/*
Copyright (c) 1991 Bell Communications Research, Inc. (Bellcore)

Permission to use, copy, modify, and distribute this material 
for any purpose and without fee is hereby granted, provided 
that the above copyright notice and this permission notice 
appear in all copies, and that the name of Bellcore not be 
used in advertising or publicity pertaining to this 
material without the specific, prior written permission 
of an authorized representative of Bellcore.  BELLCORE 
MAKES NO REPRESENTATIONS ABOUT THE ACCURACY OR SUITABILITY 
OF THIS MATERIAL FOR ANY PURPOSE.  IT IS PROVIDED "AS IS", 
WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES.
*/

#include "elm_defs.h"

#define USAGE "usage: %s [-bqu] [-o outputfile] [inputfile]\n"

#define ENCODING_BASE64	1
#define ENCODING_QP	2 /* quoted-printable */

void to64 P_((FILE *, FILE *));
void from64 P_((FILE *, FILE *, char **, int *));
void toqp P_((FILE *, FILE *));
void fromqp P_((FILE *, FILE *, char **, int *));
void output64chunk P_((int, int, int, int, FILE *));	/* used in to64() */


int main(argc, argv)
int argc;
char **argv;
{
    int do_encode, encoding_type, i;
    extern int optind;
    extern char *optarg;

    do_encode = TRUE;
    encoding_type = ENCODING_BASE64;

    while ((i = getopt(argc, argv, "bo:pqu")) != EOF) {
	switch (i) {
	case 'b':
	    encoding_type = ENCODING_BASE64;
	    break;
	 case 'o':
	    if (freopen(optarg, "w", stdout) == NULL) {
		perror(optarg);
		exit(1);
	    }
	    break;
	case 'p':
	    /* ignored for compatibility with the metamail version */
	    break;
	case 'q':
	    encoding_type = ENCODING_QP;
	    break;
	case 'u':
	    do_encode = 0;
	    break;
	default:
	    fprintf(stderr, USAGE, argv[0]);
	    exit(1);
	}
    }

    switch (argc-optind) {
    case 0:
	break;
    case 1:
	if (freopen(argv[optind], "r", stdin) == NULL) {
	    perror(argv[optind]);
	    exit(1);
	}
	break;
    default:
	fprintf(stderr, USAGE, argv[0]);
	break;
    }

    if (encoding_type == ENCODING_BASE64) {
	if (do_encode)
	    to64(stdin, stdout);
	else
	    from64(stdin, stdout, (char **)NULL, (int *)0);
    } else {
	if (do_encode)
	    toqp(stdin, stdout);
	else
	    fromqp(stdin, stdout, (char **)NULL, (int *)0);
    }

    exit(0);
}


static char basis_64[] =
   "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

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) & 0x7F) ? -1 : index_64[(c)])

void to64(infile, outfile)
FILE *infile, *outfile;
{
    int c1, c2, c3, ct=0;
    while ((c1 = getc(infile)) != EOF) {
        c2 = getc(infile);
        if (c2 == EOF) {
            output64chunk(c1, 0, 0, 2, outfile);
        } else {
            c3 = getc(infile);
            if (c3 == EOF) {
                output64chunk(c1, c2, 0, 1, outfile);
            } else {
                output64chunk(c1, c2, c3, 0, outfile);
            }
        }
        ct += 4;
        if (ct > 71) {
            putc('\n', outfile);
            ct = 0;
        }
    }
    if (ct) putc('\n', outfile);
    fflush(outfile);
}

void output64chunk(c1, c2, c3, pads, outfile)
int c1, c2, c3, pads;
FILE *outfile;
{
    putc(basis_64[c1>>2], outfile);
    putc(basis_64[((c1 & 0x3)<< 4) | ((c2 & 0xF0) >> 4)], outfile);
    if (pads == 2) {
        putc('=', outfile);
        putc('=', outfile);
    } else if (pads) {
        putc(basis_64[((c2 & 0xF) << 2) | ((c3 & 0xC0) >>6)], outfile);
        putc('=', outfile);
    } else {
        putc(basis_64[((c2 & 0xF) << 2) | ((c3 & 0xC0) >>6)], outfile);
        putc(basis_64[c3 & 0x3F], outfile);
    }
}

int PendingBoundary(s, Boundaries, BoundaryCt)
char *s;
char **Boundaries;
int *BoundaryCt;
{
    int i, len;

    if (s[0] != '-' || s[1] != '-') return(0);


    for (i=0; i < *BoundaryCt; ++i) {
	len = strlen(Boundaries[i]);
        if (!strncmp(s, Boundaries[i], len)) {
            if (s[len] == '-' && s[len+1] == '-') *BoundaryCt = i;
            return(1);
        }
    }
    return(0);
}

void from64(infile, outfile, boundaries, boundaryct)
FILE *infile, *outfile;
char **boundaries;
int *boundaryct;
{
    int c1, c2, c3, c4;
    int newline = 1, DataDone = 0;

    while ((c1 = getc(infile)) != EOF) {
        if (isspace(c1)) {
            if (c1 == '\n') {
                newline = 1;
            } else {
                newline = 0;
            }
            continue;
        }
        if (newline && boundaries && c1 == '-') {
            char Buf[200];
            /* a dash is NOT base 64, so all bets are off if NOT a boundary */
            ungetc(c1, infile);
            fgets(Buf, sizeof(Buf), infile);
            if (boundaries
                 && (Buf[0] == '-')
                 && (Buf[1] == '-')
                 && PendingBoundary(Buf, boundaries, boundaryct)) {
                return;
            }
            fprintf(stderr, "Ignoring unrecognized boundary line: %s\n", Buf);
            continue;
        }
        if (DataDone) continue;
        newline = 0;
        do {
            c2 = getc(infile);
        } while (c2 != EOF && isspace(c2));
        do {
            c3 = getc(infile);
        } while (c3 != EOF && isspace(c3));
        do {
            c4 = getc(infile);
        } while (c4 != EOF && isspace(c4));
        if (c2 == EOF || c3 == EOF || c4 == EOF) {
            fprintf(stderr, "Warning: base64 decoder saw premature EOF!\n");
            return;
        }
        if (c1 == '=' || c2 == '=') {
            DataDone=1;
            continue;
        }
        c1 = char64(c1);
        c2 = char64(c2);
        putc(((c1<<2) | ((c2&0x30)>>4)), outfile);
        if (c3 == '=') {
            DataDone = 1;
        } else {
            c3 = char64(c3);
            putc((((c2&0XF) << 4) | ((c3&0x3C) >> 2)), outfile);
            if (c4 == '=') {
                DataDone = 1;
            } else {
                c4 = char64(c4);
                putc((((c3&0x03) <<6) | c4), outfile);
            }
        }
    }
}

static char basis_hex[] = "0123456789ABCDEF";
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) & 0x80) ? -1 : index_hex[(c)])

void toqp(infile, outfile) 
FILE *infile, *outfile;
{
    int c, ct=0, prevc=255;
    while ((c = getc(infile)) != EOF) {
        if ((c < 32 && (c != '\n' && c != '\t'))
             || (c == '=')
             || (c >= 127)
             /* Following line is to avoid single periods alone on lines,
               which messes up some dumb smtp implementations, sigh... */
             || (ct == 0 && c == '.')) {
            putc('=', outfile);
            putc(basis_hex[c>>4], outfile);
            putc(basis_hex[c&0xF], outfile);
            ct += 3;
            prevc = 'A'; /* close enough */
        } else if (c == '\n') {
            if (prevc == ' ' || prevc == '\t') {
                putc('=', outfile); /* soft & hard lines */
                putc(c, outfile);
            }
            putc(c, outfile);
            ct = 0;
            prevc = c;
        } else {
            if (c == 'F' && prevc == '\n') {
                /* HORRIBLE but clever hack suggested by MTR for sendmail-avoidance */
                c = getc(infile);
                if (c == 'r') {
                    c = getc(infile);
                    if (c == 'o') {
                        c = getc(infile);
                        if (c == 'm') {
                            c = getc(infile);
                            if (c == ' ') {
                                /* This is the case we are looking for */
                                fputs("=46rom", outfile);
                                ct += 6;
                            } else {
                                fputs("From", outfile);
                                ct += 4;
                            }
                        } else {
                            fputs("Fro", outfile);
                            ct += 3;
                        }
                    } else {
                        fputs("Fr", outfile);
                        ct += 2;
                    }
                } else {
                    putc('F', outfile);
                    ++ct;
                }
                ungetc(c, infile);
                prevc = 'x'; /* close enough -- printable */
            } else { /* END horrible hack */
                putc(c, outfile);
                ++ct;
                prevc = c;
            }
        }
        if (ct > 72) {
            putc('=', outfile);
            putc('\n', outfile);
            ct = 0;
            prevc = '\n';
        }
    }
    if (ct) {
        putc('=', outfile);
        putc('\n', outfile);
    }
}

void fromqp(infile, outfile, boundaries, boundaryct) 
FILE *infile, *outfile;
char **boundaries;
int *boundaryct;
{
    unsigned int c1, c2;
    int sawnewline = 1, neednewline = 0;
    /* The neednewline hack is necessary because the newline leading into 
      a multipart boundary is part of the boundary, not the data */

    while ((c1 = getc(infile)) != EOF) {
        if (sawnewline && boundaries && (c1 == '-')) {
            char Buf[200];
            unsigned char *s;

            ungetc(c1, infile);
            fgets(Buf, sizeof(Buf), infile);
            if (boundaries
                 && (Buf[0] == '-')
                 && (Buf[1] == '-')
                 && PendingBoundary(Buf, boundaries, boundaryct)) {
                return;
            }
            /* Not a boundary, now we must treat THIS line as q-p, sigh */
            if (neednewline) {
                putc('\n', outfile);
                neednewline = 0;
            }
            for (s=(unsigned char *) Buf; *s; ++s) {
                if (*s == '=') {
                    if (!*++s) break;
                    if (*s == '\n') {
                        /* ignore it */
                        sawnewline = 1;
                    } else {
                        c1 = hexchar(*s);
                        if (!*++s) break;
                        c2 = hexchar(*s);
                        putc(c1<<4 | c2, outfile);
                    }
                } else {
#ifdef MSDOS
                    if (*s == '\n')
                        putc('\r', outfile);	/* insert CR for binary-mode write */
#endif
                    putc(*s, outfile);
                }
            }
        } else {
            if (neednewline) {
                putc('\n', outfile);
                neednewline = 0;
            }
            if (c1 == '=') {
                sawnewline = 0;
                c1 = getc(infile);
                if (c1 == '\n') {
                    /* ignore it */
                    sawnewline = 1;
                } else {
                    c2 = getc(infile);
                    c1 = hexchar(c1);
                    c2 = hexchar(c2);
                    putc(c1<<4 | c2, outfile);
                    if (c2 == '\n') sawnewline = 1;
                }
            } else {
                if (c1 == '\n') {
                    sawnewline = 1;
                    neednewline = 1;
                } else {
                    sawnewline = 0;
                    putc(c1, outfile);
                }
            }
        }
    }
    if (neednewline) {
        putc('\n', outfile);
        neednewline = 0;
    }    
}