/* vi: set sw=4 ts=4: */
/*
 * makemime: create MIME-encoded message
 * reformime: parse MIME-encoded message
 *
 * Copyright (C) 2008 by Vladimir Dronnikov <dronnikov@gmail.com>
 *
 * Licensed under GPLv2, see file LICENSE in this tarball for details.
 */
#include "libbb.h"
#include "mail.h"

/*
  makemime -c type [-o file] [-e encoding] [-C charset] [-N name] \
                   [-a "Header: Contents"] file
           -m [ type ] [-o file] [-e encoding] [-a "Header: Contents"] file
           -j [-o file] file1 file2
           @file

   file:  filename    - read or write from filename
          -           - read or write from stdin or stdout
          &n          - read or write from file descriptor n
          \( opts \)  - read from child process, that generates [ opts ]

Options:

  -c type         - create a new MIME section from "file" with this
                    Content-Type: (default is application/octet-stream).
  -C charset      - MIME charset of a new text/plain section.
  -N name         - MIME content name of the new mime section.
  -m [ type ]     - create a multipart mime section from "file" of this
                    Content-Type: (default is multipart/mixed).
  -e encoding     - use the given encoding (7bit, 8bit, quoted-printable,
                    or base64), instead of guessing.  Omit "-e" and use
                    -c auto to set Content-Type: to text/plain or
                    application/octet-stream based on picked encoding.
  -j file1 file2  - join mime section file2 to multipart section file1.
  -o file         - write the result to file, instead of stdout (not
                    allowed in child processes).
  -a header       - prepend an additional header to the output.

  @file - read all of the above options from file, one option or
          value on each line.
  {which version of makemime is this? What do we support?}
*/


/* In busybox 1.15.0.svn, makemime generates output like this
 * (empty lines are shown exactly!):
{headers added with -a HDR}
Mime-Version: 1.0
Content-Type: multipart/mixed; boundary="24269534-2145583448-1655890676"

--24269534-2145583448-1655890676
Content-Type: {set by -c, e.g. text/plain}; charset={set by -C, e.g. us-ascii}
Content-Disposition: inline; filename="A"
Content-Transfer-Encoding: base64

...file A contents...
--24269534-2145583448-1655890676
Content-Type: {set by -c, e.g. text/plain}; charset={set by -C, e.g. us-ascii}
Content-Disposition: inline; filename="B"
Content-Transfer-Encoding: base64

...file B contents...
--24269534-2145583448-1655890676--

*/


/* For reference: here is an example email to LKML which has
 * 1st unnamed part (so it serves as an email body)
 * and one attached file:
...other headers...
Content-Type: multipart/mixed; boundary="=-tOfTf3byOS0vZgxEWcX+"
...other headers...
Mime-Version: 1.0
...other headers...


--=-tOfTf3byOS0vZgxEWcX+
Content-Type: text/plain
Content-Transfer-Encoding: 7bit

...email text...
...email text...


--=-tOfTf3byOS0vZgxEWcX+
Content-Disposition: attachment; filename="xyz"
Content-Type: text/plain; name="xyz"; charset="UTF-8"
Content-Transfer-Encoding: 7bit

...file contents...
...file contents...

--=-tOfTf3byOS0vZgxEWcX+--

...random junk added by mailing list robots and such...
*/

int makemime_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int makemime_main(int argc UNUSED_PARAM, char **argv)
{
        llist_t *opt_headers = NULL, *l;
        const char *opt_output;
#define boundary opt_output

        enum {
                OPT_c = 1 << 0,         // Content-Type:
                OPT_e = 1 << 1,         // Content-Transfer-Encoding. Ignored. Assumed base64
                OPT_o = 1 << 2,         // output to
                OPT_C = 1 << 3,         // charset
                OPT_N = 1 << 4,         // COMPAT
                OPT_a = 1 << 5,         // additional headers
                OPT_m = 1 << 6,         // COMPAT
                OPT_j = 1 << 7,         // COMPAT
        };

        INIT_G();

        // parse options
        opt_complementary = "a::";
        opts = getopt32(argv,
                "c:e:o:C:N:a:m:j:",
                &G.content_type, NULL, &opt_output, &G.opt_charset, NULL, &opt_headers, NULL, NULL
        );
        //argc -= optind;
        argv += optind;

        // respect -o output
        if (opts & OPT_o)
                freopen(opt_output, "w", stdout);

        // no files given on command line? -> use stdin
        if (!*argv)
                *--argv = (char *)"-";

        // put additional headers
        for (l = opt_headers; l; l = l->link)
                puts(l->data);

        // make a random string -- it will delimit message parts
        srand(monotonic_us());
        boundary = xasprintf("%u-%u-%u",
                        (unsigned)rand(), (unsigned)rand(), (unsigned)rand());

        // put multipart header
        printf(
                "Mime-Version: 1.0\n"
                "Content-Type: multipart/mixed; boundary=\"%s\"\n"
                , boundary
        );

        // put attachments
        while (*argv) {
                printf(
                        "\n--%s\n"
                        "Content-Type: %s; charset=%s\n"
                        "Content-Disposition: inline; filename=\"%s\"\n"
                        "Content-Transfer-Encoding: base64\n"
                        , boundary
                        , G.content_type
                        , G.opt_charset
                        , bb_get_last_path_component_strip(*argv)
                );
                encode_base64(*argv++, (const char *)stdin, "");
        }

        // put multipart footer
        printf("\n--%s--\n" "\n", boundary);

        return EXIT_SUCCESS;
#undef boundary
}

static const char *find_token(const char *const string_array[], const char *key, const char *defvalue)
{
        const char *r = NULL;
        int i;
        for (i = 0; string_array[i] != NULL; i++) {
                if (strcasecmp(string_array[i], key) == 0) {
                        r = (char *)string_array[i+1];
                        break;
                }
        }
        return (r) ? r : defvalue;
}

static const char *xfind_token(const char *const string_array[], const char *key)
{
        const char *r = find_token(string_array, key, NULL);
        if (r)
                return r;
        bb_error_msg_and_die("header: %s", key);
}

enum {
        OPT_x = 1 << 0,
        OPT_X = 1 << 1,
#if ENABLE_FEATURE_REFORMIME_COMPAT
        OPT_d = 1 << 2,
        OPT_e = 1 << 3,
        OPT_i = 1 << 4,
        OPT_s = 1 << 5,
        OPT_r = 1 << 6,
        OPT_c = 1 << 7,
        OPT_m = 1 << 8,
        OPT_h = 1 << 9,
        OPT_o = 1 << 10,
        OPT_O = 1 << 11,
#endif
};

static int parse(const char *boundary, char **argv)
{
        char *line, *s, *p;
        const char *type;
        int boundary_len = strlen(boundary);
        const char *delims = " ;\"\t\r\n";
        const char *uniq;
        int ntokens;
        const char *tokens[32]; // 32 is enough

        // prepare unique string pattern
        uniq = xasprintf("%%llu.%u.%s", (unsigned)getpid(), safe_gethostname());

//bb_info_msg("PARSE[%s]", terminator);

        while ((line = xmalloc_fgets_str(stdin, "\r\n\r\n")) != NULL) {

                // seek to start of MIME section
                // N.B. to avoid false positives let us seek to the _last_ occurance
                p = NULL;
                s = line;
                while ((s = strcasestr(s, "Content-Type:")) != NULL)
                        p = s++;
                if (!p)
                        goto next;
//bb_info_msg("L[%s]", p);

                // split to tokens
                // TODO: strip of comments which are of form: (comment-text)
                ntokens = 0;
                tokens[ntokens] = NULL;
                for (s = strtok(p, delims); s; s = strtok(NULL, delims)) {
                        tokens[ntokens] = s;
                        if (ntokens < ARRAY_SIZE(tokens) - 1)
                                ntokens++;
//bb_info_msg("L[%d][%s]", ntokens, s);
                }
                tokens[ntokens] = NULL;
//bb_info_msg("N[%d]", ntokens);

                // analyse tokens
                type = find_token(tokens, "Content-Type:", "text/plain");
//bb_info_msg("T[%s]", type);
                if (0 == strncasecmp(type, "multipart/", 10)) {
                        if (0 == strcasecmp(type+10, "mixed")) {
                                parse(xfind_token(tokens, "boundary="), argv);
                        } else
                                bb_error_msg_and_die("no support of content type '%s'", type);
                } else {
                        pid_t pid = pid;
                        int rc;
                        FILE *fp;
                        // fetch charset
                        const char *charset = find_token(tokens, "charset=", CONFIG_FEATURE_MIME_CHARSET);
                        // fetch encoding
                        const char *encoding = find_token(tokens, "Content-Transfer-Encoding:", "7bit");
                        // compose target filename
                        char *filename = (char *)find_token(tokens, "filename=", NULL);
                        if (!filename)
                                filename = xasprintf(uniq, monotonic_us());
                        else
                                filename = bb_get_last_path_component_strip(xstrdup(filename));

                        // start external helper, if any
                        if (opts & OPT_X) {
                                int fd[2];
                                xpipe(fd);
                                pid = vfork();
                                if (0 == pid) {
                                        // child reads from fd[0]
                                        close(fd[1]);
                                        xmove_fd(fd[0], STDIN_FILENO);
                                        xsetenv("CONTENT_TYPE", type);
                                        xsetenv("CHARSET", charset);
                                        xsetenv("ENCODING", encoding);
                                        xsetenv("FILENAME", filename);
                                        BB_EXECVP_or_die(argv);
                                }
                                // parent dumps to fd[1]
                                close(fd[0]);
                                fp = xfdopen_for_write(fd[1]);
                                signal(SIGPIPE, SIG_IGN); // ignore EPIPE
                        // or create a file for dump
                        } else {
                                char *fname = xasprintf("%s%s", *argv, filename);
                                fp = xfopen_for_write(fname);
                                free(fname);
                        }

                        // housekeeping
                        free(filename);

                        // dump to fp
                        if (0 == strcasecmp(encoding, "base64")) {
                                decode_base64(stdin, fp);
                        } else if (0 != strcasecmp(encoding, "7bit")
                                && 0 != strcasecmp(encoding, "8bit")
                        ) {
                                // quoted-printable, binary, user-defined are unsupported so far
                                bb_error_msg_and_die("no support of encoding '%s'", encoding);
                        } else {
                                // N.B. we have written redundant \n. so truncate the file
                                // The following weird 2-tacts reading technique is due to
                                // we have to not write extra \n at the end of the file
                                // In case of -x option we could truncate the resulting file as
                                // fseek(fp, -1, SEEK_END);
                                // if (ftruncate(fileno(fp), ftell(fp)))
                                //      bb_perror_msg("ftruncate");
                                // But in case of -X we have to be much more careful. There is
                                // no means to truncate what we already have sent to the helper.
                                p = xmalloc_fgets_str(stdin, "\r\n");
                                while (p) {
                                        s = xmalloc_fgets_str(stdin, "\r\n");
                                        if (s == NULL)
                                                break;
                                        if ('-' == s[0]
                                         && '-' == s[1]
                                         && 0 == strncmp(s+2, boundary, boundary_len)
                                        ) {
                                                break;
                                        }
                                        fputs(p, fp);
                                        p = s;
                                }

/*
                                while ((s = xmalloc_fgetline_str(stdin, "\r\n")) != NULL) {
                                        if ('-' == s[0] && '-' == s[1]
                                                && 0 == strncmp(s+2, boundary, boundary_len))
                                                break;
                                        fprintf(fp, "%s\n", s);
                                }
                                // N.B. we have written redundant \n. so truncate the file
                                fseek(fp, -1, SEEK_END);
                                if (ftruncate(fileno(fp), ftell(fp)))
                                        bb_perror_msg("ftruncate");
*/
                        }
                        fclose(fp);

                        // finalize helper
                        if (opts & OPT_X) {
                                signal(SIGPIPE, SIG_DFL);
                                // exit if helper exited >0
                                rc = (wait4pid(pid) & 0xff);
                                if (rc)
                                        return rc+20;
                        }

                        // check multipart finalized
                        if (s && '-' == s[2+boundary_len] && '-' == s[2+boundary_len+1]) {
                                free(line);
                                break;
                        }
                }
 next:
                free(line);
        }

//bb_info_msg("ENDPARSE[%s]", boundary);

        return EXIT_SUCCESS;
}

/*
Usage: reformime [options]
    -d - parse a delivery status notification.
    -e - extract contents of MIME section.
    -x - extract MIME section to a file.
    -X - pipe MIME section to a program.
    -i - show MIME info.
    -s n.n.n.n - specify MIME section.
    -r - rewrite message, filling in missing MIME headers.
    -r7 - also convert 8bit/raw encoding to quoted-printable, if possible.
    -r8 - also convert quoted-printable encoding to 8bit, if possible.
    -c charset - default charset for rewriting, -o, and -O.
    -m [file] [file]... - create a MIME message digest.
    -h "header" - decode RFC 2047-encoded header.
    -o "header" - encode unstructured header using RFC 2047.
    -O "header" - encode address list header using RFC 2047.
*/

int reformime_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int reformime_main(int argc UNUSED_PARAM, char **argv)
{
        const char *opt_prefix = "";

        INIT_G();

        // parse options
        // N.B. only -x and -X are supported so far
        opt_complementary = "x--X:X--x" IF_FEATURE_REFORMIME_COMPAT(":m::");
        opts = getopt32(argv,
                "x:X" IF_FEATURE_REFORMIME_COMPAT("deis:r:c:m:h:o:O:"),
                &opt_prefix
                IF_FEATURE_REFORMIME_COMPAT(, NULL, NULL, &G.opt_charset, NULL, NULL, NULL, NULL)
        );
        //argc -= optind;
        argv += optind;

        return parse("", (opts & OPT_X) ? argv : (char **)&opt_prefix);
}