From cc6ed2684751b0a1074b37c080983b6ce737ed22 Mon Sep 17 00:00:00 2001 From: Alexander Aring Date: Fri, 9 Jan 2015 16:42:58 +0100 Subject: 6lowpan: add udp compression via nhc layer This patch move UDP header compression and uncompression into the generic 6LoWPAN nhc header compression layer. Moreover this patch activates the nhc layer compression in iphc compression and uncompression functions. Signed-off-by: Alexander Aring Cc: Martin Townsend Reviewed-by: Stefan Schmidt Acked-by: Jukka Rissanen Signed-off-by: Marcel Holtmann --- net/6lowpan/nhc_udp.c | 157 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 157 insertions(+) create mode 100644 net/6lowpan/nhc_udp.c (limited to 'net/6lowpan/nhc_udp.c') diff --git a/net/6lowpan/nhc_udp.c b/net/6lowpan/nhc_udp.c new file mode 100644 index 000000000000..c6bcaeb428ae --- /dev/null +++ b/net/6lowpan/nhc_udp.c @@ -0,0 +1,157 @@ +/* + * 6LoWPAN IPv6 UDP compression according to RFC6282 + * + * + * Authors: + * Alexander Aring + * + * Orignal written by: + * Alexander Smirnov + * Jon Smirl + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + */ + +#include "nhc.h" + +#define LOWPAN_NHC_UDP_IDLEN 1 + +static int udp_uncompress(struct sk_buff *skb, size_t needed) +{ + u8 tmp = 0, val = 0; + struct udphdr uh; + bool fail; + int err; + + fail = lowpan_fetch_skb(skb, &tmp, sizeof(tmp)); + + pr_debug("UDP header uncompression\n"); + switch (tmp & LOWPAN_NHC_UDP_CS_P_11) { + case LOWPAN_NHC_UDP_CS_P_00: + fail |= lowpan_fetch_skb(skb, &uh.source, sizeof(uh.source)); + fail |= lowpan_fetch_skb(skb, &uh.dest, sizeof(uh.dest)); + break; + case LOWPAN_NHC_UDP_CS_P_01: + fail |= lowpan_fetch_skb(skb, &uh.source, sizeof(uh.source)); + fail |= lowpan_fetch_skb(skb, &val, sizeof(val)); + uh.dest = htons(val + LOWPAN_NHC_UDP_8BIT_PORT); + break; + case LOWPAN_NHC_UDP_CS_P_10: + fail |= lowpan_fetch_skb(skb, &val, sizeof(val)); + uh.source = htons(val + LOWPAN_NHC_UDP_8BIT_PORT); + fail |= lowpan_fetch_skb(skb, &uh.dest, sizeof(uh.dest)); + break; + case LOWPAN_NHC_UDP_CS_P_11: + fail |= lowpan_fetch_skb(skb, &val, sizeof(val)); + uh.source = htons(LOWPAN_NHC_UDP_4BIT_PORT + (val >> 4)); + uh.dest = htons(LOWPAN_NHC_UDP_4BIT_PORT + (val & 0x0f)); + break; + default: + BUG(); + } + + pr_debug("uncompressed UDP ports: src = %d, dst = %d\n", + ntohs(uh.source), ntohs(uh.dest)); + + /* checksum */ + if (tmp & LOWPAN_NHC_UDP_CS_C) { + pr_debug_ratelimited("checksum elided currently not supported\n"); + fail = true; + } else { + fail |= lowpan_fetch_skb(skb, &uh.check, sizeof(uh.check)); + } + + if (fail) + return -EINVAL; + + /* UDP length needs to be infered from the lower layers + * here, we obtain the hint from the remaining size of the + * frame + */ + uh.len = htons(skb->len + sizeof(struct udphdr)); + pr_debug("uncompressed UDP length: src = %d", ntohs(uh.len)); + + /* replace the compressed UDP head by the uncompressed UDP + * header + */ + err = skb_cow(skb, needed); + if (unlikely(err)) + return err; + + skb_push(skb, sizeof(struct udphdr)); + skb_copy_to_linear_data(skb, &uh, sizeof(struct udphdr)); + + return 0; +} + +static int udp_compress(struct sk_buff *skb, u8 **hc_ptr) +{ + const struct udphdr *uh = udp_hdr(skb); + u8 tmp; + + 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"); + /* compression value */ + tmp = LOWPAN_NHC_UDP_CS_P_11; + lowpan_push_hc_data(hc_ptr, &tmp, sizeof(tmp)); + /* 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(hc_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(hc_ptr, &tmp, sizeof(tmp)); + /* source port */ + lowpan_push_hc_data(hc_ptr, &uh->source, sizeof(uh->source)); + /* destination port */ + tmp = ntohs(uh->dest) - LOWPAN_NHC_UDP_8BIT_PORT; + lowpan_push_hc_data(hc_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(hc_ptr, &tmp, sizeof(tmp)); + /* source port */ + tmp = ntohs(uh->source) - LOWPAN_NHC_UDP_8BIT_PORT; + lowpan_push_hc_data(hc_ptr, &tmp, sizeof(tmp)); + /* destination port */ + lowpan_push_hc_data(hc_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(hc_ptr, &tmp, sizeof(tmp)); + /* source port */ + lowpan_push_hc_data(hc_ptr, &uh->source, sizeof(uh->source)); + /* destination port */ + lowpan_push_hc_data(hc_ptr, &uh->dest, sizeof(uh->dest)); + } + + /* checksum is always inline */ + lowpan_push_hc_data(hc_ptr, &uh->check, sizeof(uh->check)); + + return 0; +} + +static void udp_nhid_setup(struct lowpan_nhc *nhc) +{ + nhc->id[0] = LOWPAN_NHC_UDP_ID; + nhc->idmask[0] = LOWPAN_NHC_UDP_MASK; +} + +LOWPAN_NHC(nhc_udp, "RFC6282 UDP", NEXTHDR_UDP, sizeof(struct udphdr), + udp_nhid_setup, LOWPAN_NHC_UDP_IDLEN, udp_uncompress, udp_compress); + +module_lowpan_nhc(nhc_udp); +MODULE_DESCRIPTION("6LoWPAN next header RFC6282 UDP compression"); +MODULE_LICENSE("GPL"); -- cgit