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gnrc_sixlowpan_iphc_nhc: fix NHC UDP decoding for fragmented packets #4935

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Mar 11, 2016
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gnrc_sixlowpan_iphc_nhc: fix NHC UDP decoding for fragmented packets #4935

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3 changes: 2 additions & 1 deletion sys/include/net/gnrc/sixlowpan/iphc.h
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Original file line number Diff line number Diff line change
Expand Up @@ -46,7 +46,8 @@ extern "C" {
* @return 0 on error.
*/
size_t gnrc_sixlowpan_iphc_decode(gnrc_pktsnip_t **dec_hdr, gnrc_pktsnip_t *pkt,
size_t datagram_size, size_t offset);
size_t datagram_size, size_t offset,
size_t *nh_len);

/**
* @brief Compresses a 6LoWPAN for IPHC.
Expand Down
10 changes: 6 additions & 4 deletions sys/net/gnrc/network_layer/sixlowpan/frag/rbuf.c
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Expand Up @@ -101,9 +101,9 @@ void rbuf_add(gnrc_netif_hdr_t *netif_hdr, gnrc_pktsnip_t *pkt,
}
#ifdef MODULE_GNRC_SIXLOWPAN_IPHC
else if (sixlowpan_iphc_is(data)) {
size_t iphc_len;
size_t iphc_len, nh_len = 0;
iphc_len = gnrc_sixlowpan_iphc_decode(&entry->pkt, pkt, entry->pkt->size,
sizeof(sixlowpan_frag_t));
sizeof(sixlowpan_frag_t), &nh_len);
if (iphc_len == 0) {
DEBUG("6lo rfrag: could not decode IPHC dispatch\n");
gnrc_pktbuf_release(entry->pkt);
Expand All @@ -112,8 +112,10 @@ void rbuf_add(gnrc_netif_hdr_t *netif_hdr, gnrc_pktsnip_t *pkt,
}
data += iphc_len; /* take remaining data as data */
frag_size -= iphc_len; /* and reduce frag size by IPHC dispatch length */
frag_size += sizeof(ipv6_hdr_t); /* but add IPv6 header length */
data_offset += sizeof(ipv6_hdr_t); /* start copying after IPv6 header */
/* but add IPv6 header + next header lengths */
frag_size += sizeof(ipv6_hdr_t) + nh_len;
/* start copying after IPv6 header and next headers */
data_offset += sizeof(ipv6_hdr_t) + nh_len;
}
#endif
}
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5 changes: 3 additions & 2 deletions sys/net/gnrc/network_layer/sixlowpan/gnrc_sixlowpan.c
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Original file line number Diff line number Diff line change
Expand Up @@ -129,12 +129,13 @@ static void _receive(gnrc_pktsnip_t *pkt)
#endif
#ifdef MODULE_GNRC_SIXLOWPAN_IPHC
else if (sixlowpan_iphc_is(dispatch)) {
size_t dispatch_size;
size_t dispatch_size, nh_len;
gnrc_pktsnip_t *sixlowpan, *tmp;
gnrc_pktsnip_t *dec_hdr = gnrc_pktbuf_add(NULL, NULL, sizeof(ipv6_hdr_t),
GNRC_NETTYPE_IPV6);
if ((dec_hdr == NULL) ||
(dispatch_size = gnrc_sixlowpan_iphc_decode(&dec_hdr, pkt, 0, 0)) == 0) {
(dispatch_size = gnrc_sixlowpan_iphc_decode(&dec_hdr, pkt, 0, 0,
&nh_len)) == 0) {
DEBUG("6lo: error on IPHC decoding\n");
if (dec_hdr != NULL) {
gnrc_pktbuf_release(dec_hdr);
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47 changes: 34 additions & 13 deletions sys/net/gnrc/network_layer/sixlowpan/iphc/gnrc_sixlowpan_iphc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -112,7 +112,7 @@ static inline bool _context_overlaps_iid(gnrc_sixlowpan_ctx_t *ctx,

#ifdef MODULE_GNRC_SIXLOWPAN_IPHC_NHC
inline static size_t iphc_nhc_udp_decode(gnrc_pktsnip_t *pkt, gnrc_pktsnip_t **dec_hdr,
size_t offset)
size_t datagram_size, size_t offset)
{
uint8_t *payload = pkt->data;
gnrc_pktsnip_t *ipv6 = *dec_hdr;
Expand All @@ -122,16 +122,25 @@ inline static size_t iphc_nhc_udp_decode(gnrc_pktsnip_t *pkt, gnrc_pktsnip_t **d
#else
const gnrc_nettype_t snip_type = GNRC_NETTYPE_UNDEF;
#endif
gnrc_pktsnip_t *udp = gnrc_pktbuf_add(NULL, NULL, sizeof(udp_hdr_t),
snip_type);
gnrc_pktsnip_t *udp = NULL;
uint8_t udp_nhc = payload[offset++];
uint8_t tmp;
udp_hdr_t *udp_hdr;

if (udp == NULL) {
DEBUG("6lo: error on IPHC NHC UDP decoding\n");
return 0;
if (datagram_size == 0) { /* received packet is not fragmented */
udp = gnrc_pktbuf_add(NULL, NULL, sizeof(udp_hdr_t),
snip_type);
if (udp == NULL) {
DEBUG("6lo: error on IPHC NHC UDP decoding\n");
return 0;
}
udp_hdr = udp->data;
}
else { /* received packet is fragmented */
/* reassembly is in-place => don't allocate new packet snip */
/* TODO: account for extension headers */
udp_hdr = (udp_hdr_t *)(ipv6_hdr + 1);
}
udp_hdr_t *udp_hdr = udp->data;
network_uint16_t *src_port = &(udp_hdr->src_port);
network_uint16_t *dst_port = &(udp_hdr->dst_port);

Expand Down Expand Up @@ -180,19 +189,28 @@ inline static size_t iphc_nhc_udp_decode(gnrc_pktsnip_t *pkt, gnrc_pktsnip_t **d
udp_hdr->checksum.u8[1] = payload[offset++];
}

udp_hdr->length = byteorder_htons(pkt->size - offset + sizeof(udp_hdr_t));
/* TODO subtract extension header length */
if (udp != NULL) {
udp_hdr->length = byteorder_htons(pkt->size - offset + sizeof(udp_hdr_t));
}
else {
udp_hdr->length = byteorder_htons(datagram_size - sizeof(ipv6_hdr_t));
}
ipv6_hdr->nh = PROTNUM_UDP;
ipv6_hdr->len = udp_hdr->length;

udp->next = ipv6;
*dec_hdr = udp;
if (udp != NULL) { /* prepend udp header in case of packet not being fragmented */
udp->next = ipv6;
*dec_hdr = udp;
}

return offset;
}
#endif

size_t gnrc_sixlowpan_iphc_decode(gnrc_pktsnip_t **dec_hdr, gnrc_pktsnip_t *pkt,
size_t datagram_size, size_t offset)
size_t datagram_size, size_t offset,
size_t *nh_len)
{
gnrc_pktsnip_t *ipv6;
gnrc_netif_hdr_t *netif_hdr = pkt->next->data;
Expand Down Expand Up @@ -457,7 +475,6 @@ size_t gnrc_sixlowpan_iphc_decode(gnrc_pktsnip_t **dec_hdr, gnrc_pktsnip_t *pkt,
memcpy(ipv6_hdr->dst.u8 + 12, iphc_hdr + payload_offset + 2, 4);

payload_offset += 4;

ctx->prefix_len = orig_ctx_len;
} while (0); /* ANSI-C compatible block creation for orig_ctx_len allocation */
break;
Expand All @@ -481,13 +498,17 @@ size_t gnrc_sixlowpan_iphc_decode(gnrc_pktsnip_t **dec_hdr, gnrc_pktsnip_t *pkt,
if (iphc_hdr[IPHC1_IDX] & SIXLOWPAN_IPHC1_NH) {
switch (iphc_hdr[payload_offset] & NHC_ID_MASK) {
case NHC_UDP_ID:
payload_offset = iphc_nhc_udp_decode(pkt, dec_hdr, payload_offset);
payload_offset = iphc_nhc_udp_decode(pkt, dec_hdr, datagram_size,
payload_offset + offset) - offset;
*nh_len += sizeof(udp_hdr_t);
break;

default:
break;
}
}
#else
(void)nh_len;
#endif

return payload_offset;
Expand Down