Fix TX payload for DO testnets (#9540)

* Added print

* Fix unmarshall

* Fix unmarshalling

* Simplified steps to unmarshall

* minor

* Use 'encoding/hex'

* Forget about C, this is Go!

* gosec warning

* Set maximum payload size

* nosec annotation

test/loadtime/payload/payload.go

@@ -3,7 +3,7 @@ package payload
 import (
  "bytes"
  "crypto/rand"
- "errors"
+ "encoding/hex"
  "fmt"
  "math"
 
@@ -12,6 +12,7 @@ import (
 )
 
 const keyPrefix = "a="
+const maxPayloadSize = 4 * 1024 * 1024
 
 // NewBytes generates a new payload and returns the encoded representation of
 // the payload as a slice of bytes. NewBytes uses the fields on the Options
@@ -25,10 +26,16 @@ func NewBytes(p *Payload) ([]byte, error) {
  if err != nil {
  return nil, err
  }
- if p.Size < uint64(us) {
- return nil, fmt.Errorf("configured size %d not large enough to fit unpadded transaction of size %d", p.Size, us)
+ if p.Size > maxPayloadSize {
+ return nil, fmt.Errorf("configured size %d is too large (>%d)", p.Size, maxPayloadSize)
  }
- p.Padding = make([]byte, p.Size-uint64(us))
+ pSize := int(p.Size) // #nosec -- The "if" above makes this cast safe
+ if pSize < us {
+ return nil, fmt.Errorf("configured size %d not large enough to fit unpadded transaction of size %d", pSize, us)
+ }
+
+ // We halve the padding size because we transform the TX to hex
+ p.Padding = make([]byte, (pSize-us)/2)
  _, err = rand.Read(p.Padding)
  if err != nil {
  return nil, err
@@ -37,22 +44,28 @@ func NewBytes(p *Payload) ([]byte, error) {
  if err != nil {
  return nil, err
  }
+ h := []byte(hex.EncodeToString(b))
 
  // prepend a single key so that the kv store only ever stores a single
  // transaction instead of storing all tx and ballooning in size.
- return append([]byte(keyPrefix), b...), nil
+ return append([]byte(keyPrefix), h...), nil
 }
 
 // FromBytes extracts a paylod from the byte representation of the payload.
 // FromBytes leaves the padding untouched, returning it to the caller to handle
 // or discard per their preference.
 func FromBytes(b []byte) (*Payload, error) {
- p := &Payload{}
- tr := bytes.TrimPrefix(b, []byte(keyPrefix))
- if bytes.Equal(b, tr) {
- return nil, errors.New("payload bytes missing key prefix")
+ trH := bytes.TrimPrefix(b, []byte(keyPrefix))
+ if bytes.Equal(b, trH) {
+ return nil, fmt.Errorf("payload bytes missing key prefix '%s'", keyPrefix)
+ }
+ trB, err := hex.DecodeString(string(trH))
+ if err != nil {
+ return nil, err
  }
- err := proto.Unmarshal(tr, p)
+
+ p := &Payload{}
+ err = proto.Unmarshal(trB, p)
  if err != nil {
  return nil, err
  }
@@ -83,5 +96,6 @@ func CalculateUnpaddedSize(p *Payload) (int, error) {
  if err != nil {
  return 0, err
  }
- return len(b) + len(keyPrefix), nil
+ h := []byte(hex.EncodeToString(b))
+ return len(h) + len(keyPrefix), nil
 }