Expose the handle constructors and fix multiline response parsing

ftp-client/CHANGELOG.md

@@ -1,5 +1,19 @@
 # Changelog for ftp-client
 
+## 0.5.2.0
+
+* Expose `createSIOHandle`, `createTLSConnection` and `connectTLS` so callers can
+  manage the handle lifecycle themselves rather than going through `withFTP` and
+  `withFTPS`. Thanks to @pucsdian.
+
+* Fix multiline response parsing. A response was terminated at the first
+  continuation line whose first three bytes matched the response code, so a reply
+  such as `220-First` / `220-Second` / `220 Third` was truncated to two lines. Per
+  [RFC 959](https://datatracker.ietf.org/doc/html/rfc959#page-36) only the code
+  followed by a space ends a multiline reply; the code followed by a hyphen
+  continues it. A final line consisting of the bare code is also accepted, for
+  servers that omit the trailing space. Thanks to @pucsdian.
+
 ## 0.5.1.8
 
 * Fix a crash on short response lines. `getResponse` called `head` on the bytes

ftp-client/ftp-client.cabal

@@ -5,7 +5,7 @@ cabal-version: 1.12
 -- see: https://github.com/sol/hpack
 
 name:           ftp-client
-version:        0.5.1.8
+version:        0.5.2.0
 synopsis:       Transfer files with FTP and FTPS
 description:    ftp-client is a library for communicating with an FTP server. It works over both a clear channel or TLS.
 category:       Web

ftp-client/package.yaml

@@ -1,5 +1,5 @@
 name:                ftp-client
-version:             0.5.1.8
+version:             0.5.2.0
 synopsis:            Transfer files with FTP and FTPS
 description:         ftp-client is a library for communicating with an FTP server. It works over both a clear channel or TLS.
 homepage:            https://github.com/flipstone/ftp-client

ftp-client/src/Network/FTP/Client.hs

@@ -40,6 +40,10 @@ module Network.FTP.Client (
     Handle(..),
     -- * Exceptions
     FTPException(..),
+    -- * System Handle Creation
+    createSIOHandle,
+    createTLSConnection,
+    connectTLS,
     -- * Handle Implementations
     sIOHandleImpl,
     tlsHandleImpl,
@@ -292,9 +296,15 @@ loopMultiLine h code lines = do
         -- to be kept and the loop has to continue past it.
         Nothing -> return lines
         Just nextLine -> do
+            -- RFC 959 (https://datatracker.ietf.org/doc/html/rfc959#page-36) ends a
+            -- multiline reply with the code followed by a space, and continues it
+            -- with the code followed by a hyphen. The bare code is accepted too,
+            -- for servers that omit the trailing space on an empty final line.
             let newLines = lines <> [C.dropWhile (== ' ') nextLine]
-                nextCode = C.take 3 nextLine
-            if nextCode == code
+                isLastLine =
+                    nextLine == code
+                        || C.isPrefixOf (code <> " ") nextLine
+            if isLastLine
                 then return newLines
                 else loopMultiLine h code newLines
 

ftp-client/test/test.hs

@@ -108,6 +108,43 @@ main = hspec $ do
                 , C.pack "220 Third Line\r\n"
                 ] Clear
             getResponse h `shouldReturn` expected
+        it "keeps reading continuation lines that repeat the code" $ do
+            let expected = FTPResponse
+                    F.Success 220
+                    (MultiLine
+                        [ C.pack "First Line"
+                        , C.pack "220-Second Line"
+                        , C.pack "220 Third Line"
+                        ])
+            (TestHandle _ h) <- testHandle []
+                [ C.pack "220-First Line\r\n"
+                , C.pack "220-Second Line\r\n"
+                , C.pack "220 Third Line\r\n"
+                ] Clear
+            getResponse h `shouldReturn` expected
+        it "ends a multiline response on a bare code" $ do
+            let expected = FTPResponse
+                    F.Success 220
+                    (MultiLine [C.pack "First Line", C.pack "220"])
+            (TestHandle _ h) <- testHandle []
+                [ C.pack "220-First Line\r\n"
+                , C.pack "220\r\n"
+                ] Clear
+            getResponse h `shouldReturn` expected
+        it "does not end a multiline response on a different code" $ do
+            let expected = FTPResponse
+                    F.Success 220
+                    (MultiLine
+                        [ C.pack "First Line"
+                        , C.pack "331 Not the terminator"
+                        , C.pack "220 Done"
+                        ])
+            (TestHandle _ h) <- testHandle []
+                [ C.pack "220-First Line\r\n"
+                , C.pack "331 Not the terminator\r\n"
+                , C.pack "220 Done\r\n"
+                ] Clear
+            getResponse h `shouldReturn` expected
         it "stops when the server hangs up during a multiline response" $ do
             let expected = FTPResponse
                     F.Success 220