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Extended mbus_recv_frame() error codes, improved collision handling

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- handling TCP connection reset and read(2) timeout
This commit is contained in:
jakubovsky
2012-07-03 14:35:07 +02:00
parent 82aec2ff97
commit 5d079254cc
10 changed files with 78 additions and 82 deletions
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67
mbus/mbus-tcp.c Normal file → Executable file
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@ -21,6 +21,7 @@
#include <stdio.h>
#include <string.h>
#include <strings.h>
#include <errno.h>
#include <mbus/mbus.h>
#include <mbus/mbus-tcp.h>
@ -161,69 +162,59 @@ mbus_tcp_send_frame(mbus_tcp_handle *handle, mbus_frame *frame)
//------------------------------------------------------------------------------
//
//------------------------------------------------------------------------------
int
mbus_tcp_recv_frame(mbus_tcp_handle *handle, mbus_frame *frame)
int mbus_tcp_recv_frame(mbus_tcp_handle *handle, mbus_frame *frame)
{
char buff[PACKET_BUFF_SIZE];
int len, remaining, nread, timeouts;
if (handle == NULL || frame == NULL)
{
int len, remaining, nread;
if (handle == NULL || frame == NULL) {
fprintf(stderr, "%s: Invalid parameter.\n", __PRETTY_FUNCTION__);
return -1;
}
memset((void *)buff, 0, sizeof(buff));
memset((void *) buff, 0, sizeof(buff));
//
// read data until a packet is received
//
remaining = 1; // start by reading 1 byte
len = 0;
timeouts = 0;
do {
if ((nread = read(handle->sock, &buff[len], remaining)) == -1)
{
retry:
nread = read(handle->sock, &buff[len], remaining);
switch (nread) {
case -1:
if (errno == EINTR)
goto retry;
if (errno == EAGAIN || errno == EWOULDBLOCK) {
mbus_error_str_set("M-Bus tcp transport layer timeout has been reached.");
return -3;
}
mbus_error_str_set("M-Bus tcp transport layer failed to read data.");
return -1;
case 0:
mbus_error_str_set("M-Bus tcp transport layer connection closed by remote host.");
return -4;
default:
len += nread;
}
if (nread == 0)
{
timeouts++;
if (timeouts >= 3)
{
// abort to avoid endless loop
fprintf(stderr, "%s: Timeout\n", __PRETTY_FUNCTION__);
break;
}
}
len += nread;
} while ((remaining = mbus_parse(frame, buff, len)) > 0);
if (len == 0)
{
// No data received
return -1;
}
//
// call the receive event function, if the callback function is registered
//
//
if (_mbus_recv_event)
_mbus_recv_event(MBUS_HANDLE_TYPE_TCP, buff, len);
if (remaining != 0)
{
if (remaining < 0) {
mbus_error_str_set("M-Bus layer failed to parse data.");
return -2;
}
return 0;
}