1 files changed, 99 insertions, 0 deletions
diff --git a/sploit/payload/payload_entry.py b/sploit/payload/payload_entry.py
new file mode 100644
index 0000000..7088f83
--- /dev/null
+++ b/sploit/payload/payload_entry.py
@@ -0,0 +1,99 @@
+from sploit.arch import arch, itob
+from sploit.types.index_entry import IndexEntry
+
+_PLACEHOLDER_MAGIC = b"\xef"
+
+class PayloadEntry(IndexEntry):
+    """Base class for dynamic Payload entries"""
+
+    def __repr__(self):
+        """Return human-readable entry description."""
+        return f"{self.__class__.__name__}{self.__dict__}"
+
+    def payload_insert(self, payload):
+        """
+        Called on insert into a payload object.
+
+        Override this method to perform any initialization which requires a
+        reference to the payload object.  self.base is set to the insertion
+        location.
+        """
+        pass
+
+    def payload_bytes(self, payload):
+        """
+        Called to generate bytes for this entry.
+
+        Override this method to generate and return the binary output for this
+        dynamic payload entry.  self.base is set to the current entry address
+        or offset.
+        """
+        return b""
+
+# Concrete payload entry definitions
+
+class pointer(PayloadEntry):
+    """Generate an integer which is always a fixed offset from self.base."""
+
+    def __init__(self, target=None):
+        self.target = target
+
+    def payload_insert(self, payload):
+        if self.target is None:
+            self.target = self.base
+        self.target -= self.base
+
+    def payload_bytes(self, payload):
+        return itob(self.target + self.base)
+
+class padlen(PayloadEntry):
+    """Generate padding to reach a target payload length."""
+
+    def __init__(self, size, data=None):
+        self.size = size
+        self.data = data
+
+    def _gen_padding(self, size):
+        data = self.data or arch.nopcode
+        if size < 0:
+            raise ValueError("padding: Available space is negative")
+        if (size := size / len(data)) != int(size):
+            raise ValueError("padding: Element does not divide the space evenly")
+        return data * int(size)
+
+    def payload_bytes(self, payload):
+        return self._gen_padding(self.size - (self.base - payload.base))
+
+class padabs(padlen):
+    """Generate padding to reach a target absolute address."""
+
+    def payload_bytes(self, payload):
+        return self._gen_padding(self.size - self.base)
+
+class padrel(padlen):
+    """Generate a fixed length of padding (aka: length relative to self)."""
+
+    def payload_bytes(self, payload):
+        return self._gen_padding(self.size)
+
+class padalign(padlen):
+    """Generate padding to reach next aligned address."""
+
+    def __init__(self, size=None, data=None):
+        self.size = size
+        self.data = data
+
+    def payload_bytes(self, payload):
+        size = self.size or arch.alignment
+        return self._gen_padding(-self.base % size)
+
+class placeholder(padlen):
+    """Generate fixed length of magic bytes, one word length by default."""
+
+    def __init__(self, size=None):
+        self.size = size
+        self.data = _PLACEHOLDER_MAGIC
+
+    def payload_bytes(self, payload):
+        size = self.size or arch.wordsize
+        return self._gen_padding(size)