Show nested exceptions more clearly #29612
Description
We need to make output like this (original) easier to read:
System.Net.Http.HttpRequestException: The SSL connection could not be established, see inner exception. ---> System.Security.Authentication.AuthenticationException: Authentication failed, see inner exception. ---> System.TypeInitializationException: The type initializer for 'SslMethods' threw an exception. ---> System.TypeInitializationException: The type initializer for 'Ssl' threw an exception. ---> System.TypeInitializationException: The type initializer for 'SslInitializer' threw an exception. ---> Interop+Crypto+OpenSslCryptographicException: error:25070067:DSO support routines:DSO_load:could not load the shared library
at Interop.SslInitializer..cctor()
--- End of inner exception stack trace ---
at Interop.Ssl..cctor()
--- End of inner exception stack trace ---
at Interop.Ssl.SslV2_3Method()
at Interop.Ssl.SslMethods..cctor()
--- End of inner exception stack trace ---
at Interop.OpenSsl.AllocateSslContext(SslProtocols protocols, SafeX509Handle certHandle, SafeEvpPKeyHandle certKeyHandle, EncryptionPolicy policy, SslAuthenticationOptions sslAuthenticationOptions)
...long trace
at System.Net.Security.SslStreamPal.HandshakeInternal(SafeFreeCredentials credential, SafeDeleteContext& context, SecurityBuffer inputBuffer, SecurityBuffer outputBuffer, SslAuthenticationOptions sslAuthenticationOptions)
--- End of inner exception stack trace ---
at System.Net.Security.SslState.StartSendAuthResetSignal(ProtocolToken message, AsyncProtocolRequest asyncRequest, ExceptionDispatchInfo exception)
...long trace
at System.Net.Http.ConnectHelper.EstablishSslConnectionAsyncCore(Stream stream, SslClientAuthenticationOptions sslOptions, CancellationToken cancellationToken)
--- End of inner exception stack trace ---
at System.Net.Http.ConnectHelper.EstablishSslConnectionAsyncCore(Stream stream, SslClientAuthenticationOptions sslOptions, CancellationToken cancellationToken)
...long trace
at System.Net.Http.HttpClient.FinishSendAsyncBuffered(Task`1 sendTask, HttpRequestMessage request, CancellationTokenSource cts, Boolean disposeCts)
Amongst other issues the message is too hard to read since is 630 characters all on one line, with the most interesting part usually at the far end. It's hard to figure out which stack trace belongs to which message, and which is nested in which.
In most cases the action is in Exception.ToString() but several exception subclasses have their own similar or identical scheme for handling inner exceptions (eg search for -->) and AggregateException is particularly special.
I plan to improve at least part of this, opening this issue for now.