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A custom VCL procedure that validates a JSON Web Token. This procedure can be called from within your other VCL logic. You will need to install vmod_digest to have the digest functions.
sub jwt {
if(req.http.cookie ~ "^([^;]+;[ ]*)*token=[^\.]+\.[^\.]+\.[^\.]+([ ]*;[^;]+)*$") {
set req.http.x-token = ";" + req.http.Cookie;
set req.http.x-token = regsuball(req.http.x-token, "; +", ";");
set req.http.x-token = regsuball(req.http.x-token, ";(token)=","; \1=");
set req.http.x-token = regsuball(req.http.x-token, ";[^ ][^;]*", "");
set req.http.x-token = regsuball(req.http.x-token, "^[; ]+|[; ]+$", "");
set req.http.tmpHeader = regsub(req.http.x-token,"token=([^\.]+)\.[^\.]+\.[^\.]+","\1");
set req.http.tmpTyp = regsub(digest.base64url_decode(req.http.tmpHeader),{"^.*?"typ"\s*:\s*"(\w+)".*?$"},"\1");
set req.http.tmpAlg = regsub(digest.base64url_decode(req.http.tmpHeader),{"^.*?"alg"\s*:\s*"(\w+)".*?$"},"\1");
if(req.http.tmpTyp != "JWT") {
return(synth(400, "Token is not a JWT: " + req.http.tmpHeader));
}
if(req.http.tmpAlg != "HS256") {
return(synth(400, "Token does not use HS256 hashing"));
}
set req.http.tmpPayload = regsub(req.http.x-token,"token=[^\.]+\.([^\.]+)\.[^\.]+$","\1");
set req.http.tmpRequestSig = regsub(req.http.x-token,"^[^\.]+\.[^\.]+\.([^\.]+)$","\1");
set req.http.tmpCorrectSig = digest.base64url_nopad_hex(digest.hmac_sha256("SlowWebSitesSuck",req.http.tmpHeader + "." + req.http.tmpPayload));
if(req.http.tmpRequestSig != req.http.tmpCorrectSig) {
return(synth(403, "Invalid JWT signature"));
}
set req.http.tmpPayload = digest.base64url_decode(req.http.tmpPayload);
set req.http.X-Login = regsub(req.http.tmpPayload,{"^.*?"login"\s*:\s*(\w+).*?$"},"\1");
set req.http.X-Username = regsub(req.http.tmpPayload,{"^.*?"sub"\s*:\s*"(\w+)".*?$"},"\1");
unset req.http.tmpHeader;
unset req.http.tmpTyp;
unset req.http.tmpAlg;
unset req.http.tmpPayload;
unset req.http.tmpRequestSig;
unset req.http.tmpCorrectSig;
unset req.http.tmpPayload;
}
}
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