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ppp_mppe.h
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1 #define MPPE_PAD 4 /* MPPE growth per frame */
2 #define MPPE_MAX_KEY_LEN 16 /* largest key length (128-bit) */
3 
4 /* option bits for ccp_options.mppe */
5 #define MPPE_OPT_40 0x01 /* 40 bit */
6 #define MPPE_OPT_128 0x02 /* 128 bit */
7 #define MPPE_OPT_STATEFUL 0x04 /* stateful mode */
8 /* unsupported opts */
9 #define MPPE_OPT_56 0x08 /* 56 bit */
10 #define MPPE_OPT_MPPC 0x10 /* MPPC compression */
11 #define MPPE_OPT_D 0x20 /* Unknown */
12 #define MPPE_OPT_UNSUPPORTED (MPPE_OPT_56|MPPE_OPT_MPPC|MPPE_OPT_D)
13 #define MPPE_OPT_UNKNOWN 0x40 /* Bits !defined in RFC 3078 were set */
14 
15 /*
16  * This is not nice ... the alternative is a bitfield struct though.
17  * And unfortunately, we cannot share the same bits for the option
18  * names above since C and H are the same bit. We could do a u_int32
19  * but then we have to do a htonl() all the time and/or we still need
20  * to know which octet is which.
21  */
22 #define MPPE_C_BIT 0x01 /* MPPC */
23 #define MPPE_D_BIT 0x10 /* Obsolete, usage unknown */
24 #define MPPE_L_BIT 0x20 /* 40-bit */
25 #define MPPE_S_BIT 0x40 /* 128-bit */
26 #define MPPE_M_BIT 0x80 /* 56-bit, not supported */
27 #define MPPE_H_BIT 0x01 /* Stateless (in a different byte) */
28 
29 /* Does not include H bit; used for least significant octet only. */
30 #define MPPE_ALL_BITS (MPPE_D_BIT|MPPE_L_BIT|MPPE_S_BIT|MPPE_M_BIT|MPPE_H_BIT)
31 
32 /* Build a CI from mppe opts (see RFC 3078) */
33 #define MPPE_OPTS_TO_CI(opts, ci) \
34  do { \
35  u_char *ptr = ci; /* u_char[4] */ \
36  \
37  /* H bit */ \
38  if (opts & MPPE_OPT_STATEFUL) \
39  *ptr++ = 0x0; \
40  else \
41  *ptr++ = MPPE_H_BIT; \
42  *ptr++ = 0; \
43  *ptr++ = 0; \
44  \
45  /* S,L bits */ \
46  *ptr = 0; \
47  if (opts & MPPE_OPT_128) \
48  *ptr |= MPPE_S_BIT; \
49  if (opts & MPPE_OPT_40) \
50  *ptr |= MPPE_L_BIT; \
51  /* M,D,C bits not supported */ \
52  } while (/* CONSTCOND */ 0)
53 
54 /* The reverse of the above */
55 #define MPPE_CI_TO_OPTS(ci, opts) \
56  do { \
57  u_char *ptr = ci; /* u_char[4] */ \
58  \
59  opts = 0; \
60  \
61  /* H bit */ \
62  if (!(ptr[0] & MPPE_H_BIT)) \
63  opts |= MPPE_OPT_STATEFUL; \
64  \
65  /* S,L bits */ \
66  if (ptr[3] & MPPE_S_BIT) \
67  opts |= MPPE_OPT_128; \
68  if (ptr[3] & MPPE_L_BIT) \
69  opts |= MPPE_OPT_40; \
70  \
71  /* M,D,C bits */ \
72  if (ptr[3] & MPPE_M_BIT) \
73  opts |= MPPE_OPT_56; \
74  if (ptr[3] & MPPE_D_BIT) \
75  opts |= MPPE_OPT_D; \
76  if (ptr[3] & MPPE_C_BIT) \
77  opts |= MPPE_OPT_MPPC; \
78  \
79  /* Other bits */ \
80  if (ptr[0] & ~MPPE_H_BIT) \
81  opts |= MPPE_OPT_UNKNOWN; \
82  if (ptr[1] || ptr[2]) \
83  opts |= MPPE_OPT_UNKNOWN; \
84  if (ptr[3] & ~MPPE_ALL_BITS) \
85  opts |= MPPE_OPT_UNKNOWN; \
86  } while (/* CONSTCOND */ 0)