mime_fromhdr(): fix my rewrite again..

[s-mailx.git] / mime.c

/*@ S-nail - a mail user agent derived from Berkeley Mail.
 *@ MIME support functions.
 *
 * Copyright (c) 2000-2004 Gunnar Ritter, Freiburg i. Br., Germany.
 * Copyright (c) 2012 - 2014 Steffen "Daode" Nurpmeso <sdaoden@users.sf.net>.
 */
/*
 * Copyright (c) 2000
 *      Gunnar Ritter.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by Gunnar Ritter
 *      and his contributors.
 * 4. Neither the name of Gunnar Ritter nor the names of his contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY GUNNAR RITTER AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL GUNNAR RITTER OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#ifndef HAVE_AMALGAMATION
# include "nail.h"
#endif

#define _CHARSET()      ((_cs_iter != NULL) ? _cs_iter : charset_get_8bit())

struct mtnode {
        struct mtnode   *mt_next;
        size_t          mt_mtlen;       /* Length of MIME type string */
        char            mt_line[VFIELD_SIZE(8)];
};

static char const       *const _mt_sources[] = {
                /* XXX Order fixed due to *mimetypes-load-control* handling! */
                MIME_TYPES_USR, MIME_TYPES_SYS, NULL
        },
                        *const _mt_bltin[] = {
#include "mime_types.h"
                NULL
        };

struct mtnode   *_mt_list;
char            *_cs_iter_base, *_cs_iter;

/* Initialize MIME type list */
static void     _mt_init(void);
static void     __mt_add_line(char const *line, struct mtnode **tail);

/* Get the conversion that matches *encoding* */
static enum conversion _conversion_by_encoding(void);

/* fwrite(3) while checking for displayability */
static ssize_t  _fwrite_td(struct str const *input, enum tdflags flags,
                        struct str *rest, struct quoteflt *qf);

static size_t   delctrl(char *cp, size_t sz);
static int has_highbit(register const char *s);
static int is_this_enc(const char *line, const char *encoding);
static size_t mime_write_tohdr(struct str *in, FILE *fo);
static size_t convhdra(char const *str, size_t len, FILE *fp);
static size_t mime_write_tohdr_a(struct str *in, FILE *f);
static void addstr(char **buf, size_t *sz, size_t *pos,
                char const *str, size_t len);
static void addconv(char **buf, size_t *sz, size_t *pos,
                char const *str, size_t len);

static void
_mt_init(void)
{
        struct mtnode *tail = NULL;
        char *line = NULL;
        size_t linesize = 0;
        ui_it idx, idx_ok;
        char const *ccp, *const*srcs;
        FILE *fp;

        if ((ccp = ok_vlook(mimetypes_load_control)) == NULL)
                idx_ok = (ui_it)-1;
        else for (idx_ok = 0; *ccp != '\0'; ++ccp)
                switch (*ccp) {
                case 'S':
                case 's':
                        idx_ok |= 1 << 1;
                        break;
                case 'U':
                case 'u':
                        idx_ok |= 1 << 0;
                        break;
                default:
                        /* XXX bad *mimetypes-load-control*; log error? */
                        break;
                }

        for (idx = 1, srcs = _mt_sources; *srcs != NULL; idx <<= 1, ++srcs) {
                if ((idx & idx_ok) == 0 || (ccp = file_expand(*srcs)) == NULL)
                        continue;
                if ((fp = Fopen(ccp, "r")) == NULL) {
                        /*fprintf(stderr, tr(176, "Cannot open %s\n"), fn);*/
                        continue;
                }
                while (fgetline(&line, &linesize, NULL, NULL, fp, 0))
                        __mt_add_line(line, &tail);
                Fclose(fp);
        }
        if (line != NULL)
                free(line);

        for (srcs = _mt_bltin; *srcs != NULL; ++srcs)
                __mt_add_line(*srcs, &tail);
}

static void
__mt_add_line(char const *line, struct mtnode **tail) /* XXX diag? dups!*/
{
        char const *typ;
        size_t tlen, elen;
        struct mtnode *mtn;

        if (! alphachar(*line))
                goto jleave;

        typ = line;
        while (blankchar(*line) == 0 && *line != '\0')
                ++line;
        if (*line == '\0')
                goto jleave;
        tlen = (size_t)(line - typ);

        while (blankchar(*line) != 0 && *line != '\0')
                ++line;
        if (*line == '\0')
                goto jleave;

        elen = strlen(line);
        if (line[elen - 1] == '\n' && line[--elen] == '\0')
                goto jleave;

        mtn = smalloc(sizeof(struct mtnode) -
                VFIELD_SIZEOF(struct mtnode, mt_line) +
                tlen + 1 + elen + 1);
        if (*tail != NULL)
                (*tail)->mt_next = mtn;
        else
                _mt_list = mtn;
        *tail = mtn;
        mtn->mt_next = NULL;
        mtn->mt_mtlen = tlen;
        memcpy(mtn->mt_line, typ, tlen);
        mtn->mt_line[tlen] = '\0';
        ++tlen;
        memcpy(mtn->mt_line + tlen, line, elen);
        tlen += elen;
        mtn->mt_line[tlen] = '\0';
jleave: ;
}

static enum conversion
_conversion_by_encoding(void)
{
        char const *cp;
        enum conversion ret;

        if ((cp = ok_vlook(encoding)) == NULL)
                ret = MIME_DEFAULT_ENCODING;
        else if (strcmp(cp, "quoted-printable") == 0)
                ret = CONV_TOQP;
        else if (strcmp(cp, "8bit") == 0)
                ret = CONV_8BIT;
        else if (strcmp(cp, "base64") == 0)
                ret = CONV_TOB64;
        else {
                fprintf(stderr, tr(177,
                        "Warning: invalid encoding %s, using base64\n"), cp);
                ret = CONV_TOB64;
        }
        return (ret);
}

static ssize_t
_fwrite_td(struct str const *input, enum tdflags flags, struct str *rest,
        struct quoteflt *qf)
{
        /* TODO note: after send/MIME layer rewrite we will have a string pool
         * TODO so that memory allocation count drops down massively; for now,
         * TODO v14.* that is, we pay a lot & heavily depend on the allocator */
        /* TODO well if we get a broken pipe here, and it happens to
         * TODO happen pretty easy when sleeping in a full pipe buffer,
         * TODO then the current codebase performs longjump away;
         * TODO this leaves memory leaks behind ('think up to 3 per,
         * TODO dep. upon alloca availability).  For this to be fixed
         * TODO we either need to get rid of the longjmp()s (tm) or
         * TODO the storage must come from the outside or be tracked
         * TODO in a carrier struct.  Best both.  But storage reuse
         * TODO would be a bigbig win besides */
        /* *input* _may_ point to non-modifyable buffer; but even then it only
         * needs to be dup'ed away if we have to transform the content */
        struct str in, out;
        ssize_t rv;
        (void)rest;

        in = *input;
        out.s = NULL;
        out.l = 0;

#ifdef HAVE_ICONV
        if ((flags & TD_ICONV) && iconvd != (iconv_t)-1) {
                char *buf = NULL;

                if (rest != NULL && rest->l > 0) {
                        in.l = rest->l + input->l;
                        in.s = buf = smalloc(in.l + 1);
                        memcpy(in.s, rest->s, rest->l);
                        memcpy(in.s + rest->l, input->s, input->l);
                        rest->l = 0;

                }
                if (n_iconv_str(iconvd, &out, &in, &in, TRU1) != 0 &&
                                rest != NULL && in.l > 0) {
                        /* Incomplete multibyte at EOF is special */
                        if (flags & _TD_EOF) {
                                out.s = srealloc(out.s, out.l + 4);
                                /* TODO 0xFFFD out.s[out.l++] = '[';*/
                                out.s[out.l++] = '?'; /* TODO 0xFFFD !!! */
                                /* TODO 0xFFFD out.s[out.l++] = ']';*/
                        } else
                                (void)n_str_add(rest, &in);
                }
                in = out;
                out.s = NULL;
                flags &= ~_TD_BUFCOPY;

                if (buf != NULL)
                        free(buf);
        }
#endif

        if (flags & TD_ISPR)
                makeprint(&in, &out);
        else if (flags & _TD_BUFCOPY)
                n_str_dup(&out, &in);
        else
                out = in;
        if (flags & TD_DELCTRL)
                out.l = delctrl(out.s, out.l);

        rv = quoteflt_push(qf, out.s, out.l);

        if (out.s != in.s)
                free(out.s);
        if (in.s != input->s)
                free(in.s);
        return rv;
}

static size_t
delctrl(char *cp, size_t sz)
{
        size_t  x = 0, y = 0;

        while (x < sz) {
                if (!cntrlchar(cp[x]&0377))
                        cp[y++] = cp[x];
                x++;
        }
        return y;
}

static int
has_highbit(const char *s)
{
        if (s) {
                do
                        if (*s & 0200)
                                return 1;
                while (*s++ != '\0');
        }
        return 0;
}

static int
name_highbit(struct name *np)
{
        while (np) {
                if (has_highbit(np->n_name) || has_highbit(np->n_fullname))
                        return 1;
                np = np->n_flink;
        }
        return 0;
}

FL char const *
charset_get_7bit(void)
{
        char const *t;

        if ((t = ok_vlook(charset_7bit)) == NULL)
                t = CHARSET_7BIT;
        return (t);
}

FL char const *
charset_get_8bit(void)
{
        char const *t;

        if ((t = ok_vlook(CHARSET_8BIT_OKEY)) == NULL)
                t = CHARSET_8BIT;
        return (t);
}

FL char const *
charset_get_lc(void)
{
        char const *t;

        if ((t = ok_vlook(ttycharset)) == NULL)
                t = CHARSET_8BIT;
        return (t);
}

FL void
charset_iter_reset(char const *a_charset_to_try_first)
{
        char const *sarr[3];
        size_t sarrl[3], len;
        char *cp;

        sarr[0] = a_charset_to_try_first;
#ifdef HAVE_ICONV
        if ((sarr[1] = ok_vlook(sendcharsets)) == NULL &&
                        ok_blook(sendcharsets_else_ttycharset))
                sarr[1] = charset_get_lc();
#endif
        sarr[2] = charset_get_8bit();

        sarrl[2] = len = strlen(sarr[2]);
#ifdef HAVE_ICONV
        if ((cp = UNCONST(sarr[1])) != NULL)
                len += (sarrl[1] = strlen(cp));
        else
                sarrl[1] = 0;
        if ((cp = UNCONST(sarr[0])) != NULL)
                len += (sarrl[0] = strlen(cp));
        else
                sarrl[0] = 0;
#endif

        _cs_iter_base = cp = salloc(len + 1 + 1 +1);

#ifdef HAVE_ICONV
        if ((len = sarrl[0]) != 0) {
                memcpy(cp, sarr[0], len);
                cp[len] = ',';
                cp += ++len;
        }
        if ((len = sarrl[1]) != 0) {
                memcpy(cp, sarr[1], len);
                cp[len] = ',';
                cp += ++len;
        }
#endif
        len = sarrl[2];
        memcpy(cp, sarr[2], len);
        cp[len] = '\0';
        _cs_iter = NULL;
}

FL char const *
charset_iter_next(void)
{
        return (_cs_iter = strcomma(&_cs_iter_base, 1));
}

FL char const *
charset_iter_current(void)
{
        return _cs_iter;
}

FL void
charset_iter_recurse(char *outer_storage[2]) /* TODO LEGACY FUN, REMOVE */
{
        outer_storage[0] = _cs_iter_base;
        outer_storage[1] = _cs_iter;
}

FL void
charset_iter_restore(char *outer_storage[2]) /* TODO LEGACY FUN, REMOVE */
{
        _cs_iter_base = outer_storage[0];
        _cs_iter = outer_storage[1];
}

FL char const *
need_hdrconv(struct header *hp, enum gfield w)
{
        char const *ret = NULL;

        if (w & GIDENT) {
                if (hp->h_from != NULL) {
                        if (name_highbit(hp->h_from))
                                goto jneeds;
                } else if (has_highbit(myaddrs(NULL)))
                        goto jneeds;
                if (hp->h_organization) {
                        if (has_highbit(hp->h_organization))
                                goto jneeds;
                } else if (has_highbit(ok_vlook(ORGANIZATION)))
                        goto jneeds;
                if (hp->h_replyto) {
                        if (name_highbit(hp->h_replyto))
                                goto jneeds;
                } else if (has_highbit(ok_vlook(replyto)))
                        goto jneeds;
                if (hp->h_sender) {
                        if (name_highbit(hp->h_sender))
                                goto jneeds;
                } else if (has_highbit(ok_vlook(sender)))
                        goto jneeds;
        }
        if (w & GTO && name_highbit(hp->h_to))
                goto jneeds;
        if (w & GCC && name_highbit(hp->h_cc))
                goto jneeds;
        if (w & GBCC && name_highbit(hp->h_bcc))
                goto jneeds;
        if (w & GSUBJECT && has_highbit(hp->h_subject))
jneeds:         ret = _CHARSET();
        return (ret);
}

static int
is_this_enc(const char *line, const char *encoding)
{
        int quoted = 0, c;

        if (*line == '"')
                quoted = 1, line++;
        while (*line && *encoding)
                if (c = *line++, lowerconv(c) != *encoding++)
                        return 0;
        if (quoted && *line == '"')
                return 1;
        if (*line == '\0' || whitechar(*line & 0377))
                return 1;
        return 0;
}

/*
 * Get the mime encoding from a Content-Transfer-Encoding header field.
 */
FL enum mimeenc
mime_getenc(char *p)
{
        if (is_this_enc(p, "7bit"))
                return MIME_7B;
        if (is_this_enc(p, "8bit"))
                return MIME_8B;
        if (is_this_enc(p, "base64"))
                return MIME_B64;
        if (is_this_enc(p, "binary"))
                return MIME_BIN;
        if (is_this_enc(p, "quoted-printable"))
                return MIME_QP;
        return MIME_NONE;
}

/*
 * Get a mime style parameter from a header line.
 */
FL char *
mime_getparam(char const *param, char *h)
{
        char *p = h, *q, *r;
        int c;
        size_t sz;

        sz = strlen(param);
        if (!whitechar(*p & 0377)) {
                c = '\0';
                while (*p && (*p != ';' || c == '\\')) {
                        c = c == '\\' ? '\0' : *p;
                        p++;
                }
                if (*p++ == '\0')
                        return NULL;
        }
        for (;;) {
                while (whitechar(*p & 0377))
                        p++;
                if (ascncasecmp(p, param, sz) == 0) {
                        p += sz;
                        while (whitechar(*p & 0377))
                                p++;
                        if (*p++ == '=')
                                break;
                }
                c = '\0';
                while (*p && (*p != ';' || c == '\\')) {
                        if (*p == '"' && c != '\\') {
                                p++;
                                while (*p && (*p != '"' || c == '\\')) {
                                        c = c == '\\' ? '\0' : *p;
                                        p++;
                                }
                                p++;
                        } else {
                                c = c == '\\' ? '\0' : *p;
                                p++;
                        }
                }
                if (*p++ == '\0')
                        return NULL;
        }
        while (whitechar(*p & 0377))
                p++;
        q = p;
        if (*p == '"') {
                p++;
                if ((q = strchr(p, '"')) == NULL)
                        return NULL;
        } else {
                while (*q && !whitechar(*q & 0377) && *q != ';')
                        q++;
        }
        sz = q - p;
        r = salloc(q - p + 1);
        memcpy(r, p, sz);
        *(r + sz) = '\0';
        return r;
}

FL char *
mime_get_boundary(char *h, size_t *len)
{
        char *q = NULL, *p;
        size_t sz;

        if ((p = mime_getparam("boundary", h)) != NULL) {
                sz = strlen(p);
                if (len != NULL)
                        *len = sz + 2;
                q = salloc(sz + 3);
                q[0] = q[1] = '-';
                memcpy(q + 2, p, sz);
                *(q + sz + 2) = '\0';
        }
        return (q);
}

FL char *
mime_create_boundary(void)
{
        char *bp;

        bp = salloc(48);
        snprintf(bp, 48, "=_%011lu=-%s=_",
                (ul_it)time_current.tc_time, getrandstring(47 - (11 + 6)));
        return bp;
}

FL int
mime_classify_file(FILE *fp, char const **contenttype, char const **charset,
        int *do_iconv)
{
        /* TODO classify once only PLEASE PLEASE PLEASE */
        /* TODO BTW., after the MIME/send layer rewrite we could use a MIME
         * TODO boundary of "=-=-=" if we would add a B_ in EQ spirit to F_,
         * TODO and report that state to the outer world */
#define F_              "From "
#define F_SIZEOF        (sizeof(F_) - 1)

        char f_buf[F_SIZEOF], *f_p = f_buf;
        enum {  _CLEAN          = 0,    /* Plain RFC 2822 message */
                _NCTT           = 1<<0, /* *contenttype == NULL */
                _ISTXT          = 1<<1, /* *contenttype =~ text/ */
                _ISTXTCOK       = 1<<2, /* _ISTXT+*mime-allow-text-controls* */
                _HIGHBIT        = 1<<3, /* Not 7bit clean */
                _LONGLINES      = 1<<4, /* MIME_LINELEN_LIMIT exceed. */
                _CTRLCHAR       = 1<<5, /* Control characters seen */
                _HASNUL         = 1<<6, /* Contains \0 characters */
                _NOTERMNL       = 1<<7, /* Lacks a final newline */
                _TRAILWS        = 1<<8, /* Blanks before NL */
                _FROM_          = 1<<9  /* ^From_ seen */
        } ctt = _CLEAN;
        enum conversion convert;
        sl_it curlen;
        int c, lastc;

        assert(ftell(fp) == 0x0l);

        *do_iconv = 0;

        if (*contenttype == NULL)
                ctt = _NCTT;
        else if (ascncasecmp(*contenttype, "text/", 5) == 0)
                ctt = ok_blook(mime_allow_text_controls)
                        ? _ISTXT | _ISTXTCOK : _ISTXT;
        convert = _conversion_by_encoding();

        if (fsize(fp) == 0)
                goto j7bit;

        /* We have to inspect the file content */
        for (curlen = 0, c = EOF;; ++curlen) {
                lastc = c;
                c = getc(fp);

                if (c == '\0') {
                        ctt |= _HASNUL;
                        if ((ctt & _ISTXTCOK) == 0)
                                break;
                        continue;
                }
                if (c == '\n' || c == EOF) {
                        if (curlen >= MIME_LINELEN_LIMIT)
                                ctt |= _LONGLINES;
                        if (c == EOF)
                                break;
                        if (blankchar(lastc))
                                ctt |= _TRAILWS;
                        f_p = f_buf;
                        curlen = -1;
                        continue;
                }
                /*
                 * A bit hairy is handling of \r=\x0D=CR.
                 * RFC 2045, 6.7: Control characters other than TAB, or
                 * CR and LF as parts of CRLF pairs, must not appear.
                 * \r alone does not force _CTRLCHAR below since we cannot peek
                 * the next character.
                 * Thus right here, inspect the last seen character for if its
                 * \r and set _CTRLCHAR in a delayed fashion
                 */
                /*else*/ if (lastc == '\r')
                        ctt |= _CTRLCHAR;

                /* Control character? */
                if (c < 0x20 || c == 0x7F) {
                        /* RFC 2045, 6.7, as above ... */
                        if (c != '\t' && c != '\r')
                                ctt |= _CTRLCHAR;
                        /*
                         * If there is a escape sequence in backslash notation
                         * defined for this in ANSI X3.159-1989 (ANSI C89),
                         * don't treat it as a control for real.
                         * I.e., \a=\x07=BEL, \b=\x08=BS, \t=\x09=HT.
                         * Don't follow libmagic(1) in respect to \v=\x0B=VT.
                         * \f=\x0C=NP; do ignore \e=\x1B=ESC.
                         */
                        if ((c >= '\x07' && c <= '\x0D') || c == '\x1B')
                                continue;
                        ctt |= _HASNUL; /* Force base64 */
                        if ((ctt & _ISTXTCOK) == 0)
                                break;
                } else if (c & 0x80) {
                        ctt |= _HIGHBIT;
                        /* TODO count chars with HIGHBIT? libmagic?
                         * TODO try encode part - base64 if bails? */
                        if ((ctt & (_NCTT|_ISTXT)) == 0) { /* TODO _NCTT?? */
                                ctt |= _HASNUL; /* Force base64 */
                                break;
                        }
                } else if ((ctt & _FROM_) == 0 && curlen < (sl_it)F_SIZEOF) {
                        *f_p++ = (char)c;
                        if (curlen == (sl_it)(F_SIZEOF - 1) &&
                                        PTR2SIZE(f_p - f_buf) == F_SIZEOF &&
                                        memcmp(f_buf, F_, F_SIZEOF) == 0)
                                ctt |= _FROM_;
                }
        }
        if (lastc != '\n')
                ctt |= _NOTERMNL;
        rewind(fp);

        if (ctt & _HASNUL) {
                convert = CONV_TOB64;
                /* Don't overwrite a text content-type to allow UTF-16 and
                 * such, but only on request;
                 * Otherwise enforce what file(1)/libmagic(3) would suggest */
                if (ctt & _ISTXTCOK)
                        goto jcharset;
                if (ctt & (_NCTT|_ISTXT))
                        *contenttype = "application/octet-stream";
                if (*charset == NULL)
                        *charset = "binary";
                goto jleave;
        }

        if (ctt & (_LONGLINES|_CTRLCHAR|_NOTERMNL|_TRAILWS|_FROM_)) {
                convert = CONV_TOQP;
                goto jstepi;
        }
        if (ctt & _HIGHBIT) {
jstepi:         if (ctt & (_NCTT|_ISTXT))
                        *do_iconv = (ctt & _HIGHBIT) != 0;
        } else
j7bit:          convert = CONV_7BIT;
        if (ctt & _NCTT)
                *contenttype = "text/plain";

        /* Not an attachment with specified charset? */
jcharset:
        if (*charset == NULL)
                *charset = (ctt & _HIGHBIT) ? _CHARSET() : charset_get_7bit();
jleave:
        return (convert);
#undef F_
#undef F_SIZEOF
}

FL enum mimecontent
mime_classify_content_of_part(struct mimepart const *mip)
{
        enum mimecontent mc = MIME_UNKNOWN;
        char const *ct = mip->m_ct_type_plain;

        if (asccasecmp(ct, "application/octet-stream") == 0 &&
                        mip->m_filename != NULL &&
                        ok_blook(mime_counter_evidence)) {
                ct = mime_classify_content_type_by_fileext(mip->m_filename);
                if (ct == NULL)
                        /* TODO how about let *mime-counter-evidence* have
                         * TODO a value, and if set, saving the attachment in
                         * TODO a temporary file that mime_classify_file() can
                         * TODO examine, and using MIME_TEXT if that gives us
                         * TODO something that seems to be human readable?! */
                        goto jleave;
        }
        if (strchr(ct, '/') == NULL) /* For compatibility with non-MIME */
                mc = MIME_TEXT;
        else if (asccasecmp(ct, "text/plain") == 0)
                mc = MIME_TEXT_PLAIN;
        else if (asccasecmp(ct, "text/html") == 0)
                mc = MIME_TEXT_HTML;
        else if (ascncasecmp(ct, "text/", 5) == 0)
                mc = MIME_TEXT;
        else if (asccasecmp(ct, "message/rfc822") == 0)
                mc = MIME_822;
        else if (ascncasecmp(ct, "message/", 8) == 0)
                mc = MIME_MESSAGE;
        else if (asccasecmp(ct, "multipart/alternative") == 0)
                mc = MIME_ALTERNATIVE;
        else if (asccasecmp(ct, "multipart/digest") == 0)
                mc = MIME_DIGEST;
        else if (ascncasecmp(ct, "multipart/", 10) == 0)
                mc = MIME_MULTI;
        else if (asccasecmp(ct, "application/x-pkcs7-mime") == 0 ||
                        asccasecmp(ct, "application/pkcs7-mime") == 0)
                mc = MIME_PKCS7;
jleave:
        return (mc);
}

FL char *
mime_classify_content_type_by_fileext(char const *name)
{
        char *content = NULL;
        struct mtnode *mtn;
        size_t nlen;

        if ((name = strrchr(name, '.')) == NULL || *++name == '\0')
                goto jleave;

        if (_mt_list == NULL)
                _mt_init();

        nlen = strlen(name);
        for (mtn = _mt_list; mtn != NULL; mtn = mtn->mt_next) {
                char const *ext = mtn->mt_line + mtn->mt_mtlen + 1,
                        *cp = ext;
                do {
                        while (! whitechar(*cp) && *cp != '\0')
                                ++cp;
                        /* Better to do case-insensitive comparison on
                         * extension, since the RFC doesn't specify case of
                         * attribute values? */
                        if (nlen == (size_t)(cp - ext) &&
                                        ascncasecmp(name, ext, nlen) == 0) {
                                content = savestrbuf(mtn->mt_line,
                                                mtn->mt_mtlen);
                                goto jleave;
                        }
                        while (whitechar(*cp) && *cp != '\0')
                                ++cp;
                        ext = cp;
                } while (*ext != '\0');
        }
jleave:
        return (content);
}

FL int
c_mimetypes(void *v)
{
        char **argv = v;
        struct mtnode *mtn;

        if (*argv == NULL)
                goto jlist;
        if (argv[1] != NULL)
                goto jerr;
        if (asccasecmp(*argv, "show") == 0)
                goto jlist;
        if (asccasecmp(*argv, "clear") == 0)
                goto jclear;
jerr:
        fprintf(stderr, "Synopsis: mimetypes: %s\n", tr(418,
                "Either <show> (default) or <clear> the mime.types cache"));
        v = NULL;
jleave:
        return (v == NULL ? !STOP : !OKAY); /* xxx 1:bad 0:good -- do some */

jlist:  {
        FILE *fp;
        char *cp;
        size_t l;

        if (_mt_list == NULL)
                _mt_init();

        if ((fp = Ftemp(&cp, "Ra", "w+", 0600, 1)) == NULL) {
                perror("tmpfile");
                v = NULL;
                goto jleave;
        }
        rm(cp);
        Ftfree(&cp);

        for (l = 0, mtn = _mt_list; mtn != NULL; ++l, mtn = mtn->mt_next)
                fprintf(fp, "%s\t%s\n", mtn->mt_line,
                        mtn->mt_line + mtn->mt_mtlen + 1);

        page_or_print(fp, l);
        Fclose(fp);
        }
        goto jleave;

jclear:
        while ((mtn = _mt_list) != NULL) {
                _mt_list = mtn->mt_next;
                free(mtn);
        }
        goto jleave;
}

FL void
mime_fromhdr(struct str const *in, struct str *out, enum tdflags flags)
{
   /* TODO mime_fromhdr(): is called with strings that contain newlines;
    * TODO this is the usual newline problem all around the codebase;
    * TODO i.e., if we strip it, then the display misses it ;>
    * TODO this is why it is so messy and why S-nail v14.2 plus additional
    * TODO patch for v14.5.2 (and maybe even v14.5.3 subminor) occurred, and
    * TODO why our display reflects what is contained in the message: the 1:1
    * TODO relationship of message content and display!
    * TODO instead a header line should be decoded to what it is (a single
    * TODO line that is) and it should be objective to the backend wether
    * TODO it'll be folded to fit onto the display or not, e.g., for search
    * TODO purposes etc.  then the only condition we have to honour in here
    * TODO is that whitespace in between multiple adjacent MIME encoded words
    * TODO á la RFC 2047 is discarded; i.e.: this function should deal with
    * TODO RFC 2047 and be renamed: mime_fromhdr() -> mime_rfc2047_decode() */
        struct str cin, cout;
        char *p, *op, *upper, *cs, *cbeg;
   ui32_t convert, lastenc, lastoutl;
#ifdef HAVE_ICONV
        char const *tcs;
        iconv_t fhicd = (iconv_t)-1;
#endif

        out->l = 0;
        if (in->l == 0) {
                *(out->s = smalloc(1)) = '\0';
                goto jleave;
        }
        out->s = NULL;

#ifdef HAVE_ICONV
        tcs = charset_get_lc();
#endif
        p = in->s;
        upper = p + in->l;
   lastenc = lastoutl = 0;

        while (p < upper) {
                op = p;
                if (*p == '=' && *(p + 1) == '?') {
                        p += 2;
                        cbeg = p;
                        while (p < upper && *p != '?')
                                p++;    /* strip charset */
                        if (p >= upper)
                                goto jnotmime;
                        cs = salloc(++p - cbeg);
                        memcpy(cs, cbeg, p - cbeg - 1);
                        cs[p - cbeg - 1] = '\0';
#ifdef HAVE_ICONV
                        if (fhicd != (iconv_t)-1)
                                n_iconv_close(fhicd);
                        if (asccasecmp(cs, tcs) != 0)
                                fhicd = n_iconv_open(tcs, cs);
                        else
                                fhicd = (iconv_t)-1;
#endif
                        switch (*p) {
                        case 'B': case 'b':
                                convert = CONV_FROMB64;
                                break;
                        case 'Q': case 'q':
                                convert = CONV_FROMQP;
                                break;
                        default:        /* invalid, ignore */
                                goto jnotmime;
                        }
                        if (*++p != '?')
                                goto jnotmime;
                        cin.s = ++p;
                        cin.l = 1;
                        for (;;) {
                                if (p + 1 >= upper)
                                        goto jnotmime;
                                if (*p++ == '?' && *p == '=')
                                        break;
                                cin.l++;
                        }
                        ++p;
                        cin.l--;

                        cout.s = NULL;
                        cout.l = 0;
                        if (convert == CONV_FROMB64) {
                                /* XXX Take care for, and strip LF from
                                 * XXX [Invalid Base64 encoding ignored] */
                                if (b64_decode(&cout, &cin, NULL) == STOP &&
                                                cout.s[cout.l - 1] == '\n')
                                        --cout.l;
                        } else
                                (void)qp_decode(&cout, &cin, NULL);
                        out->l = lastenc;
#ifdef HAVE_ICONV
                        if ((flags & TD_ICONV) && fhicd != (iconv_t)-1) {
                                cin.s = NULL, cin.l = 0; /* XXX string pool ! */
                                convert = n_iconv_str(fhicd, &cin, &cout,
                                                NULL, TRU1);
                                out = n_str_add(out, &cin);
                                if (convert) /* EINVAL at EOS */
                                        out = n_str_add_buf(out, "?", 1);
                                free(cin.s);
                        } else {
#endif
                                out = n_str_add(out, &cout);
#ifdef HAVE_ICONV
                        }
#endif
                        lastenc = lastoutl = out->l;
                        free(cout.s);
                } else
jnotmime: {
         bool_t onlyws;

         p = op;
         onlyws = (lastenc > 0);
         for (;;) {
            if (++op == upper)
               break;
            if (op[0] == '=' && (PTRCMP(op + 1, ==, upper) || op[1] == '?'))
               break;
            if (onlyws && !blankchar(*op))
               onlyws = FAL0;
         }

         out = n_str_add_buf(out, p, PTR2SIZE(op - p));
         p = op;
         if (!onlyws || lastoutl != lastenc)
            lastenc = out->l;
         lastoutl = out->l;
        }
  }
        out->s[out->l] = '\0';

        if (flags & TD_ISPR) {
                makeprint(out, &cout);
                free(out->s);
                *out = cout;
        }
        if (flags & TD_DELCTRL)
                out->l = delctrl(out->s, out->l);
#ifdef HAVE_ICONV
        if (fhicd != (iconv_t)-1)
                n_iconv_close(fhicd);
#endif
jleave:
        return;
}

/*
 * Convert header fields to RFC 1522 format and write to the file fo.
 */
static size_t
mime_write_tohdr(struct str *in, FILE *fo) /* TODO rewrite - FAST! */
{
        struct str cin, cout;
        char buf[B64_LINESIZE +1]; /* (No CR/LF used) */
        char const *charset7, *charset, *upper, *wbeg, *wend, *lastspc,
                *lastwordend = NULL;
        size_t sz = 0, col = 0, quoteany, wr, charsetlen,
                maxcol = 65 /* there is the header field's name, too */;
        bool_t highbit, mustquote, broken;

        charset7 = charset_get_7bit();
        charset = _CHARSET();
        wr = strlen(charset7);
        charsetlen = strlen(charset);
        charsetlen = MAX(charsetlen, wr);
        upper = in->s + in->l;

        /* xxx note this results in too much hits since =/? force quoting even
         * xxx if they don't form =? etc. */
        quoteany = mime_cte_mustquote(in->s, in->l, TRU1);

        highbit = FAL0;
        if (quoteany != 0)
                for (wbeg = in->s; wbeg < upper; ++wbeg)
                        if ((uc_it)*wbeg & 0x80)
                                highbit = TRU1;

        if (quoteany << 1 > in->l) {
                /*
                 * Print the entire field in base64.
                 */
                for (wbeg = in->s; wbeg < upper; wbeg = wend) {
                        wend = upper;
                        cin.s = UNCONST(wbeg);
                        for (;;) {
                                cin.l = wend - wbeg;
                                if (cin.l * 4/3 + 7 + charsetlen
                                                < maxcol - col) {
                                        cout.s = buf;
                                        cout.l = sizeof buf;
                                        wr = fprintf(fo, "=?%s?B?%s?=",
                                                highbit ? charset : charset7,
                                                b64_encode(&cout, &cin, B64_BUF
                                                        )->s);
                                        sz += wr, col += wr;
                                        if (wend < upper) {
                                                fwrite("\n ", sizeof (char),
                                                                2, fo);
                                                sz += 2;
                                                col = 0;
                                                maxcol = 76;
                                        }
                                        break;
                                } else {
                                        if (col) {
                                                fprintf(fo, "\n ");
                                                sz += 2;
                                                col = 0;
                                                maxcol = 76;
                                        } else
                                                wend -= 4;
                                }
                        }
                }
        } else {
                /*
                 * Print the field word-wise in quoted-printable.
                 */
                broken = FAL0;
                for (wbeg = in->s; wbeg < upper; wbeg = wend) {
                        lastspc = NULL;
                        while (wbeg < upper && whitechar(*wbeg)) {
                                lastspc = lastspc ? lastspc : wbeg;
                                wbeg++;
                                col++;
                                broken = FAL0;
                        }
                        if (wbeg == upper) {
                                if (lastspc)
                                        while (lastspc < wbeg) {
                                                putc(*lastspc&0377, fo);
                                                        lastspc++,
                                                        sz++;
                                                }
                                break;
                        }

                        if (lastspc != NULL)
                                broken = FAL0;
                        highbit = FAL0;
                        for (wend = wbeg; wend < upper && ! whitechar(*wend);
                                        ++wend)
                                if ((uc_it)*wend & 0x80)
                                        highbit = TRU1;
                        mustquote = (mime_cte_mustquote(wbeg,
                                        (size_t)(wend - wbeg), TRU1) != 0);

                        if (mustquote || broken ||
                                        ((wend - wbeg) >= 76-5 && quoteany)) {
                                for (cout.s = NULL;;) {
                                        cin.s = UNCONST(lastwordend ?
                                                        lastwordend : wbeg);
                                        cin.l = wend - cin.s;
                                        (void)qp_encode(&cout, &cin, QP_ISHEAD);
                                        wr = cout.l + charsetlen + 7;
jqp_retest:
                                        if (col <= maxcol &&
                                                        wr <= maxcol - col) {
                                                if (lastspc) {
                                                        /* TODO because we inc-
                                                         * TODO luded the WS in
                                                         * TODO the encoded str,
                                                         * TODO put SP only??
                                                         * TODO RFC: "any
                                                         * 'linear-white-space'
                                                         * that separates
                                                         * a pair of adjacent
                                                         * 'encoded-word's is
                                                         * ignored" */
                                                        putc(' ', fo);
                                                        ++sz;
                                                        ++col;
                                                }
                                                fprintf(fo, "=?%s?Q?%.*s?=",
                                                        highbit ? charset
                                                        : charset7,
                                                        (int)cout.l, cout.s);
                                                sz += wr, col += wr;
                                                break;
                                        } else if (col > 1) {
                                                /* TODO assuming SP separator,
                                                 * TODO ignore *lastspc* !?? */
                                                broken = TRU1;
                                                if (lastspc != NULL) {
                                                        putc('\n', fo);
                                                        ++sz;
                                                        col = 0;
                                                } else {
                                                        fputs("\n ",
                                                                fo);
                                                        sz += 2;
                                                        col = 1;
                                                }
                                                maxcol = 76;
                                                goto jqp_retest;
                                        } else {
                                                for (;;) { /* XXX */
                                                        wend -= 4;
                                                        assert(wend > wbeg);
                                                        if (wr - 4 < maxcol)
                                                                break;
                                                        wr -= 4;
                                                }
                                        }
                                }
                                if (cout.s != NULL)
                                        free(cout.s);
                                lastwordend = wend;
                        } else {
                                if (col &&
                                    (size_t)(wend - wbeg) > maxcol - col) {
                                        putc('\n', fo);
                                        sz++;
                                        col = 0;
                                        maxcol = 76;
                                        if (lastspc == NULL) {
                                                putc(' ', fo);
                                                sz++;
                                                maxcol--;
                                        } else
                                                maxcol -= wbeg - lastspc;
                                }
                                if (lastspc)
                                        while (lastspc < wbeg) {
                                                putc(*lastspc&0377, fo);
                                                lastspc++, sz++;
                                        }
                                wr = fwrite(wbeg, sizeof *wbeg,
                                                wend - wbeg, fo);
                                sz += wr, col += wr;
                                lastwordend = NULL;
                        }
                }
        }
        return sz;
}

/*
 * Write len characters of the passed string to the passed file,
 * doing charset and header conversion.
 */
static size_t
convhdra(char const *str, size_t len, FILE *fp)
{
#ifdef HAVE_ICONV
        struct str ciconv;
#endif
        struct str cin;
        size_t ret = 0;

        cin.s = UNCONST(str);
        cin.l = len;
#ifdef HAVE_ICONV
        ciconv.s = NULL;
        if (iconvd != (iconv_t)-1) {
                ciconv.l = 0;
                if (n_iconv_str(iconvd, &ciconv, &cin, NULL, FAL0) != 0)
                        goto jleave;
                cin = ciconv;
        }
#endif
        ret = mime_write_tohdr(&cin, fp);
#ifdef HAVE_ICONV
jleave:
        if (ciconv.s != NULL)
                free(ciconv.s);
#endif
        return ret;
}

/*
 * Write an address to a header field.
 */
static size_t
mime_write_tohdr_a(struct str *in, FILE *f)
{
        char const *cp, *lastcp;
        size_t sz = 0;

        in->s[in->l] = '\0';
        lastcp = in->s;
        if ((cp = routeaddr(in->s)) != NULL && cp > lastcp) {
                sz += convhdra(lastcp, cp - lastcp, f);
                lastcp = cp;
        } else
                cp = in->s;
        for ( ; *cp; cp++) {
                switch (*cp) {
                case '(':
                        sz += fwrite(lastcp, 1, cp - lastcp + 1, f);
                        lastcp = ++cp;
                        cp = skip_comment(cp);
                        if (--cp > lastcp)
                                sz += convhdra(lastcp, cp - lastcp, f);
                        lastcp = cp;
                        break;
                case '"':
                        while (*cp) {
                                if (*++cp == '"')
                                        break;
                                if (*cp == '\\' && cp[1])
                                        cp++;
                        }
                        break;
                }
        }
        if (cp > lastcp)
                sz += fwrite(lastcp, 1, cp - lastcp, f);
        return sz;
}

static void
addstr(char **buf, size_t *sz, size_t *pos, char const *str, size_t len)
{
        *buf = srealloc(*buf, *sz += len);
        memcpy(&(*buf)[*pos], str, len);
        *pos += len;
}

static void
addconv(char **buf, size_t *sz, size_t *pos, char const *str, size_t len)
{
        struct str in, out;

        in.s = UNCONST(str);
        in.l = len;
        mime_fromhdr(&in, &out, TD_ISPR|TD_ICONV);
        addstr(buf, sz, pos, out.s, out.l);
        free(out.s);
}

/*
 * Interpret MIME strings in parts of an address field.
 */
FL char *
mime_fromaddr(char const *name)
{
        char const *cp, *lastcp;
        char *res = NULL;
        size_t ressz = 1, rescur = 0;

        if (name == NULL)
                return (res);
        if (*name == '\0')
                return savestr(name);
        if ((cp = routeaddr(name)) != NULL && cp > name) {
                addconv(&res, &ressz, &rescur, name, cp - name);
                lastcp = cp;
        } else
                cp = lastcp = name;
        for ( ; *cp; cp++) {
                switch (*cp) {
                case '(':
                        addstr(&res, &ressz, &rescur, lastcp, cp - lastcp + 1);
                        lastcp = ++cp;
                        cp = skip_comment(cp);
                        if (--cp > lastcp)
                                addconv(&res, &ressz, &rescur, lastcp,
                                                cp - lastcp);
                        lastcp = cp;
                        break;
                case '"':
                        while (*cp) {
                                if (*++cp == '"')
                                        break;
                                if (*cp == '\\' && cp[1])
                                        cp++;
                        }
                        break;
                }
        }
        if (cp > lastcp)
                addstr(&res, &ressz, &rescur, lastcp, cp - lastcp);
        /* TODO rescur==0: inserted to silence Coverity ...; check that */
        if (rescur == 0)
                res = UNCONST("");
        else
                res[rescur] = '\0';
        {       char *x = res;
                res = savestr(res);
                free(x);
        }
        return (res);
}

FL ssize_t
xmime_write(char const *ptr, size_t size, FILE *f, enum conversion convert,
        enum tdflags dflags, struct str *rest)
{
        ssize_t rv;
        struct quoteflt *qf;

        quoteflt_reset(qf = quoteflt_dummy(), f);
        rv = mime_write(ptr, size, f, convert, dflags, qf, rest);
        assert(quoteflt_flush(qf) == 0);
        return rv;
}

FL ssize_t
mime_write(char const *ptr, size_t size, FILE *f,
        enum conversion convert, enum tdflags dflags,
        struct quoteflt *qf, struct str *rest)
{
        /* TODO note: after send/MIME layer rewrite we will have a string pool
         * TODO so that memory allocation count drops down massively; for now,
         * TODO v14.0 that is, we pay a lot & heavily depend on the allocator */
        struct str in, out;
        ssize_t sz;
        int state;

        in.s = UNCONST(ptr);
        in.l = size;
        out.s = NULL;
        out.l = 0;

        dflags |= _TD_BUFCOPY;
        if ((sz = size) == 0) {
                if (rest != NULL && rest->l != 0)
                        goto jconvert;
                goto jleave;
        }

#ifdef HAVE_ICONV
        if ((dflags & TD_ICONV) && iconvd != (iconv_t)-1 &&
                        (convert == CONV_TOQP || convert == CONV_8BIT ||
                        convert == CONV_TOB64 || convert == CONV_TOHDR)) {
                if (n_iconv_str(iconvd, &out, &in, NULL, FAL0) != 0) {
                        /* XXX report conversion error? */;
                        sz = -1;
                        goto jleave;
                }
                in = out;
                out.s = NULL;
                dflags &= ~_TD_BUFCOPY;
        }
#endif

jconvert:
        switch (convert) {
        case CONV_FROMQP:
                state = qp_decode(&out, &in, rest);
                goto jqpb64_dec;
        case CONV_TOQP:
                (void)qp_encode(&out, &in, QP_NONE);
                goto jqpb64_enc;
        case CONV_8BIT:
                sz = quoteflt_push(qf, in.s, in.l);
                break;
        case CONV_FROMB64:
                rest = NULL;
                /* FALLTHRU */
        case CONV_FROMB64_T:
                state = b64_decode(&out, &in, rest);
jqpb64_dec:
                if ((sz = out.l) != 0) {
                        size_t opl = qf->qf_pfix_len;
                        if (state != OKAY)
                                qf->qf_pfix_len = 0;
                        sz = _fwrite_td(&out, (dflags & ~_TD_BUFCOPY), rest,qf);
                        qf->qf_pfix_len = opl;
                }
                if (state != OKAY)
                        sz = -1;
                break;
        case CONV_TOB64:
                (void)b64_encode(&out, &in, B64_LF|B64_MULTILINE);
jqpb64_enc:
                sz = fwrite(out.s, sizeof *out.s, out.l, f);
                if (sz != (ssize_t)out.l)
                        sz = -1;
                break;
        case CONV_FROMHDR:
                mime_fromhdr(&in, &out,
                        TD_ISPR | TD_ICONV | (dflags & TD_DELCTRL));
                sz = quoteflt_push(qf, out.s, out.l);
                break;
        case CONV_TOHDR:
                sz = mime_write_tohdr(&in, f);
                break;
        case CONV_TOHDR_A:
                sz = mime_write_tohdr_a(&in, f);
                break;
        default:
                sz = _fwrite_td(&in, dflags, NULL, qf);
                break;
        }
jleave:
        if (out.s != NULL)
                free(out.s);
        if (in.s != ptr)
                free(in.s);
        return sz;
}