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mppe.h
1 /*
2  * mppe.h - Definitions for MPPE
3  *
4  * Copyright (c) 2008 Paul Mackerras. All rights reserved.
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions
8  * are met:
9  *
10  * 1. Redistributions of source code must retain the above copyright
11  * notice, this list of conditions and the following disclaimer.
12  *
13  * 2. Redistributions in binary form must reproduce the above copyright
14  * notice, this list of conditions and the following disclaimer in
15  * the documentation and/or other materials provided with the
16  * distribution.
17  *
18  * 3. The name(s) of the authors of this software must not be used to
19  * endorse or promote products derived from this software without
20  * prior written permission.
21  *
22  * 4. Redistributions of any form whatsoever must retain the following
23  * acknowledgment:
24  * "This product includes software developed by Paul Mackerras
25  * <paulus@samba.org>".
26  *
27  * THE AUTHORS OF THIS SOFTWARE DISCLAIM ALL WARRANTIES WITH REGARD TO
28  * THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
29  * AND FITNESS, IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
30  * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
31  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
32  * AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
33  * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
34  */
35 
36 #include "ppp_opts.h"
37 #if PPP_SUPPORT && MPPE_SUPPORT /* don't build if not configured for use in ppp_opts.h */
38 
39 #ifndef MPPE_H
40 #define MPPE_H
41 
42 #include "pppcrypt.h"
43 
44 #ifdef __cplusplus
45 extern "C" {
46 #endif
47 
48 #define MPPE_PAD 4 /* MPPE growth per frame */
49 #define MPPE_MAX_KEY_LEN 16 /* largest key length (128-bit) */
50 
51 /* option bits for ccp_options.mppe */
52 #define MPPE_OPT_40 0x01 /* 40 bit */
53 #define MPPE_OPT_128 0x02 /* 128 bit */
54 #define MPPE_OPT_STATEFUL 0x04 /* stateful mode */
55 /* unsupported opts */
56 #define MPPE_OPT_56 0x08 /* 56 bit */
57 #define MPPE_OPT_MPPC 0x10 /* MPPC compression */
58 #define MPPE_OPT_D 0x20 /* Unknown */
59 #define MPPE_OPT_UNSUPPORTED (MPPE_OPT_56|MPPE_OPT_MPPC|MPPE_OPT_D)
60 #define MPPE_OPT_UNKNOWN 0x40 /* Bits !defined in RFC 3078 were set */
61 
62 /*
63  * This is not nice ... the alternative is a bitfield struct though.
64  * And unfortunately, we cannot share the same bits for the option
65  * names above since C and H are the same bit. We could do a u_int32
66  * but then we have to do a ppp_htonl() all the time and/or we still need
67  * to know which octet is which.
68  */
69 #define MPPE_C_BIT 0x01 /* MPPC */
70 #define MPPE_D_BIT 0x10 /* Obsolete, usage unknown */
71 #define MPPE_L_BIT 0x20 /* 40-bit */
72 #define MPPE_S_BIT 0x40 /* 128-bit */
73 #define MPPE_M_BIT 0x80 /* 56-bit, not supported */
74 #define MPPE_H_BIT 0x01 /* Stateless (in a different byte) */
75 
76 /* Does not include H bit; used for least significant octet only. */
77 #define MPPE_ALL_BITS (MPPE_D_BIT|MPPE_L_BIT|MPPE_S_BIT|MPPE_M_BIT|MPPE_H_BIT)
78 
79 /* Build a CI from mppe opts (see RFC 3078) */
80 #define MPPE_OPTS_TO_CI(opts, ci) \
81  do { \
82  u_char *ptr = ci; /* u_char[4] */ \
83  \
84  /* H bit */ \
85  if (opts & MPPE_OPT_STATEFUL) \
86  *ptr++ = 0x0; \
87  else \
88  *ptr++ = MPPE_H_BIT; \
89  *ptr++ = 0; \
90  *ptr++ = 0; \
91  \
92  /* S,L bits */ \
93  *ptr = 0; \
94  if (opts & MPPE_OPT_128) \
95  *ptr |= MPPE_S_BIT; \
96  if (opts & MPPE_OPT_40) \
97  *ptr |= MPPE_L_BIT; \
98  /* M,D,C bits not supported */ \
99  } while (/* CONSTCOND */ 0)
100 
101 /* The reverse of the above */
102 #define MPPE_CI_TO_OPTS(ci, opts) \
103  do { \
104  const u_char *ptr = ci; /* u_char[4] */ \
105  \
106  opts = 0; \
107  \
108  /* H bit */ \
109  if (!(ptr[0] & MPPE_H_BIT)) \
110  opts |= MPPE_OPT_STATEFUL; \
111  \
112  /* S,L bits */ \
113  if (ptr[3] & MPPE_S_BIT) \
114  opts |= MPPE_OPT_128; \
115  if (ptr[3] & MPPE_L_BIT) \
116  opts |= MPPE_OPT_40; \
117  \
118  /* M,D,C bits */ \
119  if (ptr[3] & MPPE_M_BIT) \
120  opts |= MPPE_OPT_56; \
121  if (ptr[3] & MPPE_D_BIT) \
122  opts |= MPPE_OPT_D; \
123  if (ptr[3] & MPPE_C_BIT) \
124  opts |= MPPE_OPT_MPPC; \
125  \
126  /* Other bits */ \
127  if (ptr[0] & ~MPPE_H_BIT) \
128  opts |= MPPE_OPT_UNKNOWN; \
129  if (ptr[1] || ptr[2]) \
130  opts |= MPPE_OPT_UNKNOWN; \
131  if (ptr[3] & ~MPPE_ALL_BITS) \
132  opts |= MPPE_OPT_UNKNOWN; \
133  } while (/* CONSTCOND */ 0)
134 
135 /* Shared MPPE padding between MSCHAP and MPPE */
136 #define SHA1_PAD_SIZE 40
137 
138 static const u8_t mppe_sha1_pad1[SHA1_PAD_SIZE] = {
139  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
140  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
141  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
142  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
143 };
144 static const u8_t mppe_sha1_pad2[SHA1_PAD_SIZE] = {
145  0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2,
146  0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2,
147  0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2,
148  0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2
149 };
150 
151 /*
152  * State for an MPPE (de)compressor.
153  */
154 typedef struct ppp_mppe_state {
155  ppp_arc4_context arc4;
156  u8_t master_key[MPPE_MAX_KEY_LEN];
157  u8_t session_key[MPPE_MAX_KEY_LEN];
158  u8_t keylen; /* key length in bytes */
159  /* NB: 128-bit == 16, 40-bit == 8!
160  * If we want to support 56-bit, the unit has to change to bits
161  */
162  u8_t bits; /* MPPE control bits */
163  u16_t ccount; /* 12-bit coherency count (seqno) */
164  u16_t sanity_errors; /* take down LCP if too many */
165  unsigned int stateful :1; /* stateful mode flag */
166  unsigned int discard :1; /* stateful mode packet loss flag */
167 } ppp_mppe_state;
168 
169 void mppe_set_key(ppp_pcb *pcb, ppp_mppe_state *state, u8_t *key);
170 void mppe_init(ppp_pcb *pcb, ppp_mppe_state *state, u8_t options);
171 void mppe_comp_reset(ppp_pcb *pcb, ppp_mppe_state *state);
172 err_t mppe_compress(ppp_pcb *pcb, ppp_mppe_state *state, struct pbuf **pb, u16_t protocol);
173 void mppe_decomp_reset(ppp_pcb *pcb, ppp_mppe_state *state);
174 err_t mppe_decompress(ppp_pcb *pcb, ppp_mppe_state *state, struct pbuf **pb);
175 
176 #ifdef __cplusplus
177 }
178 #endif
179 
180 #endif /* MPPE_H */
181 #endif /* PPP_SUPPORT && MPPE_SUPPORT */
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