If we have pcap_free_datalinks(), use it. If not, then, on Windows,

just leak the list returned by pcap_list_datalinks(), as there's no
guarantee that if you have a library built with one version of the
MSVC++ run-time library, and it returns a pointer to allocated data, you
can free that data from a program linked with another version of the
MSVC++ run-time library.  (This is not an issue on UN*X.)

This should fix bug 2677.

svn path=/trunk/; revision=25668

1 files changed, 26 insertions, 0 deletions

diff --git a/capture-wpcap.c b/capture-wpcap.c
index 66bfc3652a..90baec774b 100644
--- a/capture-wpcap.c
+++ b/capture-wpcap.c
@@ -111,6 +111,10 @@ static int 	(*p_pcap_list_datalinks)(pcap_t *, int **);
 static int	(*p_pcap_set_datalink)(pcap_t *, int);
 #endif
 
+#ifdef HAVE_FREE_DATALINKS
+static int 	(*p_pcap_free_datalinks)(int *);
+#endif
+
 typedef struct {
 	const char	*name;
 	gpointer	*ptr;
@@ -174,6 +178,9 @@ load_wpcap(void)
 #ifdef HAVE_PCAP_SET_DATALINK
 		SYM(pcap_set_datalink, FALSE),
 #endif
+#ifdef HAVE_PCAP_FREE_DATALINKS
+		SYM(pcap_free_datalinks, TRUE),
+#endif
 		{ NULL, NULL, FALSE }
 	};
 
@@ -503,6 +510,25 @@ pcap_list_datalinks(pcap_t *p, int **ddlt)
 }
 #endif
 
+#ifdef HAVE_PCAP_FREE_DATALINKS
+void
+pcap_free_datalinks(int *ddlt)
+{
+	g_assert(has_wpcap);
+
+	/*
+	 * If we don't have pcap_free_datalinks() in WinPcap,
+	 * we don't free the memory - we can't use free(), as
+	 * we might not have been built with the same version
+	 * of the C runtime library as WinPcap was, and, if we're
+	 * not, free() isn't guaranteed to work on something
+	 * allocated by WinPcap.
+	 */
+	if (p_pcap_free_datalinks != NULL)
+		p_pcap_free_datalinks(ddlt);
+}
+#endif
+
 #ifdef HAVE_PCAP_DATALINK_VAL_TO_NAME
 const char *
 pcap_datalink_val_to_name(int dlt)