I have to validate the Content-Type header value before passing it to an HTTP request.
Is there a specific list for all the possible values of Content-Type?
Otherwise, is there a way to validate the content type before using it in an HTTP request?
You can find every content types here: http://www.iana.org/assignments/media-types/media-types.xhtml
The most common types are:
Type application:
application/java-archive
application/EDI-X12
application/EDIFACT
application/javascript
application/octet-stream
application/ogg
application/pdf
application/xhtml+xml
application/x-shockwave-flash
application/json
application/ld+json
application/xml
application/zip
application/x-www-form-urlencoded
Type audio:
audio/mpeg
audio/x-ms-wma
audio/vnd.rn-realaudio
audio/x-wav
Type image:
image/gif
image/jpeg
image/png
image/tiff
image/vnd.microsoft.icon
image/x-icon
image/vnd.djvu
image/svg+xml
Type multipart:
multipart/mixed
multipart/alternative
multipart/related (using by MHTML (HTML mail).)
multipart/form-data
Type text:
text/css
text/csv
text/html
text/javascript (obsolete)
text/plain
text/xml
Type video:
video/mpeg
video/mp4
video/quicktime
video/x-ms-wmv
video/x-msvideo
video/x-flv
video/webm
Type vnd:
application/vnd.android.package-archive
application/vnd.oasis.opendocument.text
application/vnd.oasis.opendocument.spreadsheet
application/vnd.oasis.opendocument.presentation
application/vnd.oasis.opendocument.graphics
application/vnd.ms-excel
application/vnd.openxmlformats-officedocument.spreadsheetml.sheet
application/vnd.ms-powerpoint
application/vnd.openxmlformats-officedocument.presentationml.presentation
application/msword
application/vnd.openxmlformats-officedocument.wordprocessingml.document
application/vnd.mozilla.xul+xml
As is defined in RFC 1341:
In the Extended BNF notation of RFC 822, a Content-Type header field value is defined as follows:
Content-Type := type "/" subtype *[";" parameter]
type := "application" / "audio" / "image" / "message" / "multipart" / "text" / "video" / x-token
x-token := < The two characters "X-" followed, with no intervening white space, by any token >
subtype := token
parameter := attribute "=" value
attribute := token
value := token / quoted-string
token := 1*<any CHAR except SPACE, CTLs, or tspecials>
tspecials := "(" / ")" / "<" / ">" / "@" ; Must be in / "," / ";" / ":" / "" / <"> ; quoted-string, / "/" / "[" / "]" / "?" / "." ; to use within / "=" ; parameter values
And a list of known MIME types that can follow it (or, as Joe remarks, the IANA source).
As you can see the list is way too big for you to validate against all of them. What you can do is validate against the general format and the type attribute to make sure that is correct (the set of options is small) and just assume that what follows it is correct (and of course catch any exceptions you might encounter when you put it to actual use).
Also note the comment above:
If another primary type is to be used for any reason, it must be given a name starting with "X-" to indicate its non-standard status and to avoid any potential conflict with a future official name.
You'll notice that a lot of HTTP requests/responses include an X- header of some sort which are self defined, keep this in mind when validating the types.
I would aim at covering a subset of possible "Content-type" values, you question seems to focus on identifying known content types.
@Jeroen RFC 1341 reference is great, but for an fairly exhaustive list IANA keeps a web page of officially registered media types here.
If you are using jaxrs or any other, then there will be a class called mediatype.User interceptor before sending the request and compare it against this.
