/*
 * Copyright (c) 1998-2003, 2006 Sendmail, Inc. and its suppliers.
 *      All rights reserved.
 * Copyright (c) 1994, 1996-1997 Eric P. Allman.  All rights reserved.
 * Copyright (c) 1994
 *      The Regents of the University of California.  All rights reserved.
 *
 * By using this file, you agree to the terms and conditions set
 * forth in the LICENSE file which can be found at the top level of
 * the sendmail distribution.
 *
 */

#include <sendmail.h>
#include <string.h>

SM_RCSID("@(#)$Id: mime.c,v 8.147 2007/09/26 23:29:11 ca Exp $")

/*
**  MIME support.
**
**      I am indebted to John Beck of Hewlett-Packard, who contributed
**      his code to me for inclusion.  As it turns out, I did not use
**      his code since he used a "minimum change" approach that used
**      several temp files, and I wanted a "minimum impact" approach
**      that would avoid copying.  However, looking over his code
**      helped me cement my understanding of the problem.
**
**      I also looked at, but did not directly use, Nathaniel
**      Borenstein's "code.c" module.  Again, it functioned as
**      a file-to-file translator, which did not fit within my
**      design bounds, but it was a useful base for understanding
**      the problem.
*/

/* use "old" mime 7 to 8 algorithm by default */
#ifndef MIME7TO8_OLD
# define MIME7TO8_OLD   1
#endif /* ! MIME7TO8_OLD */

#if MIME8TO7
static int      isboundary __P((char *, char **));
static int      mimeboundary __P((char *, char **));
static int      mime_getchar __P((SM_FILE_T *, char **, int *));
static int      mime_getchar_crlf __P((SM_FILE_T *, char **, int *));

/* character set for hex and base64 encoding */
static char     Base16Code[] =  "0123456789ABCDEF";
static char     Base64Code[] =  "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

/* types of MIME boundaries */
# define MBT_SYNTAX     0       /* syntax error */
# define MBT_NOTSEP     1       /* not a boundary */
# define MBT_INTERMED   2       /* intermediate boundary (no trailing --) */
# define MBT_FINAL      3       /* final boundary (trailing -- included) */

static char     *MimeBoundaryNames[] =
{
        "SYNTAX",       "NOTSEP",       "INTERMED",     "FINAL"
};

static bool     MapNLtoCRLF;

/*
**  MIME8TO7 -- output 8 bit body in 7 bit format
**
**      The header has already been output -- this has to do the
**      8 to 7 bit conversion.  It would be easy if we didn't have
**      to deal with nested formats (multipart/xxx and message/rfc822).
**
**      We won't be called if we don't have to do a conversion, and
**      appropriate MIME-Version: and Content-Type: fields have been
**      output.  Any Content-Transfer-Encoding: field has not been
**      output, and we can add it here.
**
**      Parameters:
**              mci -- mailer connection information.
**              header -- the header for this body part.
**              e -- envelope.
**              boundaries -- the currently pending message boundaries.
**                      NULL if we are processing the outer portion.
**              flags -- to tweak processing.
**              level -- recursion level.
**
**      Returns:
**              An indicator of what terminated the message part:
**                MBT_FINAL -- the final boundary
**                MBT_INTERMED -- an intermediate boundary
**                MBT_NOTSEP -- an end of file
**                SM_IO_EOF -- I/O error occurred
*/

struct args
{
        char    *a_field;       /* name of field */
        char    *a_value;       /* value of that field */
};

int
mime8to7(mci, header, e, boundaries, flags, level)
        register MCI *mci;
        HDR *header;
        register ENVELOPE *e;
        char **boundaries;
        int flags;
        int level;
{
        register char *p;
        int linelen;
        int bt;
        off_t offset;
        size_t sectionsize, sectionhighbits;
        int i;
        char *type;
        char *subtype;
        char *cte;
        char **pvp;
        int argc = 0;
        char *bp;
        bool use_qp = false;
        struct args argv[MAXMIMEARGS];
        char bbuf[128];
        char buf[MAXLINE];
        char pvpbuf[MAXLINE];
        extern unsigned char MimeTokenTab[256];

        if (level > MAXMIMENESTING)
        {
                if (!bitset(EF_TOODEEP, e->e_flags))
                {
                        if (tTd(43, 4))
                                sm_dprintf("mime8to7: too deep, level=%d\n",
                                           level);
                        usrerr("mime8to7: recursion level %d exceeded",
                                level);
                        e->e_flags |= EF_DONT_MIME|EF_TOODEEP;
                }
        }
        if (tTd(43, 1))
        {
                sm_dprintf("mime8to7: flags = %x, boundaries =", flags);
                if (boundaries[0] == NULL)
                        sm_dprintf(" <none>");
                else
                {
                        for (i = 0; boundaries[i] != NULL; i++)
                                sm_dprintf(" %s", boundaries[i]);
                }
                sm_dprintf("\n");
        }
        MapNLtoCRLF = true;
        p = hvalue("Content-Transfer-Encoding", header);
        if (p == NULL ||
            (pvp = prescan(p, '\0', pvpbuf, sizeof(pvpbuf), NULL,
                           MimeTokenTab, false)) == NULL ||
            pvp[0] == NULL)
        {
                cte = NULL;
        }
        else
        {
                cataddr(pvp, NULL, buf, sizeof(buf), '\0', false);
                cte = sm_rpool_strdup_x(e->e_rpool, buf);
        }

        type = subtype = NULL;
        p = hvalue("Content-Type", header);
        if (p == NULL)
        {
                if (bitset(M87F_DIGEST, flags))
                        p = "message/rfc822";
                else
                        p = "text/plain";
        }
        if (p != NULL &&
            (pvp = prescan(p, '\0', pvpbuf, sizeof(pvpbuf), NULL,
                           MimeTokenTab, false)) != NULL &&
            pvp[0] != NULL)
        {
                if (tTd(43, 40))
                {
                        for (i = 0; pvp[i] != NULL; i++)
                                sm_dprintf("pvp[%d] = \"%s\"\n", i, pvp[i]);
                }
                type = *pvp++;
                if (*pvp != NULL && strcmp(*pvp, "/") == 0 &&
                    *++pvp != NULL)
                {
                        subtype = *pvp++;
                }

                /* break out parameters */
                while (*pvp != NULL && argc < MAXMIMEARGS)
                {
                        /* skip to semicolon separator */
                        while (*pvp != NULL && strcmp(*pvp, ";") != 0)
                                pvp++;
                        if (*pvp++ == NULL || *pvp == NULL)
                                break;

                        /* complain about empty values */
                        if (strcmp(*pvp, ";") == 0)
                        {
                                usrerr("mime8to7: Empty parameter in Content-Type header");

                                /* avoid bounce loops */
                                e->e_flags |= EF_DONT_MIME;
                                continue;
                        }

                        /* extract field name */
                        argv[argc].a_field = *pvp++;

                        /* see if there is a value */
                        if (*pvp != NULL && strcmp(*pvp, "=") == 0 &&
                            (*++pvp == NULL || strcmp(*pvp, ";") != 0))
                        {
                                argv[argc].a_value = *pvp;
                                argc++;
                        }
                }
        }

        /* check for disaster cases */
        if (type == NULL)
                type = "-none-";
        if (subtype == NULL)
                subtype = "-none-";

        /* don't propagate some flags more than one level into the message */
        flags &= ~M87F_DIGEST;

        /*
        **  Check for cases that can not be encoded.
        **
        **      For example, you can't encode certain kinds of types
        **      or already-encoded messages.  If we find this case,
        **      just copy it through.
        */

        (void) sm_snprintf(buf, sizeof(buf), "%.100s/%.100s", type, subtype);
        if (wordinclass(buf, 'n') || (cte != NULL && !wordinclass(cte, 'e')))
                flags |= M87F_NO8BIT;

# ifdef USE_B_CLASS
        if (wordinclass(buf, 'b') || wordinclass(type, 'b'))
                MapNLtoCRLF = false;
# endif /* USE_B_CLASS */
        if (wordinclass(buf, 'q') || wordinclass(type, 'q'))
                use_qp = true;

        /*
        **  Multipart requires special processing.
        **
        **      Do a recursive descent into the message.
        */

        if (sm_strcasecmp(type, "multipart") == 0 &&
            (!bitset(M87F_NO8BIT, flags) || bitset(M87F_NO8TO7, flags)) &&
            !bitset(EF_TOODEEP, e->e_flags)
           )
        {

                if (sm_strcasecmp(subtype, "digest") == 0)
                        flags |= M87F_DIGEST;

                for (i = 0; i < argc; i++)
                {
                        if (sm_strcasecmp(argv[i].a_field, "boundary") == 0)
                                break;
                }
                if (i >= argc || argv[i].a_value == NULL)
                {
                        usrerr("mime8to7: Content-Type: \"%s\": %s boundary",
                                i >= argc ? "missing" : "bogus", p);
                        p = "---";

                        /* avoid bounce loops */
                        e->e_flags |= EF_DONT_MIME;
                }
                else
                {
                        p = argv[i].a_value;
                        stripquotes(p);
                }
                if (sm_strlcpy(bbuf, p, sizeof(bbuf)) >= sizeof(bbuf))
                {
                        usrerr("mime8to7: multipart boundary \"%s\" too long",
                                p);

                        /* avoid bounce loops */
                        e->e_flags |= EF_DONT_MIME;
                }

                if (tTd(43, 1))
                        sm_dprintf("mime8to7: multipart boundary \"%s\"\n",
                                bbuf);
                for (i = 0; i < MAXMIMENESTING; i++)
                {
                        if (boundaries[i] == NULL)
                                break;
                }
                if (i >= MAXMIMENESTING)
                {
                        if (tTd(43, 4))
                                sm_dprintf("mime8to7: too deep, i=%d\n", i);
                        if (!bitset(EF_TOODEEP, e->e_flags))
                                usrerr("mime8to7: multipart nesting boundary too deep");

                        /* avoid bounce loops */
                        e->e_flags |= EF_DONT_MIME|EF_TOODEEP;
                }
                else
                {
                        boundaries[i] = bbuf;
                        boundaries[i + 1] = NULL;
                }
                mci->mci_flags |= MCIF_INMIME;

                /* skip the early "comment" prologue */
                if (!putline("", mci))
                        goto writeerr;
                mci->mci_flags &= ~MCIF_INHEADER;
                bt = MBT_FINAL;
                while (sm_io_fgets(e->e_dfp, SM_TIME_DEFAULT, buf, sizeof(buf))
                        != NULL)
                {
                        bt = mimeboundary(buf, boundaries);
                        if (bt != MBT_NOTSEP)
                                break;
                        if (!putxline(buf, strlen(buf), mci,
                                        PXLF_MAPFROM|PXLF_STRIP8BIT))
                                goto writeerr;
                        if (tTd(43, 99))
                                sm_dprintf("  ...%s", buf);
                }
                if (sm_io_eof(e->e_dfp))
                        bt = MBT_FINAL;
                while (bt != MBT_FINAL)
                {
                        auto HDR *hdr = NULL;

                        (void) sm_strlcpyn(buf, sizeof(buf), 2, "--", bbuf);
                        if (!putline(buf, mci))
                                goto writeerr;
                        if (tTd(43, 35))
                                sm_dprintf("  ...%s\n", buf);
                        collect(e->e_dfp, false, &hdr, e, false);
                        if (tTd(43, 101))
                                putline("+++after collect", mci);
                        if (!putheader(mci, hdr, e, flags))
                                goto writeerr;
                        if (tTd(43, 101))
                                putline("+++after putheader", mci);
                        bt = mime8to7(mci, hdr, e, boundaries, flags,
                                      level + 1);
                        if (bt == SM_IO_EOF)
                                goto writeerr;
                }
                (void) sm_strlcpyn(buf, sizeof(buf), 3, "--", bbuf, "--");
                if (!putline(buf, mci))
                        goto writeerr;
                if (tTd(43, 35))
                        sm_dprintf("  ...%s\n", buf);
                boundaries[i] = NULL;
                mci->mci_flags &= ~MCIF_INMIME;

                /* skip the late "comment" epilogue */
                while (sm_io_fgets(e->e_dfp, SM_TIME_DEFAULT, buf, sizeof(buf))
                        != NULL)
                {
                        bt = mimeboundary(buf, boundaries);
                        if (bt != MBT_NOTSEP)
                                break;
                        if (!putxline(buf, strlen(buf), mci,
                                        PXLF_MAPFROM|PXLF_STRIP8BIT))
                                goto writeerr;
                        if (tTd(43, 99))
                                sm_dprintf("  ...%s", buf);
                }
                if (sm_io_eof(e->e_dfp))
                        bt = MBT_FINAL;
                if (tTd(43, 3))
                        sm_dprintf("\t\t\tmime8to7=>%s (multipart)\n",
                                MimeBoundaryNames[bt]);
                return bt;
        }

        /*
        **  Message/xxx types -- recurse exactly once.
        **
        **      Class 's' is predefined to have "rfc822" only.
        */

        if (sm_strcasecmp(type, "message") == 0)
        {
                if (!wordinclass(subtype, 's') ||
                    bitset(EF_TOODEEP, e->e_flags))
                {
                        flags |= M87F_NO8BIT;
                }
                else
                {
                        auto HDR *hdr = NULL;

                        if (!putline("", mci))
                                goto writeerr;

                        mci->mci_flags |= MCIF_INMIME;
                        collect(e->e_dfp, false, &hdr, e, false);
                        if (tTd(43, 101))
                                putline("+++after collect", mci);
                        if (!putheader(mci, hdr, e, flags))
                                goto writeerr;
                        if (tTd(43, 101))
                                putline("+++after putheader", mci);
                        if (hvalue("MIME-Version", hdr) == NULL &&
                            !bitset(M87F_NO8TO7, flags) &&
                            !putline("MIME-Version: 1.0", mci))
                                goto writeerr;
                        bt = mime8to7(mci, hdr, e, boundaries, flags,
                                      level + 1);
                        mci->mci_flags &= ~MCIF_INMIME;
                        return bt;
                }
        }

        /*
        **  Non-compound body type
        **
        **      Compute the ratio of seven to eight bit characters;
        **      use that as a heuristic to decide how to do the
        **      encoding.
        */

        sectionsize = sectionhighbits = 0;
        if (!bitset(M87F_NO8BIT|M87F_NO8TO7, flags))
        {
                /* remember where we were */
                offset = sm_io_tell(e->e_dfp, SM_TIME_DEFAULT);
                if (offset == -1)
                        syserr("mime8to7: cannot sm_io_tell on %cf%s",
                               DATAFL_LETTER, e->e_id);

                /* do a scan of this body type to count character types */
                while (sm_io_fgets(e->e_dfp, SM_TIME_DEFAULT, buf, sizeof(buf))
                        != NULL)
                {
                        if (mimeboundary(buf, boundaries) != MBT_NOTSEP)
                                break;
                        for (p = buf; *p != '\0'; p++)
                        {
                                /* count bytes with the high bit set */
                                sectionsize++;
                                if (bitset(0200, *p))
                                        sectionhighbits++;
                        }

                        /*
                        **  Heuristic: if 1/4 of the first 4K bytes are 8-bit,
                        **  assume base64.  This heuristic avoids double-reading
                        **  large graphics or video files.
                        */

                        if (sectionsize >= 4096 &&
                            sectionhighbits > sectionsize / 4)
                                break;
                }

                /* return to the original offset for processing */
                /* XXX use relative seeks to handle >31 bit file sizes? */
                if (sm_io_seek(e->e_dfp, SM_TIME_DEFAULT, offset, SEEK_SET) < 0)
                        syserr("mime8to7: cannot sm_io_fseek on %cf%s",
                               DATAFL_LETTER, e->e_id);
                else
                        sm_io_clearerr(e->e_dfp);
        }

        /*
        **  Heuristically determine encoding method.
        **      If more than 1/8 of the total characters have the
        **      eighth bit set, use base64; else use quoted-printable.
        **      However, only encode binary encoded data as base64,
        **      since otherwise the NL=>CRLF mapping will be a problem.
        */

        if (tTd(43, 8))
        {
                sm_dprintf("mime8to7: %ld high bit(s) in %ld byte(s), cte=%s, type=%s/%s\n",
                        (long) sectionhighbits, (long) sectionsize,
                        cte == NULL ? "[none]" : cte,
                        type == NULL ? "[none]" : type,
                        subtype == NULL ? "[none]" : subtype);
        }
        if (cte != NULL && sm_strcasecmp(cte, "binary") == 0)
                sectionsize = sectionhighbits;
        linelen = 0;
        bp = buf;
        if (sectionhighbits == 0)
        {
                /* no encoding necessary */
                if (cte != NULL &&
                    bitset(MCIF_CVT8TO7|MCIF_CVT7TO8|MCIF_INMIME,
                           mci->mci_flags) &&
                    !bitset(M87F_NO8TO7, flags))
                {
                        /*
                        **  Skip _unless_ in MIME mode and potentially
                        **  converting from 8 bit to 7 bit MIME.  See
                        **  putheader() for the counterpart where the
                        **  CTE header is skipped in the opposite
                        **  situation.
                        */

                        (void) sm_snprintf(buf, sizeof(buf),
                                "Content-Transfer-Encoding: %.200s", cte);
                        if (!putline(buf, mci))
                                goto writeerr;
                        if (tTd(43, 36))
                                sm_dprintf("  ...%s\n", buf);
                }
                if (!putline("", mci))
                        goto writeerr;
                mci->mci_flags &= ~MCIF_INHEADER;
                while (sm_io_fgets(e->e_dfp, SM_TIME_DEFAULT, buf, sizeof(buf))
                        != NULL)
                {
                        if (!bitset(MCIF_INLONGLINE, mci->mci_flags))
                        {
                                bt = mimeboundary(buf, boundaries);
                                if (bt != MBT_NOTSEP)
                                        break;
                        }
                        if (!putxline(buf, strlen(buf), mci,
                                      PXLF_MAPFROM|PXLF_NOADDEOL))
                                goto writeerr;
                }
                if (sm_io_eof(e->e_dfp))
                        bt = MBT_FINAL;
        }
        else if (!MapNLtoCRLF ||
                 (sectionsize / 8 < sectionhighbits && !use_qp))
        {
                /* use base64 encoding */
                int c1, c2;

                if (tTd(43, 36))
                        sm_dprintf("  ...Content-Transfer-Encoding: base64\n");
                if (!putline("Content-Transfer-Encoding: base64", mci))
                        goto writeerr;
                (void) sm_snprintf(buf, sizeof(buf),
                        "X-MIME-Autoconverted: from 8bit to base64 by %s id %s",
                        MyHostName, e->e_id);
                if (!putline(buf, mci) || !putline("", mci))
                        goto writeerr;
                mci->mci_flags &= ~MCIF_INHEADER;
                while ((c1 = mime_getchar_crlf(e->e_dfp, boundaries, &bt)) !=
                        SM_IO_EOF)
                {
                        if (linelen > 71)
                        {
                                *bp = '\0';
                                if (!putline(buf, mci))
                                        goto writeerr;
                                linelen = 0;
                                bp = buf;
                        }
                        linelen += 4;
                        *bp++ = Base64Code[(c1 >> 2)];
                        c1 = (c1 & 0x03) << 4;
                        c2 = mime_getchar_crlf(e->e_dfp, boundaries, &bt);
                        if (c2 == SM_IO_EOF)
                        {
                                *bp++ = Base64Code[c1];
                                *bp++ = '=';
                                *bp++ = '=';
                                break;
                        }
                        c1 |= (c2 >> 4) & 0x0f;
                        *bp++ = Base64Code[c1];
                        c1 = (c2 & 0x0f) << 2;
                        c2 = mime_getchar_crlf(e->e_dfp, boundaries, &bt);
                        if (c2 == SM_IO_EOF)
                        {
                                *bp++ = Base64Code[c1];
                                *bp++ = '=';
                                break;
                        }
                        c1 |= (c2 >> 6) & 0x03;
                        *bp++ = Base64Code[c1];
                        *bp++ = Base64Code[c2 & 0x3f];
                }
                *bp = '\0';
                if (!putline(buf, mci))
                        goto writeerr;
        }
        else
        {
                /* use quoted-printable encoding */
                int c1, c2;
                int fromstate;
                BITMAP256 badchars;

                /* set up map of characters that must be mapped */
                clrbitmap(badchars);
                for (c1 = 0x00; c1 < 0x20; c1++)
                        setbitn(c1, badchars);
                clrbitn('\t', badchars);
                for (c1 = 0x7f; c1 < 0x100; c1++)
                        setbitn(c1, badchars);
                setbitn('=', badchars);
                if (bitnset(M_EBCDIC, mci->mci_mailer->m_flags))
                        for (p = "!\"#$@[\\]^`{|}~"; *p != '\0'; p++)
                                setbitn(*p, badchars);

                if (tTd(43, 36))
                        sm_dprintf("  ...Content-Transfer-Encoding: quoted-printable\n");
                if (!putline("Content-Transfer-Encoding: quoted-printable",
                                mci))
                        goto writeerr;
                (void) sm_snprintf(buf, sizeof(buf),
                        "X-MIME-Autoconverted: from 8bit to quoted-printable by %s id %s",
                        MyHostName, e->e_id);
                if (!putline(buf, mci) || !putline("", mci))
                        goto writeerr;
                mci->mci_flags &= ~MCIF_INHEADER;
                fromstate = 0;
                c2 = '\n';
                while ((c1 = mime_getchar(e->e_dfp, boundaries, &bt)) !=
                        SM_IO_EOF)
                {
                        if (c1 == '\n')
                        {
                                if (c2 == ' ' || c2 == '\t')
                                {
                                        *bp++ = '=';
                                        *bp++ = Base16Code[(c2 >> 4) & 0x0f];
                                        *bp++ = Base16Code[c2 & 0x0f];
                                }
                                if (buf[0] == '.' && bp == &buf[1])
                                {
                                        buf[0] = '=';
                                        *bp++ = Base16Code[('.' >> 4) & 0x0f];
                                        *bp++ = Base16Code['.' & 0x0f];
                                }
                                *bp = '\0';
                                if (!putline(buf, mci))
                                        goto writeerr;
                                linelen = fromstate = 0;
                                bp = buf;
                                c2 = c1;
                                continue;
                        }
                        if (c2 == ' ' && linelen == 4 && fromstate == 4 &&
                            bitnset(M_ESCFROM, mci->mci_mailer->m_flags))
                        {
                                *bp++ = '=';
                                *bp++ = '2';
                                *bp++ = '0';
                                linelen += 3;
                        }
                        else if (c2 == ' ' || c2 == '\t')
                        {
                                *bp++ = c2;
                                linelen++;
                        }
                        if (linelen > 72 &&
                            (linelen > 75 || c1 != '.' ||
                             (linelen > 73 && c2 == '.')))
                        {
                                if (linelen > 73 && c2 == '.')
                                        bp--;
                                else
                                        c2 = '\n';
                                *bp++ = '=';
                                *bp = '\0';
                                if (!putline(buf, mci))
                                        goto writeerr;
                                linelen = fromstate = 0;
                                bp = buf;
                                if (c2 == '.')
                                {
                                        *bp++ = '.';
                                        linelen++;
                                }
                        }
                        if (bitnset(bitidx(c1), badchars))
                        {
                                *bp++ = '=';
                                *bp++ = Base16Code[(c1 >> 4) & 0x0f];
                                *bp++ = Base16Code[c1 & 0x0f];
                                linelen += 3;
                        }
                        else if (c1 != ' ' && c1 != '\t')
                        {
                                if (linelen < 4 && c1 == "From"[linelen])
                                        fromstate++;
                                *bp++ = c1;
                                linelen++;
                        }
                        c2 = c1;
                }

                /* output any saved character */
                if (c2 == ' ' || c2 == '\t')
                {
                        *bp++ = '=';
                        *bp++ = Base16Code[(c2 >> 4) & 0x0f];
                        *bp++ = Base16Code[c2 & 0x0f];
                        linelen += 3;
                }

                if (linelen > 0 || boundaries[0] != NULL)
                {
                        *bp = '\0';
                        if (!putline(buf, mci))
                                goto writeerr;
                }

        }
        if (tTd(43, 3))
                sm_dprintf("\t\t\tmime8to7=>%s (basic)\n", MimeBoundaryNames[bt]);
        return bt;

  writeerr:
        return SM_IO_EOF;
}
/*
**  MIME_GETCHAR -- get a character for MIME processing
**
**      Treats boundaries as SM_IO_EOF.
**
**      Parameters:
**              fp -- the input file.
**              boundaries -- the current MIME boundaries.
**              btp -- if the return value is SM_IO_EOF, *btp is set to
**                      the type of the boundary.
**
**      Returns:
**              The next character in the input stream.
*/

static int
mime_getchar(fp, boundaries, btp)
        register SM_FILE_T *fp;
        char **boundaries;
        int *btp;
{
        int c;
        static unsigned char *bp = NULL;
        static int buflen = 0;
        static bool atbol = true;       /* at beginning of line */
        static int bt = MBT_SYNTAX;     /* boundary type of next SM_IO_EOF */
        static unsigned char buf[128];  /* need not be a full line */
        int start = 0;                  /* indicates position of - in buffer */

        if (buflen == 1 && *bp == '\n')
        {
                /* last \n in buffer may be part of next MIME boundary */
                c = *bp;
        }
        else if (buflen > 0)
        {
                buflen--;
                return *bp++;
        }
        else
                c = sm_io_getc(fp, SM_TIME_DEFAULT);
        bp = buf;
        buflen = 0;
        if (c == '\n')
        {
                /* might be part of a MIME boundary */
                *bp++ = c;
                atbol = true;
                c = sm_io_getc(fp, SM_TIME_DEFAULT);
                if (c == '\n')
                {
                        (void) sm_io_ungetc(fp, SM_TIME_DEFAULT, c);
                        return c;
                }
                start = 1;
        }
        if (c != SM_IO_EOF)
                *bp++ = c;
        else
                bt = MBT_FINAL;
        if (atbol && c == '-')
        {
                /* check for a message boundary */
                c = sm_io_getc(fp, SM_TIME_DEFAULT);
                if (c != '-')
                {
                        if (c != SM_IO_EOF)
                                *bp++ = c;
                        else
                                bt = MBT_FINAL;
                        buflen = bp - buf - 1;
                        bp = buf;
                        return *bp++;
                }

                /* got "--", now check for rest of separator */
                *bp++ = '-';
                while (bp < &buf[sizeof(buf) - 2] &&
                       (c = sm_io_getc(fp, SM_TIME_DEFAULT)) != SM_IO_EOF &&
                       c != '\n')
                {
                        *bp++ = c;
                }
                *bp = '\0';     /* XXX simply cut off? */
                bt = mimeboundary((char *) &buf[start], boundaries);
                switch (bt)
                {
                  case MBT_FINAL:
                  case MBT_INTERMED:
                        /* we have a message boundary */
                        buflen = 0;
                        *btp = bt;
                        return SM_IO_EOF;
                }

                if (bp < &buf[sizeof(buf) - 2] && c != SM_IO_EOF)
                        *bp++ = c;
        }

        atbol = c == '\n';
        buflen = bp - buf - 1;
        if (buflen < 0)
        {
                *btp = bt;
                return SM_IO_EOF;
        }
        bp = buf;
        return *bp++;
}
/*
**  MIME_GETCHAR_CRLF -- do mime_getchar, but translate NL => CRLF
**
**      Parameters:
**              fp -- the input file.
**              boundaries -- the current MIME boundaries.
**              btp -- if the return value is SM_IO_EOF, *btp is set to
**                      the type of the boundary.
**
**      Returns:
**              The next character in the input stream.
*/

static int
mime_getchar_crlf(fp, boundaries, btp)
        register SM_FILE_T *fp;
        char **boundaries;
        int *btp;
{
        static bool sendlf = false;
        int c;

        if (sendlf)
        {
                sendlf = false;
                return '\n';
        }
        c = mime_getchar(fp, boundaries, btp);
        if (c == '\n' && MapNLtoCRLF)
        {
                sendlf = true;
                return '\r';
        }
        return c;
}
/*
**  MIMEBOUNDARY -- determine if this line is a MIME boundary & its type
**
**      Parameters:
**              line -- the input line.
**              boundaries -- the set of currently pending boundaries.
**
**      Returns:
**              MBT_NOTSEP -- if this is not a separator line
**              MBT_INTERMED -- if this is an intermediate separator
**              MBT_FINAL -- if this is a final boundary
**              MBT_SYNTAX -- if this is a boundary for the wrong
**                      enclosure -- i.e., a syntax error.
*/

static int
mimeboundary(line, boundaries)
        register char *line;
        char **boundaries;
{
        int type = MBT_NOTSEP;
        int i;
        int savec;

        if (line[0] != '-' || line[1] != '-' || boundaries == NULL)
                return MBT_NOTSEP;
        i = strlen(line);
        if (i > 0 && line[i - 1] == '\n')
                i--;

        /* strip off trailing whitespace */
        while (i > 0 && (line[i - 1] == ' ' || line[i - 1] == '\t'
#if _FFR_MIME_CR_OK
                || line[i - 1] == '\r'
#endif /* _FFR_MIME_CR_OK */
               ))
                i--;
        savec = line[i];
        line[i] = '\0';

        if (tTd(43, 5))
                sm_dprintf("mimeboundary: line=\"%s\"... ", line);

        /* check for this as an intermediate boundary */
        if (isboundary(&line[2], boundaries) >= 0)
                type = MBT_INTERMED;
        else if (i > 2 && strncmp(&line[i - 2], "--", 2) == 0)
        {
                /* check for a final boundary */
                line[i - 2] = '\0';
                if (isboundary(&line[2], boundaries) >= 0)
                        type = MBT_FINAL;
                line[i - 2] = '-';
        }

        line[i] = savec;
        if (tTd(43, 5))
                sm_dprintf("%s\n", MimeBoundaryNames[type]);
        return type;
}
/*
**  DEFCHARSET -- return default character set for message
**
**      The first choice for character set is for the mailer
**      corresponding to the envelope sender.  If neither that
**      nor the global configuration file has a default character
**      set defined, return "unknown-8bit" as recommended by
**      RFC 1428 section 3.
**
**      Parameters:
**              e -- the envelope for this message.
**
**      Returns:
**              The default character set for that mailer.
*/

char *
defcharset(e)
        register ENVELOPE *e;
{
        if (e != NULL && e->e_from.q_mailer != NULL &&
            e->e_from.q_mailer->m_defcharset != NULL)
                return e->e_from.q_mailer->m_defcharset;
        if (DefaultCharSet != NULL)
                return DefaultCharSet;
        return "unknown-8bit";
}
/*
**  ISBOUNDARY -- is a given string a currently valid boundary?
**
**      Parameters:
**              line -- the current input line.
**              boundaries -- the list of valid boundaries.
**
**      Returns:
**              The index number in boundaries if the line is found.
**              -1 -- otherwise.
**
*/

static int
isboundary(line, boundaries)
        char *line;
        char **boundaries;
{
        register int i;

        for (i = 0; i <= MAXMIMENESTING && boundaries[i] != NULL; i++)
        {
                if (strcmp(line, boundaries[i]) == 0)
                        return i;
        }
        return -1;
}
#endif /* MIME8TO7 */

#if MIME7TO8
static int      mime_fromqp __P((unsigned char *, unsigned char **, int));

/*
**  MIME7TO8 -- output 7 bit encoded MIME body in 8 bit format
**
**  This is a hack. Supports translating the two 7-bit body-encodings
**  (quoted-printable and base64) to 8-bit coded bodies.
**
**  There is not much point in supporting multipart here, as the UA
**  will be able to deal with encoded MIME bodies if it can parse MIME
**  multipart messages.
**
**  Note also that we won't be called unless it is a text/plain MIME
**  message, encoded base64 or QP and mailer flag '9' has been defined
**  on mailer.
**
**  Contributed by Marius Olaffson <marius@rhi.hi.is>.
**
**      Parameters:
**              mci -- mailer connection information.
**              header -- the header for this body part.
**              e -- envelope.
**
**      Returns:
**              true iff body was written successfully
*/

static char index_64[128] =
{
        -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
        -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
        -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,62, -1,-1,-1,63,
        52,53,54,55, 56,57,58,59, 60,61,-1,-1, -1,-1,-1,-1,
        -1, 0, 1, 2,  3, 4, 5, 6,  7, 8, 9,10, 11,12,13,14,
        15,16,17,18, 19,20,21,22, 23,24,25,-1, -1,-1,-1,-1,
        -1,26,27,28, 29,30,31,32, 33,34,35,36, 37,38,39,40,
        41,42,43,44, 45,46,47,48, 49,50,51,-1, -1,-1,-1,-1
};

# define CHAR64(c)  (((c) < 0 || (c) > 127) ? -1 : index_64[(c)])

bool
mime7to8(mci, header, e)
        register MCI *mci;
        HDR *header;
        register ENVELOPE *e;
{
        int pxflags;
        register char *p;
        char *cte;
        char **pvp;
        unsigned char *fbufp;
        char buf[MAXLINE];
        unsigned char fbuf[MAXLINE + 1];
        char pvpbuf[MAXLINE];
        extern unsigned char MimeTokenTab[256];

        p = hvalue("Content-Transfer-Encoding", header);
        if (p == NULL ||
            (pvp = prescan(p, '\0', pvpbuf, sizeof(pvpbuf), NULL,
                           MimeTokenTab, false)) == NULL ||
            pvp[0] == NULL)
        {
                /* "can't happen" -- upper level should have caught this */
                syserr("mime7to8: unparsable CTE %s", p == NULL ? "<NULL>" : p);

                /* avoid bounce loops */
                e->e_flags |= EF_DONT_MIME;

                /* cheap failsafe algorithm -- should work on text/plain */
                if (p != NULL)
                {
                        (void) sm_snprintf(buf, sizeof(buf),
                                "Content-Transfer-Encoding: %s", p);
                        if (!putline(buf, mci))
                                goto writeerr;
                }
                if (!putline("", mci))
                        goto writeerr;
                mci->mci_flags &= ~MCIF_INHEADER;
                while (sm_io_fgets(e->e_dfp, SM_TIME_DEFAULT, buf, sizeof(buf))
                        != NULL)
                {
                        if (!putline(buf, mci))
                                goto writeerr;
                }
                return true;
        }
        cataddr(pvp, NULL, buf, sizeof(buf), '\0', false);
        cte = sm_rpool_strdup_x(e->e_rpool, buf);

        mci->mci_flags |= MCIF_INHEADER;
        if (!putline("Content-Transfer-Encoding: 8bit", mci))
                goto writeerr;
        (void) sm_snprintf(buf, sizeof(buf),
                "X-MIME-Autoconverted: from %.200s to 8bit by %s id %s",
                cte, MyHostName, e->e_id);
        if (!putline(buf, mci) || !putline("", mci))
                goto writeerr;
        mci->mci_flags &= ~MCIF_INHEADER;

        /*
        **  Translate body encoding to 8-bit.  Supports two types of
        **  encodings; "base64" and "quoted-printable". Assume qp if
        **  it is not base64.
        */

        pxflags = PXLF_MAPFROM;
        if (sm_strcasecmp(cte, "base64") == 0)
        {
                int c1, c2, c3, c4;

                fbufp = fbuf;
                while ((c1 = sm_io_getc(e->e_dfp, SM_TIME_DEFAULT)) !=
                        SM_IO_EOF)
                {
                        if (isascii(c1) && isspace(c1))
                                continue;

                        do
                        {
                                c2 = sm_io_getc(e->e_dfp, SM_TIME_DEFAULT);
                        } while (isascii(c2) && isspace(c2));
                        if (c2 == SM_IO_EOF)
                                break;

                        do
                        {
                                c3 = sm_io_getc(e->e_dfp, SM_TIME_DEFAULT);
                        } while (isascii(c3) && isspace(c3));
                        if (c3 == SM_IO_EOF)
                                break;

                        do
                        {
                                c4 = sm_io_getc(e->e_dfp, SM_TIME_DEFAULT);
                        } while (isascii(c4) && isspace(c4));
                        if (c4 == SM_IO_EOF)
                                break;

                        if (c1 == '=' || c2 == '=')
                                continue;
                        c1 = CHAR64(c1);
                        c2 = CHAR64(c2);

#if MIME7TO8_OLD
#define CHK_EOL if (*--fbufp != '\n' || (fbufp > fbuf && *--fbufp != '\r')) \
                        ++fbufp;
#else /* MIME7TO8_OLD */
#define CHK_EOL if (*--fbufp != '\n' || (fbufp > fbuf && *--fbufp != '\r')) \
                {                                       \
                        ++fbufp;                        \
                        pxflags |= PXLF_NOADDEOL;       \
                }
#endif /* MIME7TO8_OLD */

#define PUTLINE64       \
        do              \
        {               \
                if (*fbufp++ == '\n' || fbufp >= &fbuf[MAXLINE])        \
                {                                                       \
                        CHK_EOL;                                        \
                        if (!putxline((char *) fbuf, fbufp - fbuf, mci, pxflags)) \
                                goto writeerr;                          \
                        pxflags &= ~PXLF_NOADDEOL;                      \
                        fbufp = fbuf;                                   \
                }       \
        } while (0)

                        *fbufp = (c1 << 2) | ((c2 & 0x30) >> 4);
                        PUTLINE64;
                        if (c3 == '=')
                                continue;
                        c3 = CHAR64(c3);
                        *fbufp = ((c2 & 0x0f) << 4) | ((c3 & 0x3c) >> 2);
                        PUTLINE64;
                        if (c4 == '=')
                                continue;
                        c4 = CHAR64(c4);
                        *fbufp = ((c3 & 0x03) << 6) | c4;
                        PUTLINE64;
                }
        }
        else
        {
                int off;

                /* quoted-printable */
                pxflags |= PXLF_NOADDEOL;
                fbufp = fbuf;
                while (sm_io_fgets(e->e_dfp, SM_TIME_DEFAULT, buf,
                                   sizeof(buf)) != NULL)
                {
                        off = mime_fromqp((unsigned char *) buf, &fbufp,
                                          &fbuf[MAXLINE] - fbufp);
again:
                        if (off < -1)
                                continue;

                        if (fbufp - fbuf > 0)
                        {
                                if (!putxline((char *) fbuf, fbufp - fbuf - 1,
                                                mci, pxflags))
                                        goto writeerr;
                        }
                        fbufp = fbuf;
                        if (off >= 0 && buf[off] != '\0')
                        {
                                off = mime_fromqp((unsigned char *) (buf + off),
                                                  &fbufp,
                                                  &fbuf[MAXLINE] - fbufp);
                                goto again;
                        }
                }
        }

        /* force out partial last line */
        if (fbufp > fbuf)
        {
                *fbufp = '\0';
                if (!putxline((char *) fbuf, fbufp - fbuf, mci, pxflags))
                        goto writeerr;
        }

        /*
        **  The decoded text may end without an EOL.  Since this function
        **  is only called for text/plain MIME messages, it is safe to
        **  add an extra one at the end just in case.  This is a hack,
        **  but so is auto-converting MIME in the first place.
        */

        if (!putline("", mci))
                goto writeerr;

        if (tTd(43, 3))
                sm_dprintf("\t\t\tmime7to8 => %s to 8bit done\n", cte);
        return true;

  writeerr:
        return false;
}
/*
**  The following is based on Borenstein's "codes.c" module, with simplifying
**  changes as we do not deal with multipart, and to do the translation in-core,
**  with an attempt to prevent overrun of output buffers.
**
**  What is needed here are changes to defend this code better against
**  bad encodings. Questionable to always return 0xFF for bad mappings.
*/

static char index_hex[128] =
{
        -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
        -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
        -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
        0, 1, 2, 3,  4, 5, 6, 7,  8, 9,-1,-1, -1,-1,-1,-1,
        -1,10,11,12, 13,14,15,-1, -1,-1,-1,-1, -1,-1,-1,-1,
        -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
        -1,10,11,12, 13,14,15,-1, -1,-1,-1,-1, -1,-1,-1,-1,
        -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1
};

# define HEXCHAR(c)  (((c) < 0 || (c) > 127) ? -1 : index_hex[(c)])

/*
**  MIME_FROMQP -- decode quoted printable string
**
**      Parameters:
**              infile -- input (encoded) string
**              outfile -- output string
**              maxlen -- size of output buffer
**
**      Returns:
**              -2 if decoding failure
**              -1 if infile completely decoded into outfile
**              >= 0 is the position in infile decoding
**                      reached before maxlen was reached
*/

static int
mime_fromqp(infile, outfile, maxlen)
        unsigned char *infile;
        unsigned char **outfile;
        int maxlen;             /* Max # of chars allowed in outfile */
{
        int c1, c2;
        int nchar = 0;
        unsigned char *b;

        /* decrement by one for trailing '\0', at least one other char */
        if (--maxlen < 1)
                return 0;

        b = infile;
        while ((c1 = *infile++) != '\0' && nchar < maxlen)
        {
                if (c1 == '=')
                {
                        if ((c1 = *infile++) == '\0')
                                break;

                        if (c1 == '\n' || (c1 = HEXCHAR(c1)) == -1)
                        {
                                /* ignore it and the rest of the buffer */
                                return -2;
                        }
                        else
                        {
                                do
                                {
                                        if ((c2 = *infile++) == '\0')
                                        {
                                                c2 = -1;
                                                break;
                                        }
                                } while ((c2 = HEXCHAR(c2)) == -1);

                                if (c2 == -1)
                                        break;
                                nchar++;
                                *(*outfile)++ = c1 << 4 | c2;
                        }
                }
                else
                {
                        nchar++;
                        *(*outfile)++ = c1;
                        if (c1 == '\n')
                                break;
                }
        }
        *(*outfile)++ = '\0';
        if (nchar >= maxlen)
                return (infile - b - 1);
        return -1;
}
#endif /* MIME7TO8 */