thdlc.c - plan9port - [fork] Plan 9 from user space | |
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thdlc.c (4283B) | |
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1 #include <u.h> | |
2 #include <libc.h> | |
3 #include <ip.h> | |
4 #include "dat.h" | |
5 #include "protos.h" | |
6 | |
7 enum { | |
8 HDLC_frame= 0x7e, | |
9 HDLC_esc= 0x7d, | |
10 | |
11 /* PPP frame fields */ | |
12 PPP_addr= 0xff, | |
13 PPP_ctl= 0x3, | |
14 PPP_initfcs= 0xffff, | |
15 PPP_goodfcs= 0xf0b8 | |
16 }; | |
17 | |
18 /* | |
19 * Calculate FCS - rfc 1331 | |
20 */ | |
21 ushort fcstab[256] = | |
22 { | |
23 0x0000, 0x1189, 0x2312, 0x329b, 0x4624, 0x57ad, 0x6536, 0x74bf, | |
24 0x8c48, 0x9dc1, 0xaf5a, 0xbed3, 0xca6c, 0xdbe5, 0xe97e, 0xf8f7, | |
25 0x1081, 0x0108, 0x3393, 0x221a, 0x56a5, 0x472c, 0x75b7, 0x643e, | |
26 0x9cc9, 0x8d40, 0xbfdb, 0xae52, 0xdaed, 0xcb64, 0xf9ff, 0xe876, | |
27 0x2102, 0x308b, 0x0210, 0x1399, 0x6726, 0x76af, 0x4434, 0x55bd, | |
28 0xad4a, 0xbcc3, 0x8e58, 0x9fd1, 0xeb6e, 0xfae7, 0xc87c, 0xd9f5, | |
29 0x3183, 0x200a, 0x1291, 0x0318, 0x77a7, 0x662e, 0x54b5, 0x453c, | |
30 0xbdcb, 0xac42, 0x9ed9, 0x8f50, 0xfbef, 0xea66, 0xd8fd, 0xc974, | |
31 0x4204, 0x538d, 0x6116, 0x709f, 0x0420, 0x15a9, 0x2732, 0x36bb, | |
32 0xce4c, 0xdfc5, 0xed5e, 0xfcd7, 0x8868, 0x99e1, 0xab7a, 0xbaf3, | |
33 0x5285, 0x430c, 0x7197, 0x601e, 0x14a1, 0x0528, 0x37b3, 0x263a, | |
34 0xdecd, 0xcf44, 0xfddf, 0xec56, 0x98e9, 0x8960, 0xbbfb, 0xaa72, | |
35 0x6306, 0x728f, 0x4014, 0x519d, 0x2522, 0x34ab, 0x0630, 0x17b9, | |
36 0xef4e, 0xfec7, 0xcc5c, 0xddd5, 0xa96a, 0xb8e3, 0x8a78, 0x9bf1, | |
37 0x7387, 0x620e, 0x5095, 0x411c, 0x35a3, 0x242a, 0x16b1, 0x0738, | |
38 0xffcf, 0xee46, 0xdcdd, 0xcd54, 0xb9eb, 0xa862, 0x9af9, 0x8b70, | |
39 0x8408, 0x9581, 0xa71a, 0xb693, 0xc22c, 0xd3a5, 0xe13e, 0xf0b7, | |
40 0x0840, 0x19c9, 0x2b52, 0x3adb, 0x4e64, 0x5fed, 0x6d76, 0x7cff, | |
41 0x9489, 0x8500, 0xb79b, 0xa612, 0xd2ad, 0xc324, 0xf1bf, 0xe036, | |
42 0x18c1, 0x0948, 0x3bd3, 0x2a5a, 0x5ee5, 0x4f6c, 0x7df7, 0x6c7e, | |
43 0xa50a, 0xb483, 0x8618, 0x9791, 0xe32e, 0xf2a7, 0xc03c, 0xd1b5, | |
44 0x2942, 0x38cb, 0x0a50, 0x1bd9, 0x6f66, 0x7eef, 0x4c74, 0x5dfd, | |
45 0xb58b, 0xa402, 0x9699, 0x8710, 0xf3af, 0xe226, 0xd0bd, 0xc134, | |
46 0x39c3, 0x284a, 0x1ad1, 0x0b58, 0x7fe7, 0x6e6e, 0x5cf5, 0x4d7c, | |
47 0xc60c, 0xd785, 0xe51e, 0xf497, 0x8028, 0x91a1, 0xa33a, 0xb2b3, | |
48 0x4a44, 0x5bcd, 0x6956, 0x78df, 0x0c60, 0x1de9, 0x2f72, 0x3efb, | |
49 0xd68d, 0xc704, 0xf59f, 0xe416, 0x90a9, 0x8120, 0xb3bb, 0xa232, | |
50 0x5ac5, 0x4b4c, 0x79d7, 0x685e, 0x1ce1, 0x0d68, 0x3ff3, 0x2e7a, | |
51 0xe70e, 0xf687, 0xc41c, 0xd595, 0xa12a, 0xb0a3, 0x8238, 0x93b1, | |
52 0x6b46, 0x7acf, 0x4854, 0x59dd, 0x2d62, 0x3ceb, 0x0e70, 0x1ff9, | |
53 0xf78f, 0xe606, 0xd49d, 0xc514, 0xb1ab, 0xa022, 0x92b9, 0x8330, | |
54 0x7bc7, 0x6a4e, 0x58d5, 0x495c, 0x3de3, 0x2c6a, 0x1ef1, 0x0f78 | |
55 }; | |
56 | |
57 static uchar inbuf[16*1024]; | |
58 static int inlen; | |
59 | |
60 static Mux p_mux[] = | |
61 { | |
62 {"ppp", (PPP_addr<<8)|PPP_ctl, } , | |
63 {0} | |
64 }; | |
65 | |
66 enum | |
67 { | |
68 Ot = 1 | |
69 }; | |
70 | |
71 static void | |
72 p_compile(Filter *f) | |
73 { | |
74 Mux *m; | |
75 | |
76 for(m = p_mux; m->name != nil; m++) | |
77 if(strcmp(f->s, m->name) == 0){ | |
78 f->pr = m->pr; | |
79 f->ulv = m->val; | |
80 f->subop = Ot; | |
81 return; | |
82 } | |
83 sysfatal("unknown ethernet field or protocol: %s", f->s); | |
84 } | |
85 | |
86 static int | |
87 p_filter(Filter *f, Msg *m) | |
88 { | |
89 ulong t; | |
90 | |
91 if(m->pe-m->ps < 2) | |
92 return 0; | |
93 | |
94 switch(f->subop){ | |
95 case Ot: | |
96 t = (m->ps[0]<<8)|m->ps[1]; | |
97 if(t != f->ulv) | |
98 return 0; | |
99 break; | |
100 } | |
101 return 1; | |
102 } | |
103 | |
104 static int | |
105 p_seprint(Msg *m) | |
106 { | |
107 ulong t; | |
108 | |
109 if(m->pe-m->ps < 2) | |
110 return -1; | |
111 | |
112 t = (m->ps[0]<<8)|m->ps[1]; | |
113 m->ps += 2; | |
114 demux(p_mux, t, t, m, &dump); | |
115 | |
116 return 0; | |
117 } | |
118 | |
119 static int | |
120 p_framer(int fd, uchar *pkt, int pktlen) | |
121 { | |
122 ushort fcs; | |
123 uchar *from, *efrom, *to, *eto; | |
124 int n; | |
125 ulong c; | |
126 | |
127 eto = pkt+pktlen; | |
128 for(;;){ | |
129 efrom = memchr(inbuf, HDLC_frame, inlen); | |
130 if(efrom == nil){ | |
131 if(inlen >= sizeof(inbuf)) | |
132 inlen = 0; | |
133 n = read(fd, inbuf+inlen, sizeof(inbuf)-inlen); | |
134 if(n <= 0) | |
135 break; | |
136 inlen += n; | |
137 continue; | |
138 } | |
139 | |
140 /* checksum and unescape the frame */ | |
141 fcs = PPP_initfcs; | |
142 to = pkt; | |
143 for(from = inbuf; from < efrom;){ | |
144 c = *from++; | |
145 if(c == HDLC_esc) | |
146 c = (*from++) ^ 0x20; | |
147 if(to < eto) | |
148 *to++ = c; | |
149 fcs = (fcs >> 8) ^ fcstab[(fcs ^ c) & 0xff]; | |
150 } | |
151 | |
152 /* move down anything that's left */ | |
153 inlen -= efrom+1-inbuf; | |
154 memmove(inbuf, efrom+1, inlen); | |
155 | |
156 /* accept if this is a good packet */ | |
157 if(fcs != PPP_goodfcs) | |
158 print("bad frame %ld %2.2ux %2.2ux!\n", to-pkt, … | |
159 else | |
160 return to-pkt; | |
161 } | |
162 return -1; | |
163 } | |
164 | |
165 Proto hdlc = | |
166 { | |
167 "hdlc", | |
168 p_compile, | |
169 p_filter, | |
170 p_seprint, | |
171 p_mux, | |
172 "%#.4lux", | |
173 nil, | |
174 p_framer | |
175 }; |