drivers/net/ppp/ppp_mppe.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #define MPPE_PAD                4      /* MPPE growth per frame */
   3 #define MPPE_MAX_KEY_LEN       16      /* largest key length (128-bit) */
   4
   5 /* option bits for ccp_options.mppe */
   6 #define MPPE_OPT_40            0x01    /* 40 bit */
   7 #define MPPE_OPT_128           0x02    /* 128 bit */
   8 #define MPPE_OPT_STATEFUL      0x04    /* stateful mode */
   9 /* unsupported opts */
  10 #define MPPE_OPT_56            0x08    /* 56 bit */
  11 #define MPPE_OPT_MPPC          0x10    /* MPPC compression */
  12 #define MPPE_OPT_D             0x20    /* Unknown */
  13 #define MPPE_OPT_UNSUPPORTED (MPPE_OPT_56|MPPE_OPT_MPPC|MPPE_OPT_D)
  14 #define MPPE_OPT_UNKNOWN       0x40    /* Bits !defined in RFC 3078 were set */
  15
  16 /*
  17  * This is not nice ... the alternative is a bitfield struct though.
  18  * And unfortunately, we cannot share the same bits for the option
  19  * names above since C and H are the same bit.  We could do a u_int32
  20  * but then we have to do a htonl() all the time and/or we still need
  21  * to know which octet is which.
  22  */
  23 #define MPPE_C_BIT             0x01    /* MPPC */
  24 #define MPPE_D_BIT             0x10    /* Obsolete, usage unknown */
  25 #define MPPE_L_BIT             0x20    /* 40-bit */
  26 #define MPPE_S_BIT             0x40    /* 128-bit */
  27 #define MPPE_M_BIT             0x80    /* 56-bit, not supported */
  28 #define MPPE_H_BIT             0x01    /* Stateless (in a different byte) */
  29
  30 /* Does not include H bit; used for least significant octet only. */
  31 #define MPPE_ALL_BITS (MPPE_D_BIT|MPPE_L_BIT|MPPE_S_BIT|MPPE_M_BIT|MPPE_H_BIT)
  32
  33 /* Build a CI from mppe opts (see RFC 3078) */
  34 #define MPPE_OPTS_TO_CI(opts, ci)              \
  35     do {                                       \
  36        u_char *ptr = ci; /* u_char[4] */       \
  37                                                \
  38        /* H bit */                             \
  39        if (opts & MPPE_OPT_STATEFUL)           \
  40            *ptr++ = 0x0;                       \
  41        else                                    \
  42            *ptr++ = MPPE_H_BIT;                \
  43        *ptr++ = 0;                             \
  44        *ptr++ = 0;                             \
  45                                                \
  46        /* S,L bits */                          \
  47        *ptr = 0;                               \
  48        if (opts & MPPE_OPT_128)                \
  49            *ptr |= MPPE_S_BIT;                 \
  50        if (opts & MPPE_OPT_40)                 \
  51            *ptr |= MPPE_L_BIT;                 \
  52        /* M,D,C bits not supported */          \
  53     } while (/* CONSTCOND */ 0)
  54
  55 /* The reverse of the above */
  56 #define MPPE_CI_TO_OPTS(ci, opts)              \
  57     do {                                       \
  58        u_char *ptr = ci; /* u_char[4] */       \
  59                                                \
  60        opts = 0;                               \
  61                                                \
  62        /* H bit */                             \
  63        if (!(ptr[0] & MPPE_H_BIT))             \
  64            opts |= MPPE_OPT_STATEFUL;          \
  65                                                \
  66        /* S,L bits */                          \
  67        if (ptr[3] & MPPE_S_BIT)                \
  68            opts |= MPPE_OPT_128;               \
  69        if (ptr[3] & MPPE_L_BIT)                \
  70            opts |= MPPE_OPT_40;                \
  71                                                \
  72        /* M,D,C bits */                        \
  73        if (ptr[3] & MPPE_M_BIT)                \
  74            opts |= MPPE_OPT_56;                \
  75        if (ptr[3] & MPPE_D_BIT)                \
  76            opts |= MPPE_OPT_D;                 \
  77        if (ptr[3] & MPPE_C_BIT)                \
  78            opts |= MPPE_OPT_MPPC;              \
  79                                                \
  80        /* Other bits */                        \
  81        if (ptr[0] & ~MPPE_H_BIT)               \
  82            opts |= MPPE_OPT_UNKNOWN;           \
  83        if (ptr[1] || ptr[2])                   \
  84            opts |= MPPE_OPT_UNKNOWN;           \
  85        if (ptr[3] & ~MPPE_ALL_BITS)            \
  86            opts |= MPPE_OPT_UNKNOWN;           \
  87     } while (/* CONSTCOND */ 0)