Disable SSL/TLS certificate validation in Network.

I use the http-conduit library version 2.0+ to fetch the contents from a http:// URL:

import Network.HTTP.Conduit
myurl = ... -- Your URL goes here
main = do content <- simpleHttp myurl
          print $ content

When running this program, I get this error:

*** Exception: TlsException (HandshakeFailed (Error_Protocol
      ("certificate rejected: certificate is not allowed to sign another certificate",
        True,CertificateUnknown)))

As can be told from the error message, the problem is the inability of Network.HTTP.Conduit to validate the server certificate appropriately (in this case, there seem to be problems in the certificate chain)

How can I change the above code to ignore the certificate error (i.e. by not verifying certificates at all)?

simpleHttp itself does not support this feature. You'll need to create a manager with modified ManagerSettings and then use that to fetch the URL.

Note that this code only applies for http-conduits version 2.0+ -- the library version 1 has a similar yet different API for this purpose.

import Network.HTTP.Conduit
import Network.Connection
import qualified Data.ByteString.Lazy.Char8 as LB

myurl = ... -- Your URL goes here

-- | Get a new Manager that doesn't verify SSL certificates
noSSLVerifyManager :: IO Manager
noSSLVerifyManager = let tlsSettings = TLSSettingsSimple {
                            -- This is where we disable certificate verification
                            settingDisableCertificateValidation = True,
                            settingDisableSession=False,
                            settingUseServerName=True}
                     in newManager $ mkManagerSettings tlsSettings Nothing

-- | Download like with simpleHttp, but using an existing manager for the task
simpleHttpWithManager :: Manager -> String -> IO LB.ByteString
simpleHttpWithManager manager url = do url' <- parseUrl url
                                       fmap responseBody $ httpLbs url' manager

main = do manager <- noSSLVerifyManager
          content <- simpleHttpWithManager manager myurl
          print $ content

Note that you should only disable SSL certificate verification if absolutely neccessary, as it makes you vulnerable for man-in-the-middle attacks