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feat(rengoku): validate and log Hunting Road config on startup

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Port ECD encryption/decryption from ReFrontier (C#) and FrontierTextHandler
(Python) into common/decryption. The cipher uses a 32-bit LCG key stream with
an 8-round Feistel-like nibble transformation and CFB chaining; all six key
sets are supported, key 4 being the default for all MHF files.

On startup, loadRengokuBinary now decrypts (ECD) and decompresses (JKR) the
binary to validate pointer bounds and entry counts, then logs a structured
summary (floor counts, spawn table counts, unique monster IDs). Failures are
non-fatal — the encrypted blob is still cached and served to clients unchanged,
preserving existing behaviour. Closes #173.
This commit is contained in:
Houmgaor
2026-03-19 23:59:34 +01:00
parent 08e7de2c5e
commit 5c2fde5cfd
6 changed files with 698 additions and 9 deletions
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39
server/channelserver/sys_channel_server.go
View File

@@ -11,6 +11,7 @@ import (
"time"
"erupe-ce/common/byteframe"
"erupe-ce/common/decryption"
cfg "erupe-ce/config"
"erupe-ce/network"
"erupe-ce/network/binpacket"
@@ -449,12 +450,11 @@ func (s *Server) Season() uint8 {
return uint8(((TimeAdjusted().Unix() / secsPerDay) + sid) % 3)
}
// ecdMagic is the ECD magic as read by binary.LittleEndian.Uint32.
// On-disk bytes: 65 63 64 1A ("ecd\x1a"), LE-decoded: 0x1A646365.
const ecdMagic = uint32(0x1A646365)
// loadRengokuBinary reads and validates rengoku_data.bin from binPath.
// Returns the raw bytes on success, or nil if the file is missing or invalid.
// loadRengokuBinary reads, validates, and caches rengoku_data.bin from binPath.
// The file is served to clients as-is (ECD-encrypted); decryption and parsing
// are performed only for structural validation and startup logging.
// Returns the raw encrypted bytes on success, or nil if the file is
// missing or structurally invalid.
func loadRengokuBinary(binPath string, logger *zap.Logger) []byte {
path := filepath.Join(binPath, "rengoku_data.bin")
data, err := os.ReadFile(path)
@@ -468,12 +468,35 @@ func loadRengokuBinary(binPath string, logger *zap.Logger) []byte {
zap.Int("bytes", len(data)))
return nil
}
if magic := binary.LittleEndian.Uint32(data[:4]); magic != ecdMagic {
if magic := binary.LittleEndian.Uint32(data[:4]); magic != decryption.ECDMagic {
logger.Warn("rengoku_data.bin has invalid ECD magic, ignoring",
zap.String("expected", "0x1a646365"),
zap.String("expected", fmt.Sprintf("0x%08x", decryption.ECDMagic)),
zap.String("got", fmt.Sprintf("0x%08x", magic)))
return nil
}
// Decrypt and decompress to validate the internal structure and emit a
// human-readable summary at startup. Failures here are non-fatal: the
// encrypted blob is still served to clients unchanged.
if plain, decErr := decryption.DecodeECD(data); decErr != nil {
logger.Warn("rengoku_data.bin ECD decryption failed — serving anyway",
zap.Error(decErr))
} else {
raw := decryption.UnpackSimple(plain)
if info, parseErr := parseRengokuBinary(raw); parseErr != nil {
logger.Warn("rengoku_data.bin structural validation failed",
zap.Error(parseErr))
} else {
logger.Info("Hunting Road config",
zap.Int("multi_floors", info.MultiFloors),
zap.Int("multi_spawn_tables", info.MultiSpawnTables),
zap.Int("solo_floors", info.SoloFloors),
zap.Int("solo_spawn_tables", info.SoloSpawnTables),
zap.Int("unique_monsters", info.UniqueMonsters),
)
}
}
logger.Info("Loaded rengoku_data.bin", zap.Int("bytes", len(data)))
return data
}