1/*
2 * Copyright (c) 2008 Apple Inc. All rights reserved.
3 *
4 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
5 *
6 * This file contains Original Code and/or Modifications of Original Code
7 * as defined in and that are subject to the Apple Public Source License
8 * Version 2.0 (the 'License'). You may not use this file except in
9 * compliance with the License. The rights granted to you under the License
10 * may not be used to create, or enable the creation or redistribution of,
11 * unlawful or unlicensed copies of an Apple operating system, or to
12 * circumvent, violate, or enable the circumvention or violation of, any
13 * terms of an Apple operating system software license agreement.
14 *
15 * Please obtain a copy of the License at
16 * http://www.opensource.apple.com/apsl/ and read it before using this file.
17 *
18 * The Original Code and all software distributed under the License are
19 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
20 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
21 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
22 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
23 * Please see the License for the specific language governing rights and
24 * limitations under the License.
25 *
26 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
27 */
28#include "kdp_serial.h"
29#include <libkern/zlib.h>
30#include <stdint.h>
31#include <stdbool.h>
32
33#define SKDP_START_CHAR 0xFA
34#define SKDP_END_CHAR 0xFB
35#define SKDP_ESC_CHAR 0xFE
36
37static enum {DS_WAITSTART, DS_READING, DS_ESCAPED} dsState;
38static unsigned char dsBuffer[1518];
39static int dsPos;
40static uint32_t dsCRC;
41static bool dsHaveCRC;
42
43
44static void kdp_serial_out(unsigned char byte, void (*outFunc)(char))
45{
46 //need to escape '\n' because the kernel serial output turns it into a cr/lf
47 if(byte == SKDP_START_CHAR || byte == SKDP_END_CHAR || byte == SKDP_ESC_CHAR || byte == '\n')
48 {
49 outFunc(SKDP_ESC_CHAR);
50 byte = ~byte;
51 }
52 outFunc(byte);
53}
54
55void kdp_serialize_packet(unsigned char *packet, unsigned int len, void (*outFunc)(char))
56{
57 unsigned int index;
58 unsigned char byte;
59 uint32_t crc;
60
61 // insert the CRC between back to back STARTs which is compatible with old clients
62 crc = (uint32_t) z_crc32(0, packet, len);
63 outFunc(SKDP_START_CHAR);
64 kdp_serial_out((crc >> 0), outFunc);
65 kdp_serial_out((crc >> 8), outFunc);
66 kdp_serial_out((crc >> 16), outFunc);
67 kdp_serial_out((crc >> 24), outFunc);
68
69 outFunc(SKDP_START_CHAR);
70 for (index = 0; index < len; index++) {
71 byte = *packet++;
72 kdp_serial_out(byte, outFunc);
73 }
74 outFunc(SKDP_END_CHAR);
75}
76
77unsigned char *kdp_unserialize_packet(unsigned char byte, unsigned int *len)
78{
79 uint32_t crc;
80
81 switch(dsState)
82 {
83 case DS_WAITSTART:
84 if(byte == SKDP_START_CHAR)
85 {
86// printf("got start char\n");
87 dsState = DS_READING;
88 dsPos = 0;
89 *len = SERIALIZE_READING;
90 dsHaveCRC = false;
91 return 0;
92 }
93 *len = SERIALIZE_WAIT_START;
94 break;
95 case DS_READING:
96 if(byte == SKDP_ESC_CHAR)
97 {
98 dsState = DS_ESCAPED;
99 *len = SERIALIZE_READING;
100 return 0;
101 }
102 if(byte == SKDP_START_CHAR)
103 {
104 if (dsPos >= 4)
105 {
106 dsHaveCRC = true;
107 dsCRC = dsBuffer[0] | (dsBuffer[1] << 8) | (dsBuffer[2] << 16) | (dsBuffer[3] << 24);
108 }
109 //else printf("unexpected start char, resetting\n");
110 dsPos = 0;
111 *len = SERIALIZE_READING;
112 return 0;
113 }
114 if(byte == SKDP_END_CHAR)
115 {
116 dsState = DS_WAITSTART;
117 if (dsHaveCRC)
118 {
119 crc = (uint32_t) z_crc32(0, &dsBuffer[0], dsPos);
120 if (crc != dsCRC)
121 {
122// printf("bad packet crc 0x%x != 0x%x\n", crc, dsCRC);
123 dsPos = 0;
124 *len = SERIALIZE_WAIT_START;
125 return 0;
126 }
127 }
128 *len = dsPos;
129 dsPos = 0;
130 return dsBuffer;
131 }
132 dsBuffer[dsPos++] = byte;
133 break;
134 case DS_ESCAPED:
135// printf("unescaping %02x to %02x\n", byte, ~byte);
136 dsBuffer[dsPos++] = ~byte;
137 dsState = DS_READING;
138 *len = SERIALIZE_READING;
139 break;
140 }
141 if(dsPos == sizeof(dsBuffer)) //too much data...forget this packet
142 {
143 dsState = DS_WAITSTART;
144 dsPos = 0;
145 *len = SERIALIZE_WAIT_START;
146 }
147
148 return 0;
149}
150