Pre-generate DH params

The program now outputs a combined PEM certificate.

A new option allows DH-param generation to be disabled.

2 files changed, 111 insertions, 71 deletions

diff --git a/README.md b/README.md
index 9db3b7b..b2d5422 100644
--- a/README.md
+++ b/README.md
@@ -1,31 +1,35 @@
-# Let's Encrypt ACME protocol
+# `acme-certify` -- A `Let's Encrypt!` ACME client
 
 ```
 Let's Encrypt! ACME client
 
 Usage: acme-certify --key FILE --domain DOMAIN --challenge-dir DIR
                     [--domain-dir DIR] [--email ADDRESS] [--terms URL]
-                    [--staging]
+                    [--skip-dhparams] [--staging] [--skip-provision-check]
   This program will generate a signed TLS certificate using the ACME protocol
   and the free Let's Encrypt! CA.
 
 Available options:
   -h,--help                Show this help text
-  --key FILE               filename of your private RSA key
-  --domain DOMAIN          the domain name(s) to certify; specify more than once
+  --key FILE               Filename of your private RSA key
+  --domain DOMAIN          The domain name(s) to certify; specify more than once
                            for a multi-domain certificate
-  --challenge-dir DIR      output directory for ACME challenges
-  --domain-dir DIR         directory in which to domain certificates and keys
+  --challenge-dir DIR      Output directory for ACME challenges
+  --domain-dir DIR         Directory in which to domain certificates and keys
                            are stored; the default is to use the (first) domain
                            name as a directory name
-  --email ADDRESS          an email address with which to register an account
-  --terms URL              the terms param of the registration request
-  --staging                use staging servers instead of live servers
+  --email ADDRESS          An email address with which to register an account
+  --terms URL              The terms param of the registration request
+  --skip-dhparams          Don't generate DH params for combined cert
+  --staging                Use staging servers instead of live servers
                            (generated certificates will not be trusted!)
+  --skip-provision-check   Don't test whether HTTP provisioning works before
+                           making ACME requests; only useful for testing.
 ```
 
-This program can be used to obtain a certificate from
-[Let's Encrypt](https://letsencrypt.org/) using their ACME protocol.
+This program can be used to obtain a certificate from the
+[Let's Encrypt](https://letsencrypt.org/) certificate authority, using their
+ACME protocol.
 
 ## Rate Limits
 
@@ -63,27 +67,35 @@ openssl genrsa 4096 > ${DOMAIN}/rsa.key
 
 ## Receive certificate
 
-The signed certificate will be saved by this program in
-``./${DOMAIN}/cert.der``. You can copy that file to the place your TLS
-server is configured to read it.
+The signed certificate will be saved by this program in `./${DOMAIN}/cert.pem`.
+A combined certificate, containing the issuer certificate, the private key, and
+(possibly) DH parameters, will be saved in `./${DOMAIN}/cert.combined.pem`. You
+can copy that file to the place your TLS server is configured to read it.
 
 You can also view the certificate like so:
 
 ```
-openssl x509 -inform der -in ${DOMAIN}/cert.der  -noout -text | less
+openssl x509 -in ${DOMAIN}/cert.pem -noout -text | less
 ```
 
 ## Create a certificate for HAProxy
 
 Vo Minh Thu, the original author of this program, suggests to include explicit
 DH key exchange parameters to prevent the [Logjam attack](https://weakdh.org/).
+This is now automatically performed by default.
+
+Note: generating DH params is CPU-intensive and takes a long time. For that
+reason, it is done once per domain, and the result is saved in
+`${DOMAIN}/dhparams.pem`.
+
+You can also disable DH generation it with `--skip-dhparams`.
+
+The certificate is generated by this program equivalently to this:
 
 ```
-> openssl x509 -inform der -in ${DOMAIN}/cert.der \
-    -out ${DOMAIN}/cert.pem
-> openssl dhparam -out ${DOMAIN}/dhparams.pem 2048
-> cat ${DOMAIN}/cert.pem \
+openssl dhparam -out ${DOMAIN}/dhparams.pem 2048
+cat ${DOMAIN}/cert.pem \
     lets-encrypt-x1-cross-signed.pem \
     ${DOMAIN}/rsa.key \
-    ${DOMAIN}/dhparams.pem > aaa.reesd.com-combined.pem
+    ${DOMAIN}/dhparams.pem > ${DOMAIN}/cert.combined.pem
 ```
diff --git a/acme-certify.hs b/acme-certify.hs
index b84a728..219b0c1 100644
--- a/acme-certify.hs
+++ b/acme-certify.hs
@@ -12,21 +12,22 @@
 module Main where
 
 import           BasePrelude
-import qualified Data.ByteString.Lazy.Char8 as LC
-import           Network.ACME               (canProvision, certify, fileProvisioner, ensureWritableDir, (</>), genReq)
-import           Network.ACME.Encoding      (Keys (..), readKeys)
+import           Network.ACME          (canProvision, certify,
+                                        ensureWritableDir, fileProvisioner,
+                                        genReq, (</>))
+import           Network.ACME.Encoding (Keys (..), readKeys)
 import           Network.URI
 import           OpenSSL
-import           OpenSSL.X509 (X509)
 import           OpenSSL.DH
 import           OpenSSL.PEM
 import           OpenSSL.RSA
-import           Options.Applicative        hiding (header)
-import qualified Options.Applicative        as Opt
+import           OpenSSL.X509          (X509)
+import           Options.Applicative   hiding (header)
+import qualified Options.Applicative   as Opt
 import           System.Directory
-import           Text.Domain.Validate       hiding (validate)
+import           System.IO
+import           Text.Domain.Validate  hiding (validate)
 import           Text.Email.Validate
-import System.IO
 
 stagingDirectoryUrl, liveDirectoryUrl :: URI
 Just liveDirectoryUrl = parseAbsoluteURI "https://acme-v01.api.letsencrypt.org/directory"
@@ -42,13 +43,15 @@ main = execParser opts >>= go
                             ]
 
 data CmdOpts = CmdOpts {
-      optKeyFile      :: String,
-      optDomains      :: [String],
-      optChallengeDir :: String,
-      optDomainDir    :: Maybe String,
-      optEmail        :: Maybe String,
-      optTerms        :: Maybe String,
-      optStaging      :: Bool
+      optKeyFile            :: String,
+      optDomains            :: [String],
+      optChallengeDir       :: String,
+      optDomainDir          :: Maybe String,
+      optEmail              :: Maybe String,
+      optTerms              :: Maybe String,
+      optSkipDH             :: Bool,
+      optStaging            :: Bool,
+      optSkipProvisionCheck :: Bool
 }
 
 defaultTerms :: URI
@@ -56,71 +59,71 @@ Just defaultTerms = parseAbsoluteURI "https://letsencrypt.org/documents/LE-SA-v1
 
 cmdopts :: Parser CmdOpts
 cmdopts = CmdOpts <$> strOption (long "key" <> metavar "FILE" <>
-                                 help "filename of your private RSA key")
+                                 help "Filename of your private RSA key")
                   <*> some
                         (strOption
                            (long "domain" <>
                             metavar "DOMAIN" <>
                             help
                               (unwords
-                                 [ "the domain name(s) to certify;"
+                                 [ "The domain name(s) to certify;"
                                  , "specify more than once for a multi-domain certificate"
                                  ])))
                   <*> strOption (long "challenge-dir" <> metavar "DIR" <>
-                                 help "output directory for ACME challenges")
+                                 help "Output directory for ACME challenges")
                   <*> optional
                         (strOption
                            (long "domain-dir" <>
                             metavar "DIR" <>
                             help
                               (unwords
-                                 [ "directory in which to domain certificates and keys are stored;"
+                                 [ "Directory in which to domain certificates and keys are stored;"
                                  , "the default is to use the (first) domain name as a directory name"
                                  ])))
                   <*> optional
                         (strOption (long "email" <> metavar "ADDRESS" <>
-                                    help "an email address with which to register an account"))
+                                    help "An email address with which to register an account"))
                   <*> optional (strOption (long "terms" <> metavar "URL" <>
-                                           help "the terms param of the registration request"))
+                                           help "The terms param of the registration request"))
+                  <*> switch
+                        (long "skip-dhparams" <> help "Don't generate DH params for combined cert")
                   <*> switch
                         (long "staging" <> help
                                              (unwords
-                                                [ "use staging servers instead of live servers"
+                                                [ "Use staging servers instead of live servers"
                                                 , "(generated certificates will not be trusted!)"
                                                 ]))
-
-genKey :: FilePath -> IO String
-genKey privKeyFile = withOpenSSL $ do
-  kp <- generateRSAKey' 4096 65537
-  pem <- writePKCS8PrivateKey kp Nothing
-  writeFile privKeyFile pem
-  return pem
-
-getOrCreateKeys :: FilePath -> IO (Maybe Keys)
-getOrCreateKeys file = do
-  exists <- doesFileExist file
-  readKeys =<< if exists then readFile file else genKey file
+                  <*> switch
+                        (long "skip-provision-check" <> help
+                                             (unwords
+                                                [ "Don't test whether HTTP provisioning works before"
+                                                , "making ACME requests; only useful for testing."
+                                                ]))
 
 go :: CmdOpts -> IO ()
 go CmdOpts { .. } = do
-  let terms           = fromMaybe defaultTerms (join $ parseAbsoluteURI <$> optTerms)
-      directoryUrl    = if optStaging then stagingDirectoryUrl else liveDirectoryUrl
-      domainKeyFile   = domainDir </> "rsa.key"
-      domainCertFile  = domainDir </> "cert.der"
-      domainDir       = fromMaybe (head optDomains) optDomainDir
-      privKeyFile     = optKeyFile
-      requestDomains  = fromMaybe (error "invalid domain name") $ sequence $ domainName . fromString <$> optDomains
+  let terms              = fromMaybe defaultTerms (join $ parseAbsoluteURI <$> optTerms)
+      directoryUrl       = if optStaging then stagingDirectoryUrl else liveDirectoryUrl
+      domainKeyFile      = domainDir </> "rsa.key"
+      domainCombinedFile = domainDir </> "cert.combined.pem"
+      domainCertFile     = domainDir </> "cert.pem"
+      domainDhFile       = domainDir </> "dhparams.pem"
+      domainDir          = fromMaybe (head optDomains) optDomainDir
+      privKeyFile        = optKeyFile
+      requestDomains     = map domainName' optDomains
 
   doesDirectoryExist domainDir `otherwiseM` createDirectory domainDir
 
+  let issuerCertFile = "lets-encrypt-x1-cross-signed.pem"
+  issuerCert <- readFile issuerCertFile >>= readX509
+
   Just domainKeys <- getOrCreateKeys domainKeyFile
   Just keys <- getOrCreateKeys privKeyFile
 
   challengeDir <- ensureWritableDir optChallengeDir "challenge directory"
   void $ ensureWritableDir domainDir "domain directory"
 
-  let skipProvisionCheck = True
-  unless skipProvisionCheck $
+  unless optSkipProvisionCheck $
     forM_ requestDomains $ canProvision challengeDir >=>
       (`unless` error "Error: cannot provision files to web server via challenge directory")
 
@@ -128,19 +131,44 @@ go CmdOpts { .. } = do
 
   let email = either (error . ("Error: invalid email address: " ++)) id . validate . fromString <$> optEmail
 
-  let issuerCertFile = "lets-encrypt-x1-cross-signed.pem"
-  issuerCert <- readFile issuerCertFile >>= readX509
+  dh <- if optSkipDH then return Nothing else Just <$> getOrCreateDH domainDhFile
+
+  certificate <- certify directoryUrl keys ((,) terms <$> email) (fileProvisioner challengeDir) certReq
+
+  let saveCombined  = combinedCert issuerCert dh domainKeys >=> writeFile domainCombinedFile
+      savePEM       = writeX509                             >=> writeFile domainCertFile
+      saveBoth x509 = savePEM x509 >> saveCombined x509
+
+  either (error . ("Error: " ++)) saveBoth certificate
+
+genKey :: IO String
+genKey = withOpenSSL $ do
+  kp <- generateRSAKey' 4096 65537
+  writePKCS8PrivateKey kp Nothing
+
+getOrCreate :: IO String -> (String -> IO a) -> FilePath -> IO a
+getOrCreate gen parse file = do
+  exists <- doesFileExist file
+  parse =<< if exists then readFile file else gen >>= save file
+  where
+    save f x = writeFile f x >> return x
 
+getOrCreateKeys :: FilePath -> IO (Maybe Keys)
+getOrCreateKeys = getOrCreate genKey readKeys
+
+getOrCreateDH :: FilePath -> IO DHP
+getOrCreateDH = getOrCreate (genDHParams' >>= writeDHParams) readDHParams
+
+domainName' :: String -> DomainName
+domainName' dom = fromMaybe (error $ "Error: invalid domain name: " ++ show dom) (domainName $ fromString dom)
+
+genDHParams' :: IO DHP
+genDHParams' = do
   hSetBuffering stdout NoBuffering
   putStr "Generating DH Params..."
   dh <- genDHParams DHGen2 2048
   putStrLn "  Done."
-
-  certificate <- certify directoryUrl keys ((,) terms <$> email) (fileProvisioner challengeDir) certReq
-
-  either (error . ("Error: " ++))
-         (combinedCert issuerCert (Just dh) domainKeys >=> writeFile domainCertFile)
-         certificate
+  return dh
 
 combinedCert :: X509 -> Maybe DHP -> Keys -> X509 -> IO String
 combinedCert issuerCert dh (Keys privKey _) cert = do