/*
* rpc_server.c
* ------------
* Remote procedure call server-side private API implementation.
*
* Copyright (c) 2016, NORDUnet A/S All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
* - Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* - Neither the name of the NORDUnet nor the names of its contributors may
* be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/*
* This is the main RPC server moddule. It creates a new thread to deal
* with each request, to prevent a long-running request (e.g. RSA keygen)
* from blocking independent requests from other clients. This has a
* number of consequences. We can't do a blocking receive in the main
* thread, because that prevents the dispatch thread from transmitting the
* response (because they both want to lock the UART - see
* stm32f4xx_hal_uart.c). So we have to do a non-blocking receive with a
* callback routine. But we can't create a thread from the callback
* routine, because it's in the context of an ISR, so we raise a semaphore
* for the main thread to create the dispatch thread.
*/
#include "cmsis_os.h"
#include "stm-init.h"
#include "stm-led.h"
#include "stm-fmc.h"
#include "stm-uart.h"
/* stm32f4xx_hal_def.h and hal.h both define HAL_OK as an enum value */
#define HAL_OK HAL_OKAY
#include "hal.h"
#include "hal_internal.h" /* hal_rpc_sendto, hal_rpc_recvfrom */
#include "xdr_internal.h" /* hal_xdr_encode_int */
/* RPC buffers. For each active RPC, there will be two - input and output.
*/
#ifndef NUM_RPC_BUFFER
/* An arbitrary number, but we don't expect to have more than 8 concurrent
* RPC requests.
*/
#define NUM_RPC_BUFFER 16
#endif
#ifndef MAX_PKT_SIZE
/* Another arbitrary number, more or less driven by the 4096-bit RSA
* keygen test.
*/
#define MAX_PKT_SIZE 4096
#endif
/* The thread entry point takes a single void* argument, so we bundle the
* packet buffer and length arguments together.
*/
typedef struct {
size_t len;
uint8_t buf[MAX_PKT_SIZE];
} rpc_buffer_t;
osPoolDef(rpc_buffer_pool, NUM_RPC_BUFFER, rpc_buffer_t);
osPoolId rpc_buffer_pool;
static rpc_buffer_t *rpc_buffer_alloc(void)
{
return (rpc_buffer_t *)osPoolCAlloc(rpc_buffer_pool);
}
/* A mutex to arbitrate concurrent UART transmits, from RPC responses.
*/
osMutexId uart_mutex;
osMutexDef(uart_mutex);
/* Borrowed from xdr.c. We know the target architecture is little-endian,
* but we pretend for the sake of appearances.
*/
#ifdef __ARMEL__ /* little endian */
static inline uint32_t htonl(uint32_t w)
{
return
((w & 0x000000ff) << 24) +
((w & 0x0000ff00) << 8) +
((w & 0x00ff0000) >> 8) +
((w & 0xff000000) >> 24);
}
#else
#define htonl(x) (x)
#endif
/* Thread entry point for the RPC request handler.
*/
static void dispatch_thread(void const *args)
{
rpc_buffer_t *ibuf = (rpc_buffer_t *)args;
rpc_buffer_t *obuf = rpc_buffer_alloc();
if (obuf == NULL) {
uint32_t err = htonl(HAL_ERROR_ALLOCATION_FAILURE);
osMutexWait(uart_mutex, osWaitForever);
hal_rpc_sendto((uint8_t *)&err, 4, NULL);
osMutexRelease(uart_mutex);
osPoolFree(rpc_buffer_pool, ibuf);
Error_Handler();
}
obuf->len = sizeof(obuf->buf);
hal_rpc_server_dispatch(ibuf->buf, ibuf->len, obuf->buf, &obuf->len);
osPoolFree(rpc_buffer_pool, ibuf);
osMutexWait(uart_mutex, osWaitForever);
hal_error_t ret = hal_rpc_sendto(obuf->buf, obuf->len, NULL);
osMutexRelease(uart_mutex);
osPoolFree(rpc_buffer_pool, obuf);
if (ret != HAL_OK)
Error_Handler();
}
osThreadDef(dispatch_thread, osPriorityNormal, DEFAULT_STACK_SIZE);
/* Semaphore to inform the main thread that there's a new RPC request.
*/
osSemaphoreId rpc_sem;
osSemaphoreDef(rpc_sem);
static uint8_t c; /* current character received from UART */
static rpc_buffer_t *ibuf; /* current RPC input buffer */
/* Add a byte to the input buffer.
*/
static inline void ibuf_push(uint8_t c) {
if (ibuf->len < MAX_PKT_SIZE)
ibuf->buf[ibuf->len++] = c;
}
/* Callback for HAL_UART_Receive_IT().
*/
void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart)
{
/* SLIP special characters */
#define END 0300 /* indicates end of packet */
#define ESC 0333 /* indicates byte stuffing */
#define ESC_END 0334 /* ESC ESC_END means END data byte */
#define ESC_ESC 0335 /* ESC ESC_ESC means ESC data byte */
static int esc_flag = 0; /* previous char was ESC */
/* got 1 char - un-SLIP it */
switch (c) {
case END:
if (ibuf->len)
osSemaphoreRelease(rpc_sem);
break;
case ESC:
esc_flag = 1;
break;
default:
if (esc_flag) {
esc_flag = 0;
switch (c) {
case ESC_END:
ibuf_push(END);
break;
case ESC_ESC:
ibuf_push(ESC);
break;
default:
ibuf_push(c);
}
}
else {
ibuf_push(c);
}
break;
}
HAL_UART_Receive_IT(huart, &c, 1);
}
/* UART interrupt handler. This eventually calls HAL_UART_RxCpltCallback.
*/
void USART2_IRQHandler(void)
{
HAL_UART_IRQHandler(&huart2);
}
/* The main thread. After the system setup, it waits for the RPC-request
* semaphore from HAL_UART_RxCpltCallback, and spawns a dispatch thread.
*/
int main()
{
stm_init();
#ifdef TARGET_CRYPTECH_DEV_BRIDGE
/* Wait six seconds to not upset the Novena at boot. */
led_on(LED_BLUE);
for (int i = 0; i < 12; i++) {
osDelay(500);
led_toggle(LED_BLUE);
}
led_off(LED_BLUE);
led_on(LED_GREEN);
#endif
/* Prepare FMC interface. */
fmc_init();
/* Haaaack. probe_cores() calls malloc(), which works from the main
* thread, but not from a spawned thread. It would be better to
* rewrite it to use static memory, but for now, just force it to
* probe early.
*/
hal_core_iterate(NULL);
rpc_buffer_pool = osPoolCreate(osPool(rpc_buffer_pool));
uart_mutex = osMutexCreate(osMutex(uart_mutex));
rpc_sem = osSemaphoreCreate(osSemaphore(rpc_sem), 0);
#ifdef TARGET_CRYPTECH_ALPHA
/* Launch other threads:
* - admin thread on USART1
* - csprng warm-up thread?
*/
#endif
if (hal_rpc_server_init() != HAL_OK)
Error_Handler();
ibuf = rpc_buffer_alloc();
if (ibuf == NULL)
/* Something is badly wrong. */
Error_Handler();
/* Start the non-blocking receive */
HAL_UART_Receive_IT(&huart2, &c, 1);
while (1) {
osSemaphoreWait(rpc_sem, osWaitForever);
if (osThreadCreate(osThread(dispatch_thread), (void *)ibuf) == NULL)
Error_Handler();
while ((ibuf = rpc_buffer_alloc()) == NULL);
/* XXX There's a potential race condition, where another request
* could write into the old ibuf, or into the null pointer if
* we're out of ibufs.
*/
}
}
