updates for dynamicOpcode (#215)

Author: shiqizng

logic/logic.go

@@ -70,6 +70,7 @@ func ReadProgram(program []byte, args [][]byte) (ints []uint64, byteArrays [][]b
 	for _, arg := range args {
 		length += len(arg)
 	}
+
 	if length > types.LogicSigMaxSize {
 		err = fmt.Errorf("program too long")
 		return
@@ -129,8 +130,9 @@ func ReadProgram(program []byte, args [][]byte) (ints []uint64, byteArrays [][]b
 		pc = pc + size
 	}
 
-	if cost > types.LogicSigMaxCost {
-		err = fmt.Errorf("program too costly to run")
+	// costs calculated dynamically starting in v4
+	if version < 4 && cost > types.LogicSigMaxCost {
+		err = fmt.Errorf("program too costly for Teal version < 4. consider using v4.")
 	}
 
 	return

logic/logic_test.go

@@ -50,10 +50,22 @@ func TestCheckProgram(t *testing.T) {
 	err = CheckProgram(program, args)
 	require.NoError(t, err)
 
-	// check 800x keccak256 fail
+	// check 800x keccak256 fail for v3 and below
+	versions := []byte{0x1, 0x2, 0x3}
 	program = append(program, []byte(strings.Repeat("\x02", 800))...) // append 800x keccak256
-	err = CheckProgram(program, args)
-	require.EqualError(t, err, "program too costly to run")
+	for _, v := range versions {
+		program[0] = v
+		err = CheckProgram(program, args)
+		require.EqualError(t, err, "program too costly for Teal version < 4. consider using v4.")
+	}
+
+	// check 800x keccak256 ok for v4 and above
+	versions = []byte{0x4}
+	for _, v := range versions {
+		program[0] = v
+		err = CheckProgram(program, args)
+		require.NoError(t, err)
+	}
 }
 
 func TestCheckProgramV2(t *testing.T) {
@@ -137,4 +149,14 @@ func TestCheckProgramV4(t *testing.T) {
 	program = []byte{0x04, 0x26, 0x03, 0x01, 0x11, 0x01, 0x10, 0x01, 0x01, 0x28, 0x29, 0xad, 0x2a, 0x12} // byte 0x11; byte 0x10; b^; byte 0x01; ==
 	err = CheckProgram(program, args)
 	require.NoError(t, err)
+
+	// callsub, retsub.
+	program = []byte{0x04, 0x20, 0x02, 0x01, 0x02, 0x22, 0x88, 0x00, 0x03, 0x23, 0x12, 0x43, 0x49, 0x08, 0x89} // int 1; callsub double; int 2; ==; return; double: dup; +; retsub;
+	err = CheckProgram(program, args)
+	require.NoError(t, err)
+
+	// loop
+	program = []byte{0x04, 0x20, 0x04, 0x01, 0x02, 0x0a, 0x10, 0x22, 0x23, 0x0b, 0x49, 0x24, 0x0c, 0x40, 0xff, 0xf8, 0x25, 0x12} // int 1; loop: int 2; *; dup; int 10; <; bnz loop; int 16; ==
+	err = CheckProgram(program, args)
+	require.NoError(t, err)
 }