1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * llc_output.c - LLC minimal output path
4 *
5 * Copyright (c) 1997 by Procom Technology, Inc.
6 * 2001-2003 by Arnaldo Carvalho de Melo <acme@conectiva.com.br>
7 */
8
9 #include <linux/if_arp.h>
10 #include <linux/netdevice.h>
11 #include <linux/skbuff.h>
12 #include <linux/export.h>
13 #include <net/llc.h>
14 #include <net/llc_pdu.h>
15
16 /**
17 * llc_mac_hdr_init - fills MAC header fields
18 * @skb: Address of the frame to initialize its MAC header
19 * @sa: The MAC source address
20 * @da: The MAC destination address
21 *
22 * Fills MAC header fields, depending on MAC type. Returns 0, If MAC type
23 * is a valid type and initialization completes correctly 1, otherwise.
24 */
25 int llc_mac_hdr_init(struct sk_buff *skb,
26 const unsigned char *sa, const unsigned char *da)
27 {
28 int rc = -EINVAL;
29
30 switch (skb->dev->type) {
31 case ARPHRD_ETHER:
32 case ARPHRD_LOOPBACK:
33 rc = dev_hard_header(skb, skb->dev, ETH_P_802_2, da, sa,
34 skb->len);
35 if (rc > 0)
36 rc = 0;
37 break;
38 default:
39 break;
40 }
41 return rc;
42 }
43
44 /**
45 * llc_build_and_send_ui_pkt - unitdata request interface for upper layers
46 * @sap: sap to use
47 * @skb: packet to send
48 * @dmac: destination mac address
49 * @dsap: destination sap
50 *
51 * Upper layers calls this function when upper layer wants to send data
52 * using connection-less mode communication (UI pdu).
53 *
54 * Accept data frame from network layer to be sent using connection-
55 * less mode communication; timeout/retries handled by network layer;
56 * package primitive as an event and send to SAP event handler
57 */
58 int llc_build_and_send_ui_pkt(struct llc_sap *sap, struct sk_buff *skb,
59 unsigned char *dmac, unsigned char dsap)
60 {
61 int rc;
62 llc_pdu_header_init(skb, LLC_PDU_TYPE_U, sap->laddr.lsap,
63 dsap, LLC_PDU_CMD);
64 llc_pdu_init_as_ui_cmd(skb);
65 rc = llc_mac_hdr_init(skb, skb->dev->dev_addr, dmac);
66 if (likely(!rc))
67 rc = dev_queue_xmit(skb);
68 else
69 kfree_skb(skb);
70 return rc;
71 }
72
73 EXPORT_SYMBOL(llc_mac_hdr_init);
74 EXPORT_SYMBOL(llc_build_and_send_ui_pkt);