CODEWITHSUNDEEP
httphttp-response-codes
vish4071
vish4071

Reputation: 5277

Non integer HTTP response codes possible?

I am aware of standard HTTP response codes and their categorization (1xx, 2xx, 3xx, 4xx and 5xx)

But, I have seen certain web requests return non-standard HTTP response codes, like 999, 1001, 1002, 1006 etc. However, I have never seen any HTTP response code that contains alphanumeric characters. Is it possible for any server to send non-integer response codes?

Upvotes: 1

Views: 733

Answers (2)

M. Justin
M. Justin

Reputation: 21122

A server response is just a sequence of bytes sent over the network. HTTP 1.x is a text-based protocol, where the request and response — including status code — are sent as structured text in a defined format. It is therefore very possible to send across alphanumeric characters where a standards-compliant server would send across a valid HTTP status code.

If a non-numeric value is sent, don't expect clients to do a sane thing with them. Clients quite reasonably expect a standards-compliant (numeric) value, and well-behaved clients would likely fail if they receive something not conforming to the standard.

Example HTTP response:

Take as a concrete example the following HTTP response message. The status code of 200 is found in the status line (HTTP/1.1 200 OK), along with the protocol version (HTTP/1.1) and reason phrase (OK).

HTTP/1.1 200 OK
Content-Type: text/plain
Content-Length: 35

This sentence is the response body.

There is nothing preventing a server from replacing the status code in the status line with literally any other text. For instance, if non-numeric values were allowed, the following might be considered a response with status code "ABC" and reason phrase "Test alphanumeric response".

HTTP/1.1 ABC Test alphanumeric response

IETF status code specification

IETF RFC 7230 requires the status code to be a three-digit integer, and RFC 7231 requires the first digit of the status code to be between 1 and 5.

3.1.2. Status Line

The first line of a response message is the status-line, consisting of the protocol version, a space (SP), the status code, another space, a possibly empty textual phrase describing the status code, and ending with CRLF.

status-line = HTTP-version SP status-code SP reason-phrase CRLF

The status-code element is a 3-digit integer code describing the result of the server's attempt to understand and satisfy the client's corresponding request.

6. Response Status Codes

[…]

The first digit of the status-code defines the class of response. The last two digits do not have any categorization role. There are five values for the first digit:

  • 1xx (Informational): The request was received, continuing process
  • 2xx (Successful): The request was successfully received, understood, and accepted
  • 3xx (Redirection): Further action needs to be taken in order to complete the request
  • 4xx (Client Error): The request contains bad syntax or cannot be fulfilled
  • 5xx (Server Error): The server failed to fulfill an apparently valid request

Upvotes: 0

Matt Timmermans
Matt Timmermans

Reputation: 59184

Non-standard is non-standard. You might call it impossible, or you might say that everything is possible until it breaks something you need.

Practically, most software passes around HTTP status codes as integers, and will reject, break, or behave in unexpected ways if they aren't.

Don't do it.

Upvotes: 2

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