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The jwt vmod allows for the manipulation, creation, and verification of JWT and JWS tokens.
The following example verifies a token signed with the HS256 algorithm
that is in the Authorization header.
vcl 4.1;
import jwt;
backend default none;
sub vcl_init {
new jwt_reader = jwt.reader();
}
sub vcl_recv {
if (!jwt_reader.parse(req.http.Authorization)) {
return (synth(401, "Invalid Authorization Token"));
}
if (!jwt_reader.set_key("secret")) {
return (synth(401, "Invalid Authorization Token"));
}
if (!jwt_reader.verify("HS256")) {
return (synth(401, "Invalid Authorization Token"));
}
# JWT token was valid
}
vcl 4.1;
import jwt;
backend default none;
sub vcl_init {
new jwt_writer = jwt.writer();
}
sub vcl_recv {
jwt_writer.set_sub(req.method + " " + req.http.host + req.url);
jwt_writer.set_alg("HS256");
# Shortlived token that allows 30 seconds clock skew.
jwt_writer.set_nbf(now - 30s);
jwt_writer.set_exp(now + 30s);
jwt_writer.set_iss(server.identity);
set req.http.jwt = jwt_writer.generate("secret");
if (jwt_writer.error()) {
# Something went wrong generating the new token.
}
}
The following example takes an existing token, verifies it, and
extends its expiration to 6 hours from the current time then sets the new token
on the request Authorization header.
vcl 4.1;
import jwt;
backend default none;
sub vcl_init {
new jwt_reader = jwt.reader();
new jwt_writer = jwt.writer();
}
sub vcl_recv {
if (!jwt_reader.parse(req.http.Authorization)) {
return (synth(401, "Invalid Authorization Token"));
}
if (!jwt_reader.set_key("secret")) {
return (synth(401, "Invalid Authorization Token"));
}
if (!jwt_reader.verify("HS256")) {
return (synth(401, "Invalid Authorization Token"));
}
# JWT token was valid, extend the lifetime.
jwt_writer.from_string(jwt_reader.to_string());
jwt_writer.set_exp(now + 6h);
if (jwt_writer.error()) {
# Something went wrong extending the expiration date.
}
set req.http.Authorization = jwt_writer.generate("secret");
if (jwt_writer.error()) {
# Something went wrong generating the new token.
}
}
OBJECT reader()
Creates a JWT Reader Object. must be called in sub vcl_init.
Arguments: None
Type: Object
Returns: Object.
BOOL .parse(STRING token)
Parse a JWT/JWS token into the reader and return whether it was able to be parsed successfully. You should always check the return of this method before calling any of the methods below.
Arguments:
token accepts type STRINGType: Method
Returns: Bool
BOOL .from_string(STRING token)
Parse a JWT/JWS token into the reader and return whether it was able to be
parsed successfully. Primarily an alias to keep convention with the
reader/writer to and from methods. You should always
check the return of this method before calling any of the other reader methods.
Arguments:
token accepts type STRINGType: Method
Returns: Bool
STRING .get_alg()
Grabs the signature algorithm for the loaded JWT token, E.g.: HS256
Arguments: None
Type: Method
Returns: String
STRING .get_typ()
Gets the typ parameter from the JWT token header, E.g.: JWT
Arguments: None
Type: Method
Returns: String
BOOL .get_b64()
Gets the b64 parameter from the JWT token header, E.g.: TRUE
Arguments: None
Type: Method
Returns: Bool
BOOL .is_jwt()
Tell whether the token is a JWT or a JWS. A JWT token will either have the
typ header parameter equal to JWT or have a payload that is base64
encoded JSON, if both of these requirements aren’t met it is a JWS and this
method will return false.
Arguments: None
Type: Method
Returns: Bool
STRING .get_sub(STRING default = 0)
Get the sub parameter of the JWT payload and return default if
it does not exist.
Arguments:
default accepts type STRING with a default value of 0 optional
Type: Method
Returns: String
STRING .get_iss(STRING default = 0)
Get the iss parameter of the JWT payload and return default if
it does not exist.
Arguments:
default accepts type STRING with a default value of 0 optional
Type: Method
Returns: String
STRING .get_jti(STRING default = 0)
Get the jti parameter of the JWT payload and return default if
it does not exist.
Arguments:
default accepts type STRING with a default value of 0 optional
Type: Method
Returns: String
TIME .get_exp()
Get the exp parameter of the JWT payload. You must call reader.has_exp()
before calling this function to make sure you have an exp to get.
Arguments: None
Type: Method
Returns: Time
BOOL .has_exp()
Get whether the JWT token has an exp parameter. This must be called before
reader.get_exp() to make sure you have an exp to return.
Arguments: None
Type: Method
Returns: Bool
TIME .get_nbf()
Get the nbf parameter of the JWT payload. You must call reader.has_nbf()
before calling this function to make sure you have an nbf to get.
Arguments: None
Type: Method
Returns: Time
BOOL .has_nbf()
Get whether the JWT token has an nbf parameter. This must be called before
reader.get_nbf() to make sure you have an nbf to return.
Arguments: None
Type: Method
Returns: Bool
TIME .get_iat()
Get the iat parameter of the JWT payload. You must call reader.has_iat()
before calling this function to make sure you have an iat to get.
Arguments: None
Type: Method
Returns: Time
BOOL .has_iat()
Get whether the JWT token has an iat parameter. This must be called before
reader.get_iat() to make sure you have an iat to return.
Arguments: None
Type: Method
Returns: Bool
STRING .get_header()
Get the header of the JWT token as a JSON string.
Arguments: None
Type: Method
Returns: String
STRING .get_header_encoded()
Get the header of the JWT token as a JSON string that is base64 encoded.
Arguments: None
Type: Method
Returns: String
STRING .get_payload()
Get the payload of the JWT token as a JSON string.
Arguments: None
Type: Method
Returns: String
STRING .get_payload_encoded()
Get the payload of the JWT token as a JSON string that is base64 encoded.
Arguments: None
Type: Method
Returns: String
STRING .get_signature()
Get the signature of the JWT token.
Arguments: None
Type: Method
Returns: String
STRING .to_string()
Gets a string representation of the token to pass to the writer’s
from_string method
Arguments: None
Type: Method
Returns: String
BOOL .set_key(STRING key)
Set the HMAC secret or RSA public key to use to verify the token.
Arguments:
key accepts type STRINGType: Method
Returns: Bool
INT .set_jwk(STRING jwk)
Set the RSA Public key(s) for the token via a JWK.
Arguments:
jwk accepts type STRINGType: Method
Returns: Int
BOOL .verify(STRING expected_alg)
Verify the JWK/JWS token. This method supports verifying the
signature algorithms None, HS256, HS384, HS512, RS256,
RS384, and RS512. The exp, iat, and nbf payload parameters
are also checked when this method is called if they are present.
If expected_alg does not match the algorithm of the passed in token verification will
fail. DO NOT USE get_alg() to populate this argument as this will allow
an attacker to forge tokens by claiming the algorithm of the token is None
which does not require signature verification. The possible values for this
argument are None, HS256, HS384, HS512, RS256,
RS384, and RS512.
This returns true if the expected_alg matches the token’s
algorithm, the signature algorithm is on of the supported ones list above,
the signature is valid, and the exp, iat, and nbf claims
are valid if they are present. If any of the aforementioned conditions are not
met the return value will be false.
Arguments:
expected_alg accepts type STRINGType: Method
Returns: Bool
OBJECT writer()
Creates a JWT Writer Object. must be called in sub vcl_init.
Arguments: None
Type: Object
Returns: Object.
VOID .parse(STRING token)
Set the header and payload the JWT/JWS token provided.
Arguments:
token accepts type STRINGType: Method
Returns: None
VOID .from_string(STRING token)
Sets the header and payload from token provided. Primarily for use with the “to_string” method of the reader.
Arguments:
token accepts type STRINGType: Method
Returns: None
VOID .set_header(STRING header)
Set the header and payload the JWT/JWS token provided. Primarily an alias of
parse to keep convention with the reader/writer to and
from methods.
Arguments:
header accepts type STRINGType: Method
Returns: None
VOID .set_payload(STRING payload)
Set the JSON payload on the JWT/JWS token.
Arguments:
payload accepts type STRINGType: Method
Returns: None
VOID .set_header_encoded(STRING header)
Set the Base64 encoded JSON payload on the JWT/JWS token.
Arguments:
header accepts type STRINGType: Method
Returns: None
VOID .set_payload_encoded(STRING payload)
Set the Base64 encoded JSON payload on the JWT/JWS token.
Arguments:
payload accepts type STRINGType: Method
Returns: None
VOID .set_alg(STRING alg)
Set the signature algorithm on the token. This method supports alg being
None, HS256, HS384, HS512, RS256,
RS384, or RS512.
Arguments:
alg accepts type STRINGType: Method
Returns: None
VOID .set_typ(STRING typ)
Set the typ parameter of the token header.
Arguments:
typ accepts type STRINGType: Method
Returns: None
VOID .set_b64(BOOL is_b64)
Set the b64 parameter of the token header.
Arguments:
is_b64 accepts type BOOLType: Method
Returns: None
VOID .set_sub(STRING sub)
Set the sub parameter of the token payload.
Arguments:
sub accepts type STRINGType: Method
Returns: None
VOID .set_iss(STRING iss)
Set the iss parameter of the token payload.
Arguments:
iss accepts type STRINGType: Method
Returns: None
VOID .set_jti(STRING jti)
Set the jti parameter of the token payload.
Arguments:
jti accepts type STRINGType: Method
Returns: None
VOID .set_exp(TIME time)
Set the exp parameter of the token payload.
Arguments:
time accepts type TIMEType: Method
Returns: None
VOID .set_nbf(TIME time)
Set the nbf parameter of the token payload.
Arguments:
time accepts type TIMEType: Method
Returns: None
VOID .set_iat(TIME time)
Set the iat parameter of the token payload.
Arguments:
time accepts type TIMEType: Method
Returns: None
VOID .set_duration(DURATION duration)
Set the exp parameter of the token payload duration in the future from
the current time.
Arguments:
duration accepts type DURATIONType: Method
Returns: None
VOID .delete_sub()
Sets the subject for the JWT token.
Arguments: None
Type: Method
Returns: None
VOID .delete_iss()
Sets the issuer for the JWT token.
Arguments: None
Type: Method
Returns: None
VOID .delete_jti()
Sets the JWT ID for the token.
Arguments: None
Type: Method
Returns: None
VOID .delete_exp()
Delete the exp parameter of the token payload.
Arguments: None
Type: Method
Returns: None
VOID .delete_nbf()
Delete the nbf parameter of the token payload.
Arguments: None
Type: Method
Returns: None
VOID .delete_iat()
Delete the iat parameter of the token payload.
Arguments: None
Type: Method
Returns: None
STRING .generate(STRING key)
Generate the full JWK/JWS token. This method supports creating with the
signature algorithms None, HS256, HS384, HS512, RS256,
RS384, and RS512.
Arguments:
key accepts type STRINGType: Method
Returns: String
STRING .to_string(STRING key)
Generate the full JWK/JWS token. This method supports creating with the
signature algorithms None, HS256, HS384, HS512, RS256,
RS384, and RS512. Primarily an alias of generate to keep
convention with the reader/writer to and from methods.
Arguments:
key accepts type STRINGType: Method
Returns: String
VOID .reset()
Reset all data on the writer including the error flag.
Arguments: None
Type: Method
Returns: None
BOOL .error()
Did any of the method calls above result in an error
Arguments: None
Type: Method
Returns: Bool
The jwt VMOD is available in Varnish Enterprise version 6.0.6r2 and later.