mppe.h

00001 /*
00002  * mppe.h - Definitions for MPPE
00003  *
00004  * Copyright (c) 2008 Paul Mackerras. All rights reserved.
00005  *
00006  * Redistribution and use in source and binary forms, with or without
00007  * modification, are permitted provided that the following conditions
00008  * are met:
00009  *
00010  * 1. Redistributions of source code must retain the above copyright
00011  *    notice, this list of conditions and the following disclaimer.
00012  *
00013  * 2. Redistributions in binary form must reproduce the above copyright
00014  *    notice, this list of conditions and the following disclaimer in
00015  *    the documentation and/or other materials provided with the
00016  *    distribution.
00017  *
00018  * 3. The name(s) of the authors of this software must not be used to
00019  *    endorse or promote products derived from this software without
00020  *    prior written permission.
00021  *
00022  * 4. Redistributions of any form whatsoever must retain the following
00023  *    acknowledgment:
00024  *    "This product includes software developed by Paul Mackerras
00025  *     <paulus@samba.org>".
00026  *
00027  * THE AUTHORS OF THIS SOFTWARE DISCLAIM ALL WARRANTIES WITH REGARD TO
00028  * THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
00029  * AND FITNESS, IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
00030  * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
00031  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
00032  * AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
00033  * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
00034  */
00035 
00036 #include "netif/ppp/ppp_opts.h"
00037 #if PPP_SUPPORT && MPPE_SUPPORT  /* don't build if not configured for use in lwipopts.h */
00038 
00039 #ifndef MPPE_H
00040 #define MPPE_H
00041 
00042 #include "netif/ppp/pppcrypt.h"
00043 
00044 #define MPPE_PAD        4   /* MPPE growth per frame */
00045 #define MPPE_MAX_KEY_LEN    16  /* largest key length (128-bit) */
00046 
00047 /* option bits for ccp_options.mppe */
00048 #define MPPE_OPT_40     0x01    /* 40 bit */
00049 #define MPPE_OPT_128        0x02    /* 128 bit */
00050 #define MPPE_OPT_STATEFUL   0x04    /* stateful mode */
00051 /* unsupported opts */
00052 #define MPPE_OPT_56     0x08    /* 56 bit */
00053 #define MPPE_OPT_MPPC       0x10    /* MPPC compression */
00054 #define MPPE_OPT_D      0x20    /* Unknown */
00055 #define MPPE_OPT_UNSUPPORTED (MPPE_OPT_56|MPPE_OPT_MPPC|MPPE_OPT_D)
00056 #define MPPE_OPT_UNKNOWN    0x40    /* Bits !defined in RFC 3078 were set */
00057 
00058 /*
00059  * This is not nice ... the alternative is a bitfield struct though.
00060  * And unfortunately, we cannot share the same bits for the option
00061  * names above since C and H are the same bit.  We could do a u_int32
00062  * but then we have to do a lwip_htonl() all the time and/or we still need
00063  * to know which octet is which.
00064  */
00065 #define MPPE_C_BIT      0x01    /* MPPC */
00066 #define MPPE_D_BIT      0x10    /* Obsolete, usage unknown */
00067 #define MPPE_L_BIT      0x20    /* 40-bit */
00068 #define MPPE_S_BIT      0x40    /* 128-bit */
00069 #define MPPE_M_BIT      0x80    /* 56-bit, not supported */
00070 #define MPPE_H_BIT      0x01    /* Stateless (in a different byte) */
00071 
00072 /* Does not include H bit; used for least significant octet only. */
00073 #define MPPE_ALL_BITS (MPPE_D_BIT|MPPE_L_BIT|MPPE_S_BIT|MPPE_M_BIT|MPPE_H_BIT)
00074 
00075 /* Build a CI from mppe opts (see RFC 3078) */
00076 #define MPPE_OPTS_TO_CI(opts, ci)       \
00077     do {                    \
00078     u_char *ptr = ci; /* u_char[4] */   \
00079                         \
00080     /* H bit */             \
00081     if (opts & MPPE_OPT_STATEFUL)       \
00082         *ptr++ = 0x0;           \
00083     else                    \
00084         *ptr++ = MPPE_H_BIT;        \
00085     *ptr++ = 0;             \
00086     *ptr++ = 0;             \
00087                         \
00088     /* S,L bits */              \
00089     *ptr = 0;               \
00090     if (opts & MPPE_OPT_128)        \
00091         *ptr |= MPPE_S_BIT;         \
00092     if (opts & MPPE_OPT_40)         \
00093         *ptr |= MPPE_L_BIT;         \
00094     /* M,D,C bits not supported */      \
00095     } while (/* CONSTCOND */ 0)
00096 
00097 /* The reverse of the above */
00098 #define MPPE_CI_TO_OPTS(ci, opts)       \
00099     do {                    \
00100     const u_char *ptr = ci; /* u_char[4] */ \
00101                         \
00102     opts = 0;               \
00103                         \
00104     /* H bit */             \
00105     if (!(ptr[0] & MPPE_H_BIT))     \
00106         opts |= MPPE_OPT_STATEFUL;      \
00107                         \
00108     /* S,L bits */              \
00109     if (ptr[3] & MPPE_S_BIT)        \
00110         opts |= MPPE_OPT_128;       \
00111     if (ptr[3] & MPPE_L_BIT)        \
00112         opts |= MPPE_OPT_40;        \
00113                         \
00114     /* M,D,C bits */            \
00115     if (ptr[3] & MPPE_M_BIT)        \
00116         opts |= MPPE_OPT_56;        \
00117     if (ptr[3] & MPPE_D_BIT)        \
00118         opts |= MPPE_OPT_D;         \
00119     if (ptr[3] & MPPE_C_BIT)        \
00120         opts |= MPPE_OPT_MPPC;      \
00121                         \
00122     /* Other bits */            \
00123     if (ptr[0] & ~MPPE_H_BIT)       \
00124         opts |= MPPE_OPT_UNKNOWN;       \
00125     if (ptr[1] || ptr[2])           \
00126         opts |= MPPE_OPT_UNKNOWN;       \
00127     if (ptr[3] & ~MPPE_ALL_BITS)        \
00128         opts |= MPPE_OPT_UNKNOWN;       \
00129     } while (/* CONSTCOND */ 0)
00130 
00131 /* Shared MPPE padding between MSCHAP and MPPE */
00132 #define SHA1_PAD_SIZE 40
00133 
00134 static const u8_t mppe_sha1_pad1[SHA1_PAD_SIZE] = {
00135   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
00136   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
00137   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
00138   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
00139 };
00140 static const u8_t mppe_sha1_pad2[SHA1_PAD_SIZE] = {
00141   0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2,
00142   0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2,
00143   0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2,
00144   0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2
00145 };
00146 
00147 /*
00148  * State for an MPPE (de)compressor.
00149  */
00150 typedef struct ppp_mppe_state {
00151     lwip_arc4_context arc4;
00152     u8_t master_key[MPPE_MAX_KEY_LEN];
00153     u8_t session_key[MPPE_MAX_KEY_LEN];
00154     u8_t keylen;                /* key length in bytes */
00155     /* NB: 128-bit == 16, 40-bit == 8!
00156      * If we want to support 56-bit, the unit has to change to bits
00157      */
00158     u8_t bits;                  /* MPPE control bits */
00159     u16_t ccount;               /* 12-bit coherency count (seqno)  */
00160     u16_t sanity_errors;        /* take down LCP if too many */
00161     unsigned int stateful  :1;  /* stateful mode flag */
00162     unsigned int discard   :1;  /* stateful mode packet loss flag */
00163 } ppp_mppe_state;
00164 
00165 void mppe_set_key(ppp_pcb *pcb, ppp_mppe_state *state, u8_t *key);
00166 void mppe_init(ppp_pcb *pcb, ppp_mppe_state *state, u8_t options);
00167 void mppe_comp_reset(ppp_pcb *pcb, ppp_mppe_state *state);
00168 err_t mppe_compress(ppp_pcb *pcb, ppp_mppe_state *state, struct pbuf **pb, u16_t protocol);
00169 void mppe_decomp_reset(ppp_pcb *pcb, ppp_mppe_state *state);
00170 err_t mppe_decompress(ppp_pcb *pcb, ppp_mppe_state *state, struct pbuf **pb);
00171 
00172 #endif /* MPPE_H */
00173 #endif /* PPP_SUPPORT && MPPE_SUPPORT */