ipme.c

linux下qmail的源码 本人加了一些注释

#include <sys/types.h>
#include <sys/param.h>
#include <sys/time.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <net/if.h>
#include <netinet/in.h>
#ifndef SIOCGIFCONF /* whatever works */
#include <sys/sockio.h>
#endif
#include "hassalen.h"
#include "byte.h"
#include "ip.h"
#include "ipalloc.h"
#include "stralloc.h"
#include "ipme.h"

static int ipmeok = 0;
ipalloc ipme = {0};

int ipme_is(ip)
struct ip_address *ip;
{
  int i;
  if (ipme_init() != 1) return -1;
  for (i = 0;i < ipme.len;++i)
    if (byte_equal(&ipme.ix[i].ip,4,ip))
      return 1;
  return 0;
}

static stralloc buf = {0};

int ipme_init()
{
  struct ifconf ifc;
  char *x;
  struct ifreq *ifr;
  struct sockaddr_in *sin;
  int len;
  int s;
  struct ip_mx ix;
 
  if (ipmeok) return 1;
  if (!ipalloc_readyplus(&ipme,0)) return 0;
  ipme.len = 0;
  ix.pref = 0;
 
  if ((s = socket(AF_INET,SOCK_STREAM,0)) == -1) return -1;
 
  len = 256;
  for (;;) {
    if (!stralloc_ready(&buf,len)) { close(s); return 0; }
    buf.len = 0;
    ifc.ifc_buf = buf.s;
    ifc.ifc_len = len;
    if (ioctl(s,SIOCGIFCONF,&ifc) >= 0) /* > is for System V */
      if (ifc.ifc_len + sizeof(*ifr) + 64 < len) { /* what a stupid interface */
        buf.len = ifc.ifc_len;
        break;
      }
    if (len > 200000) { close(s); return -1; }
    len += 100 + (len >> 2);
  }
  x = buf.s;
  while (x < buf.s + buf.len) {
    ifr = (struct ifreq *) x;
#ifdef HASSALEN
    len = sizeof(ifr->ifr_name) + ifr->ifr_addr.sa_len;
    if (len < sizeof(*ifr))
      len = sizeof(*ifr);
    if (ifr->ifr_addr.sa_family == AF_INET) {
      sin = (struct sockaddr_in *) &ifr->ifr_addr;
      byte_copy(&ix.ip,4,&sin->sin_addr);
      if (ioctl(s,SIOCGIFFLAGS,x) == 0)
        if (ifr->ifr_flags & IFF_UP)
          if (!ipalloc_append(&ipme,&ix)) { close(s); return 0; }
    }
#else
    len = sizeof(*ifr);
    if (ioctl(s,SIOCGIFFLAGS,x) == 0)
      if (ifr->ifr_flags & IFF_UP)
        if (ioctl(s,SIOCGIFADDR,x) == 0)
	  if (ifr->ifr_addr.sa_family == AF_INET) {
	    sin = (struct sockaddr_in *) &ifr->ifr_addr;
	    byte_copy(&ix.ip,4,&sin->sin_addr);
	    if (!ipalloc_append(&ipme,&ix)) { close(s); return 0; }
	  }
#endif
    x += len;
  }
  close(s);
  ipmeok = 1;
  return 1;
}