rpcserver: avoid nested decodescript p2sh addrs

dcrjson/chainsvrresults.go

@@ -79,7 +79,7 @@ type DecodeScriptResult struct {
 	ReqSigs   int32    `json:"reqSigs,omitempty"`
 	Type      string   `json:"type"`
 	Addresses []string `json:"addresses,omitempty"`
-	P2sh      string   `json:"p2sh"`
+	P2sh      string   `json:"p2sh,omitempty"`
 }
 
 // GetAddedNodeInfoResultAddr models the data of the addresses portion of the

rpcserver.go

@@ -1465,7 +1465,9 @@ func handleDecodeScript(s *rpcServer, cmd interface{}, closeChan <-chan struct{}
 		ReqSigs:   int32(reqSigs),
 		Type:      scriptClass.String(),
 		Addresses: addresses,
-		P2sh:      p2sh.EncodeAddress(),
+	}
+	if scriptClass != txscript.ScriptHashTy {
+		reply.P2sh = p2sh.EncodeAddress()
 	}
 	return reply, nil
 }

rpcserverhelp.go

@@ -157,7 +157,7 @@ var helpDescsEnUS = map[string]string{
 	"decodescriptresult-reqSigs":   "The number of required signatures",
 	"decodescriptresult-type":      "The type of the script (e.g. 'pubkeyhash')",
 	"decodescriptresult-addresses": "The decred addresses associated with this script",
-	"decodescriptresult-p2sh":      "The script hash for use in pay-to-script-hash transactions",
+	"decodescriptresult-p2sh":      "The script hash for use in pay-to-script-hash transactions (only present if the provided redeem script is not already a pay-to-script-hash script)",
 
 	// DecodeScriptCmd help.
 	"decodescript--synopsis": "Returns a JSON object with information about the provided hex-encoded script.",