mime_enc.c

   1 /*@ S-nail - a mail user agent derived from Berkeley Mail.
   2  *@ Content-Transfer-Encodings as defined in RFC 2045 (and RFC 2047;
   3  *@ for _header() versions: including "encoded word" as of RFC 2049):
   4  *@ - Quoted-Printable, section 6.7
   5  *@ - Base64, section 6.8
   6  *@ TODO We have no notion of a "current message context" and thus badly log.
   7  *@ TODO This is not final yet, v15 will bring "filters".
   8  *
   9  * Copyright (c) 2000-2004 Gunnar Ritter, Freiburg i. Br., Germany.
  10  * Copyright (c) 2012 - 2017 Steffen (Daode) Nurpmeso <steffen@sdaoden.eu>.
  11  */
  12 /* QP quoting idea, _b64_decode(), b64_encode() taken from NetBSDs mailx(1): */
  13 /* $NetBSD: mime_codecs.c,v 1.9 2009/04/10 13:08:25 christos Exp $ */
  14 /*
  15  * Copyright (c) 2006 The NetBSD Foundation, Inc.
  16  * All rights reserved.
  17  *
  18  * This code is derived from software contributed to The NetBSD Foundation
  19  * by Anon Ymous.
  20  *
  21  * Redistribution and use in source and binary forms, with or without
  22  * modification, are permitted provided that the following conditions
  23  * are met:
  24  * 1. Redistributions of source code must retain the above copyright
  25  *    notice, this list of conditions and the following disclaimer.
  26  * 2. Redistributions in binary form must reproduce the above copyright
  27  *    notice, this list of conditions and the following disclaimer in the
  28  *    documentation and/or other materials provided with the distribution.
  29  *
  30  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
  31  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  32  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  33  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
  34  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  35  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  36  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  37  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  38  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  39  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  40  * POSSIBILITY OF SUCH DAMAGE.
  41  */
  42 #undef n_FILE
  43 #define n_FILE mime_enc
  44
  45 #ifndef HAVE_AMALGAMATION
  46 # include "nail.h"
  47 #endif
  48
  49 enum a_me_qact{
  50    a_ME_N = 0,
  51    a_ME_Q = 1,       /* Must quote */
  52    a_ME_SP = 2,      /* sp */
  53    a_ME_XF = 3,      /* Special character 'F' - maybe quoted */
  54    a_ME_XD = 4,      /* Special character '.' - maybe quoted */
  55    a_ME_UU = 5,      /* In header, _ must be quoted in encoded word */
  56    a_ME_US = '_',    /* In header, ' ' must be quoted as _ in encoded word */
  57    a_ME_QM = '?',    /* In header, special character ? not always quoted */
  58    a_ME_EQ = '=',    /* In header, '=' must be quoted in encoded word */
  59    a_ME_HT ='\t',    /* Body HT=SP.  Head HT=HT, BUT quote in encoded word */
  60    a_ME_NL = 0,      /* Don't quote '\n' (NL) */
  61    a_ME_CR = a_ME_Q  /* Always quote a '\r' (CR) */
  62 };
  63
  64 /* Lookup tables to decide whether a character must be encoded or not.
  65  * Email header differences according to RFC 2047, section 4.2:
  66  * - also quote SP (as the underscore _), TAB, ?, _, CR, LF
  67  * - don't care about the special ^F[rom] and ^.$ */
  68 static ui8_t const a_me_qp_body[] = {
  69     a_ME_Q,  a_ME_Q,  a_ME_Q,  a_ME_Q,  a_ME_Q,  a_ME_Q,  a_ME_Q,  a_ME_Q,
  70     a_ME_Q, a_ME_SP, a_ME_NL,  a_ME_Q,  a_ME_Q, a_ME_CR,  a_ME_Q,  a_ME_Q,
  71     a_ME_Q,  a_ME_Q,  a_ME_Q,  a_ME_Q,  a_ME_Q,  a_ME_Q,  a_ME_Q,  a_ME_Q,
  72     a_ME_Q,  a_ME_Q,  a_ME_Q,  a_ME_Q,  a_ME_Q,  a_ME_Q,  a_ME_Q,  a_ME_Q,
  73    a_ME_SP,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,
  74     a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N, a_ME_XD,  a_ME_N,
  75     a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,
  76     a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_Q,  a_ME_N,  a_ME_N,
  77
  78     a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N, a_ME_XF,  a_ME_N,
  79     a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,
  80     a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,
  81     a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,
  82     a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,
  83     a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,
  84     a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,
  85     a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_Q,
  86 }, a_me_qp_head[] = {
  87     a_ME_Q,  a_ME_Q,  a_ME_Q,  a_ME_Q,  a_ME_Q,  a_ME_Q,  a_ME_Q,  a_ME_Q,
  88     a_ME_Q, a_ME_HT,  a_ME_Q,  a_ME_Q,  a_ME_Q,  a_ME_Q,  a_ME_Q,  a_ME_Q,
  89     a_ME_Q,  a_ME_Q,  a_ME_Q,  a_ME_Q,  a_ME_Q,  a_ME_Q,  a_ME_Q,  a_ME_Q,
  90     a_ME_Q,  a_ME_Q,  a_ME_Q,  a_ME_Q,  a_ME_Q,  a_ME_Q,  a_ME_Q,  a_ME_Q,
  91    a_ME_US,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,
  92     a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,
  93     a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,
  94     a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N, a_ME_EQ,  a_ME_N, a_ME_QM,
  95
  96     a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,
  97     a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,
  98     a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,
  99     a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N, a_ME_UU,
 100     a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,
 101     a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,
 102     a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,
 103     a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_N,  a_ME_Q,
 104 };
 105
 106 /* The decoding table is only accessed via a_ME_B64_DECUI8() */
 107 static char const a_me_b64_enctbl[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
 108       "abcdefghijklmnopqrstuvwxyz" "0123456789" "+/";
 109 static signed char const a_me_b64__dectbl[] = {
 110    -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
 111    -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
 112    -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,62, -1,-1,-1,63,
 113    52,53,54,55, 56,57,58,59, 60,61,-1,-1, -1,-2,-1,-1,
 114    -1, 0, 1, 2,  3, 4, 5, 6,  7, 8, 9,10, 11,12,13,14,
 115    15,16,17,18, 19,20,21,22, 23,24,25,-1, -1,-1,-1,-1,
 116    -1,26,27,28, 29,30,31,32, 33,34,35,36, 37,38,39,40,
 117    41,42,43,44, 45,46,47,48, 49,50,51,-1, -1,-1,-1,-1
 118 };
 119 #define a_ME_B64_EQU (ui32_t)-2
 120 #define a_ME_B64_BAD (ui32_t)-1
 121 #define a_ME_B64_DECUI8(C) \
 122    ((ui8_t)(C) >= sizeof(a_me_b64__dectbl)\
 123     ? a_ME_B64_BAD : (ui32_t)a_me_b64__dectbl[(ui8_t)(C)])
 124
 125 /* (Ugly to place an enum here) */
 126 static char const a_me_ctes[] = "7bit\0" "8bit\0" \
 127       "base64\0" "quoted-printable\0" "binary\0" \
 128       /* abbrevs */ "8b\0" "b64\0" "qp\0";
 129 enum a_me_ctes_off{
 130    a_ME_CTES_7B_OFF = 0, a_ME_CTES_7B_LEN = 4,
 131    a_ME_CTES_8B_OFF = 5, a_ME_CTES_8B_LEN = 4,
 132    a_ME_CTES_B64_OFF = 10, a_ME_CTES_B64_LEN = 6,
 133    a_ME_CTES_QP_OFF = 17,  a_ME_CTES_QP_LEN = 16,
 134    a_ME_CTES_BIN_OFF = 34, a_ME_CTES_BIN_LEN = 6,
 135
 136    a_ME_CTES_S8B_OFF = 41, a_ME_CTES_S8B_LEN = 2,
 137    a_ME_CTES_SB64_OFF = 44, a_ME_CTES_SB64_LEN = 3,
 138    a_ME_CTES_SQP_OFF = 48, a_ME_CTES_SQP_LEN = 2
 139 };
 140
 141 /* Check whether *s must be quoted according to flags, else body rules;
 142  * sol indicates whether we are at the first character of a line/field */
 143 SINLINE enum a_me_qact a_me_mustquote(char const *s, char const *e, bool_t sol,
 144                         enum mime_enc_flags flags);
 145
 146 /* Trim WS and make work point to the decodable range of in.
 147  * Return the amount of bytes a b64_decode operation on that buffer requires,
 148  * or UIZ_MAX on overflow error */
 149 static size_t a_me_b64_decode_prepare(struct str *work, struct str const *in);
 150
 151 /* Perform b64_decode on in(put) to sufficiently spaced out(put).
 152  * Return number of useful bytes in out or -1 on error.
 153  * Note: may enter endless loop if in->l < 4 and 0 return is not handled! */
 154 static ssize_t a_me_b64_decode(struct str *out, struct str *in);
 155
 156 SINLINE enum a_me_qact
 157 a_me_mustquote(char const *s, char const *e, bool_t sol,
 158       enum mime_enc_flags flags){
 159    ui8_t const *qtab;
 160    enum a_me_qact a, r;
 161    NYD2_ENTER;
 162
 163    qtab = (flags & (MIMEEF_ISHEAD | MIMEEF_ISENCWORD))
 164          ? a_me_qp_head : a_me_qp_body;
 165
 166    if((ui8_t)*s > 0x7F){
 167       r = a_ME_Q;
 168       goto jleave;
 169    }
 170
 171    a = qtab[(ui8_t)*s];
 172
 173    if((r = a) == a_ME_N || a == a_ME_Q)
 174       goto jleave;
 175
 176    r = a_ME_Q;
 177
 178    /* Special header fields */
 179    if(flags & (MIMEEF_ISHEAD | MIMEEF_ISENCWORD)){
 180       /* Special massage for encoded words */
 181       if(flags & MIMEEF_ISENCWORD){
 182          switch(a){
 183          case a_ME_HT:
 184          case a_ME_US:
 185          case a_ME_EQ:
 186             r = a;
 187             /* FALLTHRU */
 188          case a_ME_UU:
 189             goto jleave;
 190          default:
 191             break;
 192          }
 193       }
 194
 195       /* Treat '?' only special if part of '=?' .. '?=' (still too much quoting
 196        * since it's '=?CHARSET?CTE?stuff?=', and especially the trailing ?=
 197        * should be hard to match */
 198       if(a == a_ME_QM && ((!sol && s[-1] == '=') || (s < e && s[1] == '=')))
 199          goto jleave;
 200       goto jnquote;
 201    }
 202
 203    /* Body-only */
 204
 205    if(a == a_ME_SP){
 206       /* WS only if trailing white space */
 207       if(&s[1] == e || s[1] == '\n')
 208          goto jleave;
 209       goto jnquote;
 210    }
 211
 212    /* Rest are special begin-of-line cases */
 213    if(!sol)
 214       goto jnquote;
 215
 216    /* ^From */
 217    if(a == a_ME_XF){
 218       if(&s[4] < e && s[1] == 'r' && s[2] == 'o' && s[3] == 'm' && s[4] == ' ')
 219          goto jleave;
 220       goto jnquote;
 221    }
 222    /* ^.$ */
 223    if(a == a_ME_XD && (&s[1] == e || s[1] == '\n'))
 224       goto jleave;
 225 jnquote:
 226    r = 0;
 227 jleave:
 228    NYD2_LEAVE;
 229    return r;
 230 }
 231
 232 static size_t
 233 a_me_b64_decode_prepare(struct str *work, struct str const *in){
 234    char *cp;
 235    size_t cp_len;
 236    NYD2_ENTER;
 237
 238    cp = in->s;
 239    cp_len = in->l;
 240
 241    while(cp_len > 0 && spacechar(*cp))
 242       ++cp, --cp_len;
 243    work->s = cp;
 244
 245    for(cp += cp_len; cp_len > 0; --cp_len){
 246       --cp;
 247       if(!spacechar(*cp))
 248          break;
 249    }
 250    work->l = cp_len;
 251
 252    if(cp_len > 16){
 253       /* EOVERFLOW */
 254       if(UIZ_MAX / 3 <= cp_len){
 255          cp_len = UIZ_MAX;
 256          goto jleave;
 257       }
 258       cp_len = ((cp_len * 3) >> 2) + (cp_len >> 3);
 259    }
 260    cp_len += (2 * 3) +1;
 261 jleave:
 262    NYD2_LEAVE;
 263    return cp_len;
 264 }
 265
 266 static ssize_t
 267 a_me_b64_decode(struct str *out, struct str *in){
 268    ui8_t *p;
 269    ui8_t const *q, *end;
 270    ssize_t rv;
 271    NYD2_ENTER;
 272
 273    rv = -1;
 274    p = (ui8_t*)&out->s[out->l];
 275    q = (ui8_t const*)in->s;
 276
 277    for(end = &q[in->l]; PTR2SIZE(end - q) >= 4; q += 4){
 278       ui32_t a, b, c, d;
 279
 280       a = a_ME_B64_DECUI8(q[0]);
 281       b = a_ME_B64_DECUI8(q[1]);
 282       c = a_ME_B64_DECUI8(q[2]);
 283       d = a_ME_B64_DECUI8(q[3]);
 284
 285       if(n_UNLIKELY(a >= a_ME_B64_EQU || b >= a_ME_B64_EQU ||
 286             c == a_ME_B64_BAD || d == a_ME_B64_BAD))
 287          goto jleave;
 288
 289       *p++ = ((a << 2) | ((b & 0x30) >> 4));
 290       if(c == a_ME_B64_EQU){ /* got '=' */
 291          q += 4;
 292          if(n_UNLIKELY(d != a_ME_B64_EQU))
 293             goto jleave;
 294          break;
 295       }
 296
 297       *p++ = (((b & 0x0F) << 4) | ((c & 0x3C) >> 2));
 298       if(d == a_ME_B64_EQU) /* got '=' */
 299          break;
 300       *p++ = (((c & 0x03) << 6) | d);
 301    }
 302    rv ^= rv;
 303
 304 jleave:{
 305       size_t i;
 306
 307       i = PTR2SIZE((char*)p - out->s);
 308       out->l = i;
 309       if(rv == 0)
 310          rv = (ssize_t)i;
 311    }
 312    in->l -= PTR2SIZE(q - (ui8_t*)in->s);
 313    in->s = n_UNCONST(q);
 314    NYD2_LEAVE;
 315    return rv;
 316 }
 317
 318 FL enum mime_enc
 319 mime_enc_target(void){
 320    char const *cp;
 321    enum mime_enc rv;
 322    NYD2_ENTER;
 323
 324    if((cp = ok_vlook(encoding)) == NULL)
 325       rv = MIME_DEFAULT_ENCODING;
 326    else if(!asccasecmp(cp, &a_me_ctes[a_ME_CTES_S8B_OFF]) ||
 327          !asccasecmp(cp, &a_me_ctes[a_ME_CTES_8B_OFF]))
 328       rv = MIMEE_8B;
 329    else if(!asccasecmp(cp, &a_me_ctes[a_ME_CTES_SB64_OFF]) ||
 330          !asccasecmp(cp, &a_me_ctes[a_ME_CTES_B64_OFF]))
 331       rv = MIMEE_B64;
 332    else if(!asccasecmp(cp, &a_me_ctes[a_ME_CTES_SQP_OFF]) ||
 333          !asccasecmp(cp, &a_me_ctes[a_ME_CTES_QP_OFF]))
 334       rv = MIMEE_QP;
 335    else{
 336       n_err(_("Warning: invalid *encoding*, using Base64: %s\n"), cp);
 337       rv = MIMEE_B64;
 338    }
 339    NYD2_LEAVE;
 340    return rv;
 341 }
 342
 343 FL enum mime_enc
 344 mime_enc_from_ctehead(char const *hbody){
 345    enum mime_enc rv;
 346    NYD2_ENTER;
 347
 348    if(hbody == NULL)
 349       rv = MIMEE_7B;
 350    else{
 351       struct{
 352          ui8_t off;
 353          ui8_t len;
 354          ui8_t enc;
 355          ui8_t __dummy;
 356       } const *cte, cte_base[] = {
 357          {a_ME_CTES_7B_OFF, a_ME_CTES_7B_LEN, MIMEE_7B, 0},
 358          {a_ME_CTES_8B_OFF, a_ME_CTES_8B_LEN, MIMEE_8B, 0},
 359          {a_ME_CTES_B64_OFF, a_ME_CTES_B64_LEN, MIMEE_B64, 0},
 360          {a_ME_CTES_QP_OFF, a_ME_CTES_QP_LEN, MIMEE_QP, 0},
 361          {a_ME_CTES_BIN_OFF, a_ME_CTES_BIN_LEN, MIMEE_BIN, 0},
 362          {0, 0, MIMEE_NONE, 0}
 363       };
 364       union {char const *s; size_t l;} u;
 365
 366       if(*hbody == '"')
 367          for(u.s = ++hbody; *u.s != '\0' && *u.s != '"'; ++u.s)
 368             ;
 369       else
 370          for(u.s = hbody; *u.s != '\0' && !whitechar(*u.s); ++u.s)
 371             ;
 372       u.l = PTR2SIZE(u.s - hbody);
 373
 374       for(cte = cte_base;;)
 375          if(cte->len == u.l && !asccasecmp(&a_me_ctes[cte->off], hbody)){
 376             rv = cte->enc;
 377             break;
 378          }else if((++cte)->enc == MIMEE_NONE){
 379             rv = MIMEE_NONE;
 380             break;
 381          }
 382    }
 383    NYD2_LEAVE;
 384    return rv;
 385 }
 386
 387 FL char const *
 388 mime_enc_from_conversion(enum conversion const convert){
 389    char const *rv;
 390    NYD2_ENTER;
 391
 392    switch(convert){
 393    case CONV_7BIT: rv = &a_me_ctes[a_ME_CTES_7B_OFF]; break;
 394    case CONV_8BIT: rv = &a_me_ctes[a_ME_CTES_8B_OFF]; break;
 395    case CONV_TOQP: rv = &a_me_ctes[a_ME_CTES_QP_OFF]; break;
 396    case CONV_TOB64: rv = &a_me_ctes[a_ME_CTES_B64_OFF]; break;
 397    case CONV_NONE: rv = &a_me_ctes[a_ME_CTES_BIN_OFF]; break;
 398    default: rv = n_empty; break;
 399    }
 400    NYD2_LEAVE;
 401    return rv;
 402 }
 403
 404 FL size_t
 405 mime_enc_mustquote(char const *ln, size_t lnlen, enum mime_enc_flags flags){
 406    size_t rv;
 407    bool_t sol;
 408    NYD2_ENTER;
 409
 410    for(rv = 0, sol = TRU1; lnlen > 0; sol = FAL0, ++ln, --lnlen)
 411       switch(a_me_mustquote(ln, ln + lnlen, sol, flags)){
 412       case a_ME_US:
 413       case a_ME_EQ:
 414       case a_ME_HT:
 415          assert(flags & MIMEEF_ISENCWORD);
 416          /* FALLTHRU */
 417       case 0:
 418          continue;
 419       default:
 420          ++rv;
 421       }
 422    NYD2_LEAVE;
 423    return rv;
 424 }
 425
 426 FL size_t
 427 qp_encode_calc_size(size_t len){
 428    size_t bytes, lines;
 429    NYD2_ENTER;
 430
 431    /* The worst case sequence is 'CRLF' -> '=0D=0A=\n\0'.
 432     * However, we must be aware that (a) the output may span multiple lines
 433     * and (b) the input does not end with a newline itself (nonetheless):
 434     *    LC_ALL=C awk 'BEGIN{
 435     *       for (i = 1; i < 100000; ++i) printf "\xC3\xBC"
 436     *    }' |
 437     *    s-nail -:/ -dSsendcharsets=utf8 -s testsub no@where */
 438
 439    /* Several EOVERFLOW */
 440    if(len >= UIZ_MAX / 3){
 441       len = UIZ_MAX;
 442       goto jleave;
 443    }
 444    bytes = len * 3;
 445    lines = bytes / QP_LINESIZE;
 446    len += lines;
 447
 448    if(len >= UIZ_MAX / 3){
 449       len = UIZ_MAX;
 450       goto jleave;
 451    }
 452    /* Trailing hard NL may be missing, so there may be two lines.
 453     * Thus add soft + hard NL per line and a trailing NUL */
 454    bytes = len * 3;
 455    lines = (bytes / QP_LINESIZE) + 1;
 456    lines <<= 1;
 457    ++bytes;
 458    /*if(UIZ_MAX - bytes >= lines){
 459       len = UIZ_MAX;
 460       goto jleave;
 461    }*/
 462    bytes += lines;
 463    len = bytes;
 464 jleave:
 465    NYD2_LEAVE;
 466    return len;
 467 }
 468
 469 #ifdef notyet
 470 FL struct str *
 471 qp_encode_cp(struct str *out, char const *cp, enum qpflags flags){
 472    struct str in;
 473    NYD_ENTER;
 474
 475    in.s = n_UNCONST(cp);
 476    in.l = strlen(cp);
 477    out = qp_encode(out, &in, flags);
 478    NYD_LEAVE;
 479    return out;
 480 }
 481
 482 FL struct str *
 483 qp_encode_buf(struct str *out, void const *vp, size_t vp_len,
 484       enum qpflags flags){
 485    struct str in;
 486    NYD_ENTER;
 487
 488    in.s = n_UNCONST(vp);
 489    in.l = vp_len;
 490    out = qp_encode(out, &in, flags);
 491    NYD_LEAVE;
 492    return out;
 493 }
 494 #endif /* notyet */
 495
 496 FL struct str *
 497 qp_encode(struct str *out, struct str const *in, enum qpflags flags){
 498    size_t lnlen;
 499    char *qp;
 500    char const *is, *ie;
 501    bool_t sol, seenx;
 502    NYD_ENTER;
 503
 504    sol = (flags & QP_ISHEAD ? FAL0 : TRU1);
 505
 506    if(!(flags & QP_BUF)){
 507       if((lnlen = qp_encode_calc_size(in->l)) == UIZ_MAX){
 508          out = NULL;
 509          goto jerr;
 510       }
 511       out->s = (flags & QP_SALLOC) ? salloc(lnlen) : srealloc(out->s, lnlen);
 512    }
 513    qp = out->s;
 514    is = in->s;
 515    ie = is + in->l;
 516
 517    if(flags & QP_ISHEAD){
 518       enum mime_enc_flags ef;
 519
 520       ef = MIMEEF_ISHEAD | (flags & QP_ISENCWORD ? MIMEEF_ISENCWORD : 0);
 521
 522       for(seenx = FAL0, sol = TRU1; is < ie; sol = FAL0, ++qp){
 523          char c;
 524          enum a_me_qact mq;
 525
 526          mq = a_me_mustquote(is, ie, sol, ef);
 527          c = *is++;
 528
 529          if(mq == a_ME_N){
 530             /* We convert into a single *encoded-word*, that'll end up in
 531              * =?C?Q??=; quote '?' from when we're inside there on */
 532             if(seenx && c == '?')
 533                goto jheadq;
 534             *qp = c;
 535          }else if(mq == a_ME_US)
 536             *qp = a_ME_US;
 537          else{
 538             seenx = TRU1;
 539 jheadq:
 540             *qp++ = '=';
 541             qp = n_c_to_hex_base16(qp, c) + 1;
 542          }
 543       }
 544       goto jleave;
 545    }
 546
 547    /* The body needs to take care for soft line breaks etc. */
 548    for(lnlen = 0, seenx = FAL0; is < ie; sol = FAL0){
 549       char c;
 550       enum a_me_qact mq;
 551
 552       mq = a_me_mustquote(is, ie, sol, MIMEEF_NONE);
 553       c = *is++;
 554
 555       if(mq == a_ME_N && (c != '\n' || !seenx)){
 556          *qp++ = c;
 557          if(++lnlen < QP_LINESIZE - 1)
 558             continue;
 559          /* Don't write a soft line break when we're in the last possible
 560           * column and either an LF has been written or only an LF follows, as
 561           * that'll end the line anyway */
 562          /* XXX but - ensure is+1>=ie, then??
 563           * xxx and/or - what about resetting lnlen; that contra
 564           * xxx dicts input==1 input line assertion, though */
 565          if(c == '\n' || is == ie || is[0] == '\n' || is[1] == '\n')
 566             continue;
 567 jsoftnl:
 568          qp[0] = '=';
 569          qp[1] = '\n';
 570          qp += 2;
 571          lnlen = 0;
 572          continue;
 573       }
 574
 575       if(lnlen > QP_LINESIZE - 3 - 1){
 576          qp[0] = '=';
 577          qp[1] = '\n';
 578          qp += 2;
 579          lnlen = 0;
 580       }
 581       *qp++ = '=';
 582       qp = n_c_to_hex_base16(qp, c);
 583       qp += 2;
 584       lnlen += 3;
 585       if(c != '\n' || !seenx)
 586          seenx = (c == '\r');
 587       else{
 588          seenx = FAL0;
 589          goto jsoftnl;
 590       }
 591    }
 592
 593    /* Enforce soft line break if we haven't seen LF */
 594    if(in->l > 0 && *--is != '\n'){
 595       qp[0] = '=';
 596       qp[1] = '\n';
 597       qp += 2;
 598    }
 599 jleave:
 600    out->l = PTR2SIZE(qp - out->s);
 601    out->s[out->l] = '\0';
 602 jerr:
 603    NYD_LEAVE;
 604    return out;
 605 }
 606
 607 FL bool_t
 608 qp_decode_header(struct str *out, struct str const *in){
 609    struct n_string s;
 610    char const *is, *ie;
 611    NYD_ENTER;
 612
 613    /* EOVERFLOW */
 614    if(UIZ_MAX -1 - out->l <= in->l ||
 615          SI32_MAX <= out->l + in->l){ /* XXX wrong, we may replace */
 616       out->l = 0;
 617       out = NULL;
 618       goto jleave;
 619    }
 620
 621    n_string_creat(&s);
 622    n_string_reserve(n_string_take_ownership(&s, out->s,
 623          (out->l == 0 ? 0 : out->l +1), out->l),
 624       in->l + (in->l >> 2));
 625
 626    for(is = in->s, ie = &is[in->l - 1]; is <= ie;){
 627       si32_t c;
 628
 629       c = *is++;
 630       if(c == '='){
 631          if(is >= ie){
 632             goto jpushc; /* TODO According to RFC 2045, 6.7,
 633             * ++is; TODO we should warn the user, but have no context
 634             * goto jehead; TODO to do so; can't over and over */
 635          }else if((c = n_c_from_hex_base16(is)) >= 0){
 636             is += 2;
 637             goto jpushc;
 638          }else{
 639             /* Invalid according to RFC 2045, section 6.7 */
 640             /* TODO Follow RFC 2045, 6.7 advise and simply put through */
 641             c = '=';
 642             goto jpushc;
 643 /* TODO jehead:
 644  * TODO      if(n_psonce & n_PSO_UNICODE)
 645  *              n_string_push_buf(&s, n_unirepl, sizeof(n_unirepl) -1);
 646  * TODO       else{
 647  * TODO          c = '?';
 648  * TODO          goto jpushc;
 649  * TODO       }*/
 650          }
 651       }else{
 652 jpushc:
 653          if(c == '_' /* a_ME_US */)
 654             c = ' ';
 655          n_string_push_c(&s, (char)c);
 656       }
 657    }
 658
 659    out->s = n_string_cp(&s);
 660    out->l = s.s_len;
 661    n_string_gut(n_string_drop_ownership(&s));
 662 jleave:
 663    NYD_LEAVE;
 664    return (out != NULL);
 665 }
 666
 667 FL bool_t
 668 qp_decode_part(struct str *out, struct str const *in, struct str *outrest,
 669       struct str *inrest_or_null){
 670    struct n_string s, *sp;
 671    char const *is, *ie;
 672    NYD_ENTER;
 673
 674    if(outrest->l != 0){
 675       is = out->s;
 676       *out = *outrest;
 677       outrest->s = n_UNCONST(is);
 678       outrest->l = 0;
 679    }
 680
 681    /* EOVERFLOW */
 682    if(UIZ_MAX -1 - out->l <= in->l ||
 683          SI32_MAX <= out->l + in->l) /* XXX wrong, we may replace */
 684       goto jerr;
 685
 686    sp = n_string_creat(&s);
 687    sp = n_string_take_ownership(sp, out->s,
 688          (out->l == 0 ? 0 : out->l +1), out->l);
 689    sp = n_string_reserve(sp, in->l + (in->l >> 2));
 690
 691    for(is = in->s, ie = &is[in->l - 1]; is <= ie;){
 692       si32_t c;
 693
 694       if((c = *is++) != '='){
 695 jpushc:
 696          n_string_push_c(&s, (char)c);
 697          continue;
 698       }
 699
 700       /* RFC 2045, 6.7:
 701        *   Therefore, when decoding a Quoted-Printable body, any
 702        *   trailing white space on a line must be deleted, as it will
 703        *   necessarily have been added by intermediate transport
 704        *   agents */
 705       for(; is <= ie && blankchar(*is); ++is)
 706          ;
 707       if(is >= ie){
 708          /* Soft line break? */
 709          if(*is == '\n')
 710             goto jsoftnl;
 711         goto jpushc; /* TODO According to RFC 2045, 6.7,
 712          * ++is; TODO we should warn the user, but have no context
 713          * goto jebody; TODO to do so; can't over and over */
 714       }
 715
 716       /* Not a soft line break? */
 717       if(*is != '\n'){
 718          if((c = n_c_from_hex_base16(is)) >= 0){
 719             is += 2;
 720             goto jpushc;
 721          }
 722          /* Invalid according to RFC 2045, section 6.7 */
 723          /* TODO Follow RFC 2045, 6.7 advise and simply put through */
 724          c = '=';
 725          goto jpushc;
 726 /* TODO jebody:
 727  * TODO   if(n_psonce & n_PSO_UNICODE)
 728  *           n_string_push_buf(&s, n_unirepl, sizeof(n_unirepl) -1);
 729  * TODO    else{
 730  * TODO       c = '?';
 731  * TODO       goto jpushc;
 732  * TODO    }*/
 733       }
 734
 735       /* CRLF line endings are encoded as QP, followed by a soft line break, so
 736        * check for this special case, and simply forget we have seen one, so as
 737        * not to end up with the entire DOS file in a contiguous buffer */
 738 jsoftnl:
 739       if(s.s_len > 0 && s.s_dat[s.s_len - 1] == '\n'){
 740 #if 0       /* TODO qp_decode_part() we do not normalize CRLF
 741           * TODO to LF because for that we would need
 742           * TODO to know if we are about to write to
 743           * TODO the display or do save the file!
 744           * TODO 'hope the MIME/send layer rewrite will
 745           * TODO offer the possibility to DTRT */
 746          if(s.s_len > 1 && s.s_dat[s.s_len - 2] == '\r')
 747             n_string_push_c(n_string_trunc(&s, s.s_len - 2), '\n');
 748 #endif
 749          break;
 750       }
 751
 752       /* C99 */{
 753          char *cp;
 754          size_t l;
 755
 756          if((l = PTR2SIZE(ie - is)) > 0){
 757             if(inrest_or_null == NULL)
 758                goto jerr;
 759             n_str_assign_buf(inrest_or_null, is, l);
 760          }
 761          cp = outrest->s;
 762          outrest->s = n_string_cp(&s);
 763          outrest->l = s.s_len;
 764          n_string_drop_ownership(&s);
 765          if(cp != NULL)
 766             free(cp);
 767       }
 768       break;
 769    }
 770
 771    out->s = n_string_cp(&s);
 772    out->l = s.s_len;
 773    n_string_gut(n_string_drop_ownership(&s));
 774 jleave:
 775    NYD_LEAVE;
 776    return (out != NULL);
 777 jerr:
 778    out->l = 0;
 779    out = NULL;
 780    goto jleave;
 781 }
 782
 783 FL size_t
 784 b64_encode_calc_size(size_t len){
 785    NYD2_ENTER;
 786    if(len >= UIZ_MAX / 4)
 787       len = UIZ_MAX;
 788    else{
 789       len = (len * 4) / 3;
 790       len += (((len / B64_ENCODE_INPUT_PER_LINE) + 1) * 3);
 791       len += 2 + 1; /* CRLF, \0 */
 792    }
 793    NYD2_LEAVE;
 794    return len;
 795 }
 796
 797 FL struct str *
 798 b64_encode(struct str *out, struct str const *in, enum b64flags flags){
 799    ui8_t const *p;
 800    size_t i, lnlen;
 801    char *b64;
 802    NYD_ENTER;
 803
 804    assert(!(flags & B64_NOPAD) ||
 805       !(flags & (B64_CRLF | B64_LF | B64_MULTILINE)));
 806
 807    p = (ui8_t const*)in->s;
 808
 809    if(!(flags & B64_BUF)){
 810       if((i = b64_encode_calc_size(in->l)) == UIZ_MAX){
 811          out = NULL;
 812          goto jleave;
 813       }
 814       out->s = (flags & B64_SALLOC) ? salloc(i) : srealloc(out->s, i);
 815    }
 816    b64 = out->s;
 817
 818    if(!(flags & (B64_CRLF | B64_LF)))
 819       flags &= ~B64_MULTILINE;
 820
 821    for(lnlen = 0, i = in->l; (ssize_t)i > 0; p += 3, i -= 3){
 822       ui32_t a, b, c;
 823
 824       a = p[0];
 825       b64[0] = a_me_b64_enctbl[a >> 2];
 826
 827       switch(i){
 828       case 1:
 829          b64[1] = a_me_b64_enctbl[((a & 0x3) << 4)];
 830          b64[2] =
 831          b64[3] = '=';
 832          break;
 833       case 2:
 834          b = p[1];
 835          b64[1] = a_me_b64_enctbl[((a & 0x03) << 4) | ((b & 0xF0u) >> 4)];
 836          b64[2] = a_me_b64_enctbl[((b & 0x0F) << 2)];
 837          b64[3] = '=';
 838          break;
 839       default:
 840          b = p[1];
 841          c = p[2];
 842          b64[1] = a_me_b64_enctbl[((a & 0x03) << 4) | ((b & 0xF0u) >> 4)];
 843          b64[2] = a_me_b64_enctbl[((b & 0x0F) << 2) | ((c & 0xC0u) >> 6)];
 844          b64[3] = a_me_b64_enctbl[c & 0x3F];
 845          break;
 846       }
 847
 848       b64 += 4;
 849       if(!(flags & B64_MULTILINE))
 850          continue;
 851       lnlen += 4;
 852       if(lnlen < B64_LINESIZE)
 853          continue;
 854
 855       lnlen = 0;
 856       if(flags & B64_CRLF)
 857          *b64++ = '\r';
 858       if(flags & (B64_CRLF | B64_LF))
 859          *b64++ = '\n';
 860    }
 861
 862    if((flags & (B64_CRLF | B64_LF)) &&
 863          (!(flags & B64_MULTILINE) || lnlen != 0)){
 864       if(flags & B64_CRLF)
 865          *b64++ = '\r';
 866       if(flags & (B64_CRLF | B64_LF))
 867          *b64++ = '\n';
 868    }else if(flags & B64_NOPAD)
 869       while(b64 != out->s && b64[-1] == '=')
 870          --b64;
 871
 872    out->l = PTR2SIZE(b64 - out->s);
 873    out->s[out->l] = '\0';
 874
 875    /* Base64 includes + and /, replace them with _ and -.
 876     * This is base64url according to RFC 4648, then.  Since we only support
 877     * that for encoding and it is only used for boundary strings, this is
 878     * yet a primitive implementation; xxx use tables; support decoding */
 879    if(flags & B64_RFC4648URL){
 880       char c;
 881
 882       for(b64 = out->s; (c = *b64) != '\0'; ++b64)
 883          if(c == '+')
 884             *b64 = '-';
 885          else if(c == '/')
 886                *b64 = '_';
 887    }
 888 jleave:
 889    NYD_LEAVE;
 890    return out;
 891 }
 892
 893 FL struct str *
 894 b64_encode_buf(struct str *out, void const *vp, size_t vp_len,
 895       enum b64flags flags){
 896    struct str in;
 897    NYD_ENTER;
 898
 899    in.s = n_UNCONST(vp);
 900    in.l = vp_len;
 901    out = b64_encode(out, &in, flags);
 902    NYD_LEAVE;
 903    return out;
 904 }
 905
 906 #ifdef notyet
 907 FL struct str *
 908 b64_encode_cp(struct str *out, char const *cp, enum b64flags flags){
 909    struct str in;
 910    NYD_ENTER;
 911
 912    in.s = n_UNCONST(cp);
 913    in.l = strlen(cp);
 914    out = b64_encode(out, &in, flags);
 915    NYD_LEAVE;
 916    return out;
 917 }
 918 #endif /* notyet */
 919
 920 FL bool_t
 921 b64_decode(struct str *out, struct str const *in){
 922    struct str work;
 923    size_t len;
 924    NYD_ENTER;
 925
 926    out->l = 0;
 927
 928    if((len = a_me_b64_decode_prepare(&work, in)) == UIZ_MAX)
 929       goto jerr;
 930
 931    /* Ignore an empty input, as may happen for an empty final line */
 932    if(work.l == 0)
 933       out->s = srealloc(out->s, 1);
 934    else if(work.l >= 4 && !(work.l & 3)){
 935       out->s = srealloc(out->s, len +1);
 936       if((ssize_t)(len = a_me_b64_decode(out, &work)) < 0)
 937          goto jerr;
 938    }else
 939       goto jerr;
 940    out->s[out->l] = '\0';
 941 jleave:
 942    NYD_LEAVE;
 943    return (out != NULL);
 944 jerr:
 945    out = NULL;
 946    goto jleave;
 947 }
 948
 949 FL bool_t
 950 b64_decode_header(struct str *out, struct str const *in){
 951    struct str outr, inr;
 952    NYD_ENTER;
 953
 954    if(!b64_decode(out, in)){
 955       memset(&outr, 0, sizeof outr);
 956       memset(&inr, 0, sizeof inr);
 957
 958       if(!b64_decode_part(out, in, &outr, &inr) || outr.l > 0 || inr.l > 0)
 959          out = NULL;
 960
 961       if(inr.s != NULL)
 962          free(inr.s);
 963       if(outr.s != NULL)
 964          free(outr.s);
 965    }
 966    NYD_LEAVE;
 967    return (out != NULL);
 968 }
 969
 970 FL bool_t
 971 b64_decode_part(struct str *out, struct str const *in, struct str *outrest,
 972       struct str *inrest_or_null){
 973    struct str work, save;
 974    ui32_t a, b, c, b64l;
 975    char ca, cb, cc, cx;
 976    struct n_string s, workbuf;
 977    size_t len;
 978    NYD_ENTER;
 979
 980    n_string_creat(&s);
 981    if((len = out->l) > 0 && out->s[len] == '\0')
 982       n_string_take_ownership(&s, out->s, len +1, len);
 983    else{
 984       if(len > 0)
 985          n_string_push_buf(&s, out->s, len);
 986       if(out->s != NULL)
 987          free(out->s);
 988    }
 989    out->s = NULL, out->l = 0;
 990    n_string_creat(&workbuf);
 991
 992    if((len = a_me_b64_decode_prepare(&work, in)) == UIZ_MAX)
 993       goto jerr;
 994
 995    if(outrest->l > 0){
 996       n_string_push_buf(&s, outrest->s, outrest->l);
 997       outrest->l = 0;
 998    }
 999
1000    /* EOVERFLOW */
1001    if(UIZ_MAX - len <= s.s_len ||
1002          SI32_MAX <= len + s.s_len) /* XXX wrong, we may replace */
1003       goto jerr;
1004
1005    if(work.l == 0)
1006       goto jok;
1007
1008    /* This text decoder is extremely expensive, especially given that in all
1009     * but _invalid_ cases it is not even needed!  So try once to do the normal
1010     * decoding, if that fails, go the hard way */
1011    save = work;
1012    out->s = n_string_resize(&s, len + (out->l = b64l = s.s_len))->s_dat;
1013
1014    if(work.l >= 4 && a_me_b64_decode(out, &work) >= 0){
1015       n_string_trunc(&s, out->l);
1016       if(work.l == 0)
1017          goto jok;
1018    }
1019
1020    n_string_trunc(&s, b64l);
1021    work = save;
1022    out->s = NULL, out->l = 0;
1023
1024    n_UNINIT(ca, 0);
1025    n_UNINIT(cb, 0);
1026    n_UNINIT(cc, 0);
1027    for(b64l = 0;;){
1028       ui32_t x;
1029
1030       x = a_ME_B64_DECUI8((ui8_t)(cx = *work.s));
1031       switch(b64l){
1032       case 0:
1033          if(x >= a_ME_B64_EQU)
1034             goto jrepl;
1035          ca = cx;
1036          a = x;
1037          ++b64l;
1038          break;
1039       case 1:
1040          if(x >= a_ME_B64_EQU)
1041             goto jrepl;
1042          cb = cx;
1043          b = x;
1044          ++b64l;
1045          break;
1046       case 2:
1047          if(x == a_ME_B64_BAD)
1048             goto jrepl;
1049          cc = cx;
1050          c = x;
1051          ++b64l;
1052          break;
1053       case 3:
1054          if(x == a_ME_B64_BAD){
1055 jrepl:
1056             /* TODO This would be wrong since iconv(3) may be applied first! */
1057 #if 0
1058             if(n_psonce & n_PSO_UNICODE)
1059                n_string_push_buf(&s, n_unirepl, sizeof(n_unirepl) -1);
1060             else
1061                n_string_push_c(&s, '?');
1062 #endif
1063             ;
1064          }else if(c == a_ME_B64_EQU && x != a_ME_B64_EQU){
1065             /* This is not only invalid but bogus.  Skip it over! */
1066             /* TODO This would be wrong since iconv(3) may be applied first! */
1067 #if 0
1068             n_string_push_buf(&s, n_UNIREPL n_UNIREPL n_UNIREPL n_UNIREPL,
1069                (sizeof(n_UNIREPL) -1) * 4);
1070 #endif
1071             b64l = 0;
1072          }else{
1073             n_string_push_c(&s, (char)((a << 2) | ((b & 0x30) >> 4)));
1074             n_string_push_c(&s, (char)(((b & 0x0F) << 4) | ((c & 0x3C) >> 2)));
1075             if(x != a_ME_B64_EQU)
1076                n_string_push_c(&s, (char)(((c & 0x03) << 6) | x));
1077             ++b64l;
1078          }
1079          break;
1080       }
1081
1082       ++work.s;
1083       if(--work.l == 0){
1084          if(b64l > 0 && b64l != 4){
1085             if(inrest_or_null == NULL)
1086                goto jerr;
1087             inrest_or_null->s = srealloc(inrest_or_null->s, b64l +1);
1088             inrest_or_null->s[0] = ca;
1089             if(b64l > 1)
1090                inrest_or_null->s[1] = cb;
1091             if(b64l > 2)
1092                inrest_or_null->s[2] = cc;
1093             inrest_or_null->s[inrest_or_null->l = b64l] = '\0';
1094          }
1095          goto jok;
1096       }
1097       if(b64l == 4)
1098          b64l = 0;
1099    }
1100
1101 jok:
1102    out->s = n_string_cp(&s);
1103    out->l = s.s_len;
1104    n_string_drop_ownership(&s);
1105 jleave:
1106    n_string_gut(&workbuf);
1107    n_string_gut(&s);
1108    NYD_LEAVE;
1109    return (out != NULL);
1110 jerr:
1111    out = NULL;
1112    goto jleave;
1113 }
1114
1115 /* s-it-mode */