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net: net_pkt_append: Take into account MSS/MTU when adding data to a packet #119

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Merged
merged 2 commits into from
Nov 10, 2017
Merged

net: net_pkt_append: Take into account MSS/MTU when adding data to a packet #119

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55d0acc
net: net_pkt_append: Take into account MTU when adding data to a packet
pfalcon May 3, 2017
ba53b3b
net: sockets: sendto: Remove adhoc handling of max pkt payload size
pfalcon Nov 8, 2017
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36 changes: 36 additions & 0 deletions subsys/net/ip/net_pkt.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1163,6 +1163,8 @@ u16_t net_pkt_append(struct net_pkt *pkt, u16_t len, const u8_t *data,
s32_t timeout)
{
struct net_buf *frag;
struct net_context *ctx;
size_t max_len;

if (!pkt || !data) {
return 0;
Expand All @@ -1177,6 +1179,40 @@ u16_t net_pkt_append(struct net_pkt *pkt, u16_t len, const u8_t *data,
net_pkt_frag_add(pkt, frag);
}

/* Make sure we don't send more data in one packet than
* MTU allows.
* This check really belongs to net_pkt_append_bytes(),
* but instead done here for efficiency, we assume
* (at least for now) that that callers of
* net_pkt_append_bytes() are smart enough to not
* overflow MTU.
*/
max_len = 0x10000;

ctx = net_pkt_context(pkt);
if (ctx) {
#if defined(CONFIG_NET_TCP)
if (ctx->tcp) {
max_len = ctx->tcp->send_mss;
} else
#endif
{
struct net_if *iface = net_context_get_iface(ctx);
max_len = net_if_get_mtu(iface);
/* Optimize for number of jumps in the code ("if"
* instead of "if/else").
*/
max_len -= NET_IPV4TCPH_LEN;
if (net_context_get_family(ctx) != AF_INET) {
max_len -= NET_IPV6TCPH_LEN - NET_IPV4TCPH_LEN;
}
}
}

if (len > max_len) {
len = max_len;
}

return net_pkt_append_bytes(pkt, data, len, timeout);
}

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13 changes: 0 additions & 13 deletions subsys/net/lib/sockets/sockets.c
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Original file line number Diff line number Diff line change
Expand Up @@ -235,7 +235,6 @@ ssize_t zsock_sendto(int sock, const void *buf, size_t len, int flags,
struct net_pkt *send_pkt;
s32_t timeout = K_FOREVER;
struct net_context *ctx = INT_TO_POINTER(sock);
size_t max_len = net_if_get_mtu(net_context_get_iface(ctx));

ARG_UNUSED(flags);

Expand All @@ -249,18 +248,6 @@ ssize_t zsock_sendto(int sock, const void *buf, size_t len, int flags,
return -1;
}

/* Make sure we don't send more data in one packet than
* MTU allows. Optimize for number of branches in the code.
*/
max_len -= NET_IPV4TCPH_LEN;
if (net_context_get_family(ctx) != AF_INET) {
max_len -= NET_IPV6TCPH_LEN - NET_IPV4TCPH_LEN;
}

if (len > max_len) {
len = max_len;
}

len = net_pkt_append(send_pkt, len, buf, timeout);
if (!len) {
net_pkt_unref(send_pkt);
Expand Down