1 #include <u.h>
2 #include <libc.h>
3 #include <mp.h>
4 #include <fcall.h>
5 #include <thread.h>
6 #include <9p.h>
7 #include <libsec.h>
8 #include <ip.h>
9 #include "netssh.h"
10
11 extern Cipher *cryptos[];
12
13 Packet *
new_packet(Conn * c)14 new_packet(Conn *c)
15 {
16 Packet *p;
17
18 p = emalloc9p(sizeof(Packet));
19 init_packet(p);
20 p->c = c;
21 return p;
22 }
23
24 void
init_packet(Packet * p)25 init_packet(Packet *p)
26 {
27 memset(p, 0, sizeof(Packet));
28 p->rlength = 1;
29 }
30
31 void
add_byte(Packet * p,char c)32 add_byte(Packet *p, char c)
33 {
34 p->payload[p->rlength-1] = c;
35 p->rlength++;
36 }
37
38 void
add_uint32(Packet * p,ulong l)39 add_uint32(Packet *p, ulong l)
40 {
41 hnputl(p->payload+p->rlength-1, l);
42 p->rlength += 4;
43 }
44
45 ulong
get_uint32(Packet *,uchar ** data)46 get_uint32(Packet *, uchar **data)
47 {
48 ulong x;
49 x = nhgetl(*data);
50 *data += 4;
51 return x;
52 }
53
54 int
add_packet(Packet * p,void * data,int len)55 add_packet(Packet *p, void *data, int len)
56 {
57 if(p->rlength + len > Maxpayload)
58 return -1;
59 memmove(p->payload + p->rlength - 1, data, len);
60 p->rlength += len;
61 return 0;
62 }
63
64 void
add_block(Packet * p,void * data,int len)65 add_block(Packet *p, void *data, int len)
66 {
67 hnputl(p->payload + p->rlength - 1, len);
68 p->rlength += 4;
69 add_packet(p, data, len);
70 }
71
72 void
add_string(Packet * p,char * s)73 add_string(Packet *p, char *s)
74 {
75 uchar *q;
76 int n;
77 uchar nn[4];
78
79 n = strlen(s);
80 hnputl(nn, n);
81 q = p->payload + p->rlength - 1;
82 memmove(q, nn, 4);
83 memmove(q+4, s, n);
84 p->rlength += n + 4;
85 }
86
87 uchar *
get_string(Packet * p,uchar * q,char * s,int lim,int * len)88 get_string(Packet *p, uchar *q, char *s, int lim, int *len)
89 {
90 int n, m;
91
92 if (p && q > p->payload + p->rlength)
93 s[0] = '\0';
94 m = nhgetl(q);
95 q += 4;
96 if(m < lim)
97 n = m;
98 else
99 n = lim - 1;
100 memmove(s, q, n);
101 s[n] = '\0';
102 q += m;
103 if(len)
104 *len = n;
105 return q;
106 }
107
108 void
add_mp(Packet * p,mpint * x)109 add_mp(Packet *p, mpint *x)
110 {
111 uchar *q;
112 int n;
113
114 q = p->payload + p->rlength - 1;
115 n = mptobe(x, q + 4, Maxpktpay - p->rlength + 1 - 4, nil);
116 if(q[4] & 0x80){
117 memmove(q + 5, q + 4, n);
118 q[4] = 0;
119 n++;
120 }
121 hnputl(q, n);
122 p->rlength += n + 4;
123 }
124
125 mpint *
get_mp(uchar * q)126 get_mp(uchar *q)
127 {
128 return betomp(q + 4, nhgetl(q), nil);
129 }
130
131 int
finish_packet(Packet * p)132 finish_packet(Packet *p)
133 {
134 Conn *c;
135 uchar *q, *buf;
136 int blklen, i, n2, n1, maclen;
137
138 c = p->c;
139 blklen = 8;
140 if(c && debug > 1)
141 fprint(2, "%s: in finish_packet: enc %d outmac %d len %ld\n",
142 argv0, c->encrypt, c->outmac, p->rlength);
143 if(c && c->encrypt != -1){
144 blklen = cryptos[c->encrypt]->blklen;
145 if(blklen < 8)
146 blklen = 8;
147 }
148 n1 = p->rlength - 1;
149 n2 = blklen - (n1 + 5) % blklen;
150 if(n2 < 4)
151 n2 += blklen;
152 p->pad_len = n2;
153 for(i = 0, q = p->payload + n1; i < n2; ++i, ++q)
154 *q = fastrand();
155 p->rlength = n1 + n2 + 1;
156 hnputl(p->nlength, p->rlength);
157 maclen = 0;
158 if(c && c->outmac != -1){
159 maclen = SHA1dlen;
160 buf = emalloc9p(Maxpktpay);
161 hnputl(buf, c->outseq);
162 memmove(buf + 4, p->nlength, p->rlength + 4);
163 hmac_sha1(buf, p->rlength + 8, c->outik, maclen, q, nil);
164 free(buf);
165 }
166 if(c && c->encrypt != -1)
167 cryptos[c->encrypt]->encrypt(c->enccs, p->nlength, p->rlength + 4);
168 if (c)
169 c->outseq++;
170 if(debug > 1)
171 fprint(2, "%s: leaving finish packet: len %ld n1 %d n2 %d maclen %d\n",
172 argv0, p->rlength, n1, n2, maclen);
173 return p->rlength + 4 + maclen;
174 }
175
176 /*
177 * The first blklen bytes are already decrypted so we could find the
178 * length.
179 */
180 int
undo_packet(Packet * p)181 undo_packet(Packet *p)
182 {
183 Conn *c;
184 long nlength;
185 int nb;
186 uchar rmac[SHA1dlen], *buf;
187
188 c = p->c;
189 nb = 4;
190 if(c->decrypt != -1)
191 nb = cryptos[c->decrypt]->blklen;
192 if(c->inmac != -1)
193 p->rlength -= SHA1dlen; /* was magic 20 */
194 nlength = nhgetl(p->nlength);
195 if(c->decrypt != -1)
196 cryptos[c->decrypt]->decrypt(c->deccs, p->nlength + nb,
197 p->rlength + 4 - nb);
198 if(c->inmac != -1){
199 buf = emalloc9p(Maxpktpay);
200 hnputl(buf, c->inseq);
201 memmove(buf + 4, p->nlength, nlength + 4);
202 hmac_sha1(buf, nlength + 8, c->inik, SHA1dlen, rmac, nil);
203 free(buf);
204 if(memcmp(rmac, p->payload + nlength - 1, SHA1dlen) != 0){
205 fprint(2, "%s: received MAC verification failed: seq=%d\n",
206 argv0, c->inseq);
207 return -1;
208 }
209 }
210 c->inseq++;
211 p->rlength -= p->pad_len;
212 p->pad_len = 0;
213 return p->rlength - 1;
214 }
215
216 void
dump_packet(Packet * p)217 dump_packet(Packet *p)
218 {
219 int i;
220 char *buf, *q, *e;
221
222 fprint(2, "Length: %ld, Padding length: %d\n", p->rlength, p->pad_len);
223 q = buf = emalloc9p(Copybufsz);
224 e = buf + Copybufsz;
225 for(i = 0; i < p->rlength - 1; ++i){
226 q = seprint(q, e, " %02x", p->payload[i]);
227 if(i % 16 == 15)
228 q = seprint(q, e, "\n");
229 if(q - buf > Copybufsz - 4){
230 fprint(2, "%s", buf);
231 q = buf;
232 }
233 }
234 fprint(2, "%s\n", buf);
235 free(buf);
236 }
237