Implement Dchain Support

adapters/pubmatic/pubmatic.go

@@ -450,6 +450,12 @@ func (a *PubmaticAdapter) MakeBids(internalRequest *openrtb2.BidRequest, externa
 				BidVideo: &openrtb_ext.ExtBidPrebidVideo{},
 			}
 
+			if dchain, _, _, err := jsonparser.Get(bid.Ext, "dchain"); err == nil && len(dchain) > 0 {
+				typedBid.BidMeta = &openrtb_ext.ExtBidPrebidMeta{
+					DChain: dchain,
+				}
+			}
+
 			var bidExt *pubmaticBidExt
 			err := json.Unmarshal(bid.Ext, &bidExt)
 			if err != nil {

dchain/dchain.go

@@ -0,0 +1,59 @@
+package dchain
+
+import (
+	"encoding/json"
+	"strconv"
+
+	"github.com/prebid/prebid-server/v2/openrtb_ext"
+)
+
+type Dchain struct {
+	Ver      string          `json:"ver,omitempty"`
+	Complete int             `json:"complete,omitempty"`
+	Nodes    []DchainNodes   `json:"nodes,omitempty"`
+	Ext      json.RawMessage `json:"ext,omitempty"`
+}
+
+type DchainNodes struct {
+	Asi    string          `json:"asi,omitempty"`
+	Bsid   string          `json:"bsid,omitempty"`
+	Rid    string          `json:"rid,omitempty"`
+	Name   string          `json:"name,omitempty"`
+	Domain string          `json:"domain,omitempty"`
+	Ext    json.RawMessage `json:"ext,omitempty"`
+}
+
+func IsValidDchain(dchain Dchain) bool {
+	if dchain.Complete != 0 && dchain.Complete != 1 {
+		return false
+	}
+	if dchain.Nodes == nil || len(dchain.Nodes) == 0 {
+		return false
+	}
+	return true
+}
+
+func AddDchainNode(prebidMeta *openrtb_ext.ExtBidPrebidMeta) {
+	var dchain Dchain
+	if err := json.Unmarshal(prebidMeta.DChain, &dchain); err == nil && IsValidDchain(dchain) {
+		dchain.Nodes = append(dchain.Nodes,
+			DchainNodes{Asi: prebidMeta.AdapterCode},
+		)
+		prebidMeta.DChain, _ = json.Marshal(dchain)
+		return
+	}
+	basicDchain := Dchain{
+		Ver:      "1.0",
+		Complete: 0,
+		Nodes:    []DchainNodes{},
+	}
+
+	if prebidMeta.NetworkID != 0 && prebidMeta.NetworkName != "" {
+		basicDchain.Nodes = append(basicDchain.Nodes,
+			DchainNodes{Name: prebidMeta.NetworkName, Bsid: strconv.Itoa(prebidMeta.NetworkID)},
+		)
+	}
+
+	basicDchain.Nodes = append(basicDchain.Nodes, DchainNodes{Name: prebidMeta.AdapterCode})
+	prebidMeta.DChain, _ = json.Marshal(basicDchain)
+}

exchange/exchange.go

@@ -14,6 +14,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/prebid/prebid-server/v2/dchain"
 	"github.com/prebid/prebid-server/v2/privacy"
 
 	"github.com/prebid/prebid-server/v2/adapters"
@@ -1347,6 +1348,10 @@ func makeBidExtJSON(ext json.RawMessage, prebid *openrtb_ext.ExtBidPrebid, impEx
 
 	prebid.Meta.AdapterCode = adapter.String()
 
+	if prebid.Meta.DChain != nil {
+		dchain.AddDchainNode(prebid.Meta)
+	}
+
 	// ext.prebid.storedrequestattributes and ext.prebid.passthrough
 	if impExtInfo, ok := impExtInfoMap[impId]; ok {
 		prebid.Passthrough = impExtInfoMap[impId].Passthrough