Allow passing max message size (#800)

Co-authored-by: Tanguy <tanguy@status.im>

libp2p/daemon/daemonapi.nim

@@ -492,7 +492,7 @@ proc recvMessage(conn: StreamTransport): Future[seq[byte]] {.async.} =
       res = PB.getUVarint(buffer.toOpenArray(0, i), length, size)
       if res.isOk():
         break
-    if res.isErr() or size > MaxMessageSize:
+    if res.isErr() or size > 1'u shl 22:
       buffer.setLen(0)
       result = buffer
       return

libp2p/protobuf/minprotobuf.nim

@@ -19,8 +19,7 @@ export results, utility
 
 {.push public.}
 
-const
+const MaxMessageSize = 1'u shl 22
-  MaxMessageSize* = 1'u shl 22
 
 type
   ProtoFieldKind* = enum
@@ -37,6 +36,7 @@ type
     buffer*: seq[byte]
     offset*: int
     length*: int
+    maxSize*: uint
 
   ProtoHeader* = object
     wire*: ProtoFieldKind
@@ -122,23 +122,28 @@ proc vsizeof*(field: ProtoField): int {.inline.} =
     0
 
 proc initProtoBuffer*(data: seq[byte], offset = 0,
-                      options: set[ProtoFlags] = {}): ProtoBuffer =
+                      options: set[ProtoFlags] = {},
+                      maxSize = MaxMessageSize): ProtoBuffer =
   ## Initialize ProtoBuffer with shallow copy of ``data``.
   result.buffer = data
   result.offset = offset
   result.options = options
+  result.maxSize = maxSize
 
 proc initProtoBuffer*(data: openArray[byte], offset = 0,
-                      options: set[ProtoFlags] = {}): ProtoBuffer =
+                      options: set[ProtoFlags] = {},
+                      maxSize = MaxMessageSize): ProtoBuffer =
   ## Initialize ProtoBuffer with copy of ``data``.
   result.buffer = @data
   result.offset = offset
   result.options = options
+  result.maxSize = maxSize
 
-proc initProtoBuffer*(options: set[ProtoFlags] = {}): ProtoBuffer =
+proc initProtoBuffer*(options: set[ProtoFlags] = {}, maxSize = MaxMessageSize): ProtoBuffer =
   ## Initialize ProtoBuffer with new sequence of capacity ``cap``.
   result.buffer = newSeq[byte]()
   result.options = options
+  result.maxSize = maxSize
   if WithVarintLength in options:
     # Our buffer will start from position 10, so we can store length of buffer
     # in [0, 9].
@@ -335,7 +340,7 @@ proc skipValue(data: var ProtoBuffer, header: ProtoHeader): ProtoResult[void] =
     var bsize = 0'u64
     if PB.getUVarint(data.toOpenArray(), length, bsize).isOk():
       data.offset += length
-      if bsize <= uint64(MaxMessageSize):
+      if bsize <= uint64(data.maxSize):
         if data.isEnough(int(bsize)):
           data.offset += int(bsize)
           ok()
@@ -399,7 +404,7 @@ proc getValue[T:byte|char](data: var ProtoBuffer, header: ProtoHeader,
   outLength = 0
   if PB.getUVarint(data.toOpenArray(), length, bsize).isOk():
     data.offset += length
-    if bsize <= uint64(MaxMessageSize):
+    if bsize <= uint64(data.maxSize):
       if data.isEnough(int(bsize)):
         outLength = int(bsize)
         if len(outBytes) >= int(bsize):
@@ -427,7 +432,7 @@ proc getValue[T:seq[byte]|string](data: var ProtoBuffer, header: ProtoHeader,
 
   if PB.getUVarint(data.toOpenArray(), length, bsize).isOk():
     data.offset += length
-    if bsize <= uint64(MaxMessageSize):
+    if bsize <= uint64(data.maxSize):
       if data.isEnough(int(bsize)):
         outBytes.setLen(bsize)
         if bsize > 0'u64:

tests/testminprotobuf.nim

@@ -623,18 +623,27 @@ suite "MinProtobuf test suite":
 
   test "[length] too big message test":
     var pb1 = initProtoBuffer()
-    var bigString = newString(MaxMessageSize + 1)
+    var bigString = newString(pb1.maxSize + 1)
 
     for i in 0 ..< len(bigString):
       bigString[i] = 'A'
     pb1.write(1, bigString)
     pb1.finish()
-    var pb2 = initProtoBuffer(pb1.buffer)
+    block:
-    var value = newString(MaxMessageSize + 1)
+      var pb2 = initProtoBuffer(pb1.buffer)
-    var valueLen = 0
+      var value = newString(pb1.maxSize + 1)
-    let res = pb2.getField(1, value, valueLen)
+      var valueLen = 0
-    check:
+      let res = pb2.getField(1, value, valueLen)
-      res.isErr() == true
+      check:
+        res.isErr() == true
+
+    block:
+      var pb2 = initProtoBuffer(pb1.buffer, maxSize = uint.high)
+      var value = newString(pb1.maxSize + 1)
+      var valueLen = 0
+      let res = pb2.getField(1, value, valueLen)
+      check:
+        res.isErr() == false
 
   test "[length] Repeated field test":
     var pb1 = initProtoBuffer()