NPF: report the system error for PacketSetHwFilter() failures.

It *does* fail to set promiscuous mode on some devices, such as bridge
devices; knowing what error it is might help us distinguish "we don't
support promiscuous mode" from some other, unexpected error.

1 files changed, 6 insertions, 2 deletions

diff --git a/pcap-npf.c b/pcap-npf.c
index 201597d8..1b18608d 100644
--- a/pcap-npf.c
+++ b/pcap-npf.c
@@ -1175,7 +1175,9 @@ pcap_activate_npf(pcap_t *p)
 
 		if (PacketSetHwFilter(pw->adapter,NDIS_PACKET_TYPE_PROMISCUOUS) == FALSE)
 		{
-			snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "failed to set hardware filter to promiscuous mode");
+			pcap_fmt_errmsg_for_win32_err(p->errbuf,
+			    PCAP_ERRBUF_SIZE, GetLastError(),
+			    "failed to set hardware filter to promiscuous mode);
 			goto bad;
 		}
 	}
@@ -1193,7 +1195,9 @@ pcap_activate_npf(pcap_t *p)
 			NDIS_PACKET_TYPE_BROADCAST |
 			NDIS_PACKET_TYPE_MULTICAST) == FALSE)
 		{
-			snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "failed to set hardware filter to non-promiscuous mode");
+			pcap_fmt_errmsg_for_win32_err(p->errbuf,
+			    PCAP_ERRBUF_SIZE, GetLastError(),
+			    "failed to set hardware filter to non-promiscuous mode");
 			goto bad;
 		}
 	}