path: root/doc/src/manual/cowboy_req.cert.asciidoc
blob: 51f2e3c5f1a7df6f116f5aa9ab9121825c95a629 (plain) (tree)



= cowboy_req:cert(3)

== Name

cowboy_req:cert - Client TLS certificate

== Description

cert(Req :: cowboy_req:req()) -> binary() | undefined

Return the peer's TLS certificate.

Using the default configuration this function will always return
`undefined`. You need to explicitly configure Cowboy to request
the client certificate. To do this you need to set the `verify`
transport option to `verify_peer`:

{ok, _} = cowboy:start_tls(example, [
    {port, 8443},
    {certfile, "path/to/cert.pem"},
    {verify, verify_peer}
], #{
    env => #{dispatch => Dispatch}

You may also want to customize the `verify_fun` function. Please
consult the `ssl` application's manual for more details.

TCP connections do not allow a certificate and this function
will therefore always return `undefined`.

The certificate can also be obtained using pattern matching:

#{cert := Cert} = Req.

== Arguments


The Req object.

== Return value

The client TLS certificate.

== Changelog

* *2.1*: Function introduced.

== Examples

.Get the client TLS certificate.
Cert = cowboy_req:cert(Req).

== See also