Based on work from Florent Drouin, split the 32-bit link-layer type

[libpcap] / savefile.c

diff --git a/savefile.c b/savefile.c
index 06804f7fa4b4082855a9bfeeeb61f45c831d703e..d589a45e9642f0a62cc97b3b8a6aab3d2868e67a 100644 (file)
--- a/savefile.c
+++ b/savefile.c
@@ -30,7 +30,7 @@
 
 #ifndef lint
 static const char rcsid[] _U_ =
-    "@(#) $Header: /tcpdump/master/libpcap/savefile.c,v 1.166 2007-09-29 00:29:14 guy Exp $ (LBL)";
+    "@(#) $Header: /tcpdump/master/libpcap/savefile.c,v 1.167 2007-09-29 19:33:29 guy Exp $ (LBL)";
 #endif
 
 #ifdef HAVE_CONFIG_H
@@ -834,6 +834,18 @@ static struct linktype_map {
        { -1,                   -1 }
 };
 
+/*
+ * Mechanism for storing information about a capture in the upper
+ * 6 bits of a linktype value in a capture file.
+ *
+ * LT_LINKTYPE_EXT(x) extracts the additional information.
+ *
+ * The rest of the bits are for a value describing the link-layer
+ * value.  LT_LINKTYPE(x) extracts that value.
+ */
+#define LT_LINKTYPE(x)         ((x) & 0x03FFFFFF)
+#define LT_LINKTYPE_EXT(x)     ((x) & 0xFC000000)
+
 static int
 dlt_to_linktype(int dlt)
 {
@@ -1064,7 +1076,8 @@ pcap_fopen_offline(FILE *fp, char *errbuf)
        }
        p->tzoff = hdr.thiszone;
        p->snapshot = hdr.snaplen;
-       p->linktype = linktype_to_dlt(hdr.linktype);
+       p->linktype = linktype_to_dlt(LT_LINKTYPE(hdr.linktype));
+       p->linktype_ext = LT_LINKTYPE_EXT(hdr.linktype);
        if (magic == KUZNETZOV_TCPDUMP_MAGIC && p->linktype == DLT_EN10MB) {
                /*
                 * This capture might have been done in raw mode or cooked
@@ -1479,6 +1492,7 @@ pcap_dump_open(pcap_t *p, const char *fname)
                    fname, linktype);
                return (NULL);
        }
+       linktype |= p->linktype_ext;
 
        if (fname[0] == '-' && fname[1] == '\0') {
                f = stdout;
@@ -1513,6 +1527,7 @@ pcap_dump_fopen(pcap_t *p, FILE *f)
                    linktype);
                return (NULL);
        }
+       linktype |= p->linktype_ext;
 
        return (pcap_setup_dump(p, linktype, f, "stream"));
 }