Introducing checks for libcurl features

Runtime and load-time checks to ensure that the features user is relying
on are available in the libcurl library loaded

Author: kapilash

src/Common/src/Interop/Unix/libcurl/Interop.libcurl.cs

@@ -140,5 +140,8 @@ public static extern IntPtr curl_slist_append(
         [DllImport(Interop.Libraries.LibCurl)]
         public static extern void curl_slist_free_all(
             IntPtr curl_slist);
+
+        [DllImport(Interop.Libraries.LibCurl)]
+        public static extern IntPtr curl_version_info(int curlVersionStamp);
     }
 }

src/Common/src/Interop/Unix/libcurl/Interop.libcurl_types.cs

@@ -125,6 +125,30 @@ internal static partial class CURLMSG
             internal const int CURLMSG_DONE = 1;
         }
 
+        internal static partial class CURL_VERSION_Features
+        {
+            internal const int CURL_VERSION_IPV6         = (1<<0);
+            internal const int CURL_VERSION_KERBEROS4    = (1<<1);
+            internal const int CURL_VERSION_SSL          = (1<<2);
+            internal const int CURL_VERSION_LIBZ         = (1<<3);
+            internal const int CURL_VERSION_NTLM         = (1<<4);
+            internal const int CURL_VERSION_GSSNEGOTIATE = (1<<5);
+            internal const int CURL_VERSION_DEBUG        = (1<<6);
+            internal const int CURL_VERSION_ASYNCHDNS    = (1<<7);
+            internal const int CURL_VERSION_SPNEGO       = (1<<8);
+            internal const int CURL_VERSION_LARGEFILE    = (1<<9);
+            internal const int CURL_VERSION_IDN          = (1<<10);
+            internal const int CURL_VERSION_SSPI         = (1<<11);
+            internal const int CURL_VERSION_CONV         = (1<<12);
+            internal const int CURL_VERSION_CURLDEBUG    = (1<<13);
+            internal const int CURL_VERSION_TLSAUTH_SRP  = (1<<14);
+            internal const int CURL_VERSION_NTLM_WB      = (1<<15);
+            internal const int CURL_VERSION_HTTP2        = (1<<16);
+            internal const int CURL_VERSION_GSSAPI       = (1<<17);
+            internal const int CURL_VERSION_KERBEROS5    = (1<<18);
+            internal const int CURL_VERSION_UNIX_SOCKETS = (1<<19);
+        }
+
         // Type definition of CURLMsg from multi.h
         [StructLayout(LayoutKind.Explicit)]
         internal struct CURLMsg
@@ -139,6 +163,16 @@ internal struct CURLMsg
             internal int result;
         }
 
+        // Curl Version Information
+        [StructLayout(LayoutKind.Explicit)]
+        internal struct curl_version_info_data
+        {
+            [FieldOffset(0)]
+            internal int age;
+            [FieldOffset(32)]
+            internal int features;
+        }
+
         public delegate int curl_socket_callback(
             IntPtr handle,
             curl_socket_t sockfd,

src/System.Net.Http/src/Resources/Strings.resx

@@ -288,4 +288,10 @@
   <data name="net_http_unix_invalid_client_cert_option" xml:space="preserve">
     <value>libcurl supports only manual client certificate selection</value>
   </data>
+  <data name="net_http_unix_https_libcurl_too_old" xml:space="preserve">
+    <value>libcurl library available is too old</value>
+  </data>
+  <data name="net_http_unix_https_support_unavailable_libcurl" xml:space="preserve">
+    <value>libcurl library available on the system does not support https</value>
+  </data>
 </root>

src/System.Net.Http/src/System/Net/Http/Unix/CurlHandler.cs

@@ -19,9 +19,12 @@
 using CURLcode = Interop.libcurl.CURLcode;
 using CURLMcode = Interop.libcurl.CURLMcode;
 using CURLINFO = Interop.libcurl.CURLINFO;
+using CurlVersionInfoData = Interop.libcurl.curl_version_info_data;
+using CurlFeatures = Interop.libcurl.CURL_VERSION_Features;
 using CURLProxyType = Interop.libcurl.curl_proxytype;
 using size_t = System.IntPtr;
 
+
 namespace System.Net.Http
 {  
     internal partial class CurlHandler : HttpMessageHandler
@@ -34,13 +37,19 @@ internal partial class CurlHandler : HttpMessageHandler
         private const string EncodingNameDeflate = "deflate";
         private readonly static string[] AuthenticationSchemes = { "Negotiate", "Digest", "Basic" }; // the order in which libcurl goes over authentication schemes
         private static readonly string[] s_headerDelimiters = new string[] { "\r\n" };
+
         private const int s_requestBufferSize = 16384; // Default used by libcurl
         private const string NoTransferEncoding = HttpKnownHeaderNames.TransferEncoding + ":";
+        private readonly static CurlVersionInfoData curlVersionInfoData;
+        private const int CurlAge = 5;
+        private const int MinCurlAge = 3;
 
         #endregion
 
         #region Fields
-  
+
+        private static bool _supportsAutomaticDecompression;
+        private static bool _supportsSSL;
         private volatile bool _anyOperationStarted;
         private volatile bool _disposed;
         private IWebProxy _proxy = null;
@@ -63,6 +72,13 @@ static CurlHandler()
             {
                 throw new InvalidOperationException("Cannot use libcurl in this process");
             }
+            curlVersionInfoData = Marshal.PtrToStructure<CurlVersionInfoData>(Interop.libcurl.curl_version_info(CurlAge));
+            if (curlVersionInfoData.age < MinCurlAge)
+            {
+                throw new InvalidOperationException(SR.net_http_unix_https_libcurl_too_old);
+            }
+            _supportsSSL = (CurlFeatures.CURL_VERSION_SSL & curlVersionInfoData.features) != 0;
+            _supportsAutomaticDecompression = (CurlFeatures.CURL_VERSION_LIBZ & curlVersionInfoData.features) != 0;
         }
 
         internal CurlHandler()
@@ -168,7 +184,7 @@ internal bool SupportsAutomaticDecompression
         {
             get
             {
-                return true;
+                return _supportsAutomaticDecompression;
             }
         }
 
@@ -267,6 +283,11 @@ protected internal override Task<HttpResponseMessage> SendAsync(
                 throw NotImplemented.ByDesignWithMessage(SR.net_http_client_http_baseaddress_required);
             }
 
+            if (request.RequestUri.Scheme == UriSchemeHttps && !_supportsSSL)
+            {
+                throw new PlatformNotSupportedException(SR.net_http_unix_https_support_unavailable_libcurl);
+            }
+
             if (request.Headers.TransferEncodingChunked.GetValueOrDefault() && (request.Content == null))
             {
                 throw new InvalidOperationException(SR.net_http_chunked_not_allowed_with_empty_content);
@@ -427,7 +448,10 @@ private SafeCurlHandle CreateRequestHandle(RequestCompletionSource state, GCHand
 
             SetCurlCallbacks(requestHandle, state.RequestMessage, statePtr);
 
-            SetRequestHandleDecompressionOptions(requestHandle);
+            if (_supportsAutomaticDecompression)
+            {
+                SetRequestHandleDecompressionOptions(requestHandle);
+            }
 
             SetProxyOptions(requestHandle, state.RequestMessage.RequestUri);