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lowpan6: refactor decompression to not allocate a pbuf

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This commit is contained in:
goldsimon 2018-03-08 20:26:13 +01:00
parent 61a1b98cc9
commit b86f9b97e0
1 changed files with 114 additions and 44 deletions
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158
src/netif/lowpan6.c
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@ -886,31 +886,42 @@ lowpan6_output(struct netif *netif, struct pbuf *q, const ip6_addr_t *ip6addr)
return lowpan6_frag(netif, q, &src, &dest);
}
static struct pbuf *
lowpan6_decompress(struct pbuf *p, struct ieee_802154_addr *src, struct ieee_802154_addr *dest)
/** Decompress IPv6 and UDP headers compressed according to RFC 6282
*
* @param lowpan6_buffer compressed headers, first byte is the dispatch byte
* @param lowpan6_bufsize size of lowpan6_buffer (may include data after headers)
* @param decomp_buffer buffer where the decompressed headers are stored
* @param decomp_bufsize size of decomp_buffer
* @param hdr_size_comp returns the size of the compressed headers (skip to get to data)
* @param hdr_size_decomp returns the size of the decompressed headers (IPv6 + UDP)
* @param datagram_size datagram size from fragments or 0 if unfragmented
* @param compressed_size compressed datagram size (for unfragmented rx)
* @param src source address of the outer layer, used for address compression
* @param dst destination address of the outer layer, used for address compression
* @return ERR_OK if decompression succeeded, an error otherwise
*/
static err_t
lowpan6_decompress_hdr(u8_t *lowpan6_buffer, size_t lowpan6_bufsize,
u8_t *decomp_buffer, size_t decomp_bufsize,
u16_t *hdr_size_comp, u16_t *hdr_size_decomp,
u16_t datagram_size, u16_t compressed_size,
struct ieee_802154_addr *src, struct ieee_802154_addr *dest)
{
struct pbuf *q;
u8_t *lowpan6_buffer;
u16_t lowpan6_offset;
struct ip6_hdr *ip6hdr;
s8_t i;
s8_t ip6_offset = IP6_HLEN;
u16_t ip6_offset = IP6_HLEN;
#if LWIP_UDP
#define UDP_HLEN_ALLOC UDP_HLEN
#else
#define UDP_HLEN_ALLOC 0
#endif
LWIP_ASSERT("lowpan6_buffer != NULL", lowpan6_buffer != NULL);
LWIP_ASSERT("decomp_buffer != NULL", decomp_buffer != NULL);
LWIP_ASSERT("src != NULL", src != NULL);
LWIP_ASSERT("dest != NULL", dest != NULL);
q = pbuf_alloc(PBUF_IP, p->len + IP6_HLEN + UDP_HLEN_ALLOC, PBUF_POOL);
if (q == NULL) {
pbuf_free(p);
return NULL;
ip6hdr = (struct ip6_hdr *)decomp_buffer;
if (decomp_bufsize < IP6_HLEN) {
return ERR_MEM;
}
lowpan6_buffer = (u8_t *)p->payload;
ip6hdr = (struct ip6_hdr *)q->payload;
lowpan6_offset = 2;
if (lowpan6_buffer[1] & 0x80) {
lowpan6_offset++;
@ -998,9 +1009,7 @@ lowpan6_decompress(struct pbuf *p, struct ieee_802154_addr *src, struct ieee_802
}
if (i >= LWIP_6LOWPAN_NUM_CONTEXTS) {
/* Error */
pbuf_free(p);
pbuf_free(q);
return NULL;
return ERR_VAL;
}
#if LWIP_6LOWPAN_NUM_CONTEXTS > 0
ip6hdr->src.addr[0] = lowpan6_data.lowpan6_context[i].addr[0];
@ -1031,9 +1040,7 @@ lowpan6_decompress(struct pbuf *p, struct ieee_802154_addr *src, struct ieee_802
/* Multicast destination */
if (lowpan6_buffer[1] & 0x04) {
/* @todo support stateful multicast addressing */
pbuf_free(p);
pbuf_free(q);
return NULL;
return ERR_VAL;
}
if ((lowpan6_buffer[1] & 0x03) == 0x00) {
@ -1070,9 +1077,7 @@ lowpan6_decompress(struct pbuf *p, struct ieee_802154_addr *src, struct ieee_802
}
if (i >= LWIP_6LOWPAN_NUM_CONTEXTS) {
/* Error */
pbuf_free(p);
pbuf_free(q);
return NULL;
return ERR_VAL;
}
#if LWIP_6LOWPAN_NUM_CONTEXTS > 0
ip6hdr->dest.addr[0] = lowpan6_data.lowpan6_context[i].addr[0];
@ -1115,13 +1120,14 @@ lowpan6_decompress(struct pbuf *p, struct ieee_802154_addr *src, struct ieee_802
/* UDP compression */
IP6H_NEXTH_SET(ip6hdr, IP6_NEXTH_UDP);
udphdr = (struct udp_hdr *)((u8_t *)q->payload + ip6_offset);
udphdr = (struct udp_hdr *)((u8_t *)decomp_buffer + ip6_offset);
if (decomp_bufsize < IP6_HLEN + UDP_HLEN) {
return ERR_MEM;
}
if (lowpan6_buffer[lowpan6_offset] & 0x04) {
/* @todo support checksum decompress */
pbuf_free(p);
pbuf_free(q);
return NULL;
return ERR_VAL;
}
/* Decompress ports */
@ -1146,33 +1152,96 @@ lowpan6_decompress(struct pbuf *p, struct ieee_802154_addr *src, struct ieee_802
udphdr->chksum = lwip_htons(lowpan6_buffer[lowpan6_offset] << 8 | lowpan6_buffer[lowpan6_offset + 1]);
lowpan6_offset += 2;
udphdr->len = lwip_htons(p->tot_len - lowpan6_offset + UDP_HLEN);
ip6_offset += UDP_HLEN;
if (datagram_size == 0) {
datagram_size = compressed_size - lowpan6_offset + ip6_offset;
}
udphdr->len = lwip_htons(datagram_size - IP6_HLEN);
} else
#endif /* LWIP_UDP */
{
/* @todo support NHC other than UDP */
pbuf_free(p);
pbuf_free(q);
return NULL;
return ERR_VAL;
}
}
if (datagram_size == 0) {
datagram_size = compressed_size - lowpan6_offset + ip6_offset;
}
/* Infer IPv6 payload length for header */
IP6H_PLEN_SET(ip6hdr, datagram_size - IP6_HLEN);
/* Now we copy leftover contents from p to q, so we have all L2 and L3 headers (and L4?) in a single PBUF.
* Replace p with q, and free p */
if (lowpan6_offset > lowpan6_bufsize) {
/* input buffer overflow */
return ERR_VAL;
}
if (hdr_size_comp) {
*hdr_size_comp = lowpan6_offset;
}
if (hdr_size_decomp) {
*hdr_size_decomp = ip6_offset;
}
return ERR_OK;
}
static struct pbuf *
lowpan6_decompress(struct pbuf *p, u16_t datagram_size, struct ieee_802154_addr *src, struct ieee_802154_addr *dest)
{
struct pbuf *q;
u16_t lowpan6_offset, ip6_offset;
err_t err;
#if LWIP_UDP
#define UDP_HLEN_ALLOC UDP_HLEN
#else
#define UDP_HLEN_ALLOC 0
#endif
/* Allocate a buffer for decompression. This buffer will be too big and will be
trimmed once the final size is known. */
q = pbuf_alloc(PBUF_IP, p->len + IP6_HLEN + UDP_HLEN_ALLOC, PBUF_POOL);
if (q == NULL) {
pbuf_free(p);
return NULL;
}
if (q->len < IP6_HLEN + UDP_HLEN_ALLOC) {
/* The headers need to fit into the first pbuf */
pbuf_free(p);
pbuf_free(q);
return NULL;
}
/* Decompress the IPv6 (and possibly UDP) header(s) into the new pbuf */
err = lowpan6_decompress_hdr((u8_t *)p->payload, p->len, (u8_t *)q->payload, q->len,
&lowpan6_offset, &ip6_offset, datagram_size, p->tot_len, src, dest);
if (err != ERR_OK) {
pbuf_free(p);
pbuf_free(q);
return NULL;
}
/* Now we copy leftover contents from p to q, so we have all L2 and L3 headers
(and L4?) in a single pbuf: */
/* Hide the compressed headers in p */
pbuf_remove_header(p, lowpan6_offset);
MEMCPY((u8_t *)q->payload + ip6_offset, p->payload, p->len);
q->len = q->tot_len = ip6_offset + p->len;
/* Temporarily hide the headers in q... */
pbuf_remove_header(q, ip6_offset);
/* ... copy the rest of p into q... */
pbuf_copy(q, p);
/* ... and reveal the headers again... */
pbuf_add_header_force(q, ip6_offset);
/* ... trim the pbuf to its correct size... */
pbuf_realloc(q, ip6_offset + p->len);
/* ... and cat possibly remaining (data-only) pbufs */
if (p->next != NULL) {
pbuf_cat(q, p->next);
}
/* the original (first) pbuf can now be freed */
p->next = NULL;
pbuf_free(p);
/* Infer IPv6 payload length for header */
IP6H_PLEN_SET(ip6hdr, q->tot_len - IP6_HLEN);
/* all done */
return q;
}
@ -1187,7 +1256,8 @@ lowpan6_input(struct pbuf *p, struct netif *netif)
u8_t *puc;
s8_t i;
struct ieee_802154_addr src, dest;
u16_t datagram_size, datagram_offset, datagram_tag;
u16_t datagram_size = 0;
u16_t datagram_offset, datagram_tag;
struct lowpan6_reass_helper *lrh, *lrh_temp;
if (p == NULL) {
@ -1317,7 +1387,7 @@ lowpan6_input(struct pbuf *p, struct netif *netif)
pbuf_remove_header(p, 1); /* hide dispatch byte. */
} else if ((*puc & 0xe0 ) == 0x60) {
/* IPv6 headers are compressed using IPHC. */
p = lowpan6_decompress(p, &src, &dest);
p = lowpan6_decompress(p, 0, &src, &dest);
if (p == NULL) {
MIB2_STATS_NETIF_INC(netif, ifindiscards);
return ERR_OK;