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feat(savedata): add tier 1 data integrity protections

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Prevent savedata corruption and denial-of-service by adding four layers
of protection to the save pipeline:

- Bounded decompression (nullcomp.DecompressWithLimit): caps output size
  to prevent OOM from crafted payloads that expand to exhaust memory
- Bounds-checked delta patching (deltacomp.ApplyDataDiffWithLimit):
  validates offsets before writing, returns errors for negative offsets,
  truncated patches, and oversized output; ApplyDataDiff now returns
  original data on error instead of partial corruption
- Size limits on save handlers: rejects compressed payloads >512KB and
  decompressed data >1MB before processing; applied to main savedata,
  platedata, and platebox diff paths
- Rotating savedata backups: 3 slots per character with 30-minute
  interval, snapshots the previous state before overwriting, backed by
  new savedata_backups table (migration 0007)
This commit is contained in:
Houmgaor
2026-03-17 19:03:43 +01:00
parent 5009a37d19
commit b40217c7fe
13 changed files with 478 additions and 28 deletions
Download Patch File Download Diff File Expand all files Collapse all files

27
server/channelserver/handlers_plate.go
View File

@@ -77,7 +77,7 @@ func handleMsgMhfSavePlateData(s *Session, p mhfpacket.MHFPacket) {
if len(data) > 0 {
// Decompress
s.logger.Debug("Decompressing PlateData", zap.Int("compressed_size", len(data)))
data, err = nullcomp.Decompress(data)
data, err = nullcomp.DecompressWithLimit(data, plateDataMaxPayload)
if err != nil {
s.logger.Error("Failed to decompress platedata",
zap.Error(err),
@@ -91,9 +91,18 @@ func handleMsgMhfSavePlateData(s *Session, p mhfpacket.MHFPacket) {
data = make([]byte, plateDataEmptySize)
}
// Perform diff and compress it to write back to db
// Perform diff with bounds checking and compress it to write back to db
s.logger.Debug("Applying PlateData diff", zap.Int("base_size", len(data)))
saveOutput, err := nullcomp.Compress(deltacomp.ApplyDataDiff(pkt.RawDataPayload, data))
patched, err := deltacomp.ApplyDataDiffWithLimit(pkt.RawDataPayload, data, plateDataMaxPayload)
if err != nil {
s.logger.Error("Failed to apply platedata diff",
zap.Error(err),
zap.Uint32("charID", s.charID),
)
doAckSimpleSucceed(s, pkt.AckHandle, []byte{0x00, 0x00, 0x00, 0x00})
return
}
saveOutput, err := nullcomp.Compress(patched)
if err != nil {
s.logger.Error("Failed to diff and compress platedata",
zap.Error(err),
@@ -173,7 +182,7 @@ func handleMsgMhfSavePlateBox(s *Session, p mhfpacket.MHFPacket) {
if len(data) > 0 {
// Decompress
s.logger.Info("Decompressing...")
data, err = nullcomp.Decompress(data)
data, err = nullcomp.DecompressWithLimit(data, plateBoxMaxPayload)
if err != nil {
s.logger.Error("Failed to decompress platebox", zap.Error(err))
doAckSimpleSucceed(s, pkt.AckHandle, []byte{0x00, 0x00, 0x00, 0x00})
@@ -184,9 +193,15 @@ func handleMsgMhfSavePlateBox(s *Session, p mhfpacket.MHFPacket) {
data = make([]byte, plateBoxEmptySize)
}
// Perform diff and compress it to write back to db
// Perform diff with bounds checking and compress it to write back to db
s.logger.Info("Diffing...")
saveOutput, err := nullcomp.Compress(deltacomp.ApplyDataDiff(pkt.RawDataPayload, data))
patched, err := deltacomp.ApplyDataDiffWithLimit(pkt.RawDataPayload, data, plateBoxMaxPayload)
if err != nil {
s.logger.Error("Failed to apply platebox diff", zap.Error(err))
doAckSimpleSucceed(s, pkt.AckHandle, []byte{0x00, 0x00, 0x00, 0x00})
return
}
saveOutput, err := nullcomp.Compress(patched)
if err != nil {
s.logger.Error("Failed to diff and compress platebox", zap.Error(err))
doAckSimpleSucceed(s, pkt.AckHandle, []byte{0x00, 0x00, 0x00, 0x00})