X-Git-Url: https://git.tcpdump.org/tcpdump/blobdiff_plain/78651639891de4a150f23ab635ef940f6ee22d8e..c50f3934dacc4bd3fe16a900d4c63c05acb50ce3:/print-sll.c

diff --git a/print-sll.c b/print-sll.c
index d624ba23..87d82446 100644
--- a/print-sll.c
+++ b/print-sll.c
@@ -21,16 +21,9 @@
 
 /* \summary: Linux cooked sockets capture printer */
 
-#ifdef HAVE_CONFIG_H
 #include <config.h>
-#endif
 
-#ifdef HAVE_NET_IF_H
-/*
- * Include diag-control.h before <net/if.h>, which too defines a macro
- * named ND_UNREACHABLE.
- */
-#include "diag-control.h"
+#ifdef __linux__
 #include <net/if.h>
 #endif
 
@@ -399,6 +392,19 @@ sll2_print(netdissect_options *ndo, const struct sll2_header *sllp, u_int length
  * Linux "cooked capture" header of the packet, 'h->ts' is the timestamp,
  * 'h->len' is the length of the packet off the wire, and 'h->caplen'
  * is the number of bytes actually captured.
+ *
+ * On Linux, we attempt to look up the interface index and print the
+ * name of the interface on which the packet arrived or was sent.
+ *
+ * This look up is only likely to work well if done on the same machine
+ * as the one on which the capture was done, as the interface with a
+ * given index on the latter machine is unlikely to have the same
+ * name as the interface with that index on the former machine.
+ *
+ * As DLT_LINUX_SLL2 live captures are supported only on Linux, this
+ * means that if the machine on which we're reading the file isn't
+ * running Linux, it's probably not the machine that captured the file,
+ * so we don't bother trying to do the lookup on non-Linux machines.
  */
 void
 sll2_if_print(netdissect_options *ndo, const struct pcap_pkthdr *h, const u_char *p)
@@ -410,7 +416,7 @@ sll2_if_print(netdissect_options *ndo, const struct pcap_pkthdr *h, const u_char
 	u_short ether_type;
 	int llc_hdrlen;
 	u_int hdrlen;
-#ifdef HAVE_NET_IF_H
+#ifdef __linux__
 	uint32_t if_index;
 	char ifname[IF_NAMESIZE];
 #endif
@@ -419,7 +425,7 @@ sll2_if_print(netdissect_options *ndo, const struct pcap_pkthdr *h, const u_char
 	ND_TCHECK_LEN(p, SLL2_HDR_LEN);
 
 	sllp = (const struct sll2_header *)p;
-#ifdef HAVE_NET_IF_H
+#ifdef __linux__
 	if_index = GET_BE_U_4(sllp->sll2_if_index);
 	if (!if_indextoname(if_index, ifname))
 		strncpy(ifname, "?", 2);