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
37 static enum {DS_WAITSTART, DS_READING, DS_ESCAPED} dsState;
38 static unsigned char dsBuffer[1518];
39 static int dsPos;
40 static uint32_t dsCRC;
41 static bool dsHaveCRC;
42
43
44 static void
kdp_serial_out(unsigned char byte,void (* outFunc)(char))45 kdp_serial_out(unsigned char byte, void (*outFunc)(char))
46 {
47 //need to escape '\n' because the kernel serial output turns it into a cr/lf
48 if (byte == SKDP_START_CHAR || byte == SKDP_END_CHAR || byte == SKDP_ESC_CHAR || byte == '\n') {
49 outFunc(SKDP_ESC_CHAR);
50 byte = ~byte;
51 }
52 outFunc((char)byte);
53 }
54
55 void
kdp_serialize_packet(unsigned char * packet,unsigned int len,void (* outFunc)(char))56 kdp_serialize_packet(unsigned char *packet, unsigned int len, void (*outFunc)(char))
57 {
58 unsigned int index;
59 unsigned char byte;
60 uint32_t crc;
61
62 // insert the CRC between back to back STARTs which is compatible with old clients
63 crc = (uint32_t) z_crc32(0, packet, len);
64 outFunc(SKDP_START_CHAR);
65 kdp_serial_out((unsigned char)(crc >> 0), outFunc);
66 kdp_serial_out((unsigned char)(crc >> 8), outFunc);
67 kdp_serial_out((unsigned char)(crc >> 16), outFunc);
68 kdp_serial_out((unsigned char)(crc >> 24), outFunc);
69
70 outFunc(SKDP_START_CHAR);
71 for (index = 0; index < len; index++) {
72 byte = *packet++;
73 kdp_serial_out(byte, outFunc);
74 }
75 outFunc(SKDP_END_CHAR);
76 }
77
78 unsigned char *
kdp_unserialize_packet(unsigned char byte,unsigned int * len)79 kdp_unserialize_packet(unsigned char byte, unsigned int *len)
80 {
81 uint32_t crc;
82
83 switch (dsState) {
84 case DS_WAITSTART:
85 if (byte == SKDP_START_CHAR) {
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 dsState = DS_ESCAPED;
98 *len = SERIALIZE_READING;
99 return 0;
100 }
101 if (byte == SKDP_START_CHAR) {
102 if (dsPos >= 4) {
103 dsHaveCRC = true;
104 dsCRC = dsBuffer[0] | (dsBuffer[1] << 8) | (dsBuffer[2] << 16) | (dsBuffer[3] << 24);
105 }
106 //else printf("unexpected start char, resetting\n");
107 dsPos = 0;
108 *len = SERIALIZE_READING;
109 return 0;
110 }
111 if (byte == SKDP_END_CHAR) {
112 dsState = DS_WAITSTART;
113 if (dsHaveCRC) {
114 crc = (uint32_t) z_crc32(0, &dsBuffer[0], dsPos);
115 if (crc != dsCRC) {
116 // printf("bad packet crc 0x%x != 0x%x\n", crc, dsCRC);
117 dsPos = 0;
118 *len = SERIALIZE_WAIT_START;
119 return 0;
120 }
121 }
122 *len = dsPos;
123 dsPos = 0;
124 return dsBuffer;
125 }
126 dsBuffer[dsPos++] = byte;
127 break;
128 case DS_ESCAPED:
129 // printf("unescaping %02x to %02x\n", byte, ~byte);
130 dsBuffer[dsPos++] = ~byte;
131 dsState = DS_READING;
132 *len = SERIALIZE_READING;
133 break;
134 }
135 if (dsPos == sizeof(dsBuffer)) { //too much data...forget this packet
136 dsState = DS_WAITSTART;
137 dsPos = 0;
138 *len = SERIALIZE_WAIT_START;
139 }
140
141 return 0;
142 }
143