fixes + more fuzzing

src/jsony.nim

@@ -142,6 +142,8 @@ proc parseHook*(s: string, i: var int, v: var SomeFloat) =
 
 proc parseUnicodeEscape(s: string, i: var int): int =
   inc i
+  if i + 4 > s.len:
+    error("Expected unicode escape hex but end reached.", i)
   result = parseHexInt(s[i ..< i + 4])
   i += 3
   # Deal with UTF-16 surrogates. Most of the time strings are encoded as utf8
@@ -168,6 +170,8 @@ proc parseStringSlow(s: string, i: var int, v: var string) =
       break
     of '\\':
       inc i
+      if i >= s.len:
+        error("Expected escaped character but end reached.", i)
       let c = s[i]
       case c
       of '"', '\\', '/': v.add(c)
@@ -198,10 +202,12 @@ proc parseStringFast(s: string, i: var int, v: var string) =
       break
     of '\\':
       inc j
+      if j >= s.len:
+        error("Expected escaped character but end reached.", j)
       let c = s[j]
       case c
       of 'u':
-        ll += Rune(parseUnicodeEscape(s, j)).toUTF8().len
+        ll += Rune(parseUnicodeEscape(s, j)).size
       else:
         inc ll
     else:

tests/fuzz.nim

@@ -2,7 +2,7 @@ import jsony, os, random, strformat, strutils, tables
 
 type
   NodeKind = enum
-    nkRed, nkBlue, nkGree, nkBlack
+    nkRed, nkBlue, nkGreen, nkBlack
   Node = ref object
     active: bool
     kind: NodeKind
@@ -11,6 +11,7 @@ type
     id: int
     kids: seq[Node]
     table: Table[string, uint8]
+    body: string
 
 var r = initRand(2020)
 var genId: int
@@ -25,9 +26,10 @@ proc genTree(depth: int): Node =
   if r.rand(0 .. 1) == 0:
     result.active = true
   result.name = "node" & $result.id
-  result.kind = [nkRed, nkBlue, nkGree, nkBlack][r.rand(0 .. 3)]
+  result.kind = [nkRed, nkBlue, nkGreen, nkBlack][r.rand(0 .. 3)]
   result.table["cat"] = 4
   result.table["dog"] = 4
+  result.body = "abc🔒\n"
   if depth > 0:
     for i in 0 .. r.rand(0..3):
       result.kids.add genTree(depth - 1)
@@ -42,7 +44,7 @@ randomize()
 for i in 0 ..< 10000:
   var
     data = treeStr
-    pos = rand(data.len)
+    pos = rand(data.high)
     value = rand(255).char
     #pos = 18716
     #value = 125.char
@@ -52,25 +54,25 @@ for i in 0 ..< 10000:
   try:
     let node = data.fromJson(Node)
     doAssert node != nil
-  except JsonError:
+  except:
     discard
 
   var data2 = data[0 ..< pos]
   try:
     let node = data2.fromJson(Node)
     doAssert node != nil
-  except JsonError:
+  except:
     discard
 
   # JsonNode
   try:
     let node = data.fromJson()
     doAssert node != nil
-  except JsonError:
+  except:
     discard
 
   try:
     let node = data2.fromJson()
     doAssert node != nil
-  except JsonError:
+  except:
     discard

tests/fuzz_strings.nim

@@ -21,3 +21,9 @@ for i in 0 ..< 100_000:
   if s.toJson().fromJson(string) != s:
     echo "some thing wrong!"
     echo repr(s)
+
+for i in 0 ..< 10_000:
+  var s = ""
+  for i in 0 ..< rand(0 .. 1_000):
+    s.add cast[char](rand(0 .. 255))
+  discard s.toJson().fromJson(string)

tests/test_strings.nim

@@ -53,3 +53,13 @@ block:
   echo "jsony - ", parsed2.content
   echo "std/json - ", parsedStd2.content
   doAssert parsed2.content == parsedStd2.content
+
+block:
+  var s = "\"\\u00\""
+  doAssertRaises jsony.JsonError:
+    discard fromJson(s, string)
+
+block:
+  var s = "\"\\"
+  doAssertRaises jsony.JsonError:
+    discard fromJson(s, string)