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gnrc_sixlowpan_iphc: Fixed encoding when COMP=0

Summary:

Even ehen COMP is cleared, the algorithm always elides part of the address when a matching
context is found.

This behviour occurs because in the line

  if ((src_ctx != NULL) || ipv6_addr_is_link_local(&(ipv6_hdr->src)))

the COMP bit is not tested.

This patch fixes the problem by setting [src|dst]_ctx to NULL if the
context must not be used.
pr/spi.typo
Martin Elshuber 6 years ago
parent
commit
faa47a0e03
  1. 16
      sys/net/gnrc/network_layer/sixlowpan/iphc/gnrc_sixlowpan_iphc.c

16
sys/net/gnrc/network_layer/sixlowpan/iphc/gnrc_sixlowpan_iphc.c

@ -612,20 +612,24 @@ bool gnrc_sixlowpan_iphc_encode(gnrc_pktsnip_t *pkt)
/* check for available contexts */
if (!ipv6_addr_is_unspecified(&(ipv6_hdr->src))) {
src_ctx = gnrc_sixlowpan_ctx_lookup_addr(&(ipv6_hdr->src));
/* do not use for compression if GNRC_SIXLOWPAN_CTX_FLAGS_CID_MASK is not set */
if (!(src_ctx->flags_id & GNRC_SIXLOWPAN_CTX_FLAGS_COMP))
src_ctx = NULL;
}
if (!ipv6_addr_is_multicast(&ipv6_hdr->dst)) {
dst_ctx = gnrc_sixlowpan_ctx_lookup_addr(&(ipv6_hdr->dst));
/* do not use for compression if GNRC_SIXLOWPAN_CTX_FLAGS_CID_MASK is not set */
if (!(dst_ctx->flags_id & GNRC_SIXLOWPAN_CTX_FLAGS_COMP))
dst_ctx = NULL;
}
/* if contexts available and both != 0 */
/* since this moves inline_pos we have to do this ahead*/
if (((src_ctx != NULL) &&
((src_ctx->flags_id & GNRC_SIXLOWPAN_CTX_FLAGS_CID_MASK) != 0) &&
(src_ctx->flags_id & GNRC_SIXLOWPAN_CTX_FLAGS_COMP)) ||
((src_ctx->flags_id & GNRC_SIXLOWPAN_CTX_FLAGS_CID_MASK) != 0)) ||
((dst_ctx != NULL) &&
((dst_ctx->flags_id & GNRC_SIXLOWPAN_CTX_FLAGS_CID_MASK) != 0) &&
(dst_ctx->flags_id & GNRC_SIXLOWPAN_CTX_FLAGS_COMP))) {
((dst_ctx->flags_id & GNRC_SIXLOWPAN_CTX_FLAGS_CID_MASK) != 0))) {
/* add context identifier extension */
iphc_hdr[IPHC2_IDX] |= SIXLOWPAN_IPHC2_CID_EXT;
iphc_hdr[CID_EXT_IDX] = 0;
@ -704,7 +708,7 @@ bool gnrc_sixlowpan_iphc_encode(gnrc_pktsnip_t *pkt)
iphc_hdr[IPHC2_IDX] |= IPHC_SAC_SAM_UNSPEC;
}
else {
if ((src_ctx != NULL) && (src_ctx->flags_id & GNRC_SIXLOWPAN_CTX_FLAGS_COMP)) {
if (src_ctx != NULL) {
/* stateful source address compression */
iphc_hdr[IPHC2_IDX] |= SIXLOWPAN_IPHC2_SAC;
@ -829,7 +833,7 @@ bool gnrc_sixlowpan_iphc_encode(gnrc_pktsnip_t *pkt)
}
}
}
else if ((((dst_ctx != NULL) && (dst_ctx->flags_id & GNRC_SIXLOWPAN_CTX_FLAGS_COMP)) ||
else if (((dst_ctx != NULL) ||
ipv6_addr_is_link_local(&ipv6_hdr->dst)) && (netif_hdr->dst_l2addr_len > 0)) {
eui64_t iid;

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