/*
* Copyright (c) 2008 Apple Inc. All rights reserved.
*
* @APPLE_OSREFERENCE_LICENSE_HEADER_START@
*
* This file contains Original Code and/or Modifications of Original Code
* as defined in and that are subject to the Apple Public Source License
* Version 2.0 (the 'License'). You may not use this file except in
* compliance with the License. The rights granted to you under the License
* may not be used to create, or enable the creation or redistribution of,
* unlawful or unlicensed copies of an Apple operating system, or to
* circumvent, violate, or enable the circumvention or violation of, any
* terms of an Apple operating system software license agreement.
*
* Please obtain a copy of the License at
* http://www.opensource.apple.com/apsl/ and read it before using this file.
*
* The Original Code and all software distributed under the License are
* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
* Please see the License for the specific language governing rights and
* limitations under the License.
*
* @APPLE_OSREFERENCE_LICENSE_HEADER_END@
*/
#include "kdp_serial.h"
#include <libkern/zlib.h>
#include <stdint.h>
#include <stdbool.h>
#define SKDP_START_CHAR 0xFA
#define SKDP_END_CHAR 0xFB
#define SKDP_ESC_CHAR 0xFE
static enum {DS_WAITSTART, DS_READING, DS_ESCAPED} dsState;
static unsigned char dsBuffer[1518];
static int dsPos;
static uint32_t dsCRC;
static bool dsHaveCRC;
static void
kdp_serial_out(unsigned char byte, void (*outFunc)(char))
{
//need to escape '\n' because the kernel serial output turns it into a cr/lf
if (byte == SKDP_START_CHAR || byte == SKDP_END_CHAR || byte == SKDP_ESC_CHAR || byte == '\n') {
outFunc(SKDP_ESC_CHAR);
byte = ~byte;
}
outFunc((char)byte);
}
void
kdp_serialize_packet(unsigned char *packet, unsigned int len, void (*outFunc)(char))
{
unsigned int index;
unsigned char byte;
uint32_t crc;
// insert the CRC between back to back STARTs which is compatible with old clients
crc = (uint32_t) z_crc32(0, packet, len);
outFunc(SKDP_START_CHAR);
kdp_serial_out((unsigned char)(crc >> 0), outFunc);
kdp_serial_out((unsigned char)(crc >> 8), outFunc);
kdp_serial_out((unsigned char)(crc >> 16), outFunc);
kdp_serial_out((unsigned char)(crc >> 24), outFunc);
outFunc(SKDP_START_CHAR);
for (index = 0; index < len; index++) {
byte = *packet++;
kdp_serial_out(byte, outFunc);
}
outFunc(SKDP_END_CHAR);
}
unsigned char *
kdp_unserialize_packet(unsigned char byte, unsigned int *len)
{
uint32_t crc;
switch (dsState) {
case DS_WAITSTART:
if (byte == SKDP_START_CHAR) {
// printf("got start char\n");
dsState = DS_READING;
dsPos = 0;
*len = SERIALIZE_READING;
dsHaveCRC = false;
return 0;
}
*len = SERIALIZE_WAIT_START;
break;
case DS_READING:
if (byte == SKDP_ESC_CHAR) {
dsState = DS_ESCAPED;
*len = SERIALIZE_READING;
return 0;
}
if (byte == SKDP_START_CHAR) {
if (dsPos >= 4) {
dsHaveCRC = true;
dsCRC = dsBuffer[0] | (dsBuffer[1] << 8) | (dsBuffer[2] << 16) | (dsBuffer[3] << 24);
}
//else printf("unexpected start char, resetting\n");
dsPos = 0;
*len = SERIALIZE_READING;
return 0;
}
if (byte == SKDP_END_CHAR) {
dsState = DS_WAITSTART;
if (dsHaveCRC) {
crc = (uint32_t) z_crc32(0, &dsBuffer[0], dsPos);
if (crc != dsCRC) {
// printf("bad packet crc 0x%x != 0x%x\n", crc, dsCRC);
dsPos = 0;
*len = SERIALIZE_WAIT_START;
return 0;
}
}
*len = dsPos;
dsPos = 0;
return dsBuffer;
}
dsBuffer[dsPos++] = byte;
break;
case DS_ESCAPED:
// printf("unescaping %02x to %02x\n", byte, ~byte);
dsBuffer[dsPos++] = ~byte;
dsState = DS_READING;
*len = SERIALIZE_READING;
break;
}
if (dsPos == sizeof(dsBuffer)) { //too much data...forget this packet
dsState = DS_WAITSTART;
dsPos = 0;
*len = SERIALIZE_WAIT_START;
}
return 0;
}