oauth - Multiple HTTP Authorization headers?

Question

Is it possible to include multiple Authorization Headers in an HTTP message? Specifically, I would like to include one of Bearer token type (passing an OAuth access token) and one of Basic type (passing a base64 encoded username:password).

GET /presence/alice HTTP/1.1 
Host: server.example.com
Authorization: Bearer mF_9.B5f-4.1JqM
Authorization: Basic YXNkZnNhZGZzYWRmOlZLdDVOMVhk

I see no reason this should not be possible, just wanted to vet it with the community to be sure.

Answer 1

**** UPDATE Feb 2021 *** Please read the comments to this response. Their general conclusion seems to be that some web servers accept multiple Authorization schemes, but that it goes against RFC 7230/7235 ****

This should be possible, you just have to add a comma between field values, e.g:

GET /presence/alice HTTP/1.1 
Host: server.example.com
Authorization: Bearer mF_9.B5f-4.1JqM, Basic YXNkZnNhZGZzYWRmOlZLdDVOMVhk

This is defined in RFC7230, section 3.2.2, Field Order:

A sender MUST NOT generate multiple header fields with the same field name in a message unless either the entire field value for that header field is defined as a comma-separated list [i.e., #(values)] or the header field is a well-known exception (as noted below).

A recipient MAY combine multiple header fields with the same field name into one "field-name: field-value" pair, without changing the semantics of the message, by appending each subsequent field value to the combined field value in order, separated by a comma. The order in which header fields with the same field name are received is therefore significant to the interpretation of the combined field value; a proxy MUST NOT change the order of these field values when forwarding a message.

I don't know whether all web servers accept this - at the time of writing I'm in the middle of a debate with a colleague about whether it should work or not.