[PATCH v3 bluetooth-next 0/8] 6lowpan: udp compression/uncompression fix

[PATCH v3 bluetooth-next 0/8] 6lowpan: udp compression/uncompression fix

[Alexander Aring]

The current 6LoWPAN udp compression/uncompression is completely broken.
This patch series fix a lot of udp compression/uncompression issues and
add support parsing with lowpan_fetch_skb/lowpan_push_hc_data functions.

I tested it in all cases of compressions in wireshark and a contiki
sensornode.

Changes since v3:
 - add patch to introduce lowpan_push_hc_data helper function.
 - remove patch to fix nullpointer dereferencing and replace it with
   a patch which use the lowpan_push_hc_data function in compress_udp_header
   function. This fixes the nullpointer dereferencing problem also and is more
   readable.
 - add missing newline in pr_debug_ratelimited.

Changes since v2:
 - remove unnecessary casts and brackes, suggested by Werner Almesberger.
 - use pr_debug_ratelimited instead of pr_debug on patch 4/7.

Alexander Aring (8):
  6lowpan: introduce lowpan_push_hc_data function
  6lowpan: udp use lowpan_push_hc_data function
  6lowpan: fix udp compress ordering
  6lowpan: fix udp byte ordering
  6lowpan: add udp warning for elided checksum
  6lowpan: udp use lowpan_fetch_skb function
  6lowpan: udp use subtraction on both conditions
  6lowpan: cleanup udp compress function

 net/ieee802154/6lowpan.h      |   8 +++
 net/ieee802154/6lowpan_iphc.c | 114 ++++++++++++++++++++++++------------------
 2 files changed, 74 insertions(+), 48 deletions(-)

-- 
1.8.5.1

[PATCH v3 bluetooth-next 1/8] 6lowpan: introduce lowpan_push_hc_data function

[Alexander Aring]

This patch introduce the lowpan_push_hc_data function to set data in
the iphc buffer.

It's a common case to set data and increase the buffer pointer. This
helper function can be used many times in header_compress function to
generate the iphc header.

Signed-off-by: Alexander Aring <alex.aring@gmail.com>
---
 net/ieee802154/6lowpan.h | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/net/ieee802154/6lowpan.h b/net/ieee802154/6lowpan.h
index 10909e5..4981bf8 100644
--- a/net/ieee802154/6lowpan.h
+++ b/net/ieee802154/6lowpan.h
@@ -298,6 +298,13 @@ static inline bool lowpan_fetch_skb(struct sk_buff *skb,
 	return false;
 }
 
+static inline void lowpan_push_hc_data(u8 **hc_ptr, const void *data,
+				       const size_t len)
+{
+	memcpy(*hc_ptr, data, len);
+	*hc_ptr += len;
+}
+
 typedef int (*skb_delivery_cb)(struct sk_buff *skb, struct net_device *dev);
 
 int lowpan_process_data(struct sk_buff *skb, struct net_device *dev,
-- 
1.8.5.1

[PATCH v3 bluetooth-next 2/8] 6lowpan: udp use lowpan_push_hc_data function

[Alexander Aring]

This patch uses the lowpan_push_hc_data to generate iphc header.

The current implementation has some wrong pointer arithmetic issues and
works in a random case only.

Signed-off-by: Alexander Aring <alex.aring@gmail.com>
---
 net/ieee802154/6lowpan_iphc.c | 37 ++++++++++++++++++++-----------------
 1 file changed, 20 insertions(+), 17 deletions(-)

diff --git a/net/ieee802154/6lowpan_iphc.c b/net/ieee802154/6lowpan_iphc.c
index 88e7da5..77c0366 100644
--- a/net/ieee802154/6lowpan_iphc.c
+++ b/net/ieee802154/6lowpan_iphc.c
@@ -541,42 +541,45 @@ static u8 lowpan_compress_addr_64(u8 **hc06_ptr, u8 shift,
 static void compress_udp_header(u8 **hc06_ptr, struct sk_buff *skb)
 {
 	struct udphdr *uh = udp_hdr(skb);
+	u8 tmp;
 
 	if (((uh->source & LOWPAN_NHC_UDP_4BIT_MASK) ==
 				LOWPAN_NHC_UDP_4BIT_PORT) &&
 	    ((uh->dest & LOWPAN_NHC_UDP_4BIT_MASK) ==
 				LOWPAN_NHC_UDP_4BIT_PORT)) {
 		pr_debug("UDP header: both ports compression to 4 bits\n");
-		**hc06_ptr = LOWPAN_NHC_UDP_CS_P_11;
-		**(hc06_ptr + 1) = /* subtraction is faster */
+		tmp = LOWPAN_NHC_UDP_CS_P_11;
+		lowpan_push_hc_data(hc06_ptr, &tmp, sizeof(tmp));
+		tmp = /* subtraction is faster */
 		   (u8)((uh->dest - LOWPAN_NHC_UDP_4BIT_PORT) +
 		       ((uh->source & LOWPAN_NHC_UDP_4BIT_PORT) << 4));
-		*hc06_ptr += 2;
+		lowpan_push_hc_data(hc06_ptr, &tmp, sizeof(tmp));
 	} else if ((uh->dest & LOWPAN_NHC_UDP_8BIT_MASK) ==
 			LOWPAN_NHC_UDP_8BIT_PORT) {
 		pr_debug("UDP header: remove 8 bits of dest\n");
-		**hc06_ptr = LOWPAN_NHC_UDP_CS_P_01;
-		memcpy(*hc06_ptr + 1, &uh->source, 2);
-		**(hc06_ptr + 3) = (u8)(uh->dest - LOWPAN_NHC_UDP_8BIT_PORT);
-		*hc06_ptr += 4;
+		tmp = LOWPAN_NHC_UDP_CS_P_01;
+		lowpan_push_hc_data(hc06_ptr, &tmp, sizeof(tmp));
+		lowpan_push_hc_data(hc06_ptr, &uh->source, sizeof(uh->source));
+		tmp = (u8)(uh->dest - LOWPAN_NHC_UDP_8BIT_PORT);
+		lowpan_push_hc_data(hc06_ptr, &tmp, sizeof(tmp));
 	} else if ((uh->source & LOWPAN_NHC_UDP_8BIT_MASK) ==
 			LOWPAN_NHC_UDP_8BIT_PORT) {
 		pr_debug("UDP header: remove 8 bits of source\n");
-		**hc06_ptr = LOWPAN_NHC_UDP_CS_P_10;
-		memcpy(*hc06_ptr + 1, &uh->dest, 2);
-		**(hc06_ptr + 3) = (u8)(uh->source - LOWPAN_NHC_UDP_8BIT_PORT);
-		*hc06_ptr += 4;
+		tmp = LOWPAN_NHC_UDP_CS_P_10;
+		lowpan_push_hc_data(hc06_ptr, &tmp, sizeof(tmp));
+		lowpan_push_hc_data(hc06_ptr, &uh->dest, sizeof(uh->dest));
+		tmp = (u8)(uh->source - LOWPAN_NHC_UDP_8BIT_PORT);
+		lowpan_push_hc_data(hc06_ptr, &tmp, sizeof(tmp));
 	} else {
 		pr_debug("UDP header: can't compress\n");
-		**hc06_ptr = LOWPAN_NHC_UDP_CS_P_00;
-		memcpy(*hc06_ptr + 1, &uh->source, 2);
-		memcpy(*hc06_ptr + 3, &uh->dest, 2);
-		*hc06_ptr += 5;
+		tmp = LOWPAN_NHC_UDP_CS_P_00;
+		lowpan_push_hc_data(hc06_ptr, &tmp, sizeof(tmp));
+		lowpan_push_hc_data(hc06_ptr, &uh->source, sizeof(uh->source));
+		lowpan_push_hc_data(hc06_ptr, &uh->dest, sizeof(uh->dest));
 	}
 
 	/* checksum is always inline */
-	memcpy(*hc06_ptr, &uh->check, 2);
-	*hc06_ptr += 2;
+	lowpan_push_hc_data(hc06_ptr, &uh->check, sizeof(uh->check));
 
 	/* skip the UDP header */
 	skb_pull(skb, sizeof(struct udphdr));
-- 
1.8.5.1

[PATCH v3 bluetooth-next 3/8] 6lowpan: fix udp compress ordering

[Alexander Aring]

In case ((ntohs(uh->source) & LOWPAN_NHC_UDP_8BIT_MASK) the order of
uncompression is wrong. It's always first source port then destination
port as second.

See:
http://tools.ietf.org/html/rfc6282#section-4.3.3

"Fields carried in-line (in part or in whole) appear in the same order
as they do in the UDP header format"

Signed-off-by: Alexander Aring <alex.aring@gmail.com>
---
 net/ieee802154/6lowpan_iphc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ieee802154/6lowpan_iphc.c b/net/ieee802154/6lowpan_iphc.c
index 77c0366..1933f5b 100644
--- a/net/ieee802154/6lowpan_iphc.c
+++ b/net/ieee802154/6lowpan_iphc.c
@@ -567,9 +567,9 @@ static void compress_udp_header(u8 **hc06_ptr, struct sk_buff *skb)
 		pr_debug("UDP header: remove 8 bits of source\n");
 		tmp = LOWPAN_NHC_UDP_CS_P_10;
 		lowpan_push_hc_data(hc06_ptr, &tmp, sizeof(tmp));
-		lowpan_push_hc_data(hc06_ptr, &uh->dest, sizeof(uh->dest));
 		tmp = (u8)(uh->source - LOWPAN_NHC_UDP_8BIT_PORT);
 		lowpan_push_hc_data(hc06_ptr, &tmp, sizeof(tmp));
+		lowpan_push_hc_data(hc06_ptr, &uh->dest, sizeof(uh->dest));
 	} else {
 		pr_debug("UDP header: can't compress\n");
 		tmp = LOWPAN_NHC_UDP_CS_P_00;
-- 
1.8.5.1

[PATCH v3 bluetooth-next 4/8] 6lowpan: fix udp byte ordering

[Alexander Aring]

The incoming udp header in lowpan_compress_udp_header function is
already in network byte order.

Everytime we read this values for source and destination port we need
to convert this value to host byte order.

In the outcoming header we need to set this value in network byte order
which the upcoming process assumes.

Signed-off-by: Alexander Aring <alex.aring@gmail.com>
---
 net/ieee802154/6lowpan_iphc.c | 39 ++++++++++++++++++++-------------------
 1 file changed, 20 insertions(+), 19 deletions(-)

diff --git a/net/ieee802154/6lowpan_iphc.c b/net/ieee802154/6lowpan_iphc.c
index 1933f5b..02bf74d 100644
--- a/net/ieee802154/6lowpan_iphc.c
+++ b/net/ieee802154/6lowpan_iphc.c
@@ -283,20 +283,21 @@ uncompress_udp_header(struct sk_buff *skb, struct udphdr *uh)
 			break;
 		case LOWPAN_NHC_UDP_CS_P_01:
 			memcpy(&uh->source, &skb->data[0], 2);
-			uh->dest =
-			   skb->data[2] + LOWPAN_NHC_UDP_8BIT_PORT;
+			uh->dest = htons(skb->data[2] +
+					 LOWPAN_NHC_UDP_8BIT_PORT);
 			skb_pull(skb, 3);
 			break;
 		case LOWPAN_NHC_UDP_CS_P_10:
-			uh->source = skb->data[0] + LOWPAN_NHC_UDP_8BIT_PORT;
+			uh->source = htons(skb->data[0] +
+					   LOWPAN_NHC_UDP_8BIT_PORT);
 			memcpy(&uh->dest, &skb->data[1], 2);
 			skb_pull(skb, 3);
 			break;
 		case LOWPAN_NHC_UDP_CS_P_11:
-			uh->source =
-			   LOWPAN_NHC_UDP_4BIT_PORT + (skb->data[0] >> 4);
-			uh->dest =
-			   LOWPAN_NHC_UDP_4BIT_PORT + (skb->data[0] & 0x0f);
+			uh->source = htons(LOWPAN_NHC_UDP_4BIT_PORT +
+					   (skb->data[0] >> 4));
+			uh->dest = htons(LOWPAN_NHC_UDP_4BIT_PORT +
+					 (skb->data[0] & 0x0f));
 			skb_pull(skb, 1);
 			break;
 		default:
@@ -306,7 +307,7 @@ uncompress_udp_header(struct sk_buff *skb, struct udphdr *uh)
 		}
 
 		pr_debug("uncompressed UDP ports: src = %d, dst = %d\n",
-			 uh->source, uh->dest);
+			 ntohs(uh->source), ntohs(uh->dest));
 
 		/* copy checksum */
 		memcpy(&uh->check, &skb->data[0], 2);
@@ -318,7 +319,7 @@ uncompress_udp_header(struct sk_buff *skb, struct udphdr *uh)
 		 * frame
 		 */
 		uh->len = htons(skb->len + sizeof(struct udphdr));
-		pr_debug("uncompressed UDP length: src = %d", uh->len);
+		pr_debug("uncompressed UDP length: src = %d", ntohs(uh->len));
 	} else {
 		pr_debug("ERROR: unsupported NH format\n");
 		goto err;
@@ -543,31 +544,31 @@ static void compress_udp_header(u8 **hc06_ptr, struct sk_buff *skb)
 	struct udphdr *uh = udp_hdr(skb);
 	u8 tmp;
 
-	if (((uh->source & LOWPAN_NHC_UDP_4BIT_MASK) ==
-				LOWPAN_NHC_UDP_4BIT_PORT) &&
-	    ((uh->dest & LOWPAN_NHC_UDP_4BIT_MASK) ==
-				LOWPAN_NHC_UDP_4BIT_PORT)) {
+	if (((ntohs(uh->source) & LOWPAN_NHC_UDP_4BIT_MASK) ==
+	     LOWPAN_NHC_UDP_4BIT_PORT) &&
+	    ((ntohs(uh->dest) & LOWPAN_NHC_UDP_4BIT_MASK) ==
+	     LOWPAN_NHC_UDP_4BIT_PORT)) {
 		pr_debug("UDP header: both ports compression to 4 bits\n");
 		tmp = LOWPAN_NHC_UDP_CS_P_11;
 		lowpan_push_hc_data(hc06_ptr, &tmp, sizeof(tmp));
 		tmp = /* subtraction is faster */
-		   (u8)((uh->dest - LOWPAN_NHC_UDP_4BIT_PORT) +
-		       ((uh->source & LOWPAN_NHC_UDP_4BIT_PORT) << 4));
+		   (u8)((ntohs(uh->dest) - LOWPAN_NHC_UDP_4BIT_PORT) +
+		       ((ntohs(uh->source) & LOWPAN_NHC_UDP_4BIT_PORT) << 4));
 		lowpan_push_hc_data(hc06_ptr, &tmp, sizeof(tmp));
-	} else if ((uh->dest & LOWPAN_NHC_UDP_8BIT_MASK) ==
+	} else if ((ntohs(uh->dest) & LOWPAN_NHC_UDP_8BIT_MASK) ==
 			LOWPAN_NHC_UDP_8BIT_PORT) {
 		pr_debug("UDP header: remove 8 bits of dest\n");
 		tmp = LOWPAN_NHC_UDP_CS_P_01;
 		lowpan_push_hc_data(hc06_ptr, &tmp, sizeof(tmp));
 		lowpan_push_hc_data(hc06_ptr, &uh->source, sizeof(uh->source));
-		tmp = (u8)(uh->dest - LOWPAN_NHC_UDP_8BIT_PORT);
+		tmp = (u8)(ntohs(uh->dest) - LOWPAN_NHC_UDP_8BIT_PORT);
 		lowpan_push_hc_data(hc06_ptr, &tmp, sizeof(tmp));
-	} else if ((uh->source & LOWPAN_NHC_UDP_8BIT_MASK) ==
+	} else if ((ntohs(uh->source) & LOWPAN_NHC_UDP_8BIT_MASK) ==
 			LOWPAN_NHC_UDP_8BIT_PORT) {
 		pr_debug("UDP header: remove 8 bits of source\n");
 		tmp = LOWPAN_NHC_UDP_CS_P_10;
 		lowpan_push_hc_data(hc06_ptr, &tmp, sizeof(tmp));
-		tmp = (u8)(uh->source - LOWPAN_NHC_UDP_8BIT_PORT);
+		tmp = (u8)(ntohs(uh->source) - LOWPAN_NHC_UDP_8BIT_PORT);
 		lowpan_push_hc_data(hc06_ptr, &tmp, sizeof(tmp));
 		lowpan_push_hc_data(hc06_ptr, &uh->dest, sizeof(uh->dest));
 	} else {
-- 
1.8.5.1

[PATCH v3 bluetooth-next 5/8] 6lowpan: add udp warning for elided checksum

[Alexander Aring]

Bit 5 of "UDP LOWPAN_NHC Format" indicate that the checksum can be
elided.
The host need to calculate the udp checksum afterwards but this isn't
supported right now.

See:
http://tools.ietf.org/html/rfc6282#section-4.3.3
Signed-off-by: Alexander Aring <alex.aring@gmail.com>
---
 net/ieee802154/6lowpan.h      |  1 +
 net/ieee802154/6lowpan_iphc.c | 11 ++++++++---
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/net/ieee802154/6lowpan.h b/net/ieee802154/6lowpan.h
index 4981bf8..2b835db 100644
--- a/net/ieee802154/6lowpan.h
+++ b/net/ieee802154/6lowpan.h
@@ -231,6 +231,7 @@
 #define LOWPAN_NHC_UDP_CS_P_10	0xF2 /* source = 0xF0 + 8bit inline,
 					dest = 16 bit inline */
 #define LOWPAN_NHC_UDP_CS_P_11	0xF3 /* source & dest = 0xF0B + 4bit inline */
+#define LOWPAN_NHC_UDP_CS_C	0x04 /* checksum elided */
 
 #ifdef DEBUG
 /* print data in line */
diff --git a/net/ieee802154/6lowpan_iphc.c b/net/ieee802154/6lowpan_iphc.c
index 02bf74d..a70fa66 100644
--- a/net/ieee802154/6lowpan_iphc.c
+++ b/net/ieee802154/6lowpan_iphc.c
@@ -309,9 +309,14 @@ uncompress_udp_header(struct sk_buff *skb, struct udphdr *uh)
 		pr_debug("uncompressed UDP ports: src = %d, dst = %d\n",
 			 ntohs(uh->source), ntohs(uh->dest));
 
-		/* copy checksum */
-		memcpy(&uh->check, &skb->data[0], 2);
-		skb_pull(skb, 2);
+		/* checksum */
+		if (tmp & LOWPAN_NHC_UDP_CS_C) {
+			pr_debug_ratelimited("checksum elided currently not supported\n");
+			goto err;
+		} else {
+			memcpy(&uh->check, &skb->data[0], 2);
+			skb_pull(skb, 2);
+		}
 
 		/*
 		 * UDP lenght needs to be infered from the lower layers
-- 
1.8.5.1

[PATCH v3 bluetooth-next 6/8] 6lowpan: udp use lowpan_fetch_skb function

[Alexander Aring]

Cleanup the lowpan_uncompress_udp_header function to use the
lowpan_fetch_skb function.

Signed-off-by: Alexander Aring <alex.aring@gmail.com>
---
 net/ieee802154/6lowpan_iphc.c | 37 ++++++++++++++++++-------------------
 1 file changed, 18 insertions(+), 19 deletions(-)

diff --git a/net/ieee802154/6lowpan_iphc.c b/net/ieee802154/6lowpan_iphc.c
index a70fa66..8857285 100644
--- a/net/ieee802154/6lowpan_iphc.c
+++ b/net/ieee802154/6lowpan_iphc.c
@@ -265,40 +265,37 @@ lowpan_uncompress_multicast_daddr(struct sk_buff *skb,
 static int
 uncompress_udp_header(struct sk_buff *skb, struct udphdr *uh)
 {
-	u8 tmp;
+	bool fail;
+	u8 tmp = 0, val = 0;
 
 	if (!uh)
 		goto err;
 
-	if (lowpan_fetch_skb_u8(skb, &tmp))
-		goto err;
+	fail = lowpan_fetch_skb(skb, &tmp, 1);
 
 	if ((tmp & LOWPAN_NHC_UDP_MASK) == LOWPAN_NHC_UDP_ID) {
 		pr_debug("UDP header uncompression\n");
 		switch (tmp & LOWPAN_NHC_UDP_CS_P_11) {
 		case LOWPAN_NHC_UDP_CS_P_00:
-			memcpy(&uh->source, &skb->data[0], 2);
-			memcpy(&uh->dest, &skb->data[2], 2);
-			skb_pull(skb, 4);
+			fail |= lowpan_fetch_skb(skb, &uh->source, 2);
+			fail |= lowpan_fetch_skb(skb, &uh->dest, 2);
 			break;
 		case LOWPAN_NHC_UDP_CS_P_01:
-			memcpy(&uh->source, &skb->data[0], 2);
-			uh->dest = htons(skb->data[2] +
-					 LOWPAN_NHC_UDP_8BIT_PORT);
-			skb_pull(skb, 3);
+			fail |= lowpan_fetch_skb(skb, &uh->source, 2);
+			fail |= lowpan_fetch_skb(skb, &val, 1);
+			uh->dest = htons(val + LOWPAN_NHC_UDP_8BIT_PORT);
 			break;
 		case LOWPAN_NHC_UDP_CS_P_10:
-			uh->source = htons(skb->data[0] +
-					   LOWPAN_NHC_UDP_8BIT_PORT);
-			memcpy(&uh->dest, &skb->data[1], 2);
-			skb_pull(skb, 3);
+			fail |= lowpan_fetch_skb(skb, &val, 1);
+			uh->source = htons(val + LOWPAN_NHC_UDP_8BIT_PORT);
+			fail |= lowpan_fetch_skb(skb, &uh->dest, 2);
 			break;
 		case LOWPAN_NHC_UDP_CS_P_11:
+			fail |= lowpan_fetch_skb(skb, &val, 1);
 			uh->source = htons(LOWPAN_NHC_UDP_4BIT_PORT +
-					   (skb->data[0] >> 4));
+					   (val >> 4));
 			uh->dest = htons(LOWPAN_NHC_UDP_4BIT_PORT +
-					 (skb->data[0] & 0x0f));
-			skb_pull(skb, 1);
+					 (val & 0x0f));
 			break;
 		default:
 			pr_debug("ERROR: unknown UDP format\n");
@@ -314,8 +311,7 @@ uncompress_udp_header(struct sk_buff *skb, struct udphdr *uh)
 			pr_debug_ratelimited("checksum elided currently not supported\n");
 			goto err;
 		} else {
-			memcpy(&uh->check, &skb->data[0], 2);
-			skb_pull(skb, 2);
+			fail |= lowpan_fetch_skb(skb, &uh->check, 2);
 		}
 
 		/*
@@ -330,6 +326,9 @@ uncompress_udp_header(struct sk_buff *skb, struct udphdr *uh)
 		goto err;
 	}
 
+	if (fail)
+		goto err;
+
 	return 0;
 err:
 	return -EINVAL;
-- 
1.8.5.1

[PATCH v3 bluetooth-next 7/8] 6lowpan: udp use subtraction on both conditions

[Alexander Aring]

Cleanup code to handle both calculation in the same way.

Signed-off-by: Alexander Aring <alex.aring@gmail.com>
---
 net/ieee802154/6lowpan_iphc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ieee802154/6lowpan_iphc.c b/net/ieee802154/6lowpan_iphc.c
index 8857285..b298bfc 100644
--- a/net/ieee802154/6lowpan_iphc.c
+++ b/net/ieee802154/6lowpan_iphc.c
@@ -557,7 +557,7 @@ static void compress_udp_header(u8 **hc06_ptr, struct sk_buff *skb)
 		lowpan_push_hc_data(hc06_ptr, &tmp, sizeof(tmp));
 		tmp = /* subtraction is faster */
 		   (u8)((ntohs(uh->dest) - LOWPAN_NHC_UDP_4BIT_PORT) +
-		       ((ntohs(uh->source) & LOWPAN_NHC_UDP_4BIT_PORT) << 4));
+		       ((ntohs(uh->source) - LOWPAN_NHC_UDP_4BIT_PORT) << 4));
 		lowpan_push_hc_data(hc06_ptr, &tmp, sizeof(tmp));
 	} else if ((ntohs(uh->dest) & LOWPAN_NHC_UDP_8BIT_MASK) ==
 			LOWPAN_NHC_UDP_8BIT_PORT) {
-- 
1.8.5.1

[PATCH v3 bluetooth-next 8/8] 6lowpan: cleanup udp compress function

[Alexander Aring]

This patch remove unnecessary casts and brackets in compress_udp_header
function.

Signed-off-by: Alexander Aring <alex.aring@gmail.com>
---
 net/ieee802154/6lowpan_iphc.c | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/net/ieee802154/6lowpan_iphc.c b/net/ieee802154/6lowpan_iphc.c
index b298bfc..11840f9 100644
--- a/net/ieee802154/6lowpan_iphc.c
+++ b/net/ieee802154/6lowpan_iphc.c
@@ -553,33 +553,43 @@ static void compress_udp_header(u8 **hc06_ptr, struct sk_buff *skb)
 	    ((ntohs(uh->dest) & LOWPAN_NHC_UDP_4BIT_MASK) ==
 	     LOWPAN_NHC_UDP_4BIT_PORT)) {
 		pr_debug("UDP header: both ports compression to 4 bits\n");
+		/* compression value */
 		tmp = LOWPAN_NHC_UDP_CS_P_11;
 		lowpan_push_hc_data(hc06_ptr, &tmp, sizeof(tmp));
-		tmp = /* subtraction is faster */
-		   (u8)((ntohs(uh->dest) - LOWPAN_NHC_UDP_4BIT_PORT) +
-		       ((ntohs(uh->source) - LOWPAN_NHC_UDP_4BIT_PORT) << 4));
+		/* source and destination port */
+		tmp = ntohs(uh->dest) - LOWPAN_NHC_UDP_4BIT_PORT +
+		      ((ntohs(uh->source) - LOWPAN_NHC_UDP_4BIT_PORT) << 4);
 		lowpan_push_hc_data(hc06_ptr, &tmp, sizeof(tmp));
 	} else if ((ntohs(uh->dest) & LOWPAN_NHC_UDP_8BIT_MASK) ==
 			LOWPAN_NHC_UDP_8BIT_PORT) {
 		pr_debug("UDP header: remove 8 bits of dest\n");
+		/* compression value */
 		tmp = LOWPAN_NHC_UDP_CS_P_01;
 		lowpan_push_hc_data(hc06_ptr, &tmp, sizeof(tmp));
+		/* source port */
 		lowpan_push_hc_data(hc06_ptr, &uh->source, sizeof(uh->source));
-		tmp = (u8)(ntohs(uh->dest) - LOWPAN_NHC_UDP_8BIT_PORT);
+		/* destination port */
+		tmp = ntohs(uh->dest) - LOWPAN_NHC_UDP_8BIT_PORT;
 		lowpan_push_hc_data(hc06_ptr, &tmp, sizeof(tmp));
 	} else if ((ntohs(uh->source) & LOWPAN_NHC_UDP_8BIT_MASK) ==
 			LOWPAN_NHC_UDP_8BIT_PORT) {
 		pr_debug("UDP header: remove 8 bits of source\n");
+		/* compression value */
 		tmp = LOWPAN_NHC_UDP_CS_P_10;
 		lowpan_push_hc_data(hc06_ptr, &tmp, sizeof(tmp));
-		tmp = (u8)(ntohs(uh->source) - LOWPAN_NHC_UDP_8BIT_PORT);
+		/* source port */
+		tmp = ntohs(uh->source) - LOWPAN_NHC_UDP_8BIT_PORT;
 		lowpan_push_hc_data(hc06_ptr, &tmp, sizeof(tmp));
+		/* destination port */
 		lowpan_push_hc_data(hc06_ptr, &uh->dest, sizeof(uh->dest));
 	} else {
 		pr_debug("UDP header: can't compress\n");
+		/* compression value */
 		tmp = LOWPAN_NHC_UDP_CS_P_00;
 		lowpan_push_hc_data(hc06_ptr, &tmp, sizeof(tmp));
+		/* source port */
 		lowpan_push_hc_data(hc06_ptr, &uh->source, sizeof(uh->source));
+		/* destination port */
 		lowpan_push_hc_data(hc06_ptr, &uh->dest, sizeof(uh->dest));
 	}
 
-- 
1.8.5.1

Re: [PATCH v3 bluetooth-next 0/8] 6lowpan: udp compression/uncompression fix

[Marcel Holtmann]

Hi Alex,

> The current 6LoWPAN udp compression/uncompression is completely broken.
> This patch series fix a lot of udp compression/uncompression issues and
> add support parsing with lowpan_fetch_skb/lowpan_push_hc_data functions.
> 
> I tested it in all cases of compressions in wireshark and a contiki
> sensornode.
> 
> Changes since v3:
> - add patch to introduce lowpan_push_hc_data helper function.
> - remove patch to fix nullpointer dereferencing and replace it with
>   a patch which use the lowpan_push_hc_data function in compress_udp_header
>   function. This fixes the nullpointer dereferencing problem also and is more
>   readable.
> - add missing newline in pr_debug_ratelimited.
> 
> Changes since v2:
> - remove unnecessary casts and brackes, suggested by Werner Almesberger.
> - use pr_debug_ratelimited instead of pr_debug on patch 4/7.
> 
> Alexander Aring (8):
>  6lowpan: introduce lowpan_push_hc_data function
>  6lowpan: udp use lowpan_push_hc_data function
>  6lowpan: fix udp compress ordering
>  6lowpan: fix udp byte ordering
>  6lowpan: add udp warning for elided checksum
>  6lowpan: udp use lowpan_fetch_skb function
>  6lowpan: udp use subtraction on both conditions
>  6lowpan: cleanup udp compress function
> 
> net/ieee802154/6lowpan.h      |   8 +++
> net/ieee802154/6lowpan_iphc.c | 114 ++++++++++++++++++++++++------------------
> 2 files changed, 74 insertions(+), 48 deletions(-)

all 8 patches have been applied to bluetooth-next tree.

Regards

Marcel