Merge pull request ipfs/go-ipfs-http-client#156 from ipfs/fix/ipld-ErrNotFound

fix: make Block().* return correct ABI based ipld.ErrNotFound errors

This commit was moved from ipfs/go-ipfs-http-client@fdbee7c788

client/httpapi/block.go

@@ -3,7 +3,6 @@ package httpapi
 import (
 	"bytes"
 	"context"
-	"errors"
 	"fmt"
 	"io"
 
@@ -67,7 +66,7 @@ func (api *BlockAPI) Get(ctx context.Context, p path.Path) (io.Reader, error) {
 		return nil, err
 	}
 	if resp.Error != nil {
-		return nil, resp.Error
+		return nil, parseErrNotFoundWithFallbackToError(resp.Error)
 	}
 
 	//TODO: make get return ReadCloser to avoid copying
@@ -99,18 +98,14 @@ func (api *BlockAPI) Rm(ctx context.Context, p path.Path, opts ...caopts.BlockRm
 		return err
 	}
 
-	if removedBlock.Error != "" {
-		return errors.New(removedBlock.Error)
-	}
-
-	return nil
+	return parseErrNotFoundWithFallbackToMSG(removedBlock.Error)
 }
 
 func (api *BlockAPI) Stat(ctx context.Context, p path.Path) (iface.BlockStat, error) {
 	var out blockStat
 	err := api.core().Request("block/stat", p.String()).Exec(ctx, &out)
 	if err != nil {
-		return nil, err
+		return nil, parseErrNotFoundWithFallbackToError(err)
 	}
 	out.cid, err = cid.Parse(out.Key)
 	if err != nil {

client/httpapi/errors.go

@@ -0,0 +1,169 @@
+package httpapi
+
+import (
+	"errors"
+	"strings"
+	"unicode/utf8"
+
+	"github.com/ipfs/go-cid"
+	ipld "github.com/ipfs/go-ipld-format"
+	mbase "github.com/multiformats/go-multibase"
+)
+
+// This file handle parsing and returning the correct ABI based errors from error messages
+
+type prePostWrappedNotFoundError struct {
+	pre  string
+	post string
+
+	wrapped ipld.ErrNotFound
+}
+
+func (e prePostWrappedNotFoundError) String() string {
+	return e.Error()
+}
+
+func (e prePostWrappedNotFoundError) Error() string {
+	return e.pre + e.wrapped.Error() + e.post
+}
+
+func (e prePostWrappedNotFoundError) Unwrap() error {
+	return e.wrapped
+}
+
+func parseErrNotFoundWithFallbackToMSG(msg string) error {
+	err, handled := parseErrNotFound(msg)
+	if handled {
+		return err
+	}
+
+	return errors.New(msg)
+}
+
+func parseErrNotFoundWithFallbackToError(msg error) error {
+	err, handled := parseErrNotFound(msg.Error())
+	if handled {
+		return err
+	}
+
+	return msg
+}
+
+//lint:ignore ST1008 this function is not using the error as a mean to return failure but it massages it to return the correct type
+func parseErrNotFound(msg string) (error, bool) {
+	if msg == "" {
+		return nil, true // Fast path
+	}
+
+	if err, handled := parseIPLDErrNotFound(msg); handled {
+		return err, true
+	}
+
+	if err, handled := parseBlockstoreNotFound(msg); handled {
+		return err, true
+	}
+
+	return nil, false
+}
+
+// Assume CIDs break on:
+// - Whitespaces: " \t\n\r\v\f"
+// - Semicolon: ";" this is to parse ipld.ErrNotFound wrapped in multierr
+// - Double Quotes: "\"" this is for parsing %q and %#v formating
+const cidBreakSet = " \t\n\r\v\f;\""
+
+//lint:ignore ST1008 using error as values
+func parseIPLDErrNotFound(msg string) (error, bool) {
+	// The patern we search for is:
+	const ipldErrNotFoundKey = "ipld: could not find " /*CID*/
+	// We try to parse the CID, if it's invalid we give up and return a simple text error.
+	// We also accept "node" in place of the CID because that means it's an Undefined CID.
+
+	keyIndex := strings.Index(msg, ipldErrNotFoundKey)
+
+	if keyIndex < 0 { // Unknown error
+		return nil, false
+	}
+
+	cidStart := keyIndex + len(ipldErrNotFoundKey)
+
+	msgPostKey := msg[cidStart:]
+	var c cid.Cid
+	var postIndex int
+	if strings.HasPrefix(msgPostKey, "node") {
+		// Fallback case
+		c = cid.Undef
+		postIndex = len("node")
+	} else {
+		postIndex = strings.IndexFunc(msgPostKey, func(r rune) bool {
+			return strings.ContainsAny(string(r), cidBreakSet)
+		})
+		if postIndex < 0 {
+			// no breakage meaning the string look like this something + "ipld: could not find bafy"
+			postIndex = len(msgPostKey)
+		}
+
+		cidStr := msgPostKey[:postIndex]
+
+		var err error
+		c, err = cid.Decode(cidStr)
+		if err != nil {
+			// failed to decode CID give up
+			return nil, false
+		}
+
+		// check that the CID is either a CIDv0 or a base32 multibase
+		// because that what ipld.ErrNotFound.Error() -> cid.Cid.String() do currently
+		if c.Version() != 0 {
+			baseRune, _ := utf8.DecodeRuneInString(cidStr)
+			if baseRune == utf8.RuneError || baseRune != mbase.Base32 {
+				// not a multibase we expect, give up
+				return nil, false
+			}
+		}
+	}
+
+	err := ipld.ErrNotFound{Cid: c}
+	pre := msg[:keyIndex]
+	post := msgPostKey[postIndex:]
+
+	if len(pre) > 0 || len(post) > 0 {
+		return prePostWrappedNotFoundError{
+			pre:     pre,
+			post:    post,
+			wrapped: err,
+		}, true
+	}
+
+	return err, true
+}
+
+// This is a simple error type that just return msg as Error().
+// But that also match ipld.ErrNotFound when called with Is(err).
+// That is needed to keep compatiblity with code that use string.Contains(err.Error(), "blockstore: block not found")
+// and code using ipld.ErrNotFound
+type blockstoreNotFoundMatchingIPLDErrNotFound struct {
+	msg string
+}
+
+func (e blockstoreNotFoundMatchingIPLDErrNotFound) String() string {
+	return e.Error()
+}
+
+func (e blockstoreNotFoundMatchingIPLDErrNotFound) Error() string {
+	return e.msg
+}
+
+func (e blockstoreNotFoundMatchingIPLDErrNotFound) Is(err error) bool {
+	_, ok := err.(ipld.ErrNotFound)
+	return ok
+}
+
+//lint:ignore ST1008 using error as values
+func parseBlockstoreNotFound(msg string) (error, bool) {
+	if !strings.Contains(msg, "blockstore: block not found") {
+		return nil, false
+	}
+
+	return blockstoreNotFoundMatchingIPLDErrNotFound{msg: msg}, true
+}

client/httpapi/errors_test.go

@@ -0,0 +1,95 @@
+package httpapi
+
+import (
+	"errors"
+	"fmt"
+	"testing"
+
+	"github.com/ipfs/go-cid"
+	ipld "github.com/ipfs/go-ipld-format"
+	mbase "github.com/multiformats/go-multibase"
+	mh "github.com/multiformats/go-multihash"
+)
+
+var randomSha256MH = mh.Multihash{0x12, 0x20, 0x88, 0x82, 0x73, 0x37, 0x7c, 0xc1, 0xc9, 0x96, 0xad, 0xee, 0xd, 0x26, 0x84, 0x2, 0xc9, 0xc9, 0x5c, 0xf9, 0x5c, 0x4d, 0x9b, 0xc3, 0x3f, 0xfb, 0x4a, 0xd8, 0xaf, 0x28, 0x6b, 0xca, 0x1a, 0xf2}
+
+func doParseIpldNotFoundTest(t *testing.T, original error) {
+	originalMsg := original.Error()
+
+	rebuilt := parseErrNotFoundWithFallbackToMSG(originalMsg)
+
+	rebuiltMsg := rebuilt.Error()
+
+	if originalMsg != rebuiltMsg {
+		t.Errorf("expected message to be %q; got %q", originalMsg, rebuiltMsg)
+	}
+
+	originalNotFound := ipld.IsNotFound(original)
+	rebuiltNotFound := ipld.IsNotFound(rebuilt)
+	if originalNotFound != rebuiltNotFound {
+		t.Errorf("for %q expected Ipld.IsNotFound to be %t; got %t", originalMsg, originalNotFound, rebuiltNotFound)
+	}
+}
+
+func TestParseIPLDNotFound(t *testing.T) {
+	if err := parseErrNotFoundWithFallbackToMSG(""); err != nil {
+		t.Errorf("expected empty string to give no error; got %T %q", err, err.Error())
+	}
+
+	cidBreaks := make([]string, len(cidBreakSet))
+	for i, v := range cidBreakSet {
+		cidBreaks[i] = "%w" + string(v)
+	}
+
+	base58BTCEncoder, err := mbase.NewEncoder(mbase.Base58BTC)
+	if err != nil {
+		t.Fatalf("expected to find Base58BTC encoder; got error %q", err.Error())
+	}
+
+	for _, wrap := range append(cidBreaks,
+		"",
+		"merkledag: %w",
+		"testing: %w the test",
+		"%w is wrong",
+	) {
+		for _, err := range [...]error{
+			errors.New("ipld: could not find "),
+			errors.New("ipld: could not find Bad_CID"),
+			errors.New("ipld: could not find " + cid.NewCidV1(cid.Raw, randomSha256MH).Encode(base58BTCEncoder)), // Test that we only accept CIDv0 and base32 CIDs
+			errors.New("network connection timeout"),
+			ipld.ErrNotFound{Cid: cid.Undef},
+			ipld.ErrNotFound{Cid: cid.NewCidV0(randomSha256MH)},
+			ipld.ErrNotFound{Cid: cid.NewCidV1(cid.Raw, randomSha256MH)},
+		} {
+			if wrap != "" {
+				err = fmt.Errorf(wrap, err)
+			}
+
+			doParseIpldNotFoundTest(t, err)
+		}
+	}
+}
+
+func TestBlockstoreNotFoundMatchingIPLDErrNotFound(t *testing.T) {
+	if !ipld.IsNotFound(blockstoreNotFoundMatchingIPLDErrNotFound{}) {
+		t.Fatalf("expected blockstoreNotFoundMatchingIPLDErrNotFound to match ipld.IsNotFound; got false")
+	}
+
+	for _, wrap := range [...]string{
+		"",
+		"merkledag: %w",
+		"testing: %w the test",
+		"%w is wrong",
+	} {
+		for _, err := range [...]error{
+			errors.New("network connection timeout"),
+			blockstoreNotFoundMatchingIPLDErrNotFound{"blockstore: block not found"},
+		} {
+			if wrap != "" {
+				err = fmt.Errorf(wrap, err)
+			}
+
+			doParseIpldNotFoundTest(t, err)
+		}
+	}
+}