whisper: fix issue with PoW calculation

vendor/github.com/ethereum/go-ethereum/whisper/whisperv5/api.go

@@ -406,6 +406,10 @@ func (args *PostArgs) UnmarshalJSON(data []byte) (err error) {
 		args.Topic = BytesToTopic(x)
 	}
 
+	if objJSON, err := json.Marshal(&obj); err == nil {
+		glog.V(logger.Info).Infoln("shh message posted: ", string(objJSON))
+	}
+
 	return nil
 }
 

vendor/github.com/ethereum/go-ethereum/whisper/whisperv5/doc.go

@@ -56,7 +56,7 @@ const (
 	AESNonceMaxLength = 12
 
 	MaxMessageLength = 0x0FFFFF // todo: remove this restriction after testing. this should be regulated by PoW.
-	MinimumPoW       = 10.0     // todo: review after testing.
+	MinimumPoW       = 0.001     // todo: review after testing.
 
 	padSizeLimitLower = 128 // it can not be less - we don't want to reveal the absence of signature
 	padSizeLimitUpper = 256 // just an arbitrary number, could be changed without losing compatibility

vendor/github.com/ethereum/go-ethereum/whisper/whisperv5/envelope.go

@@ -21,7 +21,6 @@ package whisperv5
 import (
 	"crypto/ecdsa"
 	"encoding/binary"
-	"errors"
 	"fmt"
 	"math"
 	"time"
@@ -116,7 +115,7 @@ func (e *Envelope) Seal(options *MessageParams) error {
 	}
 
 	if target > 0 && bestBit < target {
-		return errors.New("Failed to reach the PoW target, insufficient work time")
+		return fmt.Errorf("Failed to reach the PoW target, insufficient work time. Expected: %v, got: %v", target, bestBit)
 	}
 
 	return nil