SIOCGIFCONF nicely

diff --git a/lib/libpcap/inet.c b/lib/libpcap/inet.c
index fd066d1..d32a4f8 100644 (file)
--- a/lib/libpcap/inet.c
+++ b/lib/libpcap/inet.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: inet.c,v 1.5 1996/07/19 07:52:16 deraadt Exp $        */
+/*     $OpenBSD: inet.c,v 1.6 1997/01/24 19:17:25 deraadt Exp $        */
 
 /*
  * Copyright (c) 1994, 1995, 1996
@@ -86,27 +86,36 @@ pcap_lookupdev(errbuf)
        register char *errbuf;
 {
        register int fd, minunit, n;
-       register char *cp;
+       register char *cp, *ibuf = NULL;
        register struct ifreq *ifrp, *ifend, *ifnext, *mp;
        struct ifconf ifc;
-       struct ifreq ibuf[16], ifr;
+       struct ifreq ifr;
        static char device[sizeof(ifrp->ifr_name) + 1];
+       int len = 8192;
 
        fd = socket(AF_INET, SOCK_DGRAM, 0);
        if (fd < 0) {
                (void)sprintf(errbuf, "socket: %s", pcap_strerror(errno));
                return (NULL);
        }
-       ifc.ifc_len = sizeof ibuf;
-       ifc.ifc_buf = (caddr_t)ibuf;
-
-       if (ioctl(fd, SIOCGIFCONF, (char *)&ifc) < 0 ||
-           ifc.ifc_len < sizeof(struct ifreq)) {
-               (void)sprintf(errbuf, "SIOCGIFCONF: %s", pcap_strerror(errno));
-               (void)close(fd);
-               return (NULL);
+       while (1) {
+               ifc.ifc_len = len;
+               ifc.ifc_buf = ibuf = realloc(ibuf, len);
+               if (ibuf == NULL) {
+                       close(fd);
+                       return (NULL);
+               }
+               if (ioctl(fd, SIOCGIFCONF, (char *)&ifc) < 0) {
+                       (void)close(fd);
+                       free(ibuf);
+                       return (NULL);
+               }
+               if (ifc.ifc_len + sizeof(ifr) < len)
+                       break;
+               len *= 2;
        }
-       ifrp = ibuf;
+
+       ifrp = (struct ifreq *)ibuf;
        ifend = (struct ifreq *)((char *)ibuf + ifc.ifc_len);
 
        mp = NULL;
@@ -134,6 +143,7 @@ pcap_lookupdev(errbuf)
                        (void)sprintf(errbuf, "SIOCGIFFLAGS: %s",
                            pcap_strerror(errno));
                        (void)close(fd);
+                       free(ibuf);
                        return (NULL);
                }
 
@@ -149,6 +159,7 @@ pcap_lookupdev(errbuf)
                        mp = ifrp;
                }
        }
+       free(ibuf);
        (void)close(fd);
        if (mp == NULL) {
                (void)strcpy(errbuf, "no suitable device found");