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Diffstat (limited to '')
| -rw-r--r-- | net/6lowpan/nhc_udp.c | 176 |
1 files changed, 176 insertions, 0 deletions
diff --git a/net/6lowpan/nhc_udp.c b/net/6lowpan/nhc_udp.c new file mode 100644 index 000000000..0a506c772 --- /dev/null +++ b/net/6lowpan/nhc_udp.c @@ -0,0 +1,176 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * 6LoWPAN IPv6 UDP compression according to RFC6282 + * + * Authors: + * Alexander Aring <aar@pengutronix.de> + * + * Original written by: + * Alexander Smirnov <alex.bluesman.smirnov@gmail.com> + * Jon Smirl <jonsmirl@gmail.com> + */ + +#include "nhc.h" + +#define LOWPAN_NHC_UDP_MASK 0xF8 +#define LOWPAN_NHC_UDP_ID 0xF0 + +#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 */ + +/* all inline */ +#define LOWPAN_NHC_UDP_CS_P_00 0xF0 +/* source 16bit inline, dest = 0xF0 + 8 bit inline */ +#define LOWPAN_NHC_UDP_CS_P_01 0xF1 +/* source = 0xF0 + 8bit inline, dest = 16 bit inline */ +#define LOWPAN_NHC_UDP_CS_P_10 0xF2 +/* source & dest = 0xF0B + 4bit inline */ +#define LOWPAN_NHC_UDP_CS_P_11 0xF3 +/* checksum elided */ +#define LOWPAN_NHC_UDP_CS_C 0x04 + +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 inferred from the lower layers + * here, we obtain the hint from the remaining size of the + * frame + */ + switch (lowpan_dev(skb->dev)->lltype) { + case LOWPAN_LLTYPE_IEEE802154: + if (lowpan_802154_cb(skb)->d_size) + uh.len = htons(lowpan_802154_cb(skb)->d_size - + sizeof(struct ipv6hdr)); + else + uh.len = htons(skb->len + sizeof(struct udphdr)); + break; + default: + uh.len = htons(skb->len + sizeof(struct udphdr)); + break; + } + 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; +} + +LOWPAN_NHC(nhc_udp, "RFC6282 UDP", NEXTHDR_UDP, sizeof(struct udphdr), + LOWPAN_NHC_UDP_ID, LOWPAN_NHC_UDP_MASK, udp_uncompress, udp_compress); + +module_lowpan_nhc(nhc_udp); +MODULE_DESCRIPTION("6LoWPAN next header RFC6282 UDP compression"); +MODULE_LICENSE("GPL"); |