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-rw-r--r--net/6lowpan/nhc_udp.c176
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");