| 1 | |
| 2 | |
| 3 | * X.25 Packet Layer release 002
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| 4 | *
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| 5 | * This is ALPHA test software. This code may break your machine, randomly fail to work with new
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| 6 | * releases, misbehave and/or generally screw up. It might even work.
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| 7 | *
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| 8 | * This code REQUIRES 2.1.15 or higher
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| 9 | *
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| 10 | * History
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| 11 | * X.25 001 Jonathan Naylor Started coding.
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| 12 | * 2000-09-04 Henner Eisen Prevent freeing a dangling skb.
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| 13 |
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| 14 |
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| 15 | #define pr_fmt(fmt) "X25: " fmt
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| 16 |
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| 17 | #include <linux/kernel.h>
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| 18 | #include <linux/netdevice.h>
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| 19 | #include <linux/skbuff.h>
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| 20 | #include <linux/slab.h>
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| 21 | #include <net/sock.h>
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| 22 | #include <linux/if_arp.h>
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| 23 | #include <net/x25.h>
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| 24 | #include <net/x25device.h>
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| 25 |
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| 26 | static int x25_receive_data(struct sk_buff *skb, struct x25_neigh *nb)
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| 27 | {
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| 28 | struct sock *sk;
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| 29 | unsigned short frametype;
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| 30 | unsigned int lci;
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| 31 |
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| 32 | if (!pskb_may_pull(skb, X25_STD_MIN_LEN))
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| 33 | return 0;
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| 34 |
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| 35 | frametype = skb->data[2];
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| 36 | lci = ((skb->data[0] << 8) & 0xF00) + ((skb->data[1] << 0) & 0x0FF);
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| 37 |
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| 38 | |
| 39 | * LCI of zero is always for us, and its always a link control
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| 40 | * frame.
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| 41 |
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| 42 | if (lci == 0) {
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| 43 | x25_link_control(skb, nb, frametype);
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| 44 | return 0;
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| 45 | }
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| 46 |
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| 47 | |
| 48 | * Find an existing socket.
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| 49 |
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| 50 | if ((sk = x25_find_socket(lci, nb)) != NULL) {
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| 51 | int queued = 1;
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| 52 |
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| 53 | skb_reset_transport_header(skb);
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| 54 | bh_lock_sock(sk);
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| 55 | if (!sock_owned_by_user(sk)) {
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| 56 | queued = x25_process_rx_frame(sk, skb);
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| 57 | } else {
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| 58 | queued = !sk_add_backlog(sk, skb, READ_ONCE(sk->sk_rcvbuf));
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| 59 | }
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| 60 | bh_unlock_sock(sk);
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| 61 | sock_put(sk);
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| 62 | return queued;
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| 63 | }
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| 64 |
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| 65 | |
| 66 | * Is is a Call Request ? if so process it.
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| 67 |
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| 68 | if (frametype == X25_CALL_REQUEST)
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| 69 | return x25_rx_call_request(skb, nb, lci);
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| 70 |
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| 71 | |
| 72 | * Its not a Call Request, nor is it a control frame.
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| 73 | * Can we forward it?
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| 74 |
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| 75 |
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| 76 | if (x25_forward_data(lci, nb, skb)) {
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| 77 | if (frametype == X25_CLEAR_CONFIRMATION) {
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| 78 | x25_clear_forward_by_lci(lci);
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| 79 | }
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| 80 | kfree_skb(skb);
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| 81 | return 1;
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| 82 | }
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| 83 |
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| 84 | |
| 85 | x25_transmit_clear_request(nb, lci, 0x0D);
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| 86 |
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| 87 |
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| 88 | if (frametype != X25_CLEAR_CONFIRMATION)
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| 89 | pr_debug("x25_receive_data(): unknown frame type %2x\n",frametype);
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| 90 |
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| 91 | return 0;
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| 92 | }
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| 93 |
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| 94 | int x25_lapb_receive_frame(struct sk_buff *skb, struct net_device *dev,
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| 95 | struct packet_type *ptype, struct net_device *orig_dev)
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| 96 | {
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| 97 | struct sk_buff *nskb;
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| 98 | struct x25_neigh *nb;
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| 99 |
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| 100 | if (!net_eq(dev_net(dev), &init_net))
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| 101 | goto drop;
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| 102 |
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| 103 | nskb = skb_copy(skb, GFP_ATOMIC);
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| 104 | if (!nskb)
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| 105 | goto drop;
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| 106 | kfree_skb(skb);
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| 107 | skb = nskb;
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| 108 |
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| 109 | |
| 110 | * Packet received from unrecognised device, throw it away.
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| 111 |
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| 112 | nb = x25_get_neigh(dev);
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| 113 | if (!nb) {
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| 114 | pr_debug("unknown neighbour - %s\n", dev->name);
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| 115 | goto drop;
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| 116 | }
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| 117 |
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| 118 | if (!pskb_may_pull(skb, 1)) {
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| 119 | x25_neigh_put(nb);
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| 120 | goto drop;
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| 121 | }
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| 122 |
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| 123 | switch (skb->data[0]) {
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| 124 |
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| 125 | case X25_IFACE_DATA:
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| 126 | skb_pull(skb, 1);
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| 127 | if (x25_receive_data(skb, nb)) {
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| 128 | x25_neigh_put(nb);
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| 129 | goto out;
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| 130 | }
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| 131 | break;
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| 132 |
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| 133 | case X25_IFACE_CONNECT:
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| 134 | x25_link_established(nb);
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| 135 | break;
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| 136 |
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| 137 | case X25_IFACE_DISCONNECT:
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| 138 | x25_link_terminated(nb);
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| 139 | break;
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| 140 | }
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| 141 | x25_neigh_put(nb);
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| 142 | drop:
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| 143 | kfree_skb(skb);
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| 144 | out:
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| 145 | return 0;
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| 146 | }
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| 147 |
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| 148 | void x25_establish_link(struct x25_neigh *nb)
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| 149 | {
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| 150 | struct sk_buff *skb;
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| 151 | unsigned char *ptr;
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| 152 |
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| 153 | switch (nb->dev->type) {
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| 154 | case ARPHRD_X25:
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| 155 | if ((skb = alloc_skb(1, GFP_ATOMIC)) == NULL) {
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| 156 | pr_err("x25_dev: out of memory\n");
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| 157 | return;
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| 158 | }
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| 159 | ptr = skb_put(skb, 1);
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| 160 | *ptr = X25_IFACE_CONNECT;
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| 161 | break;
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| 162 |
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| 163 | default:
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| 164 | return;
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| 165 | }
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| 166 |
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| 167 | skb->protocol = htons(ETH_P_X25);
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| 168 | skb->dev = nb->dev;
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| 169 |
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| 170 | dev_queue_xmit(skb);
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| 171 | }
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| 172 |
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| 173 | void x25_send_frame(struct sk_buff *skb, struct x25_neigh *nb)
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| 174 | {
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| 175 | unsigned char *dptr;
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| 176 |
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| 177 | skb_reset_network_header(skb);
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| 178 |
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| 179 | switch (nb->dev->type) {
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| 180 | case ARPHRD_X25:
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| 181 | dptr = skb_push(skb, 1);
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| 182 | *dptr = X25_IFACE_DATA;
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| 183 | break;
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| 184 |
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| 185 | default:
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| 186 | kfree_skb(skb);
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| 187 | return;
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| 188 | }
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| 189 |
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| 190 | skb->protocol = htons(ETH_P_X25);
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| 191 | skb->dev = nb->dev;
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| 192 |
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| 193 | dev_queue_xmit(skb);
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| 194 | }
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