net/llc/llc_output.c

   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);