From: Guy Harris <gharris@sonic.net>
Date: Tue, 4 May 2021 22:03:00 +0000 (-0700)
Subject: NPF: silently ignore all MS Surface cell modem errors when setting filter.
X-Git-Tag: libpcap-1.10.1~17
X-Git-Url: https://git.tcpdump.org/libpcap/commitdiff_plain/8353bcac9d174ac2b008930519581c3f3fd813df

NPF: silently ignore all MS Surface cell modem errors when setting filter.

Ignore them if we *are* setting promiscuous mode as well.

(cherry picked from commit faf1c37e38c83f1cc9f1579008f8d0b6aec9c440)
---

diff --git a/pcap-npf.c b/pcap-npf.c
index 6e9e0f04..52aee78a 100644
--- a/pcap-npf.c
+++ b/pcap-npf.c
@@ -1223,10 +1223,40 @@ pcap_activate_npf(pcap_t *p)
 
 		if (PacketSetHwFilter(pw->adapter,NDIS_PACKET_TYPE_PROMISCUOUS) == FALSE)
 		{
-			pcap_fmt_errmsg_for_win32_err(p->errbuf,
-			    PCAP_ERRBUF_SIZE, GetLastError(),
-			    "failed to set hardware filter to promiscuous mode");
-			goto bad;
+			DWORD errcode = GetLastError();
+
+			/*
+			 * Suppress spurious error generated by non-compiant
+			 * MS Surface mobile adapters.
+			 *
+			 * If we knew that this meant "promiscuous mode
+			 * isn't supported", we could add a "promiscuous
+			 * mode isn't supported" error code and return
+			 * that, but:
+			 *
+			 *    1) we don't know that it means that
+			 *    rather than meaning "we reject attempts
+			 *    to set the filter, even though the NDIS
+			 *    specifications say you shouldn't do that"
+			 *
+			 * and
+			 *
+			 *    2) other interface types that don't
+			 *    support promiscuous mode, at least
+			 *    on UN*Xes, just silently ignore
+			 *    attempts to set promiscuous mode
+			 *
+			 * and rejecting it with an error could disrupt
+			 * attempts to capture, as many programs (tcpdump,
+			 * *shark) default to promiscuous mode.
+			 */
+			if (errcode != NPF_SURFACE_MOBILE_NONPROMISC)
+			{
+				pcap_fmt_errmsg_for_win32_err(p->errbuf,
+				    PCAP_ERRBUF_SIZE, errcode,
+				    "failed to set hardware filter to promiscuous mode");
+				goto bad;
+			}
 		}
 	}
 	else
@@ -1249,7 +1279,7 @@ pcap_activate_npf(pcap_t *p)
 
 			/*
 			 * Suppress spurious error generated by non-compiant
-			 * MS Surface mobile adaptors
+			 * MS Surface mobile adapters.
 			 */
 			if (errcode != NPF_SURFACE_MOBILE_NONPROMISC)
 			{