Plumtree sync (#393)

* wip plumtree * sync works * fix logging * ttl to 0 * fix send packet to one peer * spec * wip GCS instead of bloom * remove bloom filter remainders * clean * prune old announcements * remove announcements from sync after LEAVE * sync after 1 second * pruning * track own announcement and prune messages without announcements * fix pruning * getGcsMaxFilterBytes default value 400 bytes * parameters
2026-07-25 11:25:21 +00:00 · 2025-09-14 03:32:10 +02:00
parent 3967ef8922
commit 73c91b9509
18 changed files with 963 additions and 60 deletions
@@ -0,0 +1,82 @@
+package com.bitchat.android.model
+
+import com.bitchat.android.sync.SyncDefaults
+
+/**
+ * REQUEST_SYNC payload using GCS (Golomb-Coded Set) parameters.
+ * TLV (type, length16, value), types:
+ *  - 0x01: P (uint8) — Golomb-Rice parameter
+ *  - 0x02: M (uint32, big-endian) — hash range (N * 2^P)
+ *  - 0x03: data (opaque) — GR bitstream bytes
+ */
+data class RequestSyncPacket(
+    val p: Int,
+    val m: Long,
+    val data: ByteArray
+) {
+    fun encode(): ByteArray {
+        val out = ArrayList<Byte>()
+        fun putTLV(t: Int, v: ByteArray) {
+            out.add(t.toByte())
+            val len = v.size
+            out.add(((len ushr 8) and 0xFF).toByte())
+            out.add((len and 0xFF).toByte())
+            out.addAll(v.toList())
+        }
+        // P
+        putTLV(0x01, byteArrayOf(p.toByte()))
+        // M (uint32)
+        val m32 = m.coerceAtMost(0xffff_ffffL)
+        putTLV(
+            0x02,
+            byteArrayOf(
+                ((m32 ushr 24) and 0xFF).toByte(),
+                ((m32 ushr 16) and 0xFF).toByte(),
+                ((m32 ushr 8) and 0xFF).toByte(),
+                (m32 and 0xFF).toByte()
+            )
+        )
+        // data
+        putTLV(0x03, data)
+        return out.toByteArray()
+    }
+
+    companion object {
+        // Receiver-side safety limit (configurable constant)
+        const val MAX_ACCEPT_FILTER_BYTES: Int = SyncDefaults.MAX_ACCEPT_FILTER_BYTES
+
+        fun decode(data: ByteArray): RequestSyncPacket? {
+            var off = 0
+            var p: Int? = null
+            var m: Long? = null
+            var payload: ByteArray? = null
+
+            while (off + 3 <= data.size) {
+                val t = (data[off].toInt() and 0xFF); off += 1
+                val len = ((data[off].toInt() and 0xFF) shl 8) or (data[off+1].toInt() and 0xFF); off += 2
+                if (off + len > data.size) return null
+                val v = data.copyOfRange(off, off + len); off += len
+                when (t) {
+                    0x01 -> if (len == 1) p = (v[0].toInt() and 0xFF)
+                    0x02 -> if (len == 4) {
+                        val mm = ((v[0].toLong() and 0xFF) shl 24) or
+                                 ((v[1].toLong() and 0xFF) shl 16) or
+                                 ((v[2].toLong() and 0xFF) shl 8) or
+                                 (v[3].toLong() and 0xFF)
+                        m = mm
+                    }
+                    0x03 -> {
+                        if (v.size > MAX_ACCEPT_FILTER_BYTES) return null
+                        payload = v
+                    }
+                }
+            }
+
+            val pp = p ?: return null
+            val mm = m ?: return null
+            val dd = payload ?: return null
+            if (pp < 1 || mm <= 0L) return null
+            return RequestSyncPacket(pp, mm, dd)
+        }
+    }
+}