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-rw-r--r--net/6lowpan/nhc_udp.c157
1 files changed, 157 insertions, 0 deletions
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 @@
1/*
2 * 6LoWPAN IPv6 UDP compression according to RFC6282
3 *
4 *
5 * Authors:
6 * Alexander Aring <aar@pengutronix.de>
7 *
8 * Orignal written by:
9 * Alexander Smirnov <alex.bluesman.smirnov@gmail.com>
10 * Jon Smirl <jonsmirl@gmail.com>
11 *
12 * This program is free software; you can redistribute it and/or
13 * modify it under the terms of the GNU General Public License
14 * as published by the Free Software Foundation; either version
15 * 2 of the License, or (at your option) any later version.
16 */
17
18#include "nhc.h"
19
20#define LOWPAN_NHC_UDP_IDLEN 1
21
22static int udp_uncompress(struct sk_buff *skb, size_t needed)
23{
24 u8 tmp = 0, val = 0;
25 struct udphdr uh;
26 bool fail;
27 int err;
28
29 fail = lowpan_fetch_skb(skb, &tmp, sizeof(tmp));
30
31 pr_debug("UDP header uncompression\n");
32 switch (tmp & LOWPAN_NHC_UDP_CS_P_11) {
33 case LOWPAN_NHC_UDP_CS_P_00:
34 fail |= lowpan_fetch_skb(skb, &uh.source, sizeof(uh.source));
35 fail |= lowpan_fetch_skb(skb, &uh.dest, sizeof(uh.dest));
36 break;
37 case LOWPAN_NHC_UDP_CS_P_01:
38 fail |= lowpan_fetch_skb(skb, &uh.source, sizeof(uh.source));
39 fail |= lowpan_fetch_skb(skb, &val, sizeof(val));
40 uh.dest = htons(val + LOWPAN_NHC_UDP_8BIT_PORT);
41 break;
42 case LOWPAN_NHC_UDP_CS_P_10:
43 fail |= lowpan_fetch_skb(skb, &val, sizeof(val));
44 uh.source = htons(val + LOWPAN_NHC_UDP_8BIT_PORT);
45 fail |= lowpan_fetch_skb(skb, &uh.dest, sizeof(uh.dest));
46 break;
47 case LOWPAN_NHC_UDP_CS_P_11:
48 fail |= lowpan_fetch_skb(skb, &val, sizeof(val));
49 uh.source = htons(LOWPAN_NHC_UDP_4BIT_PORT + (val >> 4));
50 uh.dest = htons(LOWPAN_NHC_UDP_4BIT_PORT + (val & 0x0f));
51 break;
52 default:
53 BUG();
54 }
55
56 pr_debug("uncompressed UDP ports: src = %d, dst = %d\n",
57 ntohs(uh.source), ntohs(uh.dest));
58
59 /* checksum */
60 if (tmp & LOWPAN_NHC_UDP_CS_C) {
61 pr_debug_ratelimited("checksum elided currently not supported\n");
62 fail = true;
63 } else {
64 fail |= lowpan_fetch_skb(skb, &uh.check, sizeof(uh.check));
65 }
66
67 if (fail)
68 return -EINVAL;
69
70 /* UDP length needs to be infered from the lower layers
71 * here, we obtain the hint from the remaining size of the
72 * frame
73 */
74 uh.len = htons(skb->len + sizeof(struct udphdr));
75 pr_debug("uncompressed UDP length: src = %d", ntohs(uh.len));
76
77 /* replace the compressed UDP head by the uncompressed UDP
78 * header
79 */
80 err = skb_cow(skb, needed);
81 if (unlikely(err))
82 return err;
83
84 skb_push(skb, sizeof(struct udphdr));
85 skb_copy_to_linear_data(skb, &uh, sizeof(struct udphdr));
86
87 return 0;
88}
89
90static int udp_compress(struct sk_buff *skb, u8 **hc_ptr)
91{
92 const struct udphdr *uh = udp_hdr(skb);
93 u8 tmp;
94
95 if (((ntohs(uh->source) & LOWPAN_NHC_UDP_4BIT_MASK) ==
96 LOWPAN_NHC_UDP_4BIT_PORT) &&
97 ((ntohs(uh->dest) & LOWPAN_NHC_UDP_4BIT_MASK) ==
98 LOWPAN_NHC_UDP_4BIT_PORT)) {
99 pr_debug("UDP header: both ports compression to 4 bits\n");
100 /* compression value */
101 tmp = LOWPAN_NHC_UDP_CS_P_11;
102 lowpan_push_hc_data(hc_ptr, &tmp, sizeof(tmp));
103 /* source and destination port */
104 tmp = ntohs(uh->dest) - LOWPAN_NHC_UDP_4BIT_PORT +
105 ((ntohs(uh->source) - LOWPAN_NHC_UDP_4BIT_PORT) << 4);
106 lowpan_push_hc_data(hc_ptr, &tmp, sizeof(tmp));
107 } else if ((ntohs(uh->dest) & LOWPAN_NHC_UDP_8BIT_MASK) ==
108 LOWPAN_NHC_UDP_8BIT_PORT) {
109 pr_debug("UDP header: remove 8 bits of dest\n");
110 /* compression value */
111 tmp = LOWPAN_NHC_UDP_CS_P_01;
112 lowpan_push_hc_data(hc_ptr, &tmp, sizeof(tmp));
113 /* source port */
114 lowpan_push_hc_data(hc_ptr, &uh->source, sizeof(uh->source));
115 /* destination port */
116 tmp = ntohs(uh->dest) - LOWPAN_NHC_UDP_8BIT_PORT;
117 lowpan_push_hc_data(hc_ptr, &tmp, sizeof(tmp));
118 } else if ((ntohs(uh->source) & LOWPAN_NHC_UDP_8BIT_MASK) ==
119 LOWPAN_NHC_UDP_8BIT_PORT) {
120 pr_debug("UDP header: remove 8 bits of source\n");
121 /* compression value */
122 tmp = LOWPAN_NHC_UDP_CS_P_10;
123 lowpan_push_hc_data(hc_ptr, &tmp, sizeof(tmp));
124 /* source port */
125 tmp = ntohs(uh->source) - LOWPAN_NHC_UDP_8BIT_PORT;
126 lowpan_push_hc_data(hc_ptr, &tmp, sizeof(tmp));
127 /* destination port */
128 lowpan_push_hc_data(hc_ptr, &uh->dest, sizeof(uh->dest));
129 } else {
130 pr_debug("UDP header: can't compress\n");
131 /* compression value */
132 tmp = LOWPAN_NHC_UDP_CS_P_00;
133 lowpan_push_hc_data(hc_ptr, &tmp, sizeof(tmp));
134 /* source port */
135 lowpan_push_hc_data(hc_ptr, &uh->source, sizeof(uh->source));
136 /* destination port */
137 lowpan_push_hc_data(hc_ptr, &uh->dest, sizeof(uh->dest));
138 }
139
140 /* checksum is always inline */
141 lowpan_push_hc_data(hc_ptr, &uh->check, sizeof(uh->check));
142
143 return 0;
144}
145
146static void udp_nhid_setup(struct lowpan_nhc *nhc)
147{
148 nhc->id[0] = LOWPAN_NHC_UDP_ID;
149 nhc->idmask[0] = LOWPAN_NHC_UDP_MASK;
150}
151
152LOWPAN_NHC(nhc_udp, "RFC6282 UDP", NEXTHDR_UDP, sizeof(struct udphdr),
153 udp_nhid_setup, LOWPAN_NHC_UDP_IDLEN, udp_uncompress, udp_compress);
154
155module_lowpan_nhc(nhc_udp);
156MODULE_DESCRIPTION("6LoWPAN next header RFC6282 UDP compression");
157MODULE_LICENSE("GPL");
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