Replace patchelf crack with Freeloader LD_PRELOAD approach
- Multi-stage Dockerfile: discover patterns from PMS binary (capstone), compile .so with zig (musl), layer onto lscr.io/linuxserver/plex - Uses LD_PRELOAD instead of patchelf (which corrupts Plex's musl loader) - Auto-discovery: broad structural patterns with string-anchored fallback (//feature) and relationship-based fallback (BITSET_REF within BS_INIT) - hook.cpp uses __has_include for generated patterns with hardcoded fallbacks - Custom wrapper.sh (no traffic_logger preload) - Vendored Freeloader source (github.com/authrequest/Freeloader, AGPL-3.0) - Removed stale plexmediaserver_crack.so binary - Supports Plex 1.43.3+ (verified against 1.43.2 and 1.43.3)
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@@ -0,0 +1,507 @@
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#!/usr/bin/env python3
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"""
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Auto-discover hook signatures from the Plex Media Server binary.
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For each hook target, the script tries these strategies in order:
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1. Broad structural pattern (opcodes with displacements/immediates wildcarded)
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2. String-anchored discovery: find a key string, find the LEA referencing it,
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backtrack to the function prologue, auto-generate a pattern by disassembling
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the prologue and wildcarding all displacement/immediate operands via capstone.
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3. Relationship-based: search within another discovered function's body.
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If all strategies fail, the build fails with diagnostics.
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Usage:
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python3 discover_patterns.py <PMS binary> -o patterns_generated.h
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"""
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import sys
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import os
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import struct
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import argparse
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try:
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from capstone import Cs, CS_ARCH_X86, CS_MODE_64
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except ImportError:
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print("ERROR: capstone not installed. Run: pip install capstone", file=sys.stderr)
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sys.exit(2)
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# Capstone operand type constants
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CS_OP_REG = 1
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CS_OP_IMM = 2
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CS_OP_MEM = 3
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# Capstone x86 register IDs
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X86_REG_RIP = 41
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# ── ELF parsing ────────────────────────────────────────────────────────────
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def parse_elf_segments(data):
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if data[:4] != b'\x7fELF':
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raise ValueError("Not an ELF file")
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e_phoff = struct.unpack('<Q', data[32:40])[0]
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e_phentsize = struct.unpack('<H', data[54:56])[0]
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e_phnum = struct.unpack('<H', data[56:58])[0]
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segs = []
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for i in range(e_phnum):
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off = e_phoff + i * e_phentsize
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if struct.unpack('<I', data[off:off+4])[0] != 1:
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continue
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segs.append((
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struct.unpack('<Q', data[off+8:off+16])[0], # p_offset
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struct.unpack('<Q', data[off+16:off+24])[0], # p_vaddr
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struct.unpack('<Q', data[off+32:off+40])[0], # p_filesz
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))
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return segs
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def file_to_vaddr(segments, file_off):
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for p_offset, p_vaddr, p_filesz in segments:
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if p_offset <= file_off < p_offset + p_filesz:
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return file_off - p_offset + p_vaddr
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return file_off
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def vaddr_to_file(segments, vaddr):
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for p_offset, p_vaddr, p_filesz in segments:
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if p_vaddr <= vaddr < p_vaddr + p_filesz:
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return vaddr - p_vaddr + p_offset
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return vaddr
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# ── Byte pattern matching ──────────────────────────────────────────────────
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def parse_pattern(p):
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out = []
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for tok in p.split():
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if tok in ('??', '?'):
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out.append(None)
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else:
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out.append(int(tok, 16))
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return out
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def find_matches(data, pattern):
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matches = []
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plen = len(pattern)
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for i in range(len(data) - plen + 1):
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if all(pb is None or data[i+j] == pb for j, pb in enumerate(pattern)):
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matches.append(i)
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return matches
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def pattern_to_str(pat):
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return ' '.join(f'{b:02X}' if b is not None else '?' for b in pat)
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# ── Instruction analysis (capstone) ────────────────────────────────────────
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LEGACY_PREFIXES = {0x26, 0x2e, 0x36, 0x3e, 0x64, 0x65, 0x66, 0x67, 0xf0, 0xf2, 0xf3}
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def find_modrm_pos(raw, size):
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"""Find the ModRM byte position in an x86-64 instruction's raw bytes."""
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pos = 0
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while pos < size and raw[pos] in LEGACY_PREFIXES:
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pos += 1
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if pos < size and 0x40 <= raw[pos] <= 0x4f:
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pos += 1 # REX
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if pos < size and raw[pos] == 0xc5:
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pos += 2 # VEX 2-byte
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elif pos < size and raw[pos] == 0xc4:
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pos += 3 # VEX 3-byte
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if pos < size:
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if raw[pos] == 0x0f:
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pos += 1
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if pos < size and raw[pos] in (0x38, 0x3a):
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pos += 1
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pos += 1 # opcode byte
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return pos if pos < size else -1
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def wildcard_instruction(insn):
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"""Return a list of (byte|None) for an instruction, wildcarding all
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displacement and immediate operands. None means wildcard."""
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raw = list(insn.bytes)
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size = insn.size
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wildcard = [False] * size
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has_rip_mem = False
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has_nonrip_mem_disp = False
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mem_disp = 0
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has_imm = False
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for op in insn.operands:
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if op.type == CS_OP_IMM:
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has_imm = True
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elif op.type == CS_OP_MEM:
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if op.mem.base == X86_REG_RIP:
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has_rip_mem = True
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elif op.mem.disp != 0 and op.mem.base != 0:
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has_nonrip_mem_disp = True
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mem_disp = op.mem.disp
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# Determine immediate total size and how many LOW bytes to wildcard.
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# imm_total: full immediate width. imm_wc: how many low bytes to
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# wildcard (high bytes kept for specificity, e.g. 0x00 for small frames).
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imm_total = 0
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imm_wc = 0
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if has_imm:
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mnem = insn.mnemonic
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if mnem in ('call', 'jmp') or mnem.startswith('j'):
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imm_total = 4 if size >= 5 else 1
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imm_wc = imm_total
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elif mnem in ('sub', 'add', 'cmp'):
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if size == 4:
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imm_total = 1; imm_wc = 1
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else:
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imm_total = 4; imm_wc = 2 # wildcard low 2, keep high 2 zeros
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elif mnem == 'mov':
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if size >= 10:
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imm_total = 8; imm_wc = 8
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elif size >= 7:
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imm_total = 4; imm_wc = 4
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else:
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imm_total = 1; imm_wc = 1
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elif mnem == 'push':
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imm_total = 1 if size == 2 else 4; imm_wc = imm_total
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elif mnem == 'test':
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imm_total = 1 if size <= 4 else 4; imm_wc = imm_total
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else:
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imm_total = min(4, size - 1); imm_wc = imm_total
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# Determine displacement size
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disp_size = 0
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if has_rip_mem:
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disp_size = 4
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elif has_nonrip_mem_disp:
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modrm_pos = find_modrm_pos(raw, size)
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if modrm_pos >= 0:
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mod_field = (raw[modrm_pos] >> 6) & 3
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if mod_field == 1:
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disp_size = 1
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elif mod_field == 2:
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disp_size = 4
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if disp_size == 0:
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disp_size = 1 if -128 <= mem_disp <= 127 else 4
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# Wildcard displacement bytes (immediately before the immediate field)
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if disp_size > 0:
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disp_start = size - imm_total - disp_size
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for i in range(max(0, disp_start), min(size, disp_start + disp_size)):
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wildcard[i] = True
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# Wildcard the LOW imm_wc bytes of the immediate (keep high bytes)
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if imm_total > 0:
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imm_start = size - imm_total
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for i in range(max(0, imm_start), min(size, imm_start + imm_wc)):
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wildcard[i] = True
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return [(raw[i] if not wildcard[i] else None) for i in range(size)]
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def auto_wildcard_pattern(data, segments, func_file_off, length):
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"""Disassemble a function and generate a byte pattern with all
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displacement/immediate operands auto-wildcarded."""
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md = Cs(CS_ARCH_X86, CS_MODE_64)
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md.detail = True
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vaddr = file_to_vaddr(segments, func_file_off)
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code = data[func_file_off:func_file_off + length + 32]
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pattern = []
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bytes_consumed = 0
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for insn in md.disasm(code, vaddr):
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if bytes_consumed >= length:
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break
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wc_bytes = wildcard_instruction(insn)
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for b in wc_bytes:
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if bytes_consumed >= length:
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break
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pattern.append(b)
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bytes_consumed += 1
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while len(pattern) < length:
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pattern.append(None)
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return pattern[:length]
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# ── Function discovery ─────────────────────────────────────────────────────
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def find_string_in_binary(data, search_string):
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"""Find all occurrences of a null-terminated string in the binary."""
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needle = search_string.encode() + b'\x00'
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results = []
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start = 0
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while True:
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idx = data.find(needle, start)
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if idx == -1:
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break
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results.append(idx)
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start = idx + 1
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return results
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def find_lea_refs_to_string(data, segments, string_file_off):
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"""Find all LEA reg,[rip+disp32] instructions that reference a string."""
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results = []
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for p_offset, p_vaddr, p_filesz in segments:
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end = min(p_offset + p_filesz, len(data) - 7)
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for i in range(p_offset, end):
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if data[i] in (0x48, 0x4c) and data[i+1] == 0x8D:
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modrm = data[i+2]
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if (modrm & 0xC7) == 0x05:
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disp = struct.unpack('<i', data[i+3:i+7])[0]
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insn_vaddr = file_to_vaddr(segments, i)
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target_vaddr = insn_vaddr + 7 + disp
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target_file = vaddr_to_file(segments, target_vaddr)
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if target_file == string_file_off:
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reg = (modrm >> 3) & 7
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if data[i] == 0x4c:
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reg += 8
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results.append((i, reg))
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return results
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def find_func_start_backwards(data, file_off, max_scan=16384):
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"""Scan backwards for a function prologue (55 48 89 E5)."""
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for j in range(file_off, max(0, file_off - max_scan), -1):
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if data[j:j+4] == b'\x55\x48\x89\xe5':
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return j
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return None
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def find_func_end(data, segments, func_file_off, max_insns=5000):
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"""Find the end of a function by scanning for ret/int3 after the prologue."""
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md = Cs(CS_ARCH_X86, CS_MODE_64)
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vaddr = file_to_vaddr(segments, func_file_off)
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code = data[func_file_off:func_file_off + 16384]
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count = 0
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for insn in md.disasm(code, vaddr):
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count += 1
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if count > max_insns:
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break
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if insn.mnemonic in ('ret', 'repret', 'ud2'):
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return func_file_off + insn.address - vaddr + insn.size
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return func_file_off + 8192
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def string_anchored_discovery(data, segments, search_string, pattern_length,
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expected_func_start_prefix=None):
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"""Discover a function by finding a string reference, then backtracking
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to the function prologue. Auto-generates a pattern with wildcarded
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displacement/immediate operands."""
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string_locations = find_string_in_binary(data, search_string)
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if not string_locations:
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return None, f"string '{search_string}' not found in binary"
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for string_off in string_locations:
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lea_refs = find_lea_refs_to_string(data, segments, string_off)
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for lea_off, reg in lea_refs:
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func_start = find_func_start_backwards(data, lea_off)
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if not func_start:
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continue
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if expected_func_start_prefix:
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prefix = data[func_start:func_start + len(expected_func_start_prefix)]
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if prefix != expected_func_start_prefix:
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continue
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pattern = auto_wildcard_pattern(data, segments, func_start, pattern_length)
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matches = find_matches(data, pattern)
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if matches:
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return pattern, f"found via string '{search_string}' -> LEA at 0x{lea_off:08x} -> func at 0x{func_start:08x} ({len(matches)} match(es))"
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return None, f"string '{search_string}' found but no enclosing function prologue"
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def relationship_based_discovery(data, segments, ref_func_off, search_pattern_str,
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search_range=8192):
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"""Search within a function's body for a structural pattern."""
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pat = parse_pattern(search_pattern_str)
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end = min(len(data), ref_func_off + search_range)
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matches = []
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for i in range(ref_func_off, end - len(pat) + 1):
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if all(pb is None or data[i+j] == pb for j, pb in enumerate(pat)):
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matches.append(i)
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if matches:
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return pat, f"found {len(matches)} match(es) within function body"
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return None, "pattern not found within function body"
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# ── Hook target definitions ────────────────────────────────────────────────
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TARGETS = [
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{
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"name": "PREF_GETTER",
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"broad_pattern": "55 48 89 E5 41 57 41 56 53 48 83 EC ? 48 89 F3 49 89 FE 0F B6 46 17 48 89 F1 84 C0",
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"string_anchor": None,
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"relates_to": None,
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"expected_matches": (1, 3),
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"required": True,
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"length": 26,
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},
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{
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"name": "BITSET_REF",
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"broad_pattern": "48 8D 0D ? ? ? ? 48 8B 94 05 ? ? ? ? 48 87 14 08",
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"string_anchor": None,
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"relates_to": ("BS_INIT", "48 8D 0D ? ? ? ? 48 8B 94 05 ? ? ? ? 48 87 14 08"),
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"expected_matches": (1, 4),
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"required": True,
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"length": 18,
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},
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{
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"name": "BS_INIT",
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"broad_pattern": "55 48 89 E5 41 57 41 56 41 55 41 54 53 48 81 EC ? ? 00 00 49 89 FE 48 8D 9D ? ? ? ? 48 89 DF E8 ? ? ? ? 48 8B 1B 48 85 DB",
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"string_anchor": "//feature",
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"string_prefix": b'\x55\x48\x89\xe5\x41\x57\x41\x56\x41\x55\x41\x54\x53',
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"relates_to": None,
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"expected_matches": (1, 1),
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"required": True,
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"length": 44,
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},
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{
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"name": "LEGACY_USF",
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"broad_pattern": "55 48 89 E5 48 8B 07 48 85 C0 74 09",
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"string_anchor": None,
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"relates_to": None,
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"expected_matches": (1, 5),
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"required": False,
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"length": 12,
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},
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{
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"name": "LEGACY_MF",
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"broad_pattern": "55 48 89 E5 41 57 41 56 53 48 83 EC ? 49 89 F7 4C 8D 77",
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"string_anchor": None,
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"relates_to": None,
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"expected_matches": (1, 3),
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"required": False,
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"length": 18,
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},
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]
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def generate_header(patterns, output_path):
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with open(output_path, 'w') as f:
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f.write("#pragma once\n")
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f.write("// Auto-generated by discover_patterns.py — DO NOT EDIT.\n")
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f.write("// Hook signatures discovered from the PMS binary at build time.\n\n")
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for name, pattern_str, match_count, method in patterns:
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f.write(f'// {name}: {match_count} match(es) — {method}\n')
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f.write(f'static const char* PATTERN_{name} = "{pattern_str}";\n\n')
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def main():
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parser = argparse.ArgumentParser()
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parser.add_argument('pms_path')
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parser.add_argument('-o', '--output', default='patterns_generated.h')
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args = parser.parse_args()
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with open(args.pms_path, 'rb') as f:
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data = f.read()
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segments = parse_elf_segments(data)
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print(f"Loaded {args.pms_path} ({len(data)} bytes, {len(segments)} LOAD segments)")
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results = []
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discovered_func_offsets = {}
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all_ok = True
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# Pass 1: discover targets via broad pattern or string-anchored (independent)
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# Pass 2: discover relationship-dependent targets using results from pass 1
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pending = []
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for target in TARGETS:
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name = target['name']
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broad = parse_pattern(target['broad_pattern'])
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lo, hi = target['expected_matches']
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# Strategy 1: broad structural pattern
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matches = find_matches(data, broad)
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if lo <= len(matches) <= hi:
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print(f" [OK] {name}: broad pattern ({len(matches)} matches)")
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for m in matches[:3]:
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print(f" 0x{m:08x}: {data[m:m+min(len(broad)+8,32)].hex(' ')}")
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results.append((name, pattern_to_str(broad), len(matches), f"broad pattern ({len(matches)} matches)"))
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discovered_func_offsets[name] = matches[0] if matches else None
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continue
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# Strategy 2: string-anchored discovery
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if target.get('string_anchor'):
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pattern, detail = string_anchored_discovery(
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||||
data, segments, target['string_anchor'],
|
||||
target['length'], target.get('string_prefix'))
|
||||
if pattern:
|
||||
matches = find_matches(data, pattern)
|
||||
if lo <= len(matches) <= hi:
|
||||
print(f" [OK] {name}: string-anchored ({len(matches)} matches)")
|
||||
print(f" {detail}")
|
||||
for m in matches[:3]:
|
||||
print(f" 0x{m:08x}: {data[m:m+min(len(pattern)+8,32)].hex(' ')}")
|
||||
results.append((name, pattern_to_str(pattern), len(matches), f"string-anchored: {detail}"))
|
||||
discovered_func_offsets[name] = matches[0] if matches else None
|
||||
continue
|
||||
|
||||
# Defer relationship-based to pass 2
|
||||
if target.get('relates_to'):
|
||||
pending.append(target)
|
||||
elif target['required']:
|
||||
print(f" [FAIL] {name}: all strategies failed")
|
||||
print(f" Broad pattern: {pattern_to_str(broad)}")
|
||||
if target.get('string_anchor'):
|
||||
print(f" String anchor: '{target['string_anchor']}'")
|
||||
all_ok = False
|
||||
results.append((name, pattern_to_str(broad), 0, "FAILED"))
|
||||
else:
|
||||
print(f" [SKIP] {name}: not found (optional)")
|
||||
results.append((name, pattern_to_str(broad), 0, "skipped (optional)"))
|
||||
|
||||
# Pass 2: relationship-based discovery (depends on pass 1 results)
|
||||
for target in pending:
|
||||
name = target['name']
|
||||
broad = parse_pattern(target['broad_pattern'])
|
||||
lo, hi = target['expected_matches']
|
||||
ref_name, rel_pattern = target['relates_to']
|
||||
ref_off = discovered_func_offsets.get(ref_name)
|
||||
|
||||
if ref_off:
|
||||
# Search within the referenced function's body
|
||||
func_end = find_func_end(data, segments, ref_off)
|
||||
pattern, detail = relationship_based_discovery(
|
||||
data, segments, ref_off, rel_pattern, search_range=func_end - ref_off + 256)
|
||||
if pattern:
|
||||
matches = find_matches(data, pattern)
|
||||
if lo <= len(matches) <= hi:
|
||||
print(f" [OK] {name}: relationship ({ref_name}) ({len(matches)} matches)")
|
||||
print(f" {detail}")
|
||||
for m in matches[:3]:
|
||||
print(f" 0x{m:08x}: {data[m:m+min(len(pattern)+8,32)].hex(' ')}")
|
||||
results.append((name, pattern_to_str(pattern), len(matches), f"relationship ({ref_name}): {detail}"))
|
||||
discovered_func_offsets[name] = matches[0] if matches else None
|
||||
continue
|
||||
|
||||
# Relationship failed — try broad as last resort
|
||||
matches = find_matches(data, broad)
|
||||
if lo <= len(matches) <= hi:
|
||||
print(f" [OK] {name}: broad pattern ({len(matches)} matches) [fallback]")
|
||||
results.append((name, pattern_to_str(broad), len(matches), f"broad pattern fallback ({len(matches)} matches)"))
|
||||
discovered_func_offsets[name] = matches[0] if matches else None
|
||||
continue
|
||||
|
||||
if target['required']:
|
||||
print(f" [FAIL] {name}: all strategies failed (broad + string + relationship)")
|
||||
all_ok = False
|
||||
results.append((name, pattern_to_str(broad), 0, "FAILED"))
|
||||
else:
|
||||
print(f" [SKIP] {name}: not found (optional)")
|
||||
results.append((name, pattern_to_str(broad), 0, "skipped (optional)"))
|
||||
|
||||
if all_ok:
|
||||
generate_header(results, args.output)
|
||||
print(f"\nAll required patterns discovered. Header written to {args.output}")
|
||||
sys.exit(0)
|
||||
else:
|
||||
print("\nFAILED: one or more required patterns not found.", file=sys.stderr)
|
||||
sys.exit(1)
|
||||
|
||||
|
||||
if __name__ == '__main__':
|
||||
main()
|
||||
Reference in new issue
Block a user