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Add a CRC checksum to all netcmd packets to ensure that they are valid, even if they are running on top of a radio link with bit errors

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This commit is contained in:
adamdunkels 2008-07-07 23:22:38 +00:00
parent ba2323f9ed
commit 144927c12b
1 changed files with 23 additions and 11 deletions
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34
apps/shell/shell-rime-netcmd.c
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@ -28,7 +28,7 @@
*
* This file is part of the Contiki operating system.
*
* $Id: shell-rime-netcmd.c,v 1.2 2008/07/03 09:51:21 adamdunkels Exp $
* $Id: shell-rime-netcmd.c,v 1.3 2008/07/07 23:22:38 adamdunkels Exp $
*/
/**
@ -44,6 +44,7 @@
#include "dev/leds.h"
#include "lib/crc16.h"
#include "lib/random.h"
#include "net/rime.h"
@ -66,7 +67,10 @@ int snprintf(char *str, size_t size, const char *format, ...);
#define COLLECT_REXMITS 4
#define TRICKLEMSG_HDR_SIZE 2
struct trickle_msg {
uint16_t crc;
char netcmd[1];
};
@ -116,8 +120,9 @@ PROCESS_THREAD(shell_netcmd_process, ev, data)
rimebuf_clear();
msg = rimebuf_dataptr();
rimebuf_set_datalen(len + 2);
rimebuf_set_datalen(len + 2 + TRICKLEMSG_HDR_SIZE);
strcpy(msg->netcmd, data);
msg->crc = crc16_data(msg->netcmd, len, 0);
/* printf("netcmd sending '%s'\n", msg->netcmd);*/
trickle_send(&trickle);
}
@ -129,19 +134,26 @@ static void
recv_trickle(struct trickle_conn *c)
{
struct trickle_msg *msg;
int len;
msg = rimebuf_dataptr();
/* First ensure that the old process is killed. */
process_exit(&shell_netcmd_server_process);
/* Make sure that the incoming command is null-terminated (which
is should be already). */
msg->netcmd[rimebuf_datalen() - 2] = 0;
if(rimebuf_datalen() > 2 + TRICKLEMSG_HDR_SIZE) {
/* Start the server process with the incoming command. */
process_start(&shell_netcmd_server_process, msg->netcmd);
/* First ensure that the old process is killed. */
process_exit(&shell_netcmd_server_process);
len = rimebuf_datalen() - 2 - TRICKLEMSG_HDR_SIZE;
/* Make sure that the incoming command is null-terminated (which
is should be already). */
msg->netcmd[len] = 0;
if(msg->crc == crc16_data(msg->netcmd, len, 0)) {
/* Start the server process with the incoming command. */
process_start(&shell_netcmd_server_process, msg->netcmd);
}
}
}
const static struct trickle_callbacks trickle_callbacks = { recv_trickle };
/*---------------------------------------------------------------------------*/