mime_cte.c

   1 /*@ S-nail - a mail user agent derived from Berkeley Mail.
   2  *@ Content-Transfer-Encodings as defined in RFC 2045:
   3  *@ - Quoted-Printable, section 6.7
   4  *@ - Base64, section 6.8
   5  *
   6  * Copyright (c) 2000-2004 Gunnar Ritter, Freiburg i. Br., Germany.
   7  * Copyright (c) 2012 - 2014 Steffen (Daode) Nurpmeso <sdaoden@users.sf.net>.
   8  */
   9 /* QP quoting idea, _b64_decode(), b64_encode() taken from NetBSDs mailx(1): */
  10 /* $NetBSD: mime_codecs.c,v 1.9 2009/04/10 13:08:25 christos Exp $ */
  11 /*
  12  * Copyright (c) 2006 The NetBSD Foundation, Inc.
  13  * All rights reserved.
  14  *
  15  * This code is derived from software contributed to The NetBSD Foundation
  16  * by Anon Ymous.
  17  *
  18  * Redistribution and use in source and binary forms, with or without
  19  * modification, are permitted provided that the following conditions
  20  * are met:
  21  * 1. Redistributions of source code must retain the above copyright
  22  *    notice, this list of conditions and the following disclaimer.
  23  * 2. Redistributions in binary form must reproduce the above copyright
  24  *    notice, this list of conditions and the following disclaimer in the
  25  *    documentation and/or other materials provided with the distribution.
  26  *
  27  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
  28  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  29  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  30  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
  31  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  32  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  33  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  34  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  35  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  36  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  37  * POSSIBILITY OF SUCH DAMAGE.
  38  */
  39
  40 #ifndef HAVE_AMALGAMATION
  41 # include "nail.h"
  42 #endif
  43
  44 enum _qact {
  45     N =   0,   /* Do not quote */
  46     Q =   1,   /* Must quote */
  47    SP =   2,   /* sp */
  48    XF =   3,   /* Special character 'F' - maybe quoted */
  49    XD =   4,   /* Special character '.' - maybe quoted */
  50    US = '_',   /* In header, special character ' ' quoted as '_' */
  51    QM = '?',   /* In header, special character ? not always quoted */
  52    EQ =   Q,   /* '=' must be quoted */
  53    TB =  SP,   /* Treat '\t' as a space */
  54    NL =   N,   /* Don't quote '\n' (NL) */
  55    CR =   Q    /* Always quote a '\r' (CR) */
  56 };
  57
  58 /* Lookup tables to decide wether a character must be encoded or not.
  59  * Email header differences according to RFC 2047, section 4.2:
  60  * - also quote SP (as the underscore _), TAB, ?, _, CR, LF
  61  * - don't care about the special ^F[rom] and ^.$ */
  62 static ui8_t const   _qtab_body[] = {
  63     Q, Q, Q, Q,  Q, Q, Q, Q,  Q,TB,NL, Q,  Q,CR, Q, Q,
  64     Q, Q, Q, Q,  Q, Q, Q, Q,  Q, Q, Q, Q,  Q, Q, Q, Q,
  65    SP, N, N, N,  N, N, N, N,  N, N, N, N,  N, N,XD, N,
  66     N, N, N, N,  N, N, N, N,  N, N, N, N,  N,EQ, N, N,
  67
  68     N, N, N, N,  N, N,XF, N,  N, N, N, N,  N, N, N, N,
  69     N, N, N, N,  N, N, N, N,  N, N, N, N,  N, N, N, N,
  70     N, N, N, N,  N, N, N, N,  N, N, N, N,  N, N, N, N,
  71     N, N, N, N,  N, N, N, N,  N, N, N, N,  N, N, N, Q,
  72 },
  73                      _qtab_head[] = {
  74     Q, Q, Q, Q,  Q, Q, Q, Q,  Q, Q, Q, Q,  Q, Q, Q, Q,
  75     Q, Q, Q, Q,  Q, Q, Q, Q,  Q, Q, Q, Q,  Q, Q, Q, Q,
  76    US, N, N, N,  N, N, N, N,  N, N, N, N,  N, N, N, N,
  77     N, N, N, N,  N, N, N, N,  N, N, N, N,  N,EQ, N,QM,
  78
  79     N, N, N, N,  N, N, N, N,  N, N, N, N,  N, N, N, N,
  80     N, N, N, N,  N, N, N, N,  N, N, N, N,  N, N, N, Q,
  81     N, N, N, N,  N, N, N, N,  N, N, N, N,  N, N, N, N,
  82     N, N, N, N,  N, N, N, N,  N, N, N, N,  N, N, N, Q,
  83 };
  84
  85 /* Check wether **s* must be quoted according to *ishead*, else body rules;
  86  * *sol* indicates wether we are at the first character of a line/field */
  87 SINLINE enum _qact   _mustquote(char const *s, char const *e, bool_t sol,
  88                         bool_t ishead);
  89
  90 /* Convert c to/from a hexadecimal character string */
  91 SINLINE char *       _qp_ctohex(char *store, char c);
  92 SINLINE si32_t       _qp_cfromhex(char const *hex);
  93
  94 /* Trim WS and make *work* point to the decodable range of *in*.
  95  * Return the amount of bytes a b64_decode operation on that buffer requires */
  96 static size_t        _b64_decode_prepare(struct str *work,
  97                         struct str const *in);
  98
  99 /* Perform b64_decode on sufficiently spaced & multiple-of-4 base *in*put.
 100  * Return number of useful bytes in *out* or -1 on error */
 101 static ssize_t       _b64_decode(struct str *out, struct str *in);
 102
 103 SINLINE enum _qact
 104 _mustquote(char const *s, char const *e, bool_t sol, bool_t ishead)
 105 {
 106    ui8_t const *qtab;
 107    enum _qact a, r;
 108    NYD2_ENTER;
 109
 110    qtab = ishead ? _qtab_head : _qtab_body;
 111    a = ((ui8_t)*s > 0x7F) ? Q : qtab[(ui8_t)*s];
 112
 113    if ((r = a) == N || (r = a) == Q)
 114       goto jleave;
 115    r = Q;
 116
 117    /* Special header fields */
 118    if (ishead) {
 119       /* ' ' -> '_' */
 120       if (a == US) {
 121          r = US;
 122          goto jleave;
 123       }
 124       /* Treat '?' only special if part of '=?' .. '?=' (still too much quoting
 125        * since it's '=?CHARSET?CTE?stuff?=', and especially the trailing ?=
 126        * should be hard too match */
 127       if (a == QM && ((!sol && s[-1] == '=') || (s < e && s[1] == '=')))
 128          goto jleave;
 129       goto jnquote;
 130    }
 131
 132    /* Body-only */
 133
 134    if (a == SP) {
 135       /* WS only if trailing white space */
 136       if (PTRCMP(s + 1, ==, e) || s[1] == '\n')
 137          goto jleave;
 138       goto jnquote;
 139    }
 140
 141    /* Rest are special begin-of-line cases */
 142    if (!sol)
 143       goto jnquote;
 144
 145    /* ^From */
 146    if (a == XF) {
 147       if (PTRCMP(s + 4, <, e) && s[1] == 'r' && s[2] == 'o' && s[3] == 'm')
 148          goto jleave;
 149       goto jnquote;
 150    }
 151    /* ^.$ */
 152    if (a == XD && (PTRCMP(s + 1, ==, e) || s[1] == '\n'))
 153       goto jleave;
 154 jnquote:
 155    r = N;
 156 jleave:
 157    NYD2_LEAVE;
 158    return r;
 159 }
 160
 161 SINLINE char *
 162 _qp_ctohex(char *store, char c)
 163 {
 164    static char const hexmap[] = "0123456789ABCDEF";
 165    NYD2_ENTER;
 166
 167    store[2] = '\0';
 168    store[1] = hexmap[(ui8_t)c & 0x0F];
 169    c = ((ui8_t)c >> 4) & 0x0F;
 170    store[0] = hexmap[(ui8_t)c];
 171    NYD2_LEAVE;
 172    return store;
 173 }
 174
 175 SINLINE si32_t
 176 _qp_cfromhex(char const *hex)
 177 {
 178    /* Be robust, allow lowercase hexadecimal letters, too */
 179    static ui8_t const atoi16[] = {
 180       0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, /* 0x30-0x37 */
 181       0x08, 0x09, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, /* 0x38-0x3F */
 182       0xFF, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F, 0xFF, /* 0x40-0x47 */
 183       0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, /* 0x48-0x4f */
 184       0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, /* 0x50-0x57 */
 185       0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, /* 0x58-0x5f */
 186       0xFF, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F, 0xFF  /* 0x60-0x67 */
 187    };
 188
 189    ui8_t i1, i2;
 190    si32_t r;
 191    NYD2_ENTER;
 192
 193    if ((i1 = (ui8_t)hex[0] - '0') >= NELEM(atoi16) ||
 194          (i2 = (ui8_t)hex[1] - '0') >= NELEM(atoi16))
 195       goto jerr;
 196    i1 = atoi16[i1];
 197    i2 = atoi16[i2];
 198    if ((i1 | i2) & 0xF0u)
 199       goto jerr;
 200    r = i1;
 201    r <<= 4;
 202    r += i2;
 203 jleave:
 204    NYD2_LEAVE;
 205    return r;
 206 jerr:
 207    r = -1;
 208    goto jleave;
 209 }
 210
 211 static size_t
 212 _b64_decode_prepare(struct str *work, struct str const *in)
 213 {
 214    char *cp;
 215    size_t cp_len;
 216    NYD2_ENTER;
 217
 218    cp = in->s;
 219    cp_len = in->l;
 220
 221    while (cp_len > 0 && spacechar(*cp))
 222       ++cp, --cp_len;
 223    work->s = cp;
 224
 225    for (cp += cp_len; cp_len > 0; --cp_len) {
 226       char c = *--cp;
 227       if (!spacechar(c))
 228          break;
 229    }
 230    work->l = cp_len;
 231
 232    if (cp_len > 16)
 233       cp_len = ((cp_len * 3) >> 2) + (cp_len >> 3);
 234    NYD2_LEAVE;
 235    return cp_len;
 236 }
 237
 238 static ssize_t
 239 _b64_decode(struct str *out, struct str *in)
 240 {
 241    static signed char const b64index[] = {
 242       -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
 243       -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
 244       -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,62, -1,-1,-1,63,
 245       52,53,54,55, 56,57,58,59, 60,61,-1,-1, -1,-2,-1,-1,
 246       -1, 0, 1, 2,  3, 4, 5, 6,  7, 8, 9,10, 11,12,13,14,
 247       15,16,17,18, 19,20,21,22, 23,24,25,-1, -1,-1,-1,-1,
 248       -1,26,27,28, 29,30,31,32, 33,34,35,36, 37,38,39,40,
 249       41,42,43,44, 45,46,47,48, 49,50,51,-1, -1,-1,-1,-1
 250    };
 251 #define EQU          (ui32_t)-2
 252 #define BAD          (ui32_t)-1
 253 #define uchar64(c)   ((c) >= sizeof(b64index) ? BAD : (ui32_t)b64index[(c)])
 254
 255    ssize_t ret = -1;
 256    ui8_t *p;
 257    ui8_t const *q, *end;
 258    NYD2_ENTER;
 259
 260    p = (ui8_t*)out->s;
 261    q = (ui8_t const*)in->s;
 262    out->l = 0;
 263
 264    for (end = q + in->l; PTRCMP(q + 4, <=, end); q += 4) {
 265       ui32_t a = uchar64(q[0]), b = uchar64(q[1]), c = uchar64(q[2]),
 266          d = uchar64(q[3]);
 267
 268       if (a >= EQU || b >= EQU || c == BAD || d == BAD)
 269          goto jleave;
 270
 271       *p++ = ((a << 2) | ((b & 0x30) >> 4));
 272       if (c == EQU)  { /* got '=' */
 273          if (d != EQU)
 274             goto jleave;
 275          break;
 276       }
 277       *p++ = (((b & 0x0F) << 4) | ((c & 0x3C) >> 2));
 278       if (d == EQU) /* got '=' */
 279          break;
 280       *p++ = (((c & 0x03) << 6) | d);
 281    }
 282 #undef uchar64
 283 #undef EQU
 284 #undef BAD
 285
 286    ret = PTR2SIZE((char*)p - out->s);
 287    out->l = (size_t)ret;
 288 jleave:
 289    in->l -= PTR2SIZE((char*)UNCONST(q) - in->s);
 290    in->s = UNCONST(q);
 291    NYD2_LEAVE;
 292    return ret;
 293 }
 294
 295 FL char *
 296 mime_char_to_hexseq(char store[3], char c)
 297 {
 298    char *rv;
 299    NYD2_ENTER;
 300
 301    rv = _qp_ctohex(store, c);
 302    NYD2_LEAVE;
 303    return rv;
 304 }
 305
 306 FL si32_t
 307 mime_hexseq_to_char(char const *hex)
 308 {
 309    si32_t rv;
 310    NYD2_ENTER;
 311
 312    rv = _qp_cfromhex(hex);
 313    NYD2_LEAVE;
 314    return rv;
 315 }
 316
 317 FL size_t
 318 mime_cte_mustquote(char const *ln, size_t lnlen, bool_t ishead)
 319 {
 320    size_t ret;
 321    bool_t sol;
 322    NYD_ENTER;
 323
 324    for (ret = 0, sol = TRU1; lnlen > 0; sol = FAL0, ++ln, --lnlen)
 325       ret += (_mustquote(ln, ln + lnlen, sol, ishead) != N);
 326    NYD_LEAVE;
 327    return ret;
 328 }
 329
 330 FL size_t
 331 qp_encode_calc_size(size_t len)
 332 {
 333    size_t i;
 334    NYD_ENTER;
 335    /* The worst case sequence is 'CRLF' -> '=0D=0A=\n\0'.
 336     * However, we must be aware that (a) the output may span multiple lines
 337     * and (b) the input does not end with a newline itself (nonetheless):
 338     *    LC_ALL=C PERL5OPT= perl -CS -e 'print "\x{101D0}" x 100' |
 339     *    MAILRC=/dev/null LC_ALL=en_US.UTF-8 s-nail -nvvd \
 340     *       -Ssendcharsets=utf8 -s testsub ./LETTER */
 341    /* TODO This example shows two things: 1. as stated in TODO this must
 342     * TODO be sequentialised! and 2. this shouldn't end up QP-encoded! */
 343    len *= 3;
 344    i = (len / QP_LINESIZE) + 1;
 345    i <<= 1; /* Double: soft and embedded NL.. */
 346    ++i; /* \0 */
 347    len += ++i; /* ..and \0 */
 348    NYD_LEAVE;
 349    return len;
 350 }
 351
 352 #ifdef notyet
 353 FL struct str *
 354 qp_encode_cp(struct str *out, char const *cp, enum qpflags flags)
 355 {
 356    struct str in;
 357    NYD_ENTER;
 358
 359    in.s = UNCONST(cp);
 360    in.l = strlen(cp);
 361    out = qp_encode(out, &in, flags);
 362    NYD_LEAVE;
 363    return out;
 364 }
 365
 366 FL struct str *
 367 qp_encode_buf(struct str *out, void const *vp, size_t vp_len,
 368    enum qpflags flags)
 369 {
 370    struct str in;
 371    NYD_ENTER;
 372
 373    in.s = UNCONST(vp);
 374    in.l = vp_len;
 375    out = qp_encode(out, &in, flags);
 376    NYD_LEAVE;
 377    return out;
 378 }
 379 #endif /* notyet */
 380
 381 FL struct str *
 382 qp_encode(struct str *out, struct str const *in, enum qpflags flags)
 383 {
 384    bool_t sol = (flags & QP_ISHEAD ? FAL0 : TRU1), seenx;
 385    ssize_t lnlen;
 386    char *qp;
 387    char const *is, *ie;
 388    NYD_ENTER;
 389
 390    if (!(flags & QP_BUF)) {
 391       lnlen = qp_encode_calc_size(in->l);
 392       out->s = (flags & QP_SALLOC) ? salloc(lnlen) : srealloc(out->s, lnlen);
 393    }
 394    qp = out->s;
 395    is = in->s;
 396    ie = is + in->l;
 397
 398    /* QP_ISHEAD? */
 399    if (!sol) {
 400       for (seenx = FAL0, sol = TRU1; is < ie; sol = FAL0, ++qp) {
 401          enum _qact mq = _mustquote(is, ie, sol, TRU1);
 402          char c = *is++;
 403
 404          if (mq == N) {
 405             /* We convert into a single *encoded-word*, that'll end up in
 406              * =?C?Q??=; quote '?' from when we're inside there on */
 407             if (seenx && c == '?')
 408                goto jheadq;
 409             *qp = c;
 410          } else if (mq == US)
 411             *qp = US;
 412          else {
 413             seenx = TRU1;
 414 jheadq:
 415             *qp++ = '=';
 416             qp = _qp_ctohex(qp, c) + 1;
 417          }
 418       }
 419       goto jleave;
 420    }
 421
 422    /* The body needs to take care for soft line breaks etc. */
 423    for (lnlen = 0, seenx = FAL0; is < ie; sol = FAL0) {
 424       enum _qact mq = _mustquote(is, ie, sol, FAL0);
 425       char c = *is++;
 426
 427       if (mq == N && (c != '\n' || !seenx)) {
 428          *qp++ = c;
 429          if (++lnlen < QP_LINESIZE - 1)
 430             continue;
 431          /* Don't write a soft line break when we're in the last possible
 432           * column and either an LF has been written or only an LF follows, as
 433           * that'll end the line anyway */
 434          /* XXX but - ensure is+1>=ie, then??
 435           * xxx and/or - what about resetting lnlen; that contra
 436           * xxx dicts input==1 input line assertion, though */
 437          if (c == '\n' || is == ie || *is == '\n')
 438             continue;
 439 jsoftnl:
 440          qp[0] = '=';
 441          qp[1] = '\n';
 442          qp += 2;
 443          lnlen = 0;
 444          continue;
 445       }
 446
 447       if (lnlen > QP_LINESIZE - 3 - 1) {
 448          qp[0] = '=';
 449          qp[1] = '\n';
 450          qp += 2;
 451          lnlen = 0;
 452       }
 453       *qp++ = '=';
 454       qp = _qp_ctohex(qp, c);
 455       qp += 2;
 456       lnlen += 3;
 457       if (c != '\n' || !seenx)
 458          seenx = (c == '\r');
 459       else {
 460          seenx = FAL0;
 461          goto jsoftnl;
 462       }
 463    }
 464
 465    /* Enforce soft line break if we haven't seen LF */
 466    if (in->l > 0 && *--is != '\n') {
 467       qp[0] = '=';
 468       qp[1] = '\n';
 469       qp += 2;
 470    }
 471 jleave:
 472    out->l = PTR2SIZE(qp - out->s);
 473    out->s[out->l] = '\0';
 474    NYD_LEAVE;
 475    return out;
 476 }
 477
 478 FL int
 479 qp_decode(struct str *out, struct str const *in, struct str *rest)
 480 {
 481    int ret = STOP;
 482    char *os, *oc;
 483    char const *is, *ie;
 484    NYD_ENTER;
 485
 486    if (rest != NULL && rest->l != 0) {
 487       os = out->s;
 488       *out = *rest;
 489       rest->s = os;
 490       rest->l = 0;
 491    }
 492
 493    oc = os =
 494    out->s = srealloc(out->s, out->l + in->l + 3);
 495    oc += out->l;
 496    is = in->s;
 497    ie = is + in->l;
 498
 499    /* Decoding encoded-word (RFC 2049) in a header field? */
 500    if (rest == NULL) {
 501       while (is < ie) {
 502          si32_t c = *is++;
 503          if (c == '=') {
 504             if (PTRCMP(is + 1, >=, ie)) {
 505                ++is;
 506                goto jehead;
 507             }
 508             c = _qp_cfromhex(is);
 509             is += 2;
 510             if (c >= 0)
 511                *oc++ = (char)c;
 512             else {
 513                /* Invalid according to RFC 2045, section 6.7. Almost follow */
 514 jehead:
 515                /* TODO 0xFFFD
 516                *oc[0] = '['; oc[1] = '?'; oc[2] = ']';
 517                *oc += 3; 0xFFFD TODO
 518                */ *oc++ = '?';
 519             }
 520          } else
 521             *oc++ = (c == '_') ? ' ' : (char)c;
 522       }
 523       goto jleave; /* XXX QP decode, header: errors not reported */
 524    }
 525
 526    /* Decoding a complete message/mimepart body line */
 527    while (is < ie) {
 528       si32_t c = *is++;
 529       if (c != '=') {
 530          *oc++ = (char)c;
 531          continue;
 532       }
 533
 534       /* RFC 2045, 6.7:
 535        *   Therefore, when decoding a Quoted-Printable body, any
 536        *   trailing white space on a line must be deleted, as it will
 537        *   necessarily have been added by intermediate transport
 538        *   agents */
 539       for (; is < ie && blankchar(*is); ++is)
 540          ;
 541       if (PTRCMP(is + 1, >=, ie)) {
 542          /* Soft line break? */
 543          if (*is == '\n')
 544             goto jsoftnl;
 545          ++is;
 546          goto jebody;
 547       }
 548
 549       /* Not a soft line break? */
 550       if (*is != '\n') {
 551          c = _qp_cfromhex(is);
 552          is += 2;
 553          if (c >= 0)
 554             *oc++ = (char)c;
 555          else {
 556             /* Invalid according to RFC 2045, section 6.7.
 557              * Almost follow it and include the = and the follow char */
 558 jebody:
 559             /* TODO 0xFFFD
 560             *oc[0] = '['; oc[1] = '?'; oc[2] = ']';
 561             *oc += 3; 0xFFFD TODO
 562             */ *oc++ = '?';
 563          }
 564          continue;
 565       }
 566
 567       /* CRLF line endings are encoded as QP, followed by a soft line break, so
 568        * check for this special case, and simply forget we have seen one, so as
 569        * not to end up with the entire DOS file in a contiguous buffer */
 570 jsoftnl:
 571       if (oc > os && oc[-1] == '\n') {
 572 #if 0       /* TODO qp_decode() we do not normalize CRLF
 573           * TODO to LF because for that we would need
 574           * TODO to know if we are about to write to
 575           * TODO the display or do save the file!
 576           * TODO 'hope the MIME/send layer rewrite will
 577           * TODO offer the possibility to DTRT */
 578          if (oc - 1 > os && oc[-2] == '\r') {
 579             --oc;
 580             oc[-1] = '\n';
 581          }
 582 #endif
 583          break;
 584       }
 585       out->l = PTR2SIZE(oc - os);
 586       rest->s = srealloc(rest->s, rest->l + out->l);
 587       memcpy(rest->s + rest->l, out->s, out->l);
 588       rest->l += out->l;
 589       oc = os;
 590       break;
 591    }
 592    /* XXX RFC: QP decode should check no trailing WS on line */
 593 jleave:
 594    out->l = PTR2SIZE(oc - os);
 595    ret = OKAY;
 596    NYD_LEAVE;
 597    return ret;
 598 }
 599
 600 FL size_t
 601 b64_encode_calc_size(size_t len)
 602 {
 603    NYD_ENTER;
 604    len = (len * 4) / 3;
 605    len += (((len / B64_ENCODE_INPUT_PER_LINE) + 1) * 3);
 606    len += 2 + 1; /* CRLF, \0 */
 607    NYD_LEAVE;
 608    return len;
 609 }
 610
 611 FL struct str *
 612 b64_encode(struct str *out, struct str const *in, enum b64flags flags)
 613 {
 614    static char const b64table[] =
 615        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
 616
 617    ui8_t const *p;
 618    ssize_t i, lnlen;
 619    char *b64;
 620    NYD_ENTER;
 621
 622    p = (ui8_t const*)in->s;
 623
 624    if (!(flags & B64_BUF)) {
 625       i = b64_encode_calc_size(in->l);
 626       out->s = (flags & B64_SALLOC) ? salloc(i) : srealloc(out->s, i);
 627    }
 628    b64 = out->s;
 629
 630    if (!(flags & (B64_CRLF | B64_LF)))
 631       flags &= ~B64_MULTILINE;
 632
 633    for (lnlen = 0, i = (ssize_t)in->l; i > 0; p += 3, i -= 3) {
 634       ui32_t a = p[0], b, c;
 635
 636       b64[0] = b64table[a >> 2];
 637       switch (i) {
 638       case 1:
 639          b64[1] = b64table[((a & 0x3) << 4)];
 640          b64[2] =
 641          b64[3] = '=';
 642          break;
 643       case 2:
 644          b = p[1];
 645          b64[1] = b64table[((a & 0x03) << 4) | ((b & 0xF0u) >> 4)];
 646          b64[2] = b64table[((b & 0x0F) << 2)];
 647          b64[3] = '=';
 648          break;
 649       default:
 650          b = p[1];
 651          c = p[2];
 652          b64[1] = b64table[((a & 0x03) << 4) | ((b & 0xF0u) >> 4)];
 653          b64[2] = b64table[((b & 0x0F) << 2) | ((c & 0xC0u) >> 6)];
 654          b64[3] = b64table[c & 0x3F];
 655          break;
 656       }
 657
 658       b64 += 4;
 659       if (!(flags & B64_MULTILINE))
 660          continue;
 661       lnlen += 4;
 662       if (lnlen < B64_LINESIZE)
 663          continue;
 664
 665       lnlen = 0;
 666       if (flags & B64_CRLF)
 667          *b64++ = '\r';
 668       if (flags & (B64_CRLF | B64_LF))
 669          *b64++ = '\n';
 670    }
 671
 672    if ((flags & (B64_CRLF | B64_LF)) &&
 673          (!(flags & B64_MULTILINE) || lnlen != 0)) {
 674       if (flags & B64_CRLF)
 675          *b64++ = '\r';
 676       if (flags & (B64_CRLF | B64_LF))
 677          *b64++ = '\n';
 678    }
 679    out->l = PTR2SIZE(b64 - out->s);
 680    out->s[out->l] = '\0';
 681    NYD_LEAVE;
 682    return out;
 683 }
 684
 685 FL struct str *
 686 b64_encode_buf(struct str *out, void const *vp, size_t vp_len,
 687    enum b64flags flags)
 688 {
 689    struct str in;
 690    NYD_ENTER;
 691
 692    in.s = UNCONST(vp);
 693    in.l = vp_len;
 694    out = b64_encode(out, &in, flags);
 695    NYD_LEAVE;
 696    return out;
 697 }
 698
 699 #ifdef HAVE_SMTP
 700 FL struct str *
 701 b64_encode_cp(struct str *out, char const *cp, enum b64flags flags)
 702 {
 703    struct str in;
 704    NYD_ENTER;
 705
 706    in.s = UNCONST(cp);
 707    in.l = strlen(cp);
 708    out = b64_encode(out, &in, flags);
 709    NYD_LEAVE;
 710    return out;
 711 }
 712 #endif
 713
 714 FL int
 715 b64_decode(struct str *out, struct str const *in, struct str *rest)
 716 {
 717    struct str work;
 718    char *x;
 719    int ret = STOP;
 720    size_t len;
 721    NYD_ENTER;
 722
 723    len = _b64_decode_prepare(&work, in);
 724
 725    /* Ignore an empty input, as may happen for an empty final line */
 726    if (work.l == 0) {
 727       /* With B64_T there may be leftover decoded data for iconv(3), even if
 728        * that means it's incomplete multibyte character we have to copy over */
 729       /* XXX strictly speaking this should not be handled in here,
 730        * XXX since its leftover decoded data from an iconv(3);
 731        * XXX like this we shared the prototype with QP, though?? */
 732       if (rest != NULL && rest->l > 0) {
 733          x = out->s;
 734          *out = *rest;
 735          rest->s = x;
 736          rest->l = 0;
 737       } else
 738          out->l = 0;
 739       ret = OKAY;
 740       goto jleave;
 741    }
 742    if (work.l >= 4 && !(work.l & 3)) {
 743       out->s = srealloc(out->s, len);
 744       ret = OKAY;
 745    }
 746    if (ret != OKAY || (ssize_t)(len = _b64_decode(out, &work)) < 0)
 747       goto jerr;
 748 jleave:
 749    NYD_LEAVE;
 750    return ret;
 751
 752 jerr: {
 753    char const *err = _("[Invalid Base64 encoding ignored]\n");
 754    len = strlen(err);
 755    x = out->s = srealloc(out->s, len + 1 +1);
 756    if (rest != NULL && rest->l)
 757       *x++ = '\n';
 758    memcpy(x, err, len);
 759    x += len;
 760    *x = '\0';
 761    out->l = PTR2SIZE(x - out->s);
 762    if (rest != NULL)
 763       rest->l = 0;
 764    ret = STOP;
 765    goto jleave;
 766    }
 767 }
 768
 769 /* s-it-mode */