minix/net/lwip/lnksock.c

   1 /* LWIP service - lnksock.c - link sockets */
   2 /*
   3  * This module contains absolutely minimal support for AF_LINK type sockets,
   4  * because for now we need them only to support a specific set of IOCTLs, as
   5  * required by for example ifconfig(8).
   6  */
   7
   8 #include "lwip.h"
   9
  10 /* The number of link sockets. */
  11 #define NR_LNKSOCK      4
  12
  13 static struct lnksock {
  14         struct sock lnk_sock;           /* socket object, MUST be first */
  15         SIMPLEQ_ENTRY(lnksock) lnk_next; /* next in free list */
  16 } lnk_array[NR_LNKSOCK];
  17
  18 static SIMPLEQ_HEAD(, lnksock) lnk_freelist;    /* list of free link sockets */
  19
  20 static const struct sockevent_ops lnksock_ops;
  21
  22 /*
  23  * Initialize the link sockets module.
  24  */
  25 void
  26 lnksock_init(void)
  27 {
  28         unsigned int slot;
  29
  30         /* Initialize the list of free link sockets. */
  31         SIMPLEQ_INIT(&lnk_freelist);
  32
  33         for (slot = 0; slot < __arraycount(lnk_array); slot++)
  34                 SIMPLEQ_INSERT_TAIL(&lnk_freelist, &lnk_array[slot], lnk_next);
  35 }
  36
  37 /*
  38  * Create a link socket.
  39  */
  40 sockid_t
  41 lnksock_socket(int type, int protocol, struct sock ** sockp,
  42         const struct sockevent_ops ** ops)
  43 {
  44         struct lnksock *lnk;
  45
  46         if (type != SOCK_DGRAM)
  47                 return EPROTOTYPE;
  48
  49         if (protocol != 0)
  50                 return EPROTONOSUPPORT;
  51
  52         if (SIMPLEQ_EMPTY(&lnk_freelist))
  53                 return ENOBUFS;
  54
  55         lnk = SIMPLEQ_FIRST(&lnk_freelist);
  56         SIMPLEQ_REMOVE_HEAD(&lnk_freelist, lnk_next);
  57
  58         *sockp = &lnk->lnk_sock;
  59         *ops = &lnksock_ops;
  60         return SOCKID_LNK | (sockid_t)(lnk - lnk_array);
  61 }
  62
  63 /*
  64  * Free up a closed link socket.
  65  */
  66 static void
  67 lnksock_free(struct sock * sock)
  68 {
  69         struct lnksock *lnk = (struct lnksock *)sock;
  70
  71         SIMPLEQ_INSERT_HEAD(&lnk_freelist, lnk, lnk_next);
  72 }
  73
  74 static const struct sockevent_ops lnksock_ops = {
  75         .sop_ioctl              = ifconf_ioctl,
  76         .sop_free               = lnksock_free
  77 };