From 06553e55d6ff2b203c4ab1dda2d6fb15c45e2896 Mon Sep 17 00:00:00 2001

From: Guy Harris <guy@alum.mit.edu>

Date: Wed, 5 Nov 2014 14:33:14 -0800

Subject: [PATCH 5/5] Move the socket ops out of gencode.c.

Instead, do it in pcap-linux.c, and have it set a flag in the pcap_t

structure to indicate to the code in gencode.c that it needs to generate

special VLAN-handling code.

(cherry picked from 612503bb0801a49a1c6ebe9c82591289b1d2e5c9)

Conflicts:

        pcap-linux.c

---

 gencode.c    | 37 ++++++++++++++-----------------------

 pcap-int.h   | 10 ++++++++++

 pcap-linux.c | 24 ++++++++++++++++++++++++

 pcap.c       | 12 ++++++++++++

 savefile.c   |  5 +++++

 5 files changed, 65 insertions(+), 23 deletions(-)

diff --git a/gencode.c b/gencode.c

index 9c1d17b..6b3772f 100644

--- a/gencode.c

+++ b/gencode.c

@@ -58,7 +58,6 @@ static const char rcsid[] _U_ =

 #include <netinet/in.h>

 #include <arpa/inet.h>

-#include <errno.h>

 #endif /* WIN32 */

@@ -7864,23 +7863,11 @@ gen_ahostop(eaddr, dir)

 }

 #if defined(SKF_AD_VLAN_TAG) && defined(SKF_AD_VLAN_TAG_PRESENT)

-static int skf_ad_vlan_tag_present_supported(int bpf_extensions) {

-        return bpf_extensions >= SKF_AD_VLAN_TAG_PRESENT;

-}

-

 static struct block *

-gen_vlan_bpf_extensions(int vlan_num) {

+gen_vlan_bpf_extensions(int vlan_num)

+{

         struct block *b0, *b1;

         struct slist *s;

-        int val = 0, len, r;

-

-        len = sizeof(val);

-        r = getsockopt(bpf_pcap->fd, SOL_SOCKET, SO_BPF_EXTENSIONS, &val, &len;;

-        if (r < 0)

-                return NULL;

-

-        if (!skf_ad_vlan_tag_present_supported(val))

-                return NULL;

         /* generate new filter code based on extracting packet

          * metadata */

@@ -7908,7 +7895,8 @@ gen_vlan_bpf_extensions(int vlan_num) {

 #endif

 static struct block *

-gen_vlan_no_bpf_extensions(int vlan_num) {

+gen_vlan_no_bpf_extensions(int vlan_num)

+{

         struct block *b0, *b1;

         /* check for VLAN, including QinQ */

@@ -7985,14 +7973,17 @@ gen_vlan(vlan_num)

 	case DLT_NETANALYZER:

 	case DLT_NETANALYZER_TRANSPARENT:

 #if defined(SKF_AD_VLAN_TAG) && defined(SKF_AD_VLAN_TAG_PRESENT)

-                if (!vlan_stack_depth) {

-                        b0 = gen_vlan_bpf_extensions(vlan_num);

-                        if (!b0)

-                                b0 = gen_vlan_no_bpf_extensions(vlan_num);

-                }

-                else

+		if (vlan_stack_depth == 0) {

+			/*

+			 * Do we need special VLAN handling?

+			 */

+			if (bpf_pcap->bpf_codegen_flags & BPF_SPECIAL_VLAN_HANDLING)

+				b0 = gen_vlan_bpf_extensions(vlan_num);

+			else

+				b0 = gen_vlan_no_bpf_extensions(vlan_num);

+		} else

 #endif

-                        b0 = gen_vlan_no_bpf_extensions(vlan_num);

+			b0 = gen_vlan_no_bpf_extensions(vlan_num);

                 break;

 	default:

 		bpf_error("no VLAN support for data link type %d",

diff --git a/pcap-int.h b/pcap-int.h

index 0c27ec7..c9dbb5f 100644

--- a/pcap-int.h

+++ b/pcap-int.h

@@ -182,6 +182,11 @@ struct pcap {

 	pcap_direction_t direction;

 	/*

+	 * Flags to affect BPF code generation.

+	 */

+	int bpf_codegen_flags;

+

+	/*

 	 * Placeholder for filter code if bpf not in kernel.

 	 */

 	struct bpf_program fcode;

@@ -228,6 +233,11 @@ struct pcap {

 };

 /*

+ * BPF code generation flags.

+ */

+#define BPF_SPECIAL_VLAN_HANDLING	0x00000001	/* special VLAN handling for Linux */

+

+/*

  * This is a timeval as stored in a savefile.

  * It has to use the same types everywhere, independent of the actual

  * `struct timeval'; `struct timeval' has 32-bit tv_sec values on some

diff --git a/pcap-linux.c b/pcap-linux.c

index a370858..a82f4eb 100644

--- a/pcap-linux.c

+++ b/pcap-linux.c

@@ -3024,6 +3024,10 @@ activate_new(pcap_t *handle)

 #endif

 	int			err = 0;

 	struct packet_mreq	mr;

+#ifdef SO_BPF_EXTENSIONS

+	int			bpf_extensions;

+	socklen_t		len;

+#endif

 	/*

 	 * Open a socket with protocol family packet. If the

@@ -3342,6 +3346,26 @@ activate_new(pcap_t *handle)

 	/* Save the socket FD in the pcap structure */

 	handle->fd = sock_fd;

+#ifdef SO_BPF_EXTENSIONS

+	/*

+	 * Can we generate special code for VLAN checks?

+	 * (XXX - what if we need the special code but it's not supported

+	 * by the OS?  Is that possible?)

+	 */

+	len = sizeof(bpf_extensions);

+

+	if (getsockopt(sock_fd, SOL_SOCKET, SO_BPF_EXTENSIONS, &bpf_extensions, &len) == 0) {

+		if (bpf_extensions >= SKF_AD_VLAN_TAG_PRESENT) {

+			/*

+			 * Yes, we can.  Request that we do so.

+			 */

+			handle->bpf_codegen_flags |= BPF_SPECIAL_VLAN_HANDLING;

+		}

+	}

+#endif /* SO_BPF_EXTENSIONS */

+

+

+

 #if defined(SIOCGSTAMPNS) && defined(SO_TIMESTAMPNS)

 	if (handle->opt.tstamp_precision == PCAP_TSTAMP_PRECISION_NANO) {

 		int nsec_tstamps = 1;

diff --git a/pcap.c b/pcap.c

index 6b16cea..74dc708 100644

--- a/pcap.c

+++ b/pcap.c

@@ -558,6 +558,12 @@ pcap_create_common(const char *source, char *ebuf, size_t size)

 	p->opt.immediate = 0;

 	p->opt.tstamp_type = -1;	/* default to not setting time stamp type */

 	p->opt.tstamp_precision = PCAP_TSTAMP_PRECISION_MICRO;

+

+	/*

+	 * Start out with no BPF code generation flags set.

+	 */

+	p->bpf_codegen_flags = 0;

+

 	return (p);

 }

@@ -1810,6 +1816,12 @@ pcap_open_dead_with_tstamp_precision(int linktype, int snaplen, u_int precision)

 	p->setmintocopy_op = pcap_setmintocopy_dead;

 #endif

 	p->cleanup_op = pcap_cleanup_dead;

+

+	/*

+	 * A "dead" pcap_t never requires special BPF code generation.

+	 */

+	p->bpf_codegen_flags = 0;

+

 	p->activated = 1;

 	return (p);

 }

diff --git a/savefile.c b/savefile.c

index 73e3ea9..98f9c82 100644

--- a/savefile.c

+++ b/savefile.c

@@ -349,6 +349,11 @@ found:

 	 */

 	p->oneshot_callback = pcap_oneshot;

+	/*

+	 * Savefiles never require special BPF code generation.

+	 */

+	p->bpf_codegen_flags = 0;

+

 	p->activated = 1;

 	return (p);

-- 

2.4.3