wap_push_pap_mime.c

The Kannel Open Source WAP and SMS gateway works as both an SMS gateway, for implementing keyword b

 * Control entity headers must contain Content-Type: application/xml headers.
 * Rfc 2045, Appendix A does not specify the order of entity headers and states
 * that all rfc 822 headers having a string "Content" in their field-name must
 * be accepted. Rfc 822 grammar is capitulated in appendix D.
 * Message starts after the first null line, so only something after it can be
 * an extension header (or any header).
 */
static int check_control_headers(Octstr **body_part)
{
    if (check_control_content_type_header(body_part, octstr_imm("\r\n\r\n")) == 0)
        return 0;
    if (drop_optional_header(body_part, "Content-Transfer-Encoding:",
            octstr_imm("\r\n\r\n")) == 0)
        return 0;
    if (drop_optional_header(body_part, "Content-ID:", octstr_imm("\r\n\r\n")) == 0)
        return 0;
    if (drop_optional_header(body_part, "Content-Description:", octstr_imm("\r\n\r\n")) == 0)
        return 0;
    if (drop_extension_headers(body_part, octstr_imm("\r\n\r\n")) == 0)
        return 0;

    return 1;
}

static int check_control_content_type_header(Octstr **body_part, Octstr *boundary)
{
    long content_pos;
    long message_start_pos;

    message_start_pos = octstr_search(*body_part, boundary, 0);
    if ((content_pos = octstr_case_nsearch(*body_part, octstr_imm("Content-Type:"), 0,
            message_start_pos)) < 0 || 
            octstr_case_search(*body_part, octstr_imm("application/xml"), 0) < 0) {
        return 0;
    }

    if (drop_header_true(body_part, content_pos) < 0)
        return 0;
    
    return 1;
}

/*
 * This function actually removes a header (deletes corresponding part from
 * the octet string body_part), in addition of all stuff prepending it. So
 * deleting start from the octet 0. Content_pos tells where the header starts.
 */
static int drop_header_true(Octstr **body_part, long content_pos) 
{
    long next_header_pos;

    next_header_pos = -1;
    if ((next_header_pos = parse_field_value(*body_part, content_pos)) == 0)
        return 0;
    if ((next_header_pos = parse_terminator(*body_part, next_header_pos)) == 0)
        return 0;
    octstr_delete(*body_part, 0, next_header_pos);

    return 1;
}

static int drop_optional_header(Octstr **body_part, char *name, Octstr *boundary)
{
    long content_pos;
    long message_start_pos;
         
    content_pos = -1;
    message_start_pos = octstr_search(*body_part, boundary, 0);

    if ((content_pos = octstr_case_nsearch(*body_part, octstr_imm(name), 0, message_start_pos)) < 0)
        return 1;
    
    if (drop_header_true(body_part, content_pos) < 0)
        return 0;

    return 1;
}

/*
 * Extension headers are defined in rfc 822, Appendix D, as fields. We must
 * parse all rfc 822 headers containing a string "Content". These headers 
 * are optional, too. For general definition of message parts see chapter 4.1.
 * Specifically: "everything after first null line is message body".
 */
static int drop_extension_headers(Octstr **body_part, Octstr *boundary)
{
    long content_pos,
         next_header_pos;  
    long next_content_part_pos;

    next_content_part_pos = octstr_case_search(*body_part, boundary, 0);
    do {
        if ((content_pos = octstr_case_nsearch(*body_part, octstr_imm("Content"), 0,
                next_content_part_pos)) < 0)
            return 1;
        if ((next_header_pos = parse_field_name(*body_part, content_pos)) < 0)
            return 0;
        if ((next_header_pos = parse_field_value(*body_part, 
                 next_header_pos)) < 0)
	    return 0;
        if ((next_header_pos = parse_terminator(*body_part, 
                 next_header_pos)) == 0)
            return 0;
    } while (islwspchar(octstr_get_char(*body_part, next_header_pos)));

    octstr_delete(*body_part, content_pos, next_header_pos - content_pos);
   
    return 1;
}

static long parse_field_value(Octstr *pap_content, long pos)
{
    int c;

    while (!is_cr(c = octstr_get_char(pap_content, pos)) &&
	     pos < octstr_len(pap_content)) {
         ++pos;
    }
 
    if (is_lf(c)) {
        if (is_lf(octstr_get_char(pap_content, pos))) {
	    ++pos;
        } else {
	    return -1;
        }
    }

    if (pos == octstr_len(pap_content)) {
        return -1;
    }

    return pos;
}

static long parse_field_name(Octstr *content, long pos)
{
    while (octstr_get_char(content, pos) != ':' && 
               pos < octstr_len(content))
           ++pos;

    if (pos == octstr_len(content))
        return -1;

    return pos;
}

/*
 * Transfer entity headers of a body part (it is, from the content entity) 
 * to a header list. Push Message, chapter 6.2.1.10 states that Content-Type
 * header is mandatory. 
 * Message proper starts after first empty line. We search only to it, and
 * remove the line here.
 * Return 0 when error, 1 otherwise. In addition, return the modified body
 * part and content headers.
 */
static int pass_data_headers(Octstr **body_part, List **data_headers)
{
    *data_headers = http_create_empty_headers();

    if (check_data_content_type_header(body_part, data_headers, octstr_imm("\r\n\r\n")) == 0) {
        warning(0, "MIME: pass_data_headers: Content-Type header missing"); 
        return 0;
    }
        
    if (pass_optional_header(body_part, "Content-Transfer-Encoding", data_headers,
            octstr_imm("\r\n\r\n")) < 0)
        goto operror;
    if (pass_optional_header(body_part, "Content-ID", data_headers, octstr_imm("\r\n\r\n")) < 0)
        goto operror;
    if (pass_optional_header(body_part, "Content-Description", data_headers, 
            octstr_imm("\r\n\r\n")) < 0)
        goto operror;
    if (pass_extension_headers(body_part, data_headers, octstr_imm("\r\n\r\n")) == 0)
        goto operror;
   
    octstr_delete(*body_part, 0, octstr_len(octstr_imm("\r\n")));   

    return 1;

operror:
    warning(0, "MIME: pass_data_headers: an unparsable optional header");
    return 0;
}

/*
 * Checks if body_part contains a Content-Type header. Tranfers this header to
 * a list content_headers. (Only part before 'boundary').
 * Return 1, when Content-Type headers was found, 0 otherwise
 */
static int check_data_content_type_header(Octstr **body_part, List **content_headers,
                                          Octstr *boundary)
{
    long header_pos,
         next_header_pos;
    Octstr *content_header;
    long message_start_pos;

    header_pos = next_header_pos = -1;
    content_header = octstr_create("Content-Type");
    message_start_pos = octstr_search(*body_part, boundary, 0);
    
    if ((header_pos = octstr_case_nsearch(*body_part, content_header, 0,
             message_start_pos)) < 0) {
        goto error;
    }
    if ((next_header_pos = pass_field_value(body_part, &content_header, 
	    header_pos + octstr_len(content_header))) < 0) {
        goto error;
    }
    if ((next_header_pos = parse_terminator(*body_part, next_header_pos)) < 0) {
        goto error;
    }

    octstr_delete(*body_part, header_pos, next_header_pos - header_pos);
    list_append(*content_headers, octstr_duplicate(content_header));
    octstr_destroy(content_header);

    return 1;

error:
    octstr_destroy(content_header);
    return 0;
}

/*
 * We try to find an optional header, so a failure to find one is not an 
 * error. Return -1 when error, 0 when header name not found, 1 otherwise.
 * Search only until 'boundary'.
 */
static int pass_optional_header(Octstr **body_part, char *name, List **content_headers,
                                Octstr *boundary)
{
    long content_pos,
         next_header_pos;
    Octstr *osname,
           *osvalue;
    long message_start_pos;

    content_pos = next_header_pos = -1;
    osname = octstr_create(name);
    osvalue = octstr_create("");
    message_start_pos = octstr_search(*body_part, boundary, 0);

    if ((content_pos = octstr_case_nsearch(*body_part, osname, 0, message_start_pos)) < 0) 
        goto noheader;
    if ((next_header_pos = pass_field_value(body_part, &osvalue, 
	     content_pos + octstr_len(osname))) < 0)
        goto error;   
    if ((next_header_pos = 
	     parse_terminator(*body_part, next_header_pos)) == 0)
        goto error;

    drop_separator(&osvalue, &next_header_pos);
    http_header_add(*content_headers, name, octstr_get_cstr(osvalue));
    octstr_delete(*body_part, content_pos, next_header_pos - content_pos);

    octstr_destroy(osname);
    octstr_destroy(osvalue);
    return 1;

error:
    octstr_destroy(osvalue);
    octstr_destroy(osname);
    return -1;

noheader:
    octstr_destroy(osvalue);
    octstr_destroy(osname);
    return 0;
}

/*
 * Remove ':' plus spaces from the header value
 */
static void drop_separator(Octstr **header_value, long *pos)
{
   long count;

   octstr_delete(*header_value, 0, 1);            /* remove :*/
   count = octstr_drop_leading_blanks(header_value);
   pos = pos - 1 - count;
} 

/*
 * Return number of spaces dropped.
 */
static long octstr_drop_leading_blanks(Octstr **header_value)
{
    long count;

    count = 0;
    while (octstr_get_char(*header_value, 0) == ' ') {
        octstr_delete(*header_value, 0, 1);
        ++count;
    }

    return count;
}

/*
 * Extension headers are optional, see Push Message, chapter 6.2. Field struc-
 * ture is defined in rfc 822, chapter 3.2. Extension headers are defined in 
 * rfc 2045, chapter 9, grammar in appendix A. (Only to the next null line).
 * Return 0 when error, 1 otherwise.
 */
static int pass_extension_headers(Octstr **body_part, List **content_headers, Octstr *boundary)
{
    long next_field_part_pos,
         count;  
    Octstr *header_name,
           *header_value; 
    long next_content_part_pos;

    header_name = octstr_create("");
    header_value = octstr_create("");
    count = 0;
    next_field_part_pos = 0;
    next_content_part_pos = octstr_search(*body_part, boundary, 0);

    do {
        if ((octstr_case_nsearch(*body_part, octstr_imm("Content"), 0,
                next_content_part_pos)) < 0)
            goto end; 
        if ((next_field_part_pos = pass_field_name(body_part, &header_name,
                 next_field_part_pos)) < 0)
            goto error;
        if ((next_field_part_pos = pass_field_value(body_part, &header_value, 
                 next_field_part_pos)) < 0)
            goto error;
        if ((next_field_part_pos = parse_terminator(*body_part, 
                 next_field_part_pos)) == 0)
            goto error;
        drop_separator(&header_value, &next_field_part_pos);
        http_header_add(*content_headers, octstr_get_cstr(header_name), 
            octstr_get_cstr(header_value));
    } while (islwspchar(octstr_get_char(*body_part, next_field_part_pos)));

    octstr_delete(*body_part, 0, next_field_part_pos);

/*
 * An intentional fall-through. We must eventually use a function for memory
 * cleaning.
 */
end:
    octstr_destroy(header_name);
    octstr_destroy(header_value);
    return 1;

error:
    octstr_destroy(header_name);
    octstr_destroy(header_value);
    return 0;
}

static long pass_field_value(Octstr **body_part, Octstr **header, 
                             long pos)
{
    int c;
    long start;
    Octstr *field = NULL;

    start = pos;
    while (!is_cr(c = octstr_get_char(*body_part, pos)) &&
             pos < octstr_len(*body_part)) {
        ++pos;
    }
 
    if (pos == octstr_len(*body_part)) {
        return -1;
    }

    field = octstr_copy(*body_part, start, pos - start);
    octstr_append(*header, field);

    octstr_destroy(field);
    return pos;
}

static long pass_field_name(Octstr **body_part, Octstr **field_part, 
                            long pos)
{
    int c;
    long start;
    Octstr *name = NULL;

    start = pos;
    while (((c = octstr_get_char(*body_part, pos)) != ':') &&
            pos < octstr_len(*body_part)) {
        ++pos;
    }

    if (pos == octstr_len(*body_part)) {
        return -1;
    }

    name = octstr_copy(*body_part, start, pos - start);
    octstr_append(*field_part, name);

    octstr_destroy(name);
    return pos;
}

/* This is actually CRLF epilogue. */
static int parse_epilogue(Octstr **mime_content)
{
    long pos;

    if (octstr_len(*mime_content) == 0)
        return 0;
    
    if ((pos = parse_terminator(*mime_content, 0)) < 0)
        return -1;

    octstr_delete(*mime_content, 0, octstr_len(*mime_content));
    return 0;
}