feat:user defined struct casting

tests/failing_tests/xdp/xdp_test_1.py

@@ -0,0 +1,46 @@
+from vmlinux import XDP_PASS, XDP_DROP
+from vmlinux import (
+    struct_xdp_md,
+    struct_ethhdr,
+)
+from pythonbpf import bpf, section, bpfglobal, compile, compile_to_ir, struct
+from ctypes import c_int64, c_ubyte, c_ushort, c_uint32
+
+@bpf
+@struct
+class iphdr:
+    useless: c_ushort
+    tot_len: c_ushort
+    id: c_ushort
+    frag_off: c_ushort
+    ttl: c_ubyte
+    protocol: c_ubyte
+    check: c_ushort
+    saddr: c_uint32
+    daddr: c_uint32
+
+@bpf
+@section("xdp")
+def ip_detector(ctx: struct_xdp_md) -> c_int64:
+    data = ctx.data
+    data_end = ctx.data_end
+    eth = struct_ethhdr(ctx.data)
+    nh = ctx.data + 14
+    if nh + 20 > data_end:
+        return c_int64(XDP_DROP)
+    iph = iphdr(nh)
+    h_proto = eth.h_proto
+    h_proto_ext = c_int64(h_proto)
+    ipv4 = iph.saddr
+    print(f"ipaddress: {ipv4}")
+    return c_int64(XDP_PASS)
+
+
+@bpf
+@bpfglobal
+def LICENSE() -> str:
+    return "GPL"
+
+
+compile_to_ir("xdp_test_1.py", "xdp_test_1.ll")
+compile()