com32/lib/syslinux/pxe_dns.c

   1 /* ----------------------------------------------------------------------- *
   2  *
   3  *   Copyright 2010 Intel Corporation; author: H. Peter Anvin
   4  *
   5  *   Permission is hereby granted, free of charge, to any person
   6  *   obtaining a copy of this software and associated documentation
   7  *   files (the "Software"), to deal in the Software without
   8  *   restriction, including without limitation the rights to use,
   9  *   copy, modify, merge, publish, distribute, sublicense, and/or
  10  *   sell copies of the Software, and to permit persons to whom
  11  *   the Software is furnished to do so, subject to the following
  12  *   conditions:
  13  *
  14  *   The above copyright notice and this permission notice shall
  15  *   be included in all copies or substantial portions of the Software.
  16  *
  17  *   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  18  *   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
  19  *   OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  20  *   NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
  21  *   HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
  22  *   WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  23  *   FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  24  *   OTHER DEALINGS IN THE SOFTWARE.
  25  *
  26  * ----------------------------------------------------------------------- */
  27
  28 /*
  29  * pxe_dns.c
  30  *
  31  * Resolve a hostname via DNS
  32  */
  33
  34 #include <stdio.h>
  35 #include <stdlib.h>
  36 #include <stdint.h>
  37 #include <string.h>
  38 #include <com32.h>
  39
  40 #include <syslinux/pxe.h>
  41
  42 /* Returns the status code from PXE (0 on success),
  43    or -1 on invocation failure */
  44 uint32_t pxe_dns(const char *hostname)
  45 {
  46     com32sys_t regs;
  47     union {
  48         unsigned char b[4];
  49         uint32_t ip;
  50     } q;
  51     char *lm_hostname;
  52
  53     /* Is this a dot-quad? */
  54     if (sscanf(hostname, "%hhu.%hhu.%hhu.%hhu",
  55                &q.b[0], &q.b[1], &q.b[2], &q.b[3]) == 4)
  56         return q.ip;
  57
  58     lm_hostname = lstrdup(hostname);
  59     if (!lm_hostname)
  60         return 0;
  61
  62     memset(&regs, 0, sizeof regs);
  63     regs.eax.w[0] = 0x0010;
  64     regs.es = SEG(lm_hostname);
  65     /* regs.ebx.w[0] = OFFS(lm_hostname); */
  66
  67     __intcall(0x22, &regs, &regs);
  68
  69     lfree(lm_hostname);
  70
  71     if (regs.eflags.l & EFLAGS_CF)
  72         return 0;
  73
  74     return regs.eax.l;
  75 }