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![Wang Hai](/assets/img/avatar_default.png)
s/Orignal/Original/ s/infered/inferred/ Reported-by: Hulk Robot <hulkci@huawei.com> Signed-off-by: Wang Hai <wanghai38@huawei.com> Acked-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: David S. Miller <davem@davemloft.net>
183 lines
5.5 KiB
C
183 lines
5.5 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* 6LoWPAN IPv6 UDP compression according to RFC6282
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*
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* Authors:
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* Alexander Aring <aar@pengutronix.de>
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*
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* Original written by:
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* Alexander Smirnov <alex.bluesman.smirnov@gmail.com>
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* Jon Smirl <jonsmirl@gmail.com>
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*/
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#include "nhc.h"
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#define LOWPAN_NHC_UDP_MASK 0xF8
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#define LOWPAN_NHC_UDP_ID 0xF0
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#define LOWPAN_NHC_UDP_IDLEN 1
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#define LOWPAN_NHC_UDP_4BIT_PORT 0xF0B0
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#define LOWPAN_NHC_UDP_4BIT_MASK 0xFFF0
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#define LOWPAN_NHC_UDP_8BIT_PORT 0xF000
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#define LOWPAN_NHC_UDP_8BIT_MASK 0xFF00
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/* values for port compression, _with checksum_ ie bit 5 set to 0 */
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/* all inline */
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#define LOWPAN_NHC_UDP_CS_P_00 0xF0
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/* source 16bit inline, dest = 0xF0 + 8 bit inline */
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#define LOWPAN_NHC_UDP_CS_P_01 0xF1
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/* source = 0xF0 + 8bit inline, dest = 16 bit inline */
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#define LOWPAN_NHC_UDP_CS_P_10 0xF2
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/* source & dest = 0xF0B + 4bit inline */
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#define LOWPAN_NHC_UDP_CS_P_11 0xF3
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/* checksum elided */
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#define LOWPAN_NHC_UDP_CS_C 0x04
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static int udp_uncompress(struct sk_buff *skb, size_t needed)
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{
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u8 tmp = 0, val = 0;
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struct udphdr uh;
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bool fail;
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int err;
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fail = lowpan_fetch_skb(skb, &tmp, sizeof(tmp));
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pr_debug("UDP header uncompression\n");
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switch (tmp & LOWPAN_NHC_UDP_CS_P_11) {
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case LOWPAN_NHC_UDP_CS_P_00:
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fail |= lowpan_fetch_skb(skb, &uh.source, sizeof(uh.source));
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fail |= lowpan_fetch_skb(skb, &uh.dest, sizeof(uh.dest));
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break;
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case LOWPAN_NHC_UDP_CS_P_01:
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fail |= lowpan_fetch_skb(skb, &uh.source, sizeof(uh.source));
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fail |= lowpan_fetch_skb(skb, &val, sizeof(val));
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uh.dest = htons(val + LOWPAN_NHC_UDP_8BIT_PORT);
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break;
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case LOWPAN_NHC_UDP_CS_P_10:
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fail |= lowpan_fetch_skb(skb, &val, sizeof(val));
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uh.source = htons(val + LOWPAN_NHC_UDP_8BIT_PORT);
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fail |= lowpan_fetch_skb(skb, &uh.dest, sizeof(uh.dest));
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break;
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case LOWPAN_NHC_UDP_CS_P_11:
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fail |= lowpan_fetch_skb(skb, &val, sizeof(val));
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uh.source = htons(LOWPAN_NHC_UDP_4BIT_PORT + (val >> 4));
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uh.dest = htons(LOWPAN_NHC_UDP_4BIT_PORT + (val & 0x0f));
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break;
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default:
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BUG();
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}
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pr_debug("uncompressed UDP ports: src = %d, dst = %d\n",
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ntohs(uh.source), ntohs(uh.dest));
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/* checksum */
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if (tmp & LOWPAN_NHC_UDP_CS_C) {
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pr_debug_ratelimited("checksum elided currently not supported\n");
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fail = true;
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} else {
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fail |= lowpan_fetch_skb(skb, &uh.check, sizeof(uh.check));
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}
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if (fail)
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return -EINVAL;
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/* UDP length needs to be inferred from the lower layers
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* here, we obtain the hint from the remaining size of the
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* frame
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*/
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switch (lowpan_dev(skb->dev)->lltype) {
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case LOWPAN_LLTYPE_IEEE802154:
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if (lowpan_802154_cb(skb)->d_size)
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uh.len = htons(lowpan_802154_cb(skb)->d_size -
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sizeof(struct ipv6hdr));
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else
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uh.len = htons(skb->len + sizeof(struct udphdr));
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break;
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default:
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uh.len = htons(skb->len + sizeof(struct udphdr));
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break;
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}
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pr_debug("uncompressed UDP length: src = %d", ntohs(uh.len));
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/* replace the compressed UDP head by the uncompressed UDP
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* header
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*/
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err = skb_cow(skb, needed);
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if (unlikely(err))
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return err;
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skb_push(skb, sizeof(struct udphdr));
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skb_copy_to_linear_data(skb, &uh, sizeof(struct udphdr));
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return 0;
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}
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static int udp_compress(struct sk_buff *skb, u8 **hc_ptr)
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{
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const struct udphdr *uh = udp_hdr(skb);
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u8 tmp;
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if (((ntohs(uh->source) & LOWPAN_NHC_UDP_4BIT_MASK) ==
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LOWPAN_NHC_UDP_4BIT_PORT) &&
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((ntohs(uh->dest) & LOWPAN_NHC_UDP_4BIT_MASK) ==
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LOWPAN_NHC_UDP_4BIT_PORT)) {
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pr_debug("UDP header: both ports compression to 4 bits\n");
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/* compression value */
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tmp = LOWPAN_NHC_UDP_CS_P_11;
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lowpan_push_hc_data(hc_ptr, &tmp, sizeof(tmp));
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/* source and destination port */
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tmp = ntohs(uh->dest) - LOWPAN_NHC_UDP_4BIT_PORT +
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((ntohs(uh->source) - LOWPAN_NHC_UDP_4BIT_PORT) << 4);
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lowpan_push_hc_data(hc_ptr, &tmp, sizeof(tmp));
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} else if ((ntohs(uh->dest) & LOWPAN_NHC_UDP_8BIT_MASK) ==
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LOWPAN_NHC_UDP_8BIT_PORT) {
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pr_debug("UDP header: remove 8 bits of dest\n");
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/* compression value */
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tmp = LOWPAN_NHC_UDP_CS_P_01;
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lowpan_push_hc_data(hc_ptr, &tmp, sizeof(tmp));
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/* source port */
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lowpan_push_hc_data(hc_ptr, &uh->source, sizeof(uh->source));
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/* destination port */
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tmp = ntohs(uh->dest) - LOWPAN_NHC_UDP_8BIT_PORT;
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lowpan_push_hc_data(hc_ptr, &tmp, sizeof(tmp));
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} else if ((ntohs(uh->source) & LOWPAN_NHC_UDP_8BIT_MASK) ==
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LOWPAN_NHC_UDP_8BIT_PORT) {
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pr_debug("UDP header: remove 8 bits of source\n");
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/* compression value */
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tmp = LOWPAN_NHC_UDP_CS_P_10;
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lowpan_push_hc_data(hc_ptr, &tmp, sizeof(tmp));
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/* source port */
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tmp = ntohs(uh->source) - LOWPAN_NHC_UDP_8BIT_PORT;
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lowpan_push_hc_data(hc_ptr, &tmp, sizeof(tmp));
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/* destination port */
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lowpan_push_hc_data(hc_ptr, &uh->dest, sizeof(uh->dest));
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} else {
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pr_debug("UDP header: can't compress\n");
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/* compression value */
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tmp = LOWPAN_NHC_UDP_CS_P_00;
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lowpan_push_hc_data(hc_ptr, &tmp, sizeof(tmp));
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/* source port */
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lowpan_push_hc_data(hc_ptr, &uh->source, sizeof(uh->source));
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/* destination port */
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lowpan_push_hc_data(hc_ptr, &uh->dest, sizeof(uh->dest));
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}
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/* checksum is always inline */
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lowpan_push_hc_data(hc_ptr, &uh->check, sizeof(uh->check));
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return 0;
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}
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static void udp_nhid_setup(struct lowpan_nhc *nhc)
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{
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nhc->id[0] = LOWPAN_NHC_UDP_ID;
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nhc->idmask[0] = LOWPAN_NHC_UDP_MASK;
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}
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LOWPAN_NHC(nhc_udp, "RFC6282 UDP", NEXTHDR_UDP, sizeof(struct udphdr),
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udp_nhid_setup, LOWPAN_NHC_UDP_IDLEN, udp_uncompress, udp_compress);
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module_lowpan_nhc(nhc_udp);
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MODULE_DESCRIPTION("6LoWPAN next header RFC6282 UDP compression");
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MODULE_LICENSE("GPL");
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