[PATCH 4/6] [6LoWPAN] UDP header compression
From: Alexander Smirnov <hidden>
Date: 2011-11-02 16:35:11
Subsystem:
ieee 802.15.4 subsystem, networking [general], the rest · Maintainers:
Alexander Aring, Stefan Schmidt, Miquel Raynal, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
Possibly related (same subject, not in this thread)
- 2011-11-08 · Re: [PATCH 4/6] [6LoWPAN] UDP header compression · Dmitry Eremin-Solenikov <hidden>
This patch adds support for UDP header compression. Derived from Contiki OS. Signed-off-by: Alexander Smirnov <redacted> --- net/ieee802154/6lowpan.c | 51 ++++++++++++++++++++++++++++++++++++++++++--- net/ieee802154/6lowpan.h | 5 ++++ 2 files changed, 52 insertions(+), 4 deletions(-)
diff --git a/net/ieee802154/6lowpan.c b/net/ieee802154/6lowpan.c
index c4aae4e..6da3357 100644
--- a/net/ieee802154/6lowpan.c
+++ b/net/ieee802154/6lowpan.c@@ -365,8 +365,6 @@ static int lowpan_header_create(struct sk_buff *skb, if (hdr->nexthdr == UIP_PROTO_UDP) iphc0 |= LOWPAN_IPHC_NH_C; -/* TODO: next header compression */ - if ((iphc0 & LOWPAN_IPHC_NH_C) == 0) { *hc06_ptr = hdr->nexthdr; hc06_ptr += 1;
@@ -454,8 +452,53 @@ static int lowpan_header_create(struct sk_buff *skb, } } - /* TODO: UDP header compression */ - /* TODO: Next Header compression */ + /* UDP header compression */ + if (hdr->nexthdr == UIP_PROTO_UDP) { + struct udphdr *uh = udp_hdr(skb); + + pr_debug("(%s): UDP header compression\n", __func__); + + 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("(%s): both ports compression to 4 bits\n", + __func__); + *hc06_ptr = LOWPAN_NHC_UDP_CS_P_11; + *(hc06_ptr + 1) = /* subtraction is faster */ + (u8)((uh->dest - LOWPAN_NHC_UDP_4BIT_PORT) + + ((uh->source & LOWPAN_NHC_UDP_4BIT_PORT) << 4)); + hc06_ptr += 2; + } else if ((uh->dest & LOWPAN_NHC_UDP_8BIT_MASK) == + LOWPAN_NHC_UDP_8BIT_PORT) { + pr_debug("(%s): remove 8 bits of dest\n", __func__); + *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; + } else if ((uh->source & LOWPAN_NHC_UDP_8BIT_MASK) == + LOWPAN_NHC_UDP_8BIT_PORT) { + pr_debug("(%s): remove 8 bits of source\n", __func__); + *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; + } else { + pr_debug("(%s): can't compress header\n", __func__); + *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; + } + + /* checksum is always inline */ + memcpy(hc06_ptr, &uh->check, 2); + hc06_ptr += 2; + } + + /* TODO: other NH types support? */ head[0] = iphc0; head[1] = iphc1;
diff --git a/net/ieee802154/6lowpan.h b/net/ieee802154/6lowpan.h
index 5d2e5a0..aeff3f3 100644
--- a/net/ieee802154/6lowpan.h
+++ b/net/ieee802154/6lowpan.h@@ -219,6 +219,11 @@ #define LOWPAN_NHC_UDP_CHECKSUMC 0x04 #define LOWPAN_NHC_UDP_CHECKSUMI 0x00 +#define LOWPAN_NHC_UDP_4BIT_PORT 0xF0B0 +#define LOWPAN_NHC_UDP_4BIT_MASK 0xFFF0 +#define LOWPAN_NHC_UDP_8BIT_PORT 0xF000 +#define LOWPAN_NHC_UDP_8BIT_MASK 0xFF00 + /* values for port compression, _with checksum_ ie bit 5 set to 0 */ #define LOWPAN_NHC_UDP_CS_P_00 0xF0 /* all inline */ #define LOWPAN_NHC_UDP_CS_P_01 0xF1 /* source 16bit inline,
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1.7.2.5
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