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gnrc_sixlowpan_frag: allow send of multiple datagrams simultaneously #11021

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merged 4 commits into from
May 27, 2019
Merged

gnrc_sixlowpan_frag: allow send of multiple datagrams simultaneously #11021

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a55320a
gnrc_sixlowpan_frag: expose tag progression functionality
miri64 Feb 11, 2019
b6f19c0
gnrc_sixlowpan_frag: allow send of multiple datagrams simultaneously
miri64 Feb 15, 2019
04472d3
gnrc_sixlowpan_frag: reorder stack variables for better stack usage
miri64 Feb 15, 2019
93050d2
gnrc_sixlowpan_frag: unify common operations
miri64 Feb 15, 2019
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13 changes: 13 additions & 0 deletions sys/include/net/gnrc/sixlowpan/config.h
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Original file line number Diff line number Diff line change
Expand Up @@ -48,6 +48,19 @@ extern "C" {
#define GNRC_SIXLOWPAN_MSG_QUEUE_SIZE (8U)
#endif

/**
* @brief Number of datagrams that can be fragmented simultaneously
*
* This determines the number of @ref gnrc_sixlowpan_msg_frag_t instances
* available.
*
* @note Only applicable with
* [gnrc_sixlowpan_frag](@ref net_gnrc_sixlowpan_frag) module
*/
#ifndef GNRC_SIXLOWPAN_MSG_FRAG_SIZE
#define GNRC_SIXLOWPAN_MSG_FRAG_SIZE (1U)
#endif

/**
* @brief Size of the reassembly buffer
*
Expand Down
8 changes: 8 additions & 0 deletions sys/include/net/gnrc/sixlowpan/frag.h
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Original file line number Diff line number Diff line change
Expand Up @@ -91,6 +91,7 @@ typedef struct {
typedef struct {
gnrc_pktsnip_t *pkt; /**< Pointer to the IPv6 packet to be fragmented */
uint16_t datagram_size; /**< Length of just the (uncompressed) IPv6 packet to be fragmented */
uint16_t tag; /**< Tag used for the fragment */
uint16_t offset; /**< Offset of the Nth fragment from the beginning of the
* payload datagram */
} gnrc_sixlowpan_msg_frag_t;
Expand Down Expand Up @@ -129,6 +130,13 @@ void gnrc_sixlowpan_frag_send(gnrc_pktsnip_t *pkt, void *ctx, unsigned page);
*/
void gnrc_sixlowpan_frag_recv(gnrc_pktsnip_t *pkt, void *ctx, unsigned page);

/**
* @brief Generate a new datagram tag for sending
*
* @return A new datagram tag.
*/
uint16_t gnrc_sixlowpan_frag_next_tag(void);

/**
* @brief Garbage collect reassembly buffer.
*/
Expand Down
103 changes: 56 additions & 47 deletions sys/net/gnrc/network_layer/sixlowpan/frag/gnrc_sixlowpan_frag.c
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Original file line number Diff line number Diff line change
Expand Up @@ -31,14 +31,14 @@
#define ENABLE_DEBUG (0)
#include "debug.h"

static gnrc_sixlowpan_msg_frag_t _fragment_msg;
static gnrc_sixlowpan_msg_frag_t _fragment_msg[GNRC_SIXLOWPAN_MSG_FRAG_SIZE];

#if ENABLE_DEBUG
/* For PRIu16 etc. */
#include <inttypes.h>
#endif

static uint16_t _tag;
static uint16_t _current_tag;

static inline uint16_t _floor8(uint16_t length)
{
Expand All @@ -50,25 +50,29 @@ static inline size_t _min(size_t a, size_t b)
return (a < b) ? a : b;
}

static gnrc_pktsnip_t *_build_frag_pkt(gnrc_pktsnip_t *pkt, size_t payload_len,
size_t size)
static gnrc_pktsnip_t *_build_frag_pkt(gnrc_pktsnip_t *pkt,
gnrc_sixlowpan_msg_frag_t *fragment_msg,
size_t payload_len, size_t size)
{
gnrc_netif_hdr_t *hdr = pkt->data, *new_hdr;
sixlowpan_frag_t *frag_hdr;
gnrc_netif_hdr_t *netif_hdr = pkt->data, *new_netif_hdr;
gnrc_pktsnip_t *netif, *frag;

netif = gnrc_netif_hdr_build(gnrc_netif_hdr_get_src_addr(hdr), hdr->src_l2addr_len,
gnrc_netif_hdr_get_dst_addr(hdr), hdr->dst_l2addr_len);
netif = gnrc_netif_hdr_build(gnrc_netif_hdr_get_src_addr(netif_hdr),
netif_hdr->src_l2addr_len,
gnrc_netif_hdr_get_dst_addr(netif_hdr),
netif_hdr->dst_l2addr_len);

if (netif == NULL) {
DEBUG("6lo frag: error allocating new link-layer header\n");
return NULL;
}

new_hdr = netif->data;
new_hdr->if_pid = hdr->if_pid;
new_hdr->flags = hdr->flags;
new_hdr->rssi = hdr->rssi;
new_hdr->lqi = hdr->lqi;
new_netif_hdr = netif->data;
new_netif_hdr->if_pid = netif_hdr->if_pid;
new_netif_hdr->flags = netif_hdr->flags;
new_netif_hdr->rssi = netif_hdr->rssi;
new_netif_hdr->lqi = netif_hdr->lqi;

frag = gnrc_pktbuf_add(NULL, NULL, _min(size, payload_len),
GNRC_NETTYPE_SIXLOWPAN);
Expand All @@ -78,30 +82,36 @@ static gnrc_pktsnip_t *_build_frag_pkt(gnrc_pktsnip_t *pkt, size_t payload_len,
gnrc_pktbuf_release(netif);
return NULL;
}
frag_hdr = frag->data;
/* XXX: truncation of datagram_size > 4095 may happen here */
frag_hdr->disp_size = byteorder_htons(fragment_msg->datagram_size);
frag_hdr->tag = byteorder_htons(fragment_msg->tag);


LL_PREPEND(frag, netif);

return frag;
}

static uint16_t _send_1st_fragment(gnrc_netif_t *iface, gnrc_pktsnip_t *pkt,
size_t payload_len, size_t datagram_size)
static uint16_t _send_1st_fragment(gnrc_netif_t *iface,
gnrc_sixlowpan_msg_frag_t *fragment_msg,
size_t payload_len)
{
gnrc_pktsnip_t *frag;
uint16_t local_offset = 0;
gnrc_pktsnip_t *frag, *pkt = fragment_msg->pkt;
sixlowpan_frag_t *hdr;
uint8_t *data;
/* payload_len: actual size of the packet vs
* datagram_size: size of the uncompressed IPv6 packet */
int payload_diff = (datagram_size - payload_len);
int payload_diff = (fragment_msg->datagram_size - payload_len);
uint16_t local_offset = 0;
/* virtually add payload_diff to flooring to account for offset (must be divisable by 8)
* in uncompressed datagram */
uint16_t max_frag_size = _floor8(iface->sixlo.max_frag_size + payload_diff -
sizeof(sixlowpan_frag_t)) - payload_diff;
sixlowpan_frag_t *hdr;
uint8_t *data;

DEBUG("6lo frag: determined max_frag_size = %" PRIu16 "\n", max_frag_size);

frag = _build_frag_pkt(pkt, payload_len,
frag = _build_frag_pkt(pkt, fragment_msg, payload_len,
max_frag_size + sizeof(sixlowpan_frag_t));

if (frag == NULL) {
Expand All @@ -110,10 +120,7 @@ static uint16_t _send_1st_fragment(gnrc_netif_t *iface, gnrc_pktsnip_t *pkt,

hdr = frag->next->data;
data = (uint8_t *)(hdr + 1);

hdr->disp_size = byteorder_htons((uint16_t)datagram_size);
hdr->disp_size.u8[0] |= SIXLOWPAN_FRAG_1_DISP;
hdr->tag = byteorder_htons(_tag);

/* Tell the link layer that we will send more fragments */
gnrc_netif_hdr_t *netif_hdr = frag->data;
Expand All @@ -136,26 +143,26 @@ static uint16_t _send_1st_fragment(gnrc_netif_t *iface, gnrc_pktsnip_t *pkt,

DEBUG("6lo frag: send first fragment (datagram size: %u, "
"datagram tag: %" PRIu16 ", fragment size: %" PRIu16 ")\n",
(unsigned int)datagram_size, _tag, local_offset);
fragment_msg->datagram_size, fragment_msg->tag, local_offset);
gnrc_sixlowpan_dispatch_send(frag, NULL, 0);
return local_offset;
}

static uint16_t _send_nth_fragment(gnrc_netif_t *iface, gnrc_pktsnip_t *pkt,
size_t payload_len, size_t datagram_size,
uint16_t offset)
static uint16_t _send_nth_fragment(gnrc_netif_t *iface,
gnrc_sixlowpan_msg_frag_t *fragment_msg,
size_t payload_len)
{
gnrc_pktsnip_t *frag;
gnrc_pktsnip_t *frag, *pkt = fragment_msg->pkt;
sixlowpan_frag_n_t *hdr;
uint8_t *data;
uint16_t local_offset = 0, offset_count = 0, offset = fragment_msg->offset;
/* since dispatches aren't supposed to go into subsequent fragments, we need not account
* for payload difference as for the first fragment */
uint16_t max_frag_size = _floor8(iface->sixlo.max_frag_size - sizeof(sixlowpan_frag_n_t));
uint16_t local_offset = 0, offset_count = 0;
sixlowpan_frag_n_t *hdr;
uint8_t *data;

DEBUG("6lo frag: determined max_frag_size = %" PRIu16 "\n", max_frag_size);

frag = _build_frag_pkt(pkt,
frag = _build_frag_pkt(pkt, fragment_msg,
payload_len - offset + sizeof(sixlowpan_frag_n_t),
max_frag_size + sizeof(sixlowpan_frag_n_t));

Expand All @@ -165,13 +172,10 @@ static uint16_t _send_nth_fragment(gnrc_netif_t *iface, gnrc_pktsnip_t *pkt,

hdr = frag->next->data;
data = (uint8_t *)(hdr + 1);

/* XXX: truncation of datagram_size > 4095 may happen here */
hdr->disp_size = byteorder_htons((uint16_t)datagram_size);
hdr->disp_size.u8[0] |= SIXLOWPAN_FRAG_N_DISP;
hdr->tag = byteorder_htons(_tag);
/* don't mention payload diff in offset */
hdr->offset = (uint8_t)((offset + (datagram_size - payload_len)) >> 3);
hdr->offset = (uint8_t)((offset +
(fragment_msg->datagram_size - payload_len)) >> 3);
pkt = pkt->next; /* don't copy netif header */

while ((pkt != NULL) && (offset_count != offset)) { /* go to offset */
Expand Down Expand Up @@ -221,15 +225,20 @@ static uint16_t _send_nth_fragment(gnrc_netif_t *iface, gnrc_pktsnip_t *pkt,
DEBUG("6lo frag: send subsequent fragment (datagram size: %u, "
"datagram tag: %" PRIu16 ", offset: %" PRIu8 " (%u bytes), "
"fragment size: %" PRIu16 ")\n",
(unsigned int)datagram_size, _tag, hdr->offset, hdr->offset << 3,
local_offset);
fragment_msg->datagram_size, fragment_msg->tag, hdr->offset,
hdr->offset << 3, local_offset);
gnrc_sixlowpan_dispatch_send(frag, NULL, 0);
return local_offset;
}

gnrc_sixlowpan_msg_frag_t *gnrc_sixlowpan_msg_frag_get(void)
{
return (_fragment_msg.pkt == NULL) ? &_fragment_msg : NULL;
for (unsigned i = 0; i < GNRC_SIXLOWPAN_MSG_FRAG_SIZE; i++) {
if (_fragment_msg[i].pkt == NULL) {
return &_fragment_msg[i];
}
}
return NULL;
}

void gnrc_sixlowpan_frag_send(gnrc_pktsnip_t *pkt, void *ctx, unsigned page)
Expand Down Expand Up @@ -259,20 +268,15 @@ void gnrc_sixlowpan_frag_send(gnrc_pktsnip_t *pkt, void *ctx, unsigned page)

/* Check whether to send the first or an Nth fragment */
if (fragment_msg->offset == 0) {
/* increment tag for successive, fragmented datagrams */
_tag++;
if ((res = _send_1st_fragment(iface, fragment_msg->pkt, payload_len,
fragment_msg->datagram_size)) == 0) {
if ((res = _send_1st_fragment(iface, fragment_msg, payload_len)) == 0) {
/* error sending first fragment */
DEBUG("6lo frag: error sending 1st fragment\n");
goto error;
}
}
/* (offset + (datagram_size - payload_len) < datagram_size) simplified */
else if (fragment_msg->offset < payload_len) {
if ((res = _send_nth_fragment(iface, fragment_msg->pkt, payload_len,
fragment_msg->datagram_size,
fragment_msg->offset)) == 0) {
if ((res = _send_nth_fragment(iface, fragment_msg, payload_len)) == 0) {
/* error sending subsequent fragment */
DEBUG("6lo frag: error sending subsequent fragment"
"(offset = %u)\n", fragment_msg->offset);
Expand Down Expand Up @@ -320,6 +324,11 @@ void gnrc_sixlowpan_frag_recv(gnrc_pktsnip_t *pkt, void *ctx, unsigned page)
rbuf_add(hdr, pkt, offset, page);
}

uint16_t gnrc_sixlowpan_frag_next_tag(void)
{
return (++_current_tag);
}

void gnrc_sixlowpan_frag_rbuf_gc(void)
{
rbuf_gc();
Expand Down
1 change: 1 addition & 0 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 @@ -131,6 +131,7 @@ void gnrc_sixlowpan_multiplex_by_size(gnrc_pktsnip_t *pkt,
}
fragment_msg->pkt = pkt;
fragment_msg->datagram_size = orig_datagram_size;
fragment_msg->tag = gnrc_sixlowpan_frag_next_tag();
/* Sending the first fragment has an offset==0 */
fragment_msg->offset = 0;

Expand Down