tSConn.c - plan9port - [fork] Plan 9 from user space
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tSConn.c (4441B)
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1 #include <u.h>
2 #include <libc.h>
3 #include <mp.h>
4 #include <libsec.h>
5 #include "SConn.h"
6
7 extern int verbose;
8
9 typedef struct ConnState {
10 uchar secret[SHA1dlen];
11 ulong seqno;
12 RC4state rc4;
13 } ConnState;
14
15 #undef SS
16 typedef struct SS {
17 int fd; /* file descriptor for read/write of encrypted data */
18 int alg; /* if nonzero, "alg sha rc4_128" */
19 ConnState in, out;
20 } SS;
21
22 static int
23 SC_secret(SConn *conn, uchar *sigma, int direction)
24 {
25 SS *ss = (SS*)(conn->chan);
26 int nsigma = conn->secretlen;
27
28 if(direction != 0){
29 hmac_sha1(sigma, nsigma, (uchar*)"one", 3, ss->out.secret, nil);
30 hmac_sha1(sigma, nsigma, (uchar*)"two", 3, ss->in.secret, nil);
31 }else{
32 hmac_sha1(sigma, nsigma, (uchar*)"two", 3, ss->out.secret, nil);
33 hmac_sha1(sigma, nsigma, (uchar*)"one", 3, ss->in.secret, nil);
34 }
35 setupRC4state(&ss->in.rc4, ss->in.secret, 16); /* restrict to 128 bits */
36 setupRC4state(&ss->out.rc4, ss->out.secret, 16);
37 ss->alg = 1;
38 return 0;
39 }
40
41 static void
42 hash(uchar secret[SHA1dlen], uchar *data, int len, int seqno, uchar d[SHA1dlen])
43 {
44 DigestState sha;
45 uchar seq[4];
46
47 seq[0] = seqno>>24;
48 seq[1] = seqno>>16;
49 seq[2] = seqno>>8;
50 seq[3] = seqno;
51 memset(&sha, 0, sizeof sha);
52 sha1(secret, SHA1dlen, nil, &sha);
53 sha1(data, len, nil, &sha);
54 sha1(seq, 4, d, &sha);
55 }
56
57 static int
58 verify(uchar secret[SHA1dlen], uchar *data, int len, int seqno, uchar d[SHA1dlen])
59 {
60 DigestState sha;
61 uchar seq[4];
62 uchar digest[SHA1dlen];
63
64 seq[0] = seqno>>24;
65 seq[1] = seqno>>16;
66 seq[2] = seqno>>8;
67 seq[3] = seqno;
68 memset(&sha, 0, sizeof sha);
69 sha1(secret, SHA1dlen, nil, &sha);
70 sha1(data, len, nil, &sha);
71 sha1(seq, 4, digest, &sha);
72 return memcmp(d, digest, SHA1dlen);
73 }
74
75 static int
76 SC_read(SConn *conn, uchar *buf, int n)
77 {
78 SS *ss = (SS*)(conn->chan);
79 uchar count[2], digest[SHA1dlen];
80 int len, nr;
81
82 if(read(ss->fd, count, 2) != 2 || (count[0]&0x80) == 0){
83 snprint((char*)buf,n,"!SC_read invalid count");
84 return -1;
85 }
86 len = (count[0]&0x7f)<<8 | count[1]; /* SSL-style count; no pad */
87 if(ss->alg){
88 len -= SHA1dlen;
89 if(len <= 0 || readn(ss->fd, digest, SHA1dlen) != SHA1dlen){
90 snprint((char*)buf,n,"!SC_read missing sha1");
91 return -1;
92 }
93 if(len > n || readn(ss->fd, buf, len) != len){
94 snprint((char*)buf,n,"!SC_read missing data");
95 return -1;
96 }
97 rc4(&ss->in.rc4, digest, SHA1dlen);
98 rc4(&ss->in.rc4, buf, len);
99 if(verify(ss->in.secret, buf, len, ss->in.seqno, digest) != 0){
100 snprint((char*)buf,n,"!SC_read integrity check failed");
101 return -1;
102 }
103 }else{
104 if(len <= 0 || len > n){
105 snprint((char*)buf,n,"!SC_read implausible record length");
106 return -1;
107 }
108 if( (nr = readn(ss->fd, buf, len)) != len){
109 snprint((char*)buf,n,"!SC_read expected %d bytes, but got %d", len, nr);
110 return -1;
111 }
112 }
113 ss->in.seqno++;
114 return len;
115 }
116
117 static int
118 SC_write(SConn *conn, uchar *buf, int n)
119 {
120 SS *ss = (SS*)(conn->chan);
121 uchar count[2], digest[SHA1dlen], enc[Maxmsg+1];
122 int len;
123
124 if(n <= 0 || n > Maxmsg+1){
125 werrstr("!SC_write invalid n %d", n);
126 return -1;
127 }
128 len = n;
129 if(ss->alg)
130 len += SHA1dlen;
131 count[0] = 0x80 | len>>8;
132 count[1] = len;
133 if(write(ss->fd, count, 2) != 2){
134 werrstr("!SC_write invalid count");
135 return -1;
136 }
137 if(ss->alg){
138 hash(ss->out.secret, buf, n, ss->out.seqno, digest);
139 rc4(&ss->out.rc4, digest, SHA1dlen);
140 memcpy(enc, buf, n);
141 rc4(&ss->out.rc4, enc, n);
142 if(write(ss->fd, digest, SHA1dlen) != SHA1dlen ||
143 write(ss->fd, enc, n) != n){
144 werrstr("!SC_write error on send");
145 return -1;
146 }
147 }else{
148 if(write(ss->fd, buf, n) != n){
149 werrstr("!SC_write error on send");
150 return -1;
151 }
152 }
153 ss->out.seqno++;
154 return n;
155 }
156
157 static void
158 SC_free(SConn *conn)
159 {
160 SS *ss = (SS*)(conn->chan);
161
162 close(ss->fd);
163 free(ss);
164 free(conn);
165 }
166
167 SConn*
168 newSConn(int fd)
169 {
170 SS *ss;
171 SConn *conn;
172
173 if(fd < 0)
174 return nil;
175 ss = (SS*)emalloc(sizeof(*ss));
176 conn = (SConn*)emalloc(sizeof(*conn));
177 ss->fd = fd;
178 ss->alg = 0;
179 conn->chan = (void*)ss;
180 conn->secretlen = SHA1dlen;
181 conn->free = SC_free;
182 conn->secret = SC_secret;
183 conn->read = SC_read;
184 conn->write = SC_write;
185 return conn;
186 }
187
188 void
189 writerr(SConn *conn, char *s)
190 {
191 char buf[Maxmsg];
192
193 snprint(buf, Maxmsg, "!%s", s);
194 conn->write(conn, (uchar*)buf, strlen(buf));
195 }
196
197 int
198 readstr(SConn *conn, char *s)
199 {
200 int n;
201
202 n = conn->read(conn, (uchar*)s, Maxmsg);
203 if(n >= 0){
204 s[n] = 0;
205 if(s[0] == '!'){
206 memmove(s, s+1, n);
207 n = -1;
208 }
209 }else{
210 strcpy(s, "read error");
211 }
212 return n;
213 }