HTTP header resundant header

Question

Is adding an extra redudandant header to the HTTP request may cause any functionality harm?

for example:

Adding :

myheader=blablabla

Look at http://stackoverflow.com/questions/3561381/custom-http-headers-naming-conventions. — Roberto Reale, Jul 24 '14 at 13:01

score 0 · Answer 1 · edited May 23 '17 at 10:33

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An X- prefix was customary for those headers, but no longer. It shouldn't break anything as long as your headers are formatted correctly (so: myheader: blablabla, not myheader=blablabla)

edited May 23 '17 at 10:33

Community

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answered Jul 24 '14 at 13:02

Wrikken

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Surely myheader: blablabla :-) Thanks. – dushkin Jul 27 '14 at 06:40

score 0 · Answer 2 · edited Oct 07 '21 at 06:26

The HTTP 1.1 specification says (about entity headers);

Unrecognized header fields SHOULD be ignored by the recipient and MUST be forwarded by transparent proxies.

In other words - since the wording is SHOULD, not MUST - recipients are allowed to react to unknown headers, so technically your extra header could cause harm.

In practice though I have never seen a recipient do this, and with the surfacing of newer RFCs regarding custom header use seeing an adverse effect is very unlikely.

HTTP header resundant header

2 Answers2