248 lines
8.2 KiB
Python
248 lines
8.2 KiB
Python
#!/usr/bin/env python3
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"""
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NBD server v9 - PERC H710 chunk translation + merged GDT overlay only.
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No feature flag patching. No checksum zeroing. No journal disabling.
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Just serves the filesystem exactly as it was written, with a complete
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GDT built by merging primary (for non-metadata-chunk entries) and
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backup group 1 (for entries that fall in metadata chunks).
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Primary and backup GDT bad entries are completely disjoint (0 overlap),
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so this gives 100% GDT coverage with authentic data and valid checksums.
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Usage:
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# First build the merged GDT:
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# python3 build_merged_gdt.py (saves /tmp/merged_gdt.bin)
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python3 nbd_server_v9.py &
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nbd-client 127.0.0.1 10809 /dev/nbd0 -N ""
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ext4magic /dev/nbd0 -s 4096 -n 32768 -R -I 1585918 -a $(date -d "2023-01-01" +%s) -d /mnt/recovered
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"""
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import socket, struct, threading, sys, os
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DEV = '/dev/md0'
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MERGED_GDT = '/tmp/merged_gdt.bin'
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CHUNK_BYTES = 128 * 512
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LV_PHYS_START = 5120000 * 512
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VIRT_SIZE = 9365766144 * 512
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# GDT location in virtual address space
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BSIZE = 4096
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GDT_ENTRY_SZ = 64
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NUM_GROUPS = 35728
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GDT_VIRT_START = BSIZE # block 1 = byte 4096
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GDT_VIRT_END = BSIZE + NUM_GROUPS * GDT_ENTRY_SZ
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# NBD protocol
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NBDMAGIC = 0x4e42444d41474943
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IHAVEOPT = 0x49484156454F5054
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REPLYMAGIC = 0x3e889045565a9
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NBD_OPT_EXPORT_NAME = 1
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NBD_OPT_ABORT = 2
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NBD_OPT_LIST = 3
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NBD_OPT_GO = 7
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NBD_REP_ACK = 1
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NBD_REP_SERVER = 2
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NBD_REP_INFO = 3
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NBD_REP_ERR_UNSUP = (1 << 31) | 1
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NBD_INFO_EXPORT = 0
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NBD_FLAG_HAS_FLAGS = 1 << 0
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NBD_FLAG_READ_ONLY = 1 << 1
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NBD_FLAG_SEND_FLUSH = 1 << 2
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NBD_REQUEST_MAGIC = 0x25609513
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NBD_REPLY_MAGIC = 0x67446698
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NBD_CMD_READ = 0
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NBD_CMD_DISC = 2
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NBD_CMD_FLUSH = 3
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TX_FLAGS = NBD_FLAG_HAS_FLAGS | NBD_FLAG_READ_ONLY | NBD_FLAG_SEND_FLUSH
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# Load merged GDT at startup
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print(f'Loading merged GDT from {MERGED_GDT}...')
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if not os.path.exists(MERGED_GDT):
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print(f'ERROR: {MERGED_GDT} not found.')
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print('Run the GDT builder script first.')
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sys.exit(1)
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with open(MERGED_GDT, 'rb') as f:
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MERGED_GDT_DATA = f.read()
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expected = NUM_GROUPS * GDT_ENTRY_SZ
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if len(MERGED_GDT_DATA) != expected:
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print(f'ERROR: merged GDT is {len(MERGED_GDT_DATA)} bytes, '
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f'expected {expected}')
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sys.exit(1)
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print(f'Merged GDT loaded: {len(MERGED_GDT_DATA)//1024}KB '
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f'({NUM_GROUPS} groups)')
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def raw_read(virt_offset, length):
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"""Pure PERC chunk translation, no modifications."""
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result = bytearray(length)
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pos = virt_offset
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remaining = length
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with open(DEV, 'rb') as f:
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while remaining > 0:
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group = pos // (5 * CHUNK_BYTES)
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in_group = pos % (5 * CHUNK_BYTES)
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chunk_idx = in_group // CHUNK_BYTES
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intra = in_group % CHUNK_BYTES
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seg_len = min(CHUNK_BYTES - intra, remaining)
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dst_off = pos - virt_offset
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if chunk_idx != 4:
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phys = (LV_PHYS_START
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+ group * 4 * CHUNK_BYTES
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+ chunk_idx * CHUNK_BYTES
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+ intra)
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f.seek(phys)
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data = f.read(seg_len)
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result[dst_off:dst_off + len(data)] = data
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pos += seg_len
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remaining -= seg_len
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return result
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def read_virtual(virt_offset, length):
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"""
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Read with merged GDT overlay.
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Only the primary GDT region (bytes 4096 to 4096+NUM_GROUPS*64)
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is modified — replaced with the pre-built merged GDT.
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Everything else is pure chunk translation, unmodified.
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"""
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data = raw_read(virt_offset, length)
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req_end = virt_offset + length
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# Overlay merged GDT where request overlaps primary GDT region
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if virt_offset < GDT_VIRT_END and req_end > GDT_VIRT_START:
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ol_start = max(virt_offset, GDT_VIRT_START)
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ol_end = min(req_end, GDT_VIRT_END)
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src_off = ol_start - GDT_VIRT_START
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dst_off = ol_start - virt_offset
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n = ol_end - ol_start
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data[dst_off:dst_off + n] = MERGED_GDT_DATA[src_off:src_off + n]
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return bytes(data)
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def recv_all(conn, n):
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buf = b''
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while len(buf) < n:
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d = conn.recv(n - len(buf))
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if not d:
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raise ConnectionError('disconnected')
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buf += d
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return buf
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def send_reply(conn, opt, rtype, data=b''):
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conn.sendall(struct.pack('>Q', REPLYMAGIC))
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conn.sendall(struct.pack('>I', opt))
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conn.sendall(struct.pack('>I', rtype))
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conn.sendall(struct.pack('>I', len(data)))
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if data:
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conn.sendall(data)
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def handle_client(conn, addr):
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print(f'[nbd] {addr} connected')
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try:
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conn.sendall(struct.pack('>Q', NBDMAGIC))
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conn.sendall(struct.pack('>Q', IHAVEOPT))
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conn.sendall(struct.pack('>H', 0x0003))
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recv_all(conn, 4)
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while True:
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hdr = recv_all(conn, 16)
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_, opt, opt_len = struct.unpack('>QII', hdr)
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opt_data = recv_all(conn, opt_len) if opt_len else b''
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if opt == NBD_OPT_EXPORT_NAME:
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conn.sendall(struct.pack('>Q', VIRT_SIZE))
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conn.sendall(struct.pack('>H', TX_FLAGS))
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break
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elif opt == NBD_OPT_GO:
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info = struct.pack('>HQH', NBD_INFO_EXPORT,
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VIRT_SIZE, TX_FLAGS)
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send_reply(conn, opt, NBD_REP_INFO, info)
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send_reply(conn, opt, NBD_REP_ACK)
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break
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elif opt == NBD_OPT_LIST:
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send_reply(conn, opt, NBD_REP_SERVER,
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struct.pack('>I', 0))
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send_reply(conn, opt, NBD_REP_ACK)
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elif opt == NBD_OPT_ABORT:
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send_reply(conn, opt, NBD_REP_ACK)
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return
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else:
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send_reply(conn, opt, NBD_REP_ERR_UNSUP)
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print(f'[nbd] {addr} transmission')
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while True:
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hdr = recv_all(conn, 28)
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magic, flags, cmd, handle, offset, length = \
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struct.unpack('>IHHQQI', hdr)
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if magic != NBD_REQUEST_MAGIC:
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return
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if cmd == NBD_CMD_READ:
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try:
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payload = read_virtual(offset, length)
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except Exception as e:
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print(f'[nbd] read error {offset}+{length}: {e}')
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payload = b'\x00' * length
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conn.sendall(struct.pack('>IIQ',
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NBD_REPLY_MAGIC, 0, handle))
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conn.sendall(payload)
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elif cmd == NBD_CMD_FLUSH:
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conn.sendall(struct.pack('>IIQ',
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NBD_REPLY_MAGIC, 0, handle))
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elif cmd == NBD_CMD_DISC:
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print(f'[nbd] {addr} disconnected')
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return
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else:
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conn.sendall(struct.pack('>IIQ',
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NBD_REPLY_MAGIC, 1, handle))
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except (ConnectionError, BrokenPipeError, ConnectionResetError):
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print(f'[nbd] {addr} dropped')
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except Exception as e:
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print(f'[nbd] {addr} error: {e}')
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import traceback; traceback.print_exc()
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finally:
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conn.close()
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def main():
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print('PERC H710 recovery NBD server v9')
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print(f' device : {DEV}')
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print(f' lv_start : byte {LV_PHYS_START}')
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print(f' virt_size : {VIRT_SIZE//1024**3} GB')
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print(f' GDT region : bytes {GDT_VIRT_START}-{GDT_VIRT_END}')
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print(f' patch : merged GDT only (primary + backup group 1)')
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print(f' no patches : superblock, features, checksums all authentic')
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print()
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srv = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
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srv.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
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srv.bind(('127.0.0.1', 10809))
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srv.listen(5)
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print('Listening on 127.0.0.1:10809')
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print(' nbd-client 127.0.0.1 10809 /dev/nbd0 -N ""')
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print()
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print('Then try:')
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print(' e2fsck -n /dev/nbd0')
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print(' fls /dev/nbd0 1585918')
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print(' ext4magic /dev/nbd0 -s 4096 -n 32768 -R -I 1585918 \\')
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print(' -a $(date -d "2023-01-01" +%s) -d /mnt/recovered')
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print()
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while True:
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conn, addr = srv.accept()
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threading.Thread(target=handle_client, args=(conn, addr),
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daemon=True).start()
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if __name__ == '__main__':
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main()
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