[Cryptech-Commits] [sw/stm32] 02/02: Check CRC32 of data received from host.

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fredrik at thulin.net pushed a commit to branch ft-crc32
in repository sw/stm32.

commit 4344fa71c11453bb316ea990b270fb019e9bfa36
Author: Fredrik Thulin <fredrik at thulin.net>
AuthorDate: Thu Mar 23 19:45:35 2017 +0100

    Check CRC32 of data received from host.
---
 projects/hsm/hsm.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/projects/hsm/hsm.c b/projects/hsm/hsm.c
index 9a314ff..1cd595e 100644
--- a/projects/hsm/hsm.c
+++ b/projects/hsm/hsm.c
@@ -184,6 +184,7 @@ hal_error_t hal_serial_send_char(uint8_t c)
 void dispatch_thread(void const *args)
 {
     rpc_buffer_t obuf_s, *obuf = &obuf_s, *ibuf;
+    hal_crc32_t crc;
 
     while (1) {
         memset(obuf, 0, sizeof(*obuf));
@@ -195,6 +196,28 @@ void dispatch_thread(void const *args)
             continue;
         ibuf = (rpc_buffer_t *)evt.value.p;
 
+	if (ibuf->len < 8)
+	    continue;
+
+	crc = hal_crc32_init();
+	/* Calculate CRC32 checksum of the contents, after SLIP decoding */
+	crc = hal_crc32_update(crc, ibuf->buf, ibuf->len);
+	crc = hal_crc32_finalize(crc);
+
+	if (crc != 0xffffffff) {
+	    /* XXX Full-stop on CRC errors is probably not the best long-term solution,
+	     * but it helps while we are sorting out any remaining issues.
+	     */
+	    led_on(LED_RED);
+	    /* Steal UART lock to stop all threads */
+	    uart_lock();
+	    Error_Handler();
+	}
+
+	/* Remove CRC from end of ibuf->buf */
+	ibuf->len -= 4;
+	ibuf->buf[ibuf->len] = 0xc0;
+
         /* Process the request */
 	hal_error_t ret = hal_rpc_server_dispatch(ibuf->buf, ibuf->len, obuf->buf, &obuf->len);
         osMailFree(ibuf_queue, (void *)ibuf);