path: root/src/libical/sspm.c

/*======================================================================
 FILE: sspm.c Parse Mime
 CREATOR: eric 25 June 2000

 (C) COPYRIGHT 2000, Eric Busboom <eric@civicknowledge.com>

 This library is free software; you can redistribute it and/or modify
 it under the terms of either:

    The LGPL as published by the Free Software Foundation, version
    2.1, available at: https://www.gnu.org/licenses/lgpl-2.1.html

 Or:

    The Mozilla Public License Version 2.0. You may obtain a copy of
    the License at https://www.mozilla.org/MPL/

 This library is free software; you can redistribute it and/or modify
 it under the terms of either:

    The LGPL as published by the Free Software Foundation, version
    2.1, available at: https://www.gnu.org/licenses/lgpl-2.1.html

 Or:

    The Mozilla Public License Version 2.0. You may obtain a copy of
    the License at https://www.mozilla.org/MPL/

 The Initial Developer of the Original Code is Eric Busboom
======================================================================*/

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include "sspm.h"

#include <assert.h>
#include <ctype.h>
#include <stdlib.h>

#define TMP_BUF_SIZE 1024

enum line_type
{
    EMPTY,
    BLANK,
    MIME_HEADER,
    MAIL_HEADER,
    HEADER_CONTINUATION,
    BOUNDARY,
    TERMINATING_BOUNDARY,
    UNKNOWN_TYPE
};

enum mime_state
{
    UNKNOWN_STATE,
    IN_HEADER,
    END_OF_HEADER,
    IN_BODY,
    OPENING_PART,
    END_OF_PART,
    TERMINAL_END_OF_PART,
    END_OF_INPUT
};

struct mime_impl
{
    struct sspm_part *parts;
    size_t max_parts;
    int part_no;
    int level;
    const struct sspm_action_map *actions;
    char *(*get_string) (char *s, size_t size, void *data);
    void *get_string_data;
    char temp[TMP_BUF_SIZE];
    enum mime_state state;
};

static void *sspm_make_multipart_part(struct mime_impl *impl, struct sspm_header *header);
static void *sspm_make_multipart_subpart(struct mime_impl *impl, struct sspm_header *parent_header);

static struct major_content_type_map
{
    enum sspm_major_type type;
    const char *str;

} major_content_type_map[] = {
    {SSPM_MULTIPART_MAJOR_TYPE, "multipart"},
    {SSPM_TEXT_MAJOR_TYPE, "text"},
    {SSPM_TEXT_MAJOR_TYPE, "text"},
    {SSPM_IMAGE_MAJOR_TYPE, "image"},
    {SSPM_AUDIO_MAJOR_TYPE, "audio"},
    {SSPM_VIDEO_MAJOR_TYPE, "video"},
    {SSPM_APPLICATION_MAJOR_TYPE, "application"},
    {SSPM_MULTIPART_MAJOR_TYPE, "multipart"},
    {SSPM_MESSAGE_MAJOR_TYPE, "message"},
    {SSPM_UNKNOWN_MAJOR_TYPE, ""}
};

static struct minor_content_type_map
{
    enum sspm_minor_type type;
    const char *str;

} minor_content_type_map[] = {
    {SSPM_ANY_MINOR_TYPE, "*"},
    {SSPM_PLAIN_MINOR_TYPE, "plain"},
    {SSPM_RFC822_MINOR_TYPE, "rfc822"},
    {SSPM_DIGEST_MINOR_TYPE, "digest"},
    {SSPM_CALENDAR_MINOR_TYPE, "calendar"},
    {SSPM_MIXED_MINOR_TYPE, "mixed"},
    {SSPM_RELATED_MINOR_TYPE, "related"},
    {SSPM_ALTERNATIVE_MINOR_TYPE, "alternative"},
    {SSPM_PARALLEL_MINOR_TYPE, "parallel"},
    {SSPM_UNKNOWN_MINOR_TYPE, ""}
};

static struct encoding_map
{
    enum sspm_encoding encoding;
    const char *str;
} sspm_encoding_map[] = {
    {SSPM_NO_ENCODING, ""},
    {SSPM_QUOTED_PRINTABLE_ENCODING, "quoted-printable"},
    {SSPM_8BIT_ENCODING, "8bit"},
    {SSPM_7BIT_ENCODING, "7bit"},
    {SSPM_BINARY_ENCODING, "binary"},
    {SSPM_BASE64_ENCODING, "base64"},
    {SSPM_UNKNOWN_ENCODING, ""}

};

static char *sspm_strdup(const char *str)
{
    char *s;

    s = strdup(str);
    return s;
}

static char *sspm_get_parameter(const char *line, const char *parameter)
{
    char *p, *s, *q;
    static char name[1024];

    /* Find where the parameter name is in the line */
    p = strstr(line, parameter);

    if (p == 0) {
        return 0;
    }

    /* skip over the parameter name, the '=' and any blank spaces */

    p += strlen(parameter);

    while (*p == ' ' || *p == '=') {
        p++;
    }

    /*now find the next semicolon */

    s = strchr(p, ';');

    /* Strip of leading quote */
    q = strchr(p, '\"');

    if (q != 0) {
        p = q + 1;
    }

    if (s != 0) {
        strncpy(name, p, (size_t) s - (size_t) p);
    } else {
        strncpy(name, p, sizeof(name) - 1);
        name[sizeof(name) - 1] = '\0';
    }

    /* Strip off trailing quote, if it exists */

    q = strrchr(name, '\"');

    if (q != 0) {
        *q = '\0';
    }

    return name;
}

static char *sspm_property_name(const char *line)
{
    static char name[1024];
    char *c = strchr(line, ':');

    if (c != 0) {
        strncpy(name, line, (size_t) c - (size_t) line);
        name[(size_t) c - (size_t) line] = '\0';
        return name;
    } else {
        return 0;
    }
}

static char *sspm_value(char *line)
{
    static char value[1024];

    char *c, *s, *p;

    /* Find the first colon and the next semicolon */

    value[0] = 0;
    c = strchr(line, ':');
    if (!c) {
        return value;
    }
    s = strchr(c, ';');

    /* Skip the colon */
    c++;

    if (s == 0) {
        s = c + strlen(line);
    }

    for (p = value; c != s; c++) {
        if (*c != ' ' && *c != '\n') {
            *(p++) = *c;
        }
    }

    *p = '\0';

    return value;
}

static const char *mime_headers[] = {
    "Content-Type",
    "Content-Transfer-Encoding",
    "Content-Disposition",
    "Content-Id",
    "Mime-Version",
    0
};

static void *sspm_default_new_part(void)
{
    return 0;
}

static void sspm_default_add_line(void *part, struct sspm_header *header,
                                  const char *line, size_t size)
{
    _unused(part);
    _unused(header);
    _unused(line);
    _unused(size);
}

static void *sspm_default_end_part(void *part)
{
    _unused(part);
    return 0;
}

static void sspm_default_free_part(void *part)
{
    _unused(part);
}

static struct sspm_action_map sspm_action_map[] = {
    {SSPM_UNKNOWN_MAJOR_TYPE, SSPM_UNKNOWN_MINOR_TYPE, sspm_default_new_part, sspm_default_add_line,
     sspm_default_end_part, sspm_default_free_part},
};

static int sspm_is_mime_header(char *line)
{
    char *name = sspm_property_name(line);
    int i;

    if (name == 0) {
        return 0;
    }

    for (i = 0; mime_headers[i] != 0; i++) {
        if (strcasecmp(name, mime_headers[i]) == 0) {
            return 1;
        }
    }

    return 0;
}

static int sspm_is_mail_header(char *line)
{
    char *name = sspm_property_name(line);

    if (name != 0) {
        return 1;
    }

    return 0;
}

static int sspm_is_blank(char *line)
{
    char *p;
    char c = 0;

    for (p = line; *p != 0; p++) {
        if (!(*p == ' ' || *p == '\t' || *p == '\n')) {
            c++;
        }
    }

    if (c == 0) {
        return 1;
    }

    return 0;
}

static int sspm_is_continuation_line(char *line)
{
    if (line[0] == ' ' || line[0] == '\t') {
        return 1;
    }

    return 0;
}

static int sspm_is_mime_boundary(char *line)
{
    if (line[0] == '-' && line[1] == '-') {
        return 1;
    }

    return 0;
}

static int sspm_is_mime_terminating_boundary(char *line)
{
    if (sspm_is_mime_boundary(line) && strstr(line, "--\n")) {
        return 1;
    }

    return 0;
}

static enum line_type get_line_type(char *line)
{
    if (line == 0) {
        return EMPTY;
    } else if (sspm_is_blank(line)) {
        return BLANK;
    } else if (sspm_is_mime_header(line)) {
        return MIME_HEADER;
    } else if (sspm_is_mail_header(line)) {
        return MAIL_HEADER;
    } else if (sspm_is_continuation_line(line)) {
        return HEADER_CONTINUATION;
    } else if (sspm_is_mime_terminating_boundary(line)) {
        return TERMINATING_BOUNDARY;
    } else if (sspm_is_mime_boundary(line)) {
        return BOUNDARY;
    } else {
        return UNKNOWN_TYPE;
    }
}

static struct sspm_action_map get_action(struct mime_impl *impl,
                                         enum sspm_major_type major, enum sspm_minor_type minor)
{
    size_t i;
    size_t len;

    /* Read caller suppled action map */

    if (impl->actions != 0) {
        for (i = 0; impl->actions[i].major != SSPM_UNKNOWN_MAJOR_TYPE; i++) {
            if ((major == impl->actions[i].major &&
                 minor == impl->actions[i].minor) ||
                (major == impl->actions[i].major && minor == SSPM_ANY_MINOR_TYPE)) {
                return impl->actions[i];
            }
        }
    }

    /* Else, read default action map */
    len = sizeof(sspm_action_map) / sizeof(sspm_action_map[0]);
    for (i = 0; i < len && sspm_action_map[i].major != SSPM_UNKNOWN_MAJOR_TYPE; i++) {
        if ((major == sspm_action_map[i].major &&
             minor == sspm_action_map[i].minor) ||
            (major == sspm_action_map[i].major && minor == SSPM_ANY_MINOR_TYPE)) {
            return sspm_action_map[i];
        }
    }
    assert(i < len);    /*should return before now */
    return sspm_action_map[0];
}

static char *sspm_lowercase(char *str)
{
    char *p = 0;
    char *new;

    if (str == 0) {
        return 0;
    }
    new = sspm_strdup(str);
    for (p = new; *p != 0; p++) {
        *p = tolower((int)*p);
    }

    return new;
}

static enum sspm_major_type sspm_find_major_content_type(char *type)
{
    int i;

    char *ltype = sspm_lowercase(type);

    for (i = 0; major_content_type_map[i].type != SSPM_UNKNOWN_MAJOR_TYPE; i++) {
        if (strncmp(ltype, major_content_type_map[i].str,
                    strlen(major_content_type_map[i].str)) == 0) {
            free(ltype);
            return major_content_type_map[i].type;
        }
    }
    free(ltype);
    return major_content_type_map[i].type;      /* Should return SSPM_UNKNOWN_MINOR_TYPE */
}

static enum sspm_minor_type sspm_find_minor_content_type(char *type)
{
    int i;
    char *ltype = sspm_lowercase(type);

    char *p = strchr(ltype, '/');

    if (p == 0) {
        free(ltype);
        return SSPM_UNKNOWN_MINOR_TYPE;
    }

    p++;        /* Skip the '/' */

    for (i = 0; minor_content_type_map[i].type != SSPM_UNKNOWN_MINOR_TYPE; i++) {
        if (strncmp(p, minor_content_type_map[i].str, strlen(minor_content_type_map[i].str)) == 0) {
            free(ltype);
            return minor_content_type_map[i].type;
        }
    }

    free(ltype);
    return minor_content_type_map[i].type;      /* Should return SSPM_UNKNOWN_MINOR_TYPE */
}

const char *sspm_major_type_string(enum sspm_major_type type)
{
    int i;

    for (i = 0; major_content_type_map[i].type != SSPM_UNKNOWN_MAJOR_TYPE; i++) {
        if (type == major_content_type_map[i].type) {
            return major_content_type_map[i].str;
        }
    }

    return major_content_type_map[i].str;       /* Should return SSPM_UNKNOWN_MINOR_TYPE */
}

const char *sspm_minor_type_string(enum sspm_minor_type type)
{
    int i;

    for (i = 0; minor_content_type_map[i].type != SSPM_UNKNOWN_MINOR_TYPE; i++) {
        if (type == minor_content_type_map[i].type) {
            return minor_content_type_map[i].str;
        }
    }

    return minor_content_type_map[i].str;       /* Should return SSPM_UNKNOWN_MINOR_TYPE */
}

const char *sspm_encoding_string(enum sspm_encoding type)
{
    int i;

    for (i = 0; sspm_encoding_map[i].encoding != SSPM_UNKNOWN_ENCODING; i++) {
        if (type == sspm_encoding_map[i].encoding) {
            return sspm_encoding_map[i].str;
        }
    }

    return sspm_encoding_map[i].str;    /* Should return SSPM_UNKNOWN_MINOR_TYPE */
}

/* Interpret a header line and add its data to the header
   structure. */
static void sspm_build_header(struct sspm_header *header, char *line)
{
    char *prop;
    char *val;

    val = sspm_strdup(sspm_value(line));
    prop = sspm_strdup(sspm_property_name(line));

    if (strcasecmp(prop, "Content-Type") == 0) {

        /* Create a new mime_header, fill in content-type
           and possibly boundary */

        char *boundary = sspm_get_parameter(line, "boundary");

        header->def = 0;
        header->major = sspm_find_major_content_type(val);
        header->minor = sspm_find_minor_content_type(val);

        if (header->minor == SSPM_UNKNOWN_MINOR_TYPE) {
            char *p = strchr(val, '/');

            if (header->minor_text != 0) {
                free(header->minor_text);
            }
            if (p != 0) {
                p++;    /* Skip the '/' */

                header->minor_text = sspm_strdup(p);
            } else {
                /* Error, malformed content type */
                header->minor_text = sspm_strdup("unknown");
            }
        }
        if (boundary != 0) {
            if (header->boundary != 0) {
                free(header->boundary);
            }
            header->boundary = sspm_strdup(boundary);
        }

    } else if (strcasecmp(prop, "Content-Transfer-Encoding") == 0) {
        char *encoding = sspm_value(line);
        char *lencoding = sspm_lowercase(encoding);

        if (strcasecmp(lencoding, "base64") == 0) {
            header->encoding = SSPM_BASE64_ENCODING;
        } else if (strcasecmp(lencoding, "quoted-printable") == 0) {
            header->encoding = SSPM_QUOTED_PRINTABLE_ENCODING;
        } else if (strcasecmp(lencoding, "binary") == 0) {
            header->encoding = SSPM_BINARY_ENCODING;
        } else if (strcasecmp(lencoding, "7bit") == 0) {
            header->encoding = SSPM_7BIT_ENCODING;
        } else if (strcasecmp(lencoding, "8bit") == 0) {
            header->encoding = SSPM_8BIT_ENCODING;
        } else {
            header->encoding = SSPM_UNKNOWN_ENCODING;
        }

        free(lencoding);

        header->def = 0;

    } else if (strcasecmp(prop, "Content-Id") == 0) {
        char *cid = sspm_value(line);

        if (header->content_id != 0) {
            free(header->content_id);
        }

        header->content_id = sspm_strdup(cid);
        header->def = 0;
    }
    free(val);
    free(prop);
}

static char *sspm_get_next_line(struct mime_impl *impl)
{
    char *s;

    s = impl->get_string(impl->temp, TMP_BUF_SIZE, impl->get_string_data);

    if (s == 0) {
        impl->state = END_OF_INPUT;
    }
    return s;
}

static void sspm_store_part(struct mime_impl *impl, struct sspm_header header,
                            int level, void *part, size_t size)
{
    impl->parts[impl->part_no].header = header;
    impl->parts[impl->part_no].level = level;
    impl->parts[impl->part_no].data = part;
    impl->parts[impl->part_no].data_size = size;
    impl->part_no++;
}

static void sspm_set_error(struct sspm_header *header, enum sspm_error error, char *message)
{
    header->error = error;

    if (header->error_text != 0) {
        free(header->error_text);
    }

    header->def = 0;

    if (message != 0) {
        header->error_text = sspm_strdup(message);
    } else {
        header->error_text = 0;
    }
}

static void sspm_read_header(struct mime_impl *impl, struct sspm_header *header)
{
#define MAX_HEADER_LINES 25

    char *buf;
    char header_lines[MAX_HEADER_LINES][TMP_BUF_SIZE];  /* HACK, hard limits TODO */
    int current_line = -1;
    int end = 0;

    memset(header_lines, 0, sizeof(header_lines));
    memset(header, 0, sizeof(struct sspm_header));

    /* Set up default header */
    header->def = 1;
    header->major = SSPM_TEXT_MAJOR_TYPE;
    header->minor = SSPM_PLAIN_MINOR_TYPE;
    header->error = SSPM_NO_ERROR;
    header->error_text = 0;

    /* Read all of the lines into memory */
    while (current_line < (MAX_HEADER_LINES - 2) &&
           (end == 0) && ((buf = sspm_get_next_line(impl)) != 0)) {

        enum line_type line_type = get_line_type(buf);

        switch (line_type) {
        case BLANK:{
                end = 1;
                impl->state = END_OF_HEADER;
                break;
            }

        case MAIL_HEADER:
        case MIME_HEADER:{
                impl->state = IN_HEADER;
                current_line++;

                assert(strlen(buf) < TMP_BUF_SIZE);

                strncpy(header_lines[current_line], buf, TMP_BUF_SIZE);
                header_lines[current_line][TMP_BUF_SIZE - 1] = '\0';

                break;
            }

        case HEADER_CONTINUATION:{
                char *last_line;
                char *buf_start;

                if (current_line < 0) {
                    /* This is not really a continuation line, since
                       we have not see any header line yet */
                    sspm_set_error(header, SSPM_MALFORMED_HEADER_ERROR, buf);
                    return;
                }

                last_line = header_lines[current_line];
                impl->state = IN_HEADER;

                /* skip over the spaces in buf start, and remove the new
                   line at the end of the lat line */
                if (last_line[strlen(last_line) - 1] == '\n') {
                    last_line[strlen(last_line) - 1] = '\0';
                }
                buf_start = buf;
                while (*buf_start == ' ' || *buf_start == '\t') {
                    buf_start++;
                }

                assert(strlen(buf_start) + strlen(last_line) < TMP_BUF_SIZE);

                strncat(last_line, buf_start, TMP_BUF_SIZE - strlen(last_line) - 1);

                break;
            }

        default:{
                sspm_set_error(header, SSPM_MALFORMED_HEADER_ERROR, buf);
                return;
            }
        }
    }

    for (current_line = 0;
         current_line < MAX_HEADER_LINES && header_lines[current_line][0] != 0; current_line++) {

        sspm_build_header(header, header_lines[current_line]);
    }
}

static void sspm_make_part(struct mime_impl *impl,
                           struct sspm_header *header,
                           struct sspm_header *parent_header, void **end_part, size_t *size)
{
    /* For a single part type, read to the boundary, if there is a
       boundary. Otherwise, read until the end of input.  This routine
       assumes that the caller has read the header and has left the input
       at the first blank line */

    char *line;
    void *part;
    int end = 0;

    struct sspm_action_map action = get_action(impl,
                                               header->major,
                                               header->minor);

    *size = 0;
    part = action.new_part();

    impl->state = IN_BODY;

    while (end == 0 && (line = sspm_get_next_line(impl)) != 0) {

        if (sspm_is_mime_boundary(line)) {

            /* If there is a boundary, then this must be a multipart
               part, so there must be a parent_header. */
            if (parent_header == 0) {
                char *boundary;

                end = 1;
                *end_part = 0;

                sspm_set_error(header, SSPM_UNEXPECTED_BOUNDARY_ERROR, line);

                /* Read until the paired terminating boundary */
                if ((boundary = (char *)malloc(strlen(line) + 5)) == 0) {
                    fprintf(stderr, "Out of memory");
                    abort();
                }
                strcpy(boundary, line);
                strcat(boundary, "--");
                while ((line = sspm_get_next_line(impl)) != 0) {
                    /*printf("Error: %s\n",line); */
                    if (strcmp(boundary, line) == 0) {
                        break;
                    }
                }
                free(boundary);

                break;
            }

            if (strcmp((line + 2), parent_header->boundary) == 0) {
                *end_part = action.end_part(part);

                if (sspm_is_mime_boundary(line)) {
                    impl->state = END_OF_PART;
                } else if (sspm_is_mime_terminating_boundary(line)) {
                    impl->state = TERMINAL_END_OF_PART;
                }
                end = 1;
            } else {
                /* Error, this is not the correct terminating boundary */

                /* read and discard until we get the right boundary.  */
                char *boundary;
                char msg[256];

                snprintf(msg, 256, "Expected: %s--. Got: %s", parent_header->boundary, line);

                sspm_set_error(parent_header, SSPM_WRONG_BOUNDARY_ERROR, msg);

                /* Read until the paired terminating boundary */
                if ((boundary = (char *)malloc(strlen(line) + 5)) == 0) {
                    fprintf(stderr, "Out of memory");
                    abort();
                }
                strcpy(boundary, line);
                strcat(boundary, "--");
                while ((line = sspm_get_next_line(impl)) != 0) {
                    if (strcmp(boundary, line) == 0) {
                        break;
                    }
                }
                free(boundary);
            }
        } else {
            char *data = 0;
            char *rtrn = 0;

            *size = strlen(line);

            data = (char *)malloc(*size + 2);
            assert(data != 0);
            if (header->encoding == SSPM_BASE64_ENCODING) {
                rtrn = decode_base64(data, line, size);
            } else if (header->encoding == SSPM_QUOTED_PRINTABLE_ENCODING) {
                rtrn = decode_quoted_printable(data, line, size);
            }

            if (rtrn == 0) {
                strcpy(data, line);
            }

            /* add a end-of-string after the data, just in case binary
               data from decode64 gets passed to a tring handling
               routine in add_line  */
            data[*size + 1] = '\0';

            action.add_line(part, header, data, *size);

            free(data);
        }
    }

    if (end == 0) {
        /* End the part if the input is exhausted */
        *end_part = action.end_part(part);
    }

    return;
}

static void *sspm_make_multipart_part(struct mime_impl *impl, struct sspm_header *header)
{
    void *part = 0;

    /* Now descend a level into each of the children of this part */
    impl->level++;

    /* Now we are working on the CHILD */
    memset(&(impl->parts[impl->part_no]), 0, sizeof(struct sspm_part));

    do {
        part = sspm_make_multipart_subpart(impl, header);

        if (part == 0) {
            /* Clean up the part in progress */
            impl->parts[impl->part_no].header.major = SSPM_NO_MAJOR_TYPE;
            impl->parts[impl->part_no].header.minor = SSPM_NO_MINOR_TYPE;
        }

    } while (get_line_type(impl->temp) != TERMINATING_BOUNDARY && impl->state != END_OF_INPUT);

    impl->level--;

    return 0;
}

static void *sspm_make_multipart_subpart(struct mime_impl *impl, struct sspm_header *parent_header)
{
    struct sspm_header header;
    char *line;
    void *part;
    size_t size;

    if (parent_header->boundary == 0) {
        /* Error. Multipart headers must have a boundary */

        sspm_set_error(parent_header, SSPM_NO_BOUNDARY_ERROR, 0);
        /* read all of the reamining lines */
        while (sspm_get_next_line(impl) != 0) {
        }

        return 0;
    }

    /* Step 1: Read the opening boundary */

    if (get_line_type(impl->temp) != BOUNDARY) {
        while ((line = sspm_get_next_line(impl)) != 0) {
            if (sspm_is_mime_boundary(line)) {

                assert(parent_header != 0);

                /* Check if it is the right boundary */
                if (!sspm_is_mime_terminating_boundary(line) &&
                    strcmp((line + 2), parent_header->boundary) == 0) {
                    /* The +2 in strncmp skips over the leading "--" */

                    break;
                } else {
                    /* Got the wrong boundary, so read and discard
                       until we get the right boundary.  */
                    char *boundary;
                    char msg[256];

                    snprintf(msg, 256, "Expected: %s. Got: %s", parent_header->boundary, line);

                    sspm_set_error(parent_header, SSPM_WRONG_BOUNDARY_ERROR, msg);

                    /* Read until the paired terminating boundary */
                    if ((boundary = (char *)malloc(strlen(line) + 5)) == 0) {
                        fprintf(stderr, "Out of memory");
                        abort();
                    }
                    strcpy(boundary, line);
                    strcat(boundary, "--");
                    while ((line = sspm_get_next_line(impl)) != 0) {
                        if (strcmp(boundary, line) == 0) {
                            break;
                        }
                    }
                    free(boundary);

                    return 0;
                }
            }
        }
    }

    /* Step 2: Get the part header */
    sspm_read_header(impl, &header);

    /* If the header is still listed as default, there was probably an
       error */
    if (header.def == 1 && header.error != SSPM_NO_ERROR) {
        sspm_set_error(&header, SSPM_NO_HEADER_ERROR, 0);
        return 0;
    }

    if (header.error != SSPM_NO_ERROR) {
        sspm_store_part(impl, header, impl->level, 0, 0);
        return 0;
    }

    /* Step 3: read the body */

    if (header.major == SSPM_MULTIPART_MAJOR_TYPE) {
        struct sspm_header *child_header;

        child_header = &(impl->parts[impl->part_no].header);

        /* Store the multipart part */
        sspm_store_part(impl, header, impl->level, 0, 0);

        /* now get all of the sub-parts */
        part = sspm_make_multipart_part(impl, child_header);

        if (get_line_type(impl->temp) != TERMINATING_BOUNDARY) {

            sspm_set_error(child_header, SSPM_NO_BOUNDARY_ERROR, impl->temp);
            return 0;
        }

        (void)sspm_get_next_line(impl); /* Step past the terminating boundary */

    } else {
        sspm_make_part(impl, &header, parent_header, &part, &size);

        memset(&(impl->parts[impl->part_no]), 0, sizeof(struct sspm_part));

        sspm_store_part(impl, header, impl->level, part, size);
    }

    return part;
}

/* Root routine for parsing mime entries*/
int sspm_parse_mime(struct sspm_part *parts,
                    size_t max_parts,
                    const struct sspm_action_map *actions,
                    char *(*get_string) (char *s, size_t size, void *data),
                    void *get_string_data, struct sspm_header *first_header)
{
    struct mime_impl impl;
    struct sspm_header header;
    int i;

    _unused(first_header);

    /* Initialize all of the data */
    memset(&impl, 0, sizeof(struct mime_impl));
    memset(&header, 0, sizeof(struct sspm_header));

    for (i = 0; i < (int)max_parts; i++) {
        parts[i].header.major = SSPM_NO_MAJOR_TYPE;
        parts[i].header.minor = SSPM_NO_MINOR_TYPE;
    }

    impl.parts = parts;
    impl.max_parts = max_parts;
    impl.part_no = 0;
    impl.actions = actions;
    impl.get_string = get_string;
    impl.get_string_data = get_string_data;

    /* Read the header of the message. This will be the email header,
       unless first_header is specified. But ( HACK) that var is not
       currently being used */
    sspm_read_header(&impl, &header);

    if (header.major == SSPM_MULTIPART_MAJOR_TYPE) {
        struct sspm_header *child_header;

        child_header = &(impl.parts[impl.part_no].header);

        sspm_store_part(&impl, header, impl.level, 0, 0);
        (void)sspm_make_multipart_part(&impl, child_header);

    } else {
        void *part;
        size_t size;

        sspm_make_part(&impl, &header, 0, &part, &size);

        memset(&(impl.parts[impl.part_no]), 0, sizeof(struct sspm_part));

        sspm_store_part(&impl, header, impl.level, part, size);
    }

    return 0;
}

static void sspm_free_header(struct sspm_header *header)
{
    if (header->boundary != 0) {
        free(header->boundary);
    }
    if (header->minor_text != 0) {
        free(header->minor_text);
    }
    if (header->charset != 0) {
        free(header->charset);
    }
    if (header->filename != 0) {
        free(header->filename);
    }
    if (header->content_id != 0) {
        free(header->content_id);
    }
    if (header->error_text != 0) {
        free(header->error_text);
    }
}

void sspm_free_parts(struct sspm_part *parts, size_t max_parts)
{
    int i;

    for (i = 0; i < (int)max_parts && parts[i].header.major != SSPM_NO_MAJOR_TYPE; i++) {
        sspm_free_header(&(parts[i].header));
    }
}

/***********************************************************************
The remaining code is beased on code from the mimelite distribution,
which has the following notice:

| Authorship:
|    Copyright (c) 1994 Gisle Hannemyr.
|    Permission is granted to hack, make and distribute copies of this
|    program as long as this copyright notice is not removed.
|    Flames, bug reports, comments and improvements to:
|       snail: Gisle Hannemyr, Brageveien 3A, 0452 Oslo, Norway
|       email: Inet: gisle@oslonett.no

The code is heavily modified by Eric Busboom.

***********************************************************************/

char *decode_quoted_printable(char *dest, char *src, size_t *size)
{
    int cc;
    size_t i = 0;

    while (*src != 0 && i < *size) {
        if (*src == '=') {

            src++;
            if (!*src) {
                break;
            }

            /* remove soft line breaks */
            if ((*src == '\n') || (*src == '\r')) {
                src++;
                if ((*src == '\n') || (*src == '\r')) {
                    src++;
                }
                continue;
            }

            cc = isdigit((int)*src) ? (*src - '0') : (*src - 55);
            cc *= 0x10;
            src++;
            if (!*src) {
                break;
            }
            cc += isdigit((int)*src) ? (*src - '0') : (*src - 55);

            *dest = cc;

        } else {
            *dest = *src;
        }

        dest++;
        src++;
        i++;
    }

    *dest = '\0';

    *size = i;
    return (dest);
}

char *decode_base64(char *dest, char *src, size_t *size)
{
    int cc = 0;
    char buf[4] = { 0, 0, 0, 0 };
    int p = 0;
    int valid_data = 0;
    size_t size_out = 0;

    while (*src && p < (int)*size && (cc != -1)) {

        /* convert a character into the Base64 alphabet */
        cc = *src++;

        if ((cc >= 'A') && (cc <= 'Z')) {
            cc = cc - 'A';
        } else if ((cc >= 'a') && (cc <= 'z')) {
            cc = cc - 'a' + 26;
        } else if ((cc >= '0') && (cc <= '9')) {
            cc = cc - '0' + 52;
        } else if (cc == '/') {
            cc = 63;
        } else if (cc == '+') {
            cc = 62;
        } else {
            cc = -1;
        }

        assert(cc < 64);

        /* If we've reached the end, fill the remaining slots in
           the bucket and do a final conversion */
        if (cc == -1) {
            if (valid_data == 0) {
                return 0;
            }

            while (p % 4 != 3) {
                p++;
                buf[p % 4] = 0;
            }
        } else {
            buf[p % 4] = cc;
            size_out++;
            valid_data = 1;
        }

        /* When we have 4 base64 letters, convert them into three
           bytes */
        if (p % 4 == 3) {
            *dest++ = (buf[0] << 2) | ((buf[1] & 0x30) >> 4);
            *dest++ = ((buf[1] & 0x0F) << 4) | ((buf[2] & 0x3C) >> 2);
            *dest++ = ((buf[2] & 0x03) << 6) | (buf[3] & 0x3F);

            memset(buf, 0, 4);
        }

        p++;
    }
    /* Calculate the size of the converted data */
    *size = ((size_t) (size_out / 4)) * 3;
    if (size_out % 4 == 2) {
        *size += 1;
    }
    if (size_out % 4 == 3) {
        *size += 2;
    }

    return (dest);
}

/***********************************************************************

 Routines to output MIME

**********************************************************************/

struct sspm_buffer
{
    char *buffer;
    char *pos;
    size_t buf_size;
    int line_pos;
};

static void sspm_append_string(struct sspm_buffer *buf, const char *string);

static void sspm_append_hex(struct sspm_buffer *buf, char ch)
{
    char tmp[4];

    snprintf(tmp, sizeof(tmp), "=%02X", (unsigned int)ch);

    sspm_append_string(buf, tmp);
}

/* a copy of icalmemory_append_char */
static void sspm_append_char(struct sspm_buffer *buf, char ch)
{
    char *new_buf;
    char *new_pos;

    size_t data_length, final_length;

    data_length = (size_t) buf->pos - (size_t) buf->buffer;

    final_length = data_length + 2;

    if (final_length > (size_t) buf->buf_size) {

        buf->buf_size = (buf->buf_size) * 2 + final_length + 1;

        new_buf = realloc(buf->buffer, buf->buf_size);

        new_pos = (void *)((size_t) new_buf + data_length);

        buf->pos = new_pos;
        buf->buffer = new_buf;
    }

    *(buf->pos) = ch;
    buf->pos += 1;
    *(buf->pos) = 0;
}

/* A copy of icalmemory_append_string */
void sspm_append_string(struct sspm_buffer *buf, const char *string)
{
    char *new_buf;
    char *new_pos;

    size_t data_length, final_length, string_length;

    string_length = strlen(string);
    data_length = (size_t) buf->pos - (size_t) buf->buffer;
    final_length = data_length + string_length;

    if (final_length >= (size_t) buf->buf_size) {

        buf->buf_size = (buf->buf_size) * 2 + final_length;

        new_buf = realloc(buf->buffer, buf->buf_size);

        new_pos = (void *)((size_t) new_buf + data_length);

        buf->pos = new_pos;
        buf->buffer = new_buf;
    }

    strcpy(buf->pos, string);

    buf->pos += string_length;
}

static int sspm_is_printable(char c)
{
    return (c >= 33) && (c <= 126) && (c != '=');
}

static void sspm_encode_quoted_printable(struct sspm_buffer *buf, char *data)
{
    char *p;
    int lpos = 0;

    for (p = data; *p != 0; p++) {

        if (sspm_is_printable(*p)) {
            /* plain characters can represent themselves */
            /* RFC2045 Rule #2 */
            sspm_append_char(buf, *p);
            lpos++;
        } else if (*p == '\t' || *p == ' ') {

            /* For tabs and spaces, only encode if they appear at the
               end of the line */
            /* RFC2045 Rule #3 */

            char n = *(p + 1);

            if (n == '\n' || n == '\r') {
                sspm_append_hex(buf, *p);
                lpos += 3;
            } else {
                sspm_append_char(buf, *p);
                lpos++;
            }

        } else if (*p == '\n' || *p == '\r') {
            sspm_append_char(buf, *p);

            lpos = 0;

        } else {
            /* All others need to be encoded */
            sspm_append_hex(buf, *p);
            lpos += 3;
        }

        /* Add line breaks */
        if (lpos > 72) {
            lpos = 0;
            sspm_append_string(buf, "=\n");
        }
    }
}

static const char BaseTable[64] = {
    'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
    'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
    'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
    'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/'
};

static void sspm_write_base64(struct sspm_buffer *buf, char *inbuf, int size)
{
    char outbuf[4];
    int i;

    outbuf[0] = outbuf[1] = outbuf[2] = outbuf[3] = 65;

    switch (size) {

    case 4:
        outbuf[3] = inbuf[2] & 0x3F;
        /* falls through */

    case 3:
        outbuf[2] = ((inbuf[1] & 0x0F) << 2) | ((inbuf[2] & 0xC0) >> 6);
        /* falls through */

    case 2:
        outbuf[0] = (inbuf[0] & 0xFC) >> 2;
        outbuf[1] = ((inbuf[0] & 0x03) << 4) | ((inbuf[1] & 0xF0) >> 4);
        break;

    default:
        assert(0);
    }

    for (i = 0; i < 4; i++) {

        if (outbuf[i] == 65) {
            sspm_append_char(buf, '=');
        } else {
            sspm_append_char(buf, BaseTable[(int)outbuf[i]]);
        }
    }
}

static void sspm_encode_base64(struct sspm_buffer *buf, char *data, size_t size)
{
    char *p;
    char inbuf[3];
    int i = 0;
    int first = 1;
    int lpos = 0;

    _unused(size);

    inbuf[0] = inbuf[1] = inbuf[2] = 0;

    for (p = data; *p != 0; p++) {

        if (i % 3 == 0 && first == 0) {

            sspm_write_base64(buf, inbuf, 4);
            lpos += 4;

            inbuf[0] = inbuf[1] = inbuf[2] = 0;
        }

        assert(lpos % 4 == 0);

        if (lpos == 72) {
            sspm_append_string(buf, "\n");
            lpos = 0;
        }

        inbuf[i % 3] = *p;

        i++;
        first = 0;
    }

    /* If the inbuf was not exactly filled on the last byte, we need
       to spit out the odd bytes that did get in -- either one or
       two. This will result in an output of two bytes and '==' or
       three bytes and '=', respectively */

    if (i % 3 == 1 && first == 0) {
        sspm_write_base64(buf, inbuf, 2);
    } else if (i % 3 == 2 && first == 0) {
        sspm_write_base64(buf, inbuf, 3);
    }
}

static void sspm_write_header(struct sspm_buffer *buf, struct sspm_header *header)
{
    int i;
    char temp[TMP_BUF_SIZE];
    const char *major;
    const char *minor;

    /* Content-type */

    major = sspm_major_type_string(header->major);
    minor = sspm_minor_type_string(header->minor);

    if (header->minor == SSPM_UNKNOWN_MINOR_TYPE) {
        assert(header->minor_text != 0);
        minor = header->minor_text;
    }

    snprintf(temp, sizeof(temp), "Content-Type: %s/%s", major, minor);

    sspm_append_string(buf, temp);

    if (header->boundary != 0) {
        snprintf(temp, sizeof(temp), ";boundary=\"%s\"", header->boundary);
        sspm_append_string(buf, temp);
    }

    /* Append any content type parameters */
    if (header->content_type_params != 0) {
        for (i = 0; *(header->content_type_params[i]) != 0; i++) {
            snprintf(temp, sizeof(temp), "%s", header->content_type_params[i]);
            sspm_append_char(buf, ';');
            sspm_append_string(buf, temp);
        }
    }

    sspm_append_char(buf, '\n');

    /*Content-Transfer-Encoding */

    if (header->encoding != SSPM_UNKNOWN_ENCODING && header->encoding != SSPM_NO_ENCODING) {
        snprintf(temp, sizeof(temp), "Content-Transfer-Encoding: %s\n",
                 sspm_encoding_string(header->encoding));
    }

    sspm_append_char(buf, '\n');
}

static void sspm_write_part(struct sspm_buffer *buf, struct sspm_part *part, int *part_num)
{
    _unused(part_num);

    /* Write header */
    sspm_write_header(buf, &(part->header));

    /* Write part data */

    if (part->data == 0) {
        return;
    }

    if (part->header.encoding == SSPM_BASE64_ENCODING) {
        assert(part->data_size != 0);
        sspm_encode_base64(buf, part->data, part->data_size);
    } else if (part->header.encoding == SSPM_QUOTED_PRINTABLE_ENCODING) {
        sspm_encode_quoted_printable(buf, part->data);
    } else {
        sspm_append_string(buf, part->data);
    }

    sspm_append_string(buf, "\n\n");
}

static void sspm_write_multipart_part(struct sspm_buffer *buf,
                                      struct sspm_part *parts, int *part_num)
{
    int parent_level, level;
    struct sspm_header *header = &(parts[*part_num].header);

    /* Write the header for the multipart part */
    sspm_write_header(buf, header);

    parent_level = parts[*part_num].level;

    (*part_num)++;

    level = parts[*part_num].level;

    while (parts[*part_num].header.major != SSPM_NO_MAJOR_TYPE && level == parent_level + 1) {

        assert(header->boundary != NULL);
        sspm_append_string(buf, header->boundary);
        sspm_append_char(buf, '\n');

        if (parts[*part_num].header.major == SSPM_MULTIPART_MAJOR_TYPE) {
            sspm_write_multipart_part(buf, parts, part_num);
        } else {
            sspm_write_part(buf, &(parts[*part_num]), part_num);
        }

        (*part_num)++;
        level = parts[*part_num].level;
    }

    sspm_append_string(buf, "\n\n--");
    sspm_append_string(buf, header->boundary);
    sspm_append_string(buf, "\n");

    (*part_num)--;      /* undo last, spurious, increment */
}

int sspm_write_mime(struct sspm_part *parts, size_t num_parts,
                    char **output_string, const char *header)
{
    struct sspm_buffer buf;
    int part_num = 0;
    size_t slen;

    _unused(num_parts);

    buf.buffer = malloc(4096);
    buf.buffer[0] = '\0';
    buf.pos = buf.buffer;
    buf.buf_size = 10;
    buf.line_pos = 0;

    /* write caller's header */
    if (header != 0) {
        sspm_append_string(&buf, header);
    }

    slen = strlen(buf.buffer);
    if (slen > 0 && buf.buffer[slen - 1] != '\n') {
        sspm_append_char(&buf, '\n');
    }

    /* write mime-version header */
    sspm_append_string(&buf, "Mime-Version: 1.0\n");

    /* End of header */

    /* Write body parts */
    while (parts[part_num].header.major != SSPM_NO_MAJOR_TYPE) {
        if (parts[part_num].header.major == SSPM_MULTIPART_MAJOR_TYPE) {
            sspm_write_multipart_part(&buf, parts, &part_num);
        } else {
            sspm_write_part(&buf, &(parts[part_num]), &part_num);
        }

        part_num++;
    }

    *output_string = buf.buffer;

    return 0;
}