BOOL TNLHTTPContentTypeIsTextual()

in Source/TNLHTTP.m [68:108]

• 29 lines of code
• 9 McCabe index (conditional complexity)

BOOL TNLHTTPContentTypeIsTextual(NSString * __nullable contentType)
{
    if (!contentType) {
        return NO;
    }

    // Is this a componentized mimetype? e.g. "application/json;charset=utf-8"
    NSArray<NSString *> *components = [contentType componentsSeparatedByString:@";"];
    if (components.count <= 1) {
        // nope, do the easy check
        return TNLHTTPContentTypeIsTextualInternal(contentType);
    }

    // It is componentized, get the content type and check it
    contentType = [components.firstObject stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
    if (!TNLHTTPContentTypeIsTextualInternal(contentType)) {
        // content type is not textual
        return NO;
    }

    // Content type is textual, need to confirm the character set is acceptable (we restrict to utf-8 and ascii for simplicity)
    for (NSUInteger i = 1; i < components.count; i++) {
        NSString *extraInfo = components[i].lowercaseString;
        NSArray<NSString *> *extraComponents = [extraInfo componentsSeparatedByString:@"="];
        NSString *key = [extraComponents.firstObject stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
        if ([key isEqualToString:@"charset"]) {
            // charset was provided, so check it and return if the character set is utf8/ascii
            NSString *value = [extraComponents.lastObject stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
            if ([value isEqualToString:@"utf-8"]) {
                return YES;
            } else if ([value isEqualToString:@"ascii"] || [value isEqualToString:@"us-ascii"]) {
                return YES;
            }

            return NO;
        }
    }

    // no charset provided, presume utf-8
    return YES;
}