gateway: import backend remote utils

gateway/backend_remote.go

@@ -0,0 +1 @@
+package gateway

gateway/backend_remote_utils.go

@@ -0,0 +1,74 @@
+package gateway
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"net/url"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/ipfs/boxo/path"
+)
+
+// contentPathToCarUrl returns an URL that allows retrieval of specified resource
+// from a trustless gateway that implements IPIP-402
+func contentPathToCarUrl(path path.ImmutablePath, params CarParams) *url.URL {
+	return &url.URL{
+		Path:     path.String(),
+		RawQuery: carParamsToString(params),
+	}
+}
+
+// carParamsToString converts CarParams to URL parameters compatible with IPIP-402
+func carParamsToString(params CarParams) string {
+	paramsBuilder := strings.Builder{}
+	paramsBuilder.WriteString("format=car") // always send explicit format in URL, this  makes debugging easier, even when Accept header was set
+	if params.Scope != "" {
+		paramsBuilder.WriteString("&dag-scope=")
+		paramsBuilder.WriteString(string(params.Scope))
+	}
+	if params.Range != nil {
+		paramsBuilder.WriteString("&entity-bytes=")
+		paramsBuilder.WriteString(strconv.FormatInt(params.Range.From, 10))
+		paramsBuilder.WriteString(":")
+		if params.Range.To != nil {
+			paramsBuilder.WriteString(strconv.FormatInt(*params.Range.To, 10))
+		} else {
+			paramsBuilder.WriteString("*")
+		}
+	}
+	return paramsBuilder.String()
+}
+
+// TODO: do not export this?
+// GatewayError translates underlying blockstore error into one that gateway code will return as HTTP 502 or 504
+// it also makes sure Retry-After hint from remote blockstore will be passed to HTTP client, if present.
+func GatewayError(err error) error {
+	if errors.Is(err, &ErrorStatusCode{}) ||
+		errors.Is(err, &ErrorRetryAfter{}) {
+		// already correct error
+		return err
+	}
+
+	// All timeouts should produce 504 Gateway Timeout
+	if errors.Is(err, context.DeadlineExceeded) || // TODO: already handled in [webError], right?
+		// errors.Is(err, caboose.ErrTimeout) || // TODO: We're removing this
+		// Unfortunately this is not an exported type so we have to check for the content.
+		strings.Contains(err.Error(), "Client.Timeout exceeded") {
+		return fmt.Errorf("%w: %s", ErrGatewayTimeout, err.Error())
+	}
+
+	// TODO: return this?
+	// (Saturn) errors that support the RetryAfter interface need to be converted
+	// to the correct gateway error, such that the HTTP header is set.
+	for v := err; v != nil; v = errors.Unwrap(v) {
+		if r, ok := v.(interface{ RetryAfter() time.Duration }); ok {
+			return NewErrorRetryAfter(err, r.RetryAfter())
+		}
+	}
+
+	// everything else returns 502 Bad Gateway
+	return fmt.Errorf("%w: %s", ErrBadGateway, err.Error())
+}

gateway/backend_remote_utils_test.go

@@ -0,0 +1,98 @@
+package gateway
+
+import (
+	"errors"
+	"fmt"
+	"testing"
+	"time"
+
+	"github.com/ipfs/boxo/path"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestContentPathToCarUrl(t *testing.T) {
+	t.Parallel()
+
+	negativeOffset := int64(-42)
+	testCases := []struct {
+		contentPath string // to be turned into ImmutablePath
+		carParams   CarParams
+		expectedUrl string // url.URL.String()
+	}{
+		{
+			contentPath: "/ipfs/bafybeigdyrzt5sfp7udm7hu76uh7y26nf3efuylqabf3oclgtqy55fbzdi",
+			carParams:   CarParams{},
+			expectedUrl: "/ipfs/bafybeigdyrzt5sfp7udm7hu76uh7y26nf3efuylqabf3oclgtqy55fbzdi?format=car",
+		},
+		{
+			contentPath: "/ipfs/bafybeigdyrzt5sfp7udm7hu76uh7y26nf3efuylqabf3oclgtqy55fbzdi",
+			carParams:   CarParams{Scope: "entity", Range: &DagByteRange{From: 0, To: nil}},
+			expectedUrl: "/ipfs/bafybeigdyrzt5sfp7udm7hu76uh7y26nf3efuylqabf3oclgtqy55fbzdi?format=car&dag-scope=entity&entity-bytes=0:*",
+		},
+		{
+			contentPath: "/ipfs/bafybeigdyrzt5sfp7udm7hu76uh7y26nf3efuylqabf3oclgtqy55fbzdi",
+			carParams:   CarParams{Scope: "block"},
+			expectedUrl: "/ipfs/bafybeigdyrzt5sfp7udm7hu76uh7y26nf3efuylqabf3oclgtqy55fbzdi?format=car&dag-scope=block",
+		},
+		{
+			contentPath: "/ipfs/bafybeigdyrzt5sfp7udm7hu76uh7y26nf3efuylqabf3oclgtqy55fbzdi",
+			carParams:   CarParams{Scope: "entity", Range: &DagByteRange{From: 4, To: &negativeOffset}},
+			expectedUrl: "/ipfs/bafybeigdyrzt5sfp7udm7hu76uh7y26nf3efuylqabf3oclgtqy55fbzdi?format=car&dag-scope=entity&entity-bytes=4:-42",
+		},
+		{
+			// a regression test for case described in https://github.com/ipfs/gateway-conformance/issues/115
+			contentPath: "/ipfs/bafybeiaysi4s6lnjev27ln5icwm6tueaw2vdykrtjkwiphwekaywqhcjze/I/Auditorio_de_Tenerife%2C_Santa_Cruz_de_Tenerife%2C_España%2C_2012-12-15%2C_DD_02.jpg.webp",
+			carParams:   CarParams{Scope: "entity", Range: &DagByteRange{From: 0, To: nil}},
+			expectedUrl: "/ipfs/bafybeiaysi4s6lnjev27ln5icwm6tueaw2vdykrtjkwiphwekaywqhcjze/I/Auditorio_de_Tenerife%252C_Santa_Cruz_de_Tenerife%252C_Espa%C3%B1a%252C_2012-12-15%252C_DD_02.jpg.webp?format=car&dag-scope=entity&entity-bytes=0:*",
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run("TestContentPathToCarUrl", func(t *testing.T) {
+			p, err := path.NewPath(tc.contentPath)
+			require.NoError(t, err)
+
+			contentPath, err := path.NewImmutablePath(p)
+			require.NoError(t, err)
+
+			result := contentPathToCarUrl(contentPath, tc.carParams).String()
+			require.Equal(t, tc.expectedUrl, result)
+		})
+	}
+}
+
+type testErr struct {
+	message    string
+	retryAfter time.Duration
+}
+
+func (e *testErr) Error() string {
+	return e.message
+}
+
+func (e *testErr) RetryAfter() time.Duration {
+	return e.retryAfter
+}
+
+func TestGatewayErrorRetryAfter(t *testing.T) {
+	t.Parallel()
+
+	originalErr := &testErr{message: "test", retryAfter: time.Minute}
+	var (
+		convertedErr error
+		gatewayErr   *ErrorRetryAfter
+	)
+
+	// Test unwrapped
+	convertedErr = GatewayError(originalErr)
+	ok := errors.As(convertedErr, &gatewayErr)
+	assert.True(t, ok)
+	assert.EqualValues(t, originalErr.retryAfter, gatewayErr.RetryAfter)
+
+	// Test wrapped.
+	convertedErr = GatewayError(fmt.Errorf("wrapped error: %w", originalErr))
+	ok = errors.As(convertedErr, &gatewayErr)
+	assert.True(t, ok)
+	assert.EqualValues(t, originalErr.retryAfter, gatewayErr.RetryAfter)
+}