Bernhard,
I'm currently (though very infrequently) in the process of working on
httpd, so I'm not really sure on which version you are based.
However, there are two correct ways when to free application buffers:
- when data is copied with tcp_write(), application data can be freed
when tcp_write() returns ERR_OK since then data is bufferd internally
(this is left == 0)
- when data is *not* copied with tcp_write(), these buffers must stay
unchanged until the data is actually ACKed (i.e. will not be sent again
by lwIP tcp). This is the case when the number of bytes acked (the len
argument of http_sent()) equals the size of data you wrote.
Since the httpd in contrib tells tcp_write() to copy data to internal
buffers, the version of http_sent below is OK.
Simon
Bernhard 'Gustl' Bauer wrote:
Kieran Mansley schrieb:
Each time tcp_sent is called it tells you how much data has been
released. Keep a count of this. When your count equals the size of
data you sent, you know it's all done.
This is the original http_sent:
static err_t http_sent(void *arg, struct tcp_pcb *pcb, u16_t len) {
struct http_state *hs;
LWIP_UNUSED_ARG(len);
hs = arg;
hs->retries = 0;
if (hs->left > 0) {
send_data(pcb, hs);
} else {
close_conn(pcb, hs);
}
return ERR_OK;
}
If hs->left == 0 this does not mean that all data has already been sent
out. The last packet is just somewere in the pipeline. So the connection
cannot be closed yet.
I can remember something puzzled my when doing the first steps: Used
buffers where freed by a function called from the timers. Probably this
was the cause.
I would suggest to add bytes_to_send and bytes_acked to struct
http_state and to change the function like this:
static err_t http_sent(void *arg, struct tcp_pcb *pcb, u16_t len) {
struct http_state *hs;
LWIP_UNUSED_ARG(len);
hs = arg;
hs->retries = 0;
hs->bytes_acked+=len;
if (hs->left > 0) {
send_data(pcb, hs);
}
if (hs->bytes_acked==hs->bytes_to_send) {
close_conn(pcb, hs);
}
return ERR_OK;
}
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