Fixed issue 3539, added test

tests/stdlib/tnet_ll.nim

@@ -0,0 +1,39 @@
+discard """
+  action: run
+"""
+
+when defined(windows):
+  import winlean
+elif defined(posix):
+  import posix
+else:
+  {.error: "Unsupported OS".}
+
+import unittest, strutils
+
+suite "inet_ntop tests":
+
+  setup:
+    when defined(windows):
+      var wsa: WSAData
+      discard wsaStartup(0x101'i16, wsa.addr)
+  
+  test "IP V4":
+    var ip4 = 0x10111213
+    var buff: array[0..255, char]
+    let r = inet_ntop(AF_INET, ip4.addr, buff[0].addr, buff.sizeof.int32)
+    let res = if r == nil: "" else: $r
+    check: res == "19.18.17.16"
+      
+
+  test "IP V6":
+    when defined(windows):
+      let ipv6Support = (getVersion() and 0xff) > 0x5
+    else:
+      let ipv6Support = true
+          
+    var ip6 = [0x1000'u16, 0x1001, 0x2000, 0x2001, 0x3000, 0x3001, 0x4000, 0x4001]
+    var buff: array[0..255, char]
+    let r = inet_ntop(AF_INET6, ip6[0].addr, buff[0].addr, buff.sizeof.int32)
+    let res = if r == nil: "" else: $r
+    check: not ipv6Support or res == "10:110:20:120:30:130:40:140"