connection release is in af_x25.c. |
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*/ |
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static int x25_state3_machine(struct sock *sk, struct sk_buff *skb, int frametype, int ns, int nr, int q, int d, int m) |
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{ |
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int queued = 0; |
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int modulus; |
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struct x25_sock *x25 = x25_sk(sk); |
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modulus = (x25->neighbour->extended) ? X25_EMODULUS : X25_SMODULUS; |
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switch (frametype) { |
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case X25_RESET_REQUEST: |
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x25_write_internal(sk, X25_RESET_CONFIRMATION); |
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x25_stop_timer(sk); |
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x25->condition = 0x00; |
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x25->vs = 0; |
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x25->vr = 0; |
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x25->va = 0; |
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x25->vl = 0; |
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x25_requeue_frames(sk); |
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break; |
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case X25_CLEAR_REQUEST: |
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if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2)) |
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goto out_clear; |
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x25_write_internal(sk, X25_CLEAR_CONFIRMATION); |
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x25_disconnect(sk, 0, skb->data[3], skb->data[4]); |
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break; |
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case X25_RR: |
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case X25_RNR: |
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if (!x25_validate_nr(sk, nr)) { |
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x25_clear_queues(sk); |
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x25_write_internal(sk, X25_RESET_REQUEST); |
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x25_start_t22timer(sk); |
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x25->condition = 0x00; |
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x25->vs = 0; |
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x25->vr = 0; |
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x25->va = 0; |
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x25->vl = 0; |
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x25->state = X25_STATE_4; |
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} else { |
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x25_frames_acked(sk, nr); |
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if (frametype == X25_RNR) { |
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x25->condition |= X25_COND_PEER_RX_BUSY; |
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} else { |
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x25->condition &= ~X25_COND_PEER_RX_BUSY; |
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} |
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} |
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break; |
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case X25_DATA: /* XXX */ |
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x25->condition &= ~X25_COND_PEER_RX_BUSY; |
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if ((ns != x25->vr) || !x25_validate_nr(sk, nr)) { |
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x25_clear_queues(sk); |
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x25_write_internal(sk, X25_RESET_REQUEST); |
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x25_start_t22timer(sk); |
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x25->condition = 0x00; |
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x25->vs = 0; |
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x25->vr = 0; |
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x25->va = 0; |
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x25->vl = 0; |
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x25->state = X25_STATE_4; |
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break; |
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} |
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x25_frames_acked(sk, nr); |
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if (ns == x25->vr) { |
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if (x25_queue_rx_frame(sk, skb, m) == 0) { |
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x25->vr = (x25->vr + 1) % modulus; |
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queued = 1; |
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} else { |
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/* Should never happen */ |
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x25_clear_queues(sk); |
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x25_write_internal(sk, X25_RESET_REQUEST); |
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x25_start_t22timer(sk); |
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x25->condition = 0x00; |
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x25->vs = 0; |
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x25->vr = 0; |
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x25->va = 0; |
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x25->vl = 0; |
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x25->state = X25_STATE_4; |
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break; |
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} |
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if (atomic_read(&sk->sk_rmem_alloc) > |
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(sk->sk_rcvbuf >> 1)) |
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x25->condition |= X25_COND_OWN_RX_BUSY; |
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} |
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/* |
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* If the window is full Ack it immediately, else |
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* start the holdback timer. |
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*/ |
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if (((x25->vl + x25->facilities.winsize_in) % modulus) == x25->vr) { |
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x25->condition &= ~X25_COND_ACK_PENDING; |
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x25_stop_timer(sk); |
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x25_enquiry_response(sk); |
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} else { |
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x25->condition |= X25_COND_ACK_PENDING; |
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x25_start_t2timer(sk); |
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} |
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break; |
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case X25_INTERRUPT_CONFIRMATION: |
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clear_bit(X25_INTERRUPT_FLAG, &x25->flags); |
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break; |
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case X25_INTERRUPT: |
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if (sock_flag(sk, SOCK_URGINLINE)) |
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queued = !sock_queue_rcv_skb(sk, skb); |
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else { |
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skb_set_owner_r(skb, sk); |
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skb_queue_tail(&x25->interrupt_in_queue, skb); |
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queued = 1; |
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} |
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sk_send_sigurg(sk); |
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x25_write_internal(sk, X25_INTERRUPT_CONFIRMATION); |
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break; |
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default: |
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pr_warn("unknown %02X in state 3\n", frametype); |
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break; |
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} |
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return queued; |
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out_clear: |
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x25_write_internal(sk, X25_CLEAR_REQUEST); |
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x25->state = X25_STATE_2; |
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x25_start_t23timer(sk); |
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return 0; |
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} |
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/* |
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* State machine for state 4, Awaiting Reset Confirmation State. |
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* The handling of the timer(s) is in file x25_timer.c |
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* Handling of state 0 and connection release is in af_x25.c. |
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*/ |
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static int x25_state4_machine(struct sock *sk, struct sk_buff *skb, int frametype) |
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{ |
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struct x25_sock *x25 = x25_sk(sk); |
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switch (frametype) { |
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case X25_RESET_REQUEST: |
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x25_write_internal(sk, X25_RESET_CONFIRMATION); |
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fallthrough; |
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case X25_RESET_CONFIRMATION: { |
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x25_stop_timer(sk); |
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x25->condition = 0x00; |
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x25->va = 0; |
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x25->vr = 0; |
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x25->vs = 0; |
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x25->vl = 0; |
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x25->state = X25_STATE_3; |
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x25_requeue_frames(sk); |
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break; |
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} |
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case X25_CLEAR_REQUEST: |
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if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2)) |
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goto out_clear; |
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x25_write_internal(sk, X25_CLEAR_CONFIRMATION); |
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x25_disconnect(sk, 0, skb->data[3], skb->data[4]); |
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break; |
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default: |
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break; |
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} |
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return 0; |
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out_clear: |
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x25_write_internal(sk, X25_CLEAR_REQUEST); |
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x25->state = X25_STATE_2; |
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x25_start_t23timer(sk); |
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return 0; |
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} |
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/* |
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* State machine for state 5, Call Accepted / Call Connected pending (X25_ACCPT_APPRV_FLAG). |
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* The handling of the timer(s) is in file x25_timer.c |
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* Handling of state 0 and connection release is in af_x25.c. |
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*/ |
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static int x25_state5_machine(struct sock *sk, struct sk_buff *skb, int frametype) |
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{ |
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struct x25_sock *x25 = x25_sk(sk); |
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switch (frametype) { |
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case X25_CLEAR_REQUEST: |
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if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2)) { |
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x25_write_internal(sk, X25_CLEAR_REQUEST); |
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x25->state = X25_STATE_2; |
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x25_start_t23timer(sk); |
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return 0; |
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} |
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x25_write_internal(sk, X25_CLEAR_CONFIRMATION); |
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x25_disconnect(sk, 0, skb->data[3], skb->data[4]); |
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break; |
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default: |
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break; |
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} |
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return 0; |
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} |
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/* Higher level upcall for a LAPB frame */ |
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int x25_process_rx_frame(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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int queued = 0, frametype, ns, nr, q, d, m; |
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if (x25->state == X25_STATE_0) |
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return 0; |
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frametype = x25_decode(sk, skb, &ns, &nr, &q, &d, &m); |
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switch (x25->state) { |
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case X25_STATE_1: |
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queued = x25_state1_machine(sk, skb, frametype); |
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break; |
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case X25_STATE_2: |
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queued = x25_state2_machine(sk, skb, frametype); |
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break; |
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case X25_STATE_3: |
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queued = x25_state3_machine(sk, skb, frametype, ns, nr, q, d, m); |
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break; |
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case X25_STATE_4: |
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queued = x25_state4_machine(sk, skb, frametype); |
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break; |
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case X25_STATE_5: |
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queued = x25_state5_machine(sk, skb, frametype); |
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break; |
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} |
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x25_kick(sk); |
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return queued; |
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} |
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int x25_backlog_rcv(struct sock *sk, struct sk_buff *skb) |
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{ |
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int queued = x25_process_rx_frame(sk, skb); |
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if (!queued) |
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kfree_skb(skb); |
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return 0; |
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}
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