feat: add routing filtering to delegated routing server IPIP-484

CHANGELOG.md

@@ -16,6 +16,8 @@ The following emojis are used to highlight certain changes:
 
 ### Added
 
+- `routing/http`: added support for address and protocol filtering to the delegated routing server ([IPIP-484](https://github.com/ipfs/specs/pull/484)) [#671](https://github.com/ipfs/boxo/pull/671)
+
 ### Changed
 
 ### Removed

routing/http/client/client_test.go

@@ -228,9 +228,7 @@ func TestClient_FindProviders(t *testing.T) {
 	}
 
 	bitswapRecord := makeBitswapRecord()
-	bitswapProviders := []iter.Result[types.Record]{
-		{Val: &bitswapRecord},
-	}
+	peerRecordFromBitswapRecord := types.FromBitswapRecord(&bitswapRecord)
 
 	cases := []struct {
 		name                    string
@@ -254,8 +252,8 @@ func TestClient_FindProviders(t *testing.T) {
 		},
 		{
 			name:                 "happy case (with deprecated bitswap schema)",
-			routerResult:         bitswapProviders,
-			expResult:            bitswapProviders,
+			routerResult:         []iter.Result[types.Record]{{Val: &bitswapRecord}},
+			expResult:            []iter.Result[types.Record]{{Val: peerRecordFromBitswapRecord}},
 			expStreamingResponse: true,
 		},
 		{

routing/http/server/filters.go

@@ -0,0 +1,197 @@
+package server
+
+import (
+	"reflect"
+	"slices"
+	"strings"
+
+	"github.com/ipfs/boxo/routing/http/types"
+	"github.com/ipfs/boxo/routing/http/types/iter"
+	"github.com/multiformats/go-multiaddr"
+)
+
+// filters implements IPIP-0484
+
+func parseFilter(param string) []string {
+	if param == "" {
+		return nil
+	}
+	return strings.Split(strings.ToLower(param), ",")
+}
+
+// applyFiltersToIter applies the filters to the given iterator and returns a new iterator.
+//
+// The function iterates over the input iterator, applying the specified filters to each record.
+// It supports both positive and negative filters for both addresses and protocols.
+//
+// Parameters:
+// - recordsIter: An iterator of types.Record to be filtered.
+// - filterAddrs: A slice of strings representing the address filter criteria.
+// - filterProtocols: A slice of strings representing the protocol filter criteria.
+func applyFiltersToIter(recordsIter iter.ResultIter[types.Record], filterAddrs, filterProtocols []string) iter.ResultIter[types.Record] {
+	mappedIter := iter.Map(recordsIter, func(v iter.Result[types.Record]) iter.Result[types.Record] {
+		if v.Err != nil || v.Val == nil {
+			return v
+		}
+
+		switch v.Val.GetSchema() {
+		case types.SchemaPeer:
+			record, ok := v.Val.(*types.PeerRecord)
+			if !ok {
+				logger.Errorw("problem casting find providers record", "Schema", v.Val.GetSchema(), "Type", reflect.TypeOf(v).String())
+				// drop failed type assertion
+				return iter.Result[types.Record]{}
+			}
+
+			record = applyFilters(record, filterAddrs, filterProtocols)
+			if record == nil {
+				return iter.Result[types.Record]{}
+			}
+			v.Val = record
+
+		//lint:ignore SA1019 // ignore staticcheck
+		case types.SchemaBitswap:
+			//lint:ignore SA1019 // ignore staticcheck
+			record, ok := v.Val.(*types.BitswapRecord)
+			if !ok {
+				logger.Errorw("problem casting find providers record", "Schema", v.Val.GetSchema(), "Type", reflect.TypeOf(v).String())
+				// drop failed type assertion
+				return iter.Result[types.Record]{}
+			}
+			peerRecord := types.FromBitswapRecord(record)
+			peerRecord = applyFilters(peerRecord, filterAddrs, filterProtocols)
+			if peerRecord == nil {
+				return iter.Result[types.Record]{}
+			}
+			v.Val = peerRecord
+		}
+		return v
+	})
+
+	// filter out nil results and errors
+	filteredIter := iter.Filter(mappedIter, func(v iter.Result[types.Record]) bool {
+		return v.Err == nil && v.Val != nil
+	})
+
+	return filteredIter
+}
+
+// Applies the filters. Returns nil if the provider does not pass the protocols filter
+// The address filter is more complicated because it potentially modifies the Addrs slice.
+func applyFilters(provider *types.PeerRecord, filterAddrs, filterProtocols []string) *types.PeerRecord {
+	if len(filterAddrs) == 0 && len(filterProtocols) == 0 {
+		return provider
+	}
+
+	if !protocolsAllowed(provider.Protocols, filterProtocols) {
+		// If the provider doesn't match any of the passed protocols, the provider is omitted from the response.
+		return nil
+	}
+
+	// return untouched if there's no filter or filterAddrsQuery contains "unknown" and provider has no addrs
+	if len(filterAddrs) == 0 || (len(provider.Addrs) == 0 && slices.Contains(filterAddrs, "unknown")) {
+		return provider
+	}
+
+	filteredAddrs := applyAddrFilter(provider.Addrs, filterAddrs)
+
+	// If filtering resulted in no addrs, omit the provider
+	if len(filteredAddrs) == 0 {
+		return nil
+	}
+
+	provider.Addrs = filteredAddrs
+	return provider
+}
+
+// applyAddrFilter filters a list of multiaddresses based on the provided filter query.
+//
+// Parameters:
+// - addrs: A slice of types.Multiaddr to be filtered.
+// - filterAddrsQuery: A slice of strings representing the filter criteria.
+//
+// The function supports both positive and negative filters:
+// - Positive filters (e.g., "tcp", "udp") include addresses that match the specified protocols.
+// - Negative filters (e.g., "!tcp", "!udp") exclude addresses that match the specified protocols.
+//
+// If no filters are provided, the original list of addresses is returned unchanged.
+// If only negative filters are provided, addresses not matching any negative filter are included.
+// If positive filters are provided, only addresses matching at least one positive filter (and no negative filters) are included.
+// If both positive and negative filters are provided, the address must match at least one positive filter and no negative filters to be included.
+//
+// Returns:
+// A new slice of types.Multiaddr containing only the addresses that pass the filter criteria.
+func applyAddrFilter(addrs []types.Multiaddr, filterAddrsQuery []string) []types.Multiaddr {
+	if len(filterAddrsQuery) == 0 {
+		return addrs
+	}
+
+	var filteredAddrs []types.Multiaddr
+	var positiveFilters, negativeFilters []multiaddr.Protocol
+
+	// Separate positive and negative filters
+	for _, filter := range filterAddrsQuery {
+		if strings.HasPrefix(filter, "!") {
+			negativeFilters = append(negativeFilters, multiaddr.ProtocolWithName(filter[1:]))
+		} else {
+			positiveFilters = append(positiveFilters, multiaddr.ProtocolWithName(filter))
+		}
+	}
+
+	for _, addr := range addrs {
+		protocols := addr.Protocols()
+
+		// Check negative filters
+		if containsAny(protocols, negativeFilters) {
+			continue
+		}
+
+		// If no positive filters or matches a positive filter, include the address
+		if len(positiveFilters) == 0 || containsAny(protocols, positiveFilters) {
+			filteredAddrs = append(filteredAddrs, addr)
+		}
+	}
+
+	return filteredAddrs
+}
+
+// Helper function to check if protocols contain any of the filters
+func containsAny(protocols []multiaddr.Protocol, filters []multiaddr.Protocol) bool {
+	for _, filter := range filters {
+		if containsProtocol(protocols, filter) {
+			return true
+		}
+	}
+	return false
+}
+
+func containsProtocol(protos []multiaddr.Protocol, proto multiaddr.Protocol) bool {
+	for _, p := range protos {
+		if p.Code == proto.Code {
+			return true
+		}
+	}
+	return false
+}
+
+// protocolsAllowed returns true if the peerProtocols are allowed by the filter protocols.
+func protocolsAllowed(peerProtocols []string, filterProtocols []string) bool {
+	if len(filterProtocols) == 0 {
+		// If no filter is passed, do not filter
+		return true
+	}
+
+	for _, filterProtocol := range filterProtocols {
+		if filterProtocol == "unknown" && len(peerProtocols) == 0 {
+			return true
+		}
+
+		for _, peerProtocol := range peerProtocols {
+			if strings.EqualFold(peerProtocol, filterProtocol) {
+				return true
+			}
+
+		}
+	}
+	return false
+}