Make IP address checking more obvious, and add tests for the net module.

lib/pure/net.nim

@@ -95,6 +95,7 @@ type
       address_v4*: array[0..3, uint8] ## Contains the IP address in bytes in
                                       ## case of IPv4
 
+proc isIpAddress*(address_str: string): bool
 proc parseIpAddress*(address_str: string): TIpAddress
 
 proc isDisconnectionError*(flags: set[SocketFlag],
@@ -527,9 +528,8 @@ proc connect*(socket: Socket, address: string, port = Port(0),
   
   when defined(ssl):
     if socket.isSSL:
-      try:
-        discard parseIpAddress(address)
-      except ValueError:
+      # RFC3546 for SNI specifies that IP addresses are not allowed.
+      if not isIpAddress(address):
         # Discard result in case OpenSSL version doesn't support SNI, or we're
         # not using TLSv1+
         discard SSL_set_tlsext_host_name(socket.sslHandle, address)
@@ -1259,3 +1259,13 @@ proc parseIpAddress*(address_str: string): TIpAddress =
     return parseIPv6Address(address_str)
   else:
     return parseIPv4Address(address_str)
+
+
+proc isIpAddress*(address_str: string): bool =
+  ## Checks if a string is an IP address
+  ## Returns true if it is, false otherwise
+  try:
+    discard parseIpAddress(address_str)
+  except ValueError:
+    return false
+  return true

tests/stdlib/tnet.nim

@@ -0,0 +1,47 @@
+import net
+import unittest
+
+suite "isIpAddress tests":
+  test "127.0.0.1 is valid":
+    check isIpAddress("127.0.0.1") == true
+
+  test "ipv6 localhost is valid":
+    check isIpAddress("::1") == true
+
+  test "fqdn is not an ip address":
+    check isIpAddress("example.com") == false
+
+  test "random string is not an ipaddress":
+    check isIpAddress("foo bar") == false
+
+  test "5127.0.0.1 is invalid":
+    check isIpAddress("5127.0.0.1") == false
+
+  test "ipv6 is valid":
+    check isIpAddress("2001:cdba:0000:0000:0000:0000:3257:9652") == true
+
+  test "invalid ipv6":
+    check isIpAddress("gggg:cdba:0000:0000:0000:0000:3257:9652") == false
+
+
+suite "parseIpAddress tests":
+  test "127.0.0.1 is valid":
+    discard parseIpAddress("127.0.0.1")
+
+  test "ipv6 localhost is valid":
+    discard parseIpAddress("::1")
+
+  test "fqdn is not an ip address":
+    expect(ValueError):
+      discard parseIpAddress("example.com")
+
+  test "random string is not an ipaddress":
+    expect(ValueError):
+      discard parseIpAddress("foo bar")
+
+  test "ipv6 is valid":
+    discard parseIpAddress("2001:cdba:0000:0000:0000:0000:3257:9652")
+
+  test "invalid ipv6":
+    expect(ValueError):
+      discard parseIpAddress("gggg:cdba:0000:0000:0000:0000:3257:9652")