#!/usr/bin/env python3
"""
hunt_actions.py -- static hunt for undecoded vr_action ids in shipped FLYK.EXE.

Method: parse the LE fixup tables to find code sites that reference a given
data-segment string (raw LE pages hold placeholders at fixup sites, so naive
scanning cannot work), then disassemble the surrounding function with capstone
and report the immediate constants loaded near velocirender_transmit calls --
the action id is among them.

    python hunt_actions.py "get_geom_vertices" [path-to-exe]
"""
import os, sys, struct
sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)))
from leimage import LE, rd

EXE = sys.argv[2] if len(sys.argv) > 2 else \
    r"s:\OneDrive\Tesla III\DaveMcCoy\sda4\HPDAVE\FLYK.EXE"


def parse_fixups(le):
    """Yield (src_linear, target_obj, target_off) for 32-bit offset fixups."""
    with open(le.path, 'rb') as f:
        # page fixup offset table: n_pages+1 dwords
        pgtab = rd(f, le.fixup_pg_off, 4 * (le.n_pages + 1))
        offs = struct.unpack('<%dI' % (le.n_pages + 1), pgtab)
        recs_base = le.fixup_rec_off
        # page -> linear address mapping: need object bases + page ranges
        objs = rd(f, le.obj_tab_off, 24 * le.n_objects)
        page_lin = {}
        for i in range(le.n_objects):
            vsize, base, flags, pgidx, pgcnt, _ = struct.unpack_from('<6I', objs, i * 24)
            for k in range(pgcnt):
                page_lin[pgidx + k] = base + k * le.page_size
        out = []
        for pg in range(1, le.n_pages + 1):
            lo, hi = offs[pg - 1], offs[pg]
            if hi <= lo:
                continue
            blob = rd(f, recs_base + lo, hi - lo)
            p = 0
            while p < len(blob) - 3:
                src = blob[p]; flags = blob[p + 1]; p += 2
                srcoffs = []
                if src & 0x20:                     # source list
                    cnt = blob[p]; p += 1
                else:
                    srcoffs.append(struct.unpack_from('<h', blob, p)[0]); p += 2
                    cnt = 0
                tobj_big = flags & 0x40
                if tobj_big:
                    tobj = struct.unpack_from('<H', blob, p)[0]; p += 2
                else:
                    tobj = blob[p]; p += 1
                stype = src & 0x0F
                toff = 0
                if stype != 0x02:                  # not 16-bit selector fixup
                    if flags & 0x10:
                        toff = struct.unpack_from('<I', blob, p)[0]; p += 4
                    else:
                        toff = struct.unpack_from('<H', blob, p)[0]; p += 2
                if src & 0x20:
                    for _ in range(cnt):
                        so = struct.unpack_from('<h', blob, p)[0]; p += 2
                        srcoffs.append(so)
                if stype == 0x07:                  # 32-bit offset fixup
                    for so in srcoffs:
                        if pg in page_lin and 0 <= so < le.page_size:
                            out.append((page_lin[pg] + so, tobj, toff))
        return out


def main():
    pat = sys.argv[1].encode('latin1') if len(sys.argv) > 1 else b"get_geom_vertices"
    le = LE(EXE)
    base1, code = le.image(1)
    base2, data = le.image(2)
    print(f"code obj1 @ {base1:#x} ({len(code)} bytes), data obj2 @ {base2:#x}")

    # all occurrences of the pattern in the data object
    targets = []
    i = 0
    while True:
        i = data.find(pat, i)
        if i < 0:
            break
        s = max(0, i - 60)
        start = data.rfind(b'\x00', s, i) + 1
        targets.append((start, data[start:data.find(b'\x00', i)]))
        i += 1
    if not targets:
        print("string not found"); return
    for off, s in targets:
        print(f"data+{off:#x} (lin {base2+off:#x}): {s[:70]!r}")

    fixups = parse_fixups(le)
    print(f"{len(fixups)} 32-bit fixups parsed")

    import capstone
    md = capstone.Cs(capstone.CS_ARCH_X86, capstone.CS_MODE_32)
    md.detail = False

    for off, s in targets:
        want = {base2 + off}
        sites = [src for src, tobj, toff in fixups
                 if tobj == 2 and (base2 + toff) in want]
        print(f"\n=== refs to {s[:50]!r}: {len(sites)} site(s)")
        for src in sites:
            # disassemble a window before the reference site
            lo = max(base1, src - 0x90)
            blob = code[lo - base1: src - base1 + 0x60]
            print(f"-- code around {src:#x}:")
            for ins in md.disasm(blob, lo):
                mark = '  <== strref' if ins.address <= src < ins.address + ins.size else ''
                if ins.mnemonic in ('mov', 'push', 'call', 'cmp') or mark:
                    txt = f"   {ins.address:#x}: {ins.mnemonic} {ins.op_str}{mark}"
                    if ins.mnemonic in ('mov', 'push') and ',' in ins.op_str:
                        try:
                            imm = int(ins.op_str.split(',')[1].strip(), 0)
                            if 0 < imm < 0x60:
                                txt += f"    ** small imm {imm:#x}"
                        except ValueError:
                            pass
                    print(txt)


if __name__ == '__main__':
    main()