chore: merge probe-engine into probe-cli (#201)

This is how I did it:

1. `git clone https://github.com/ooni/probe-engine internal/engine`

2. ```
(cd internal/engine && git describe --tags)
v0.23.0
```

3. `nvim go.mod` (merging `go.mod` with `internal/engine/go.mod`

4. `rm -rf internal/.git internal/engine/go.{mod,sum}`

5. `git add internal/engine`

6. `find . -type f -name \*.go -exec sed -i 's@/ooni/probe-engine@/ooni/probe-cli/v3/internal/engine@g' {} \;`

7. `go build ./...` (passes)

8. `go test -race ./...` (temporary failure on RiseupVPN)

9. `go mod tidy`

10. this commit message

Once this piece of work is done, we can build a new version of `ooniprobe` that
is using `internal/engine` directly. We need to do more work to ensure all the
other functionality in `probe-engine` (e.g. making mobile packages) are still WAI.

Part of https://github.com/ooni/probe/issues/1335

internal/engine/netx/errorx/errorx_test.go

@@ -0,0 +1,247 @@
+package errorx
+
+import (
+	"context"
+	"crypto/tls"
+	"crypto/x509"
+	"errors"
+	"io"
+	"net"
+	"syscall"
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+	"github.com/lucas-clemente/quic-go"
+	"github.com/pion/stun"
+)
+
+func TestMaybeBuildFactory(t *testing.T) {
+	err := SafeErrWrapperBuilder{
+		ConnID:        1,
+		DialID:        10,
+		Error:         errors.New("mocked error"),
+		TransactionID: 100,
+	}.MaybeBuild()
+	var target *ErrWrapper
+	if errors.As(err, &target) == false {
+		t.Fatal("not the expected error type")
+	}
+	if target.ConnID != 1 {
+		t.Fatal("wrong ConnID")
+	}
+	if target.DialID != 10 {
+		t.Fatal("wrong DialID")
+	}
+	if target.Failure != "unknown_failure: mocked error" {
+		t.Fatal("the failure string is wrong")
+	}
+	if target.TransactionID != 100 {
+		t.Fatal("the transactionID is wrong")
+	}
+	if target.WrappedErr.Error() != "mocked error" {
+		t.Fatal("the wrapped error is wrong")
+	}
+}
+
+func TestToFailureString(t *testing.T) {
+	t.Run("for already wrapped error", func(t *testing.T) {
+		err := SafeErrWrapperBuilder{Error: io.EOF}.MaybeBuild()
+		if toFailureString(err) != FailureEOFError {
+			t.Fatal("unexpected result")
+		}
+	})
+	t.Run("for ErrDNSBogon", func(t *testing.T) {
+		if toFailureString(ErrDNSBogon) != FailureDNSBogonError {
+			t.Fatal("unexpected result")
+		}
+	})
+	t.Run("for context.Canceled", func(t *testing.T) {
+		if toFailureString(context.Canceled) != FailureInterrupted {
+			t.Fatal("unexpected result")
+		}
+	})
+	t.Run("for x509.HostnameError", func(t *testing.T) {
+		var err x509.HostnameError
+		if toFailureString(err) != FailureSSLInvalidHostname {
+			t.Fatal("unexpected result")
+		}
+	})
+	t.Run("for x509.UnknownAuthorityError", func(t *testing.T) {
+		var err x509.UnknownAuthorityError
+		if toFailureString(err) != FailureSSLUnknownAuthority {
+			t.Fatal("unexpected result")
+		}
+	})
+	t.Run("for x509.CertificateInvalidError", func(t *testing.T) {
+		var err x509.CertificateInvalidError
+		if toFailureString(err) != FailureSSLInvalidCertificate {
+			t.Fatal("unexpected result")
+		}
+	})
+	t.Run("for operation was canceled error", func(t *testing.T) {
+		if toFailureString(errors.New("operation was canceled")) != FailureInterrupted {
+			t.Fatal("unexpected result")
+		}
+	})
+	t.Run("for EOF", func(t *testing.T) {
+		if toFailureString(io.EOF) != FailureEOFError {
+			t.Fatal("unexpected results")
+		}
+	})
+	t.Run("for connection_refused", func(t *testing.T) {
+		if toFailureString(syscall.ECONNREFUSED) != FailureConnectionRefused {
+			t.Fatal("unexpected results")
+		}
+	})
+	t.Run("for connection_reset", func(t *testing.T) {
+		if toFailureString(syscall.ECONNRESET) != FailureConnectionReset {
+			t.Fatal("unexpected results")
+		}
+	})
+	t.Run("for context deadline exceeded", func(t *testing.T) {
+		ctx, cancel := context.WithTimeout(context.Background(), 1)
+		defer cancel()
+		<-ctx.Done()
+		if toFailureString(ctx.Err()) != FailureGenericTimeoutError {
+			t.Fatal("unexpected results")
+		}
+	})
+	t.Run("for stun's transaction is timed out", func(t *testing.T) {
+		if toFailureString(stun.ErrTransactionTimeOut) != FailureGenericTimeoutError {
+			t.Fatal("unexpected results")
+		}
+	})
+	t.Run("for i/o error", func(t *testing.T) {
+		ctx, cancel := context.WithTimeout(context.Background(), 1)
+		defer cancel() // fail immediately
+		conn, err := (&net.Dialer{}).DialContext(ctx, "tcp", "www.google.com:80")
+		if err == nil {
+			t.Fatal("expected an error here")
+		}
+		if conn != nil {
+			t.Fatal("expected nil connection here")
+		}
+		if toFailureString(err) != FailureGenericTimeoutError {
+			t.Fatal("unexpected results")
+		}
+	})
+	t.Run("for TLS handshake timeout error", func(t *testing.T) {
+		err := errors.New("net/http: TLS handshake timeout")
+		if toFailureString(err) != FailureGenericTimeoutError {
+			t.Fatal("unexpected results")
+		}
+	})
+	t.Run("for no such host", func(t *testing.T) {
+		if toFailureString(&net.DNSError{
+			Err: "no such host",
+		}) != FailureDNSNXDOMAINError {
+			t.Fatal("unexpected results")
+		}
+	})
+	t.Run("for errors including IPv4 address", func(t *testing.T) {
+		input := errors.New("read tcp 10.0.2.15:56948->93.184.216.34:443: use of closed network connection")
+		expected := "unknown_failure: read tcp [scrubbed]->[scrubbed]: use of closed network connection"
+		out := toFailureString(input)
+		if out != expected {
+			t.Fatal(cmp.Diff(expected, out))
+		}
+	})
+	t.Run("for errors including IPv6 address", func(t *testing.T) {
+		input := errors.New("read tcp [::1]:56948->[::1]:443: use of closed network connection")
+		expected := "unknown_failure: read tcp [scrubbed]->[scrubbed]: use of closed network connection"
+		out := toFailureString(input)
+		if out != expected {
+			t.Fatal(cmp.Diff(expected, out))
+		}
+	})
+	// QUIC failures
+	t.Run("for connection_refused", func(t *testing.T) {
+		if toFailureString(errors.New("connection_refused")) != FailureConnectionRefused {
+			t.Fatal("unexpected results")
+		}
+	})
+	t.Run("for connection_reset", func(t *testing.T) {
+		if toFailureString(errors.New("stateless_reset")) != FailureConnectionReset {
+			t.Fatal("unexpected results")
+		}
+	})
+	t.Run("for incompatible quic version", func(t *testing.T) {
+		if toFailureString(errors.New("No compatible QUIC version found")) != FailureNoCompatibleQUICVersion {
+			t.Fatal("unexpected results")
+		}
+	})
+	t.Run("for i/o error", func(t *testing.T) {
+		ctx, cancel := context.WithTimeout(context.Background(), 1)
+		defer cancel() // fail immediately
+		udpAddr := &net.UDPAddr{IP: net.ParseIP("216.58.212.164"), Port: 80, Zone: ""}
+		udpConn, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4zero, Port: 0})
+		sess, err := quic.DialEarlyContext(ctx, udpConn, udpAddr, "google.com:80", &tls.Config{}, &quic.Config{})
+		if err == nil {
+			t.Fatal("expected an error here")
+		}
+		if sess != nil {
+			t.Fatal("expected nil session here")
+		}
+		if toFailureString(err) != FailureGenericTimeoutError {
+			t.Fatal("unexpected results")
+		}
+	})
+	t.Run("for QUIC handshake timeout error", func(t *testing.T) {
+		err := errors.New("Handshake did not complete in time")
+		if toFailureString(err) != FailureGenericTimeoutError {
+			t.Fatal("unexpected results")
+		}
+	})
+}
+
+func TestToOperationString(t *testing.T) {
+	t.Run("for connect", func(t *testing.T) {
+		// You're doing HTTP and connect fails. You want to know
+		// that connect failed not that HTTP failed.
+		err := &ErrWrapper{Operation: ConnectOperation}
+		if toOperationString(err, HTTPRoundTripOperation) != ConnectOperation {
+			t.Fatal("unexpected result")
+		}
+	})
+	t.Run("for http_round_trip", func(t *testing.T) {
+		// You're doing DoH and something fails inside HTTP. You want
+		// to know about the internal HTTP error, not resolve.
+		err := &ErrWrapper{Operation: HTTPRoundTripOperation}
+		if toOperationString(err, ResolveOperation) != HTTPRoundTripOperation {
+			t.Fatal("unexpected result")
+		}
+	})
+	t.Run("for resolve", func(t *testing.T) {
+		// You're doing HTTP and the DNS fails. You want to
+		// know that resolve failed.
+		err := &ErrWrapper{Operation: ResolveOperation}
+		if toOperationString(err, HTTPRoundTripOperation) != ResolveOperation {
+			t.Fatal("unexpected result")
+		}
+	})
+	t.Run("for tls_handshake", func(t *testing.T) {
+		// You're doing HTTP and the TLS handshake fails. You want
+		// to know about a TLS handshake error.
+		err := &ErrWrapper{Operation: TLSHandshakeOperation}
+		if toOperationString(err, HTTPRoundTripOperation) != TLSHandshakeOperation {
+			t.Fatal("unexpected result")
+		}
+	})
+	t.Run("for minor operation", func(t *testing.T) {
+		// You just noticed that TLS handshake failed and you
+		// have a child error telling you that read failed. Here
+		// you want to know about a TLS handshake error.
+		err := &ErrWrapper{Operation: ReadOperation}
+		if toOperationString(err, TLSHandshakeOperation) != TLSHandshakeOperation {
+			t.Fatal("unexpected result")
+		}
+	})
+	t.Run("for quic_handshake", func(t *testing.T) {
+		// You're doing HTTP and the TLS handshake fails. You want
+		// to know about a TLS handshake error.
+		err := &ErrWrapper{Operation: QUICHandshakeOperation}
+		if toOperationString(err, HTTPRoundTripOperation) != QUICHandshakeOperation {
+			t.Fatal("unexpected result")
+		}
+	})
+}