Make IP Address related functions return the empty string when used on an invalid address.

net/base/ip_address_number.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef NET_BASE_IP_ADDRESS_NUMBER_H_
 #define NET_BASE_IP_ADDRESS_NUMBER_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 19 matching lines @@
 
 static const size_t kIPv4AddressSize = 4;
 static const size_t kIPv6AddressSize = 16;
 
 // Returns true if an IP address hostname is in a range reserved by the IANA.
 // Works with both IPv4 and IPv6 addresses, and only compares against a given
 // protocols's reserved ranges.
 NET_EXPORT bool IsIPAddressReserved(const IPAddressNumber& address);
 
 // Returns the string representation of an IP address.
-// For example: "192.168.0.1" or "::1".
+// For example: "192.168.0.1" or "::1". Returns the empty string when |address|
+// is invalid.
 NET_EXPORT std::string IPAddressToString(const uint8_t* address,
                                          size_t address_len);
 
 // Returns the string representation of an IP address along with its port.
-// For example: "192.168.0.1:99" or "[::1]:80".
+// For example: "192.168.0.1:99" or "[::1]:80". Returns the empty string when
+// |address| is invalid (the port will be ignored).
 NET_EXPORT std::string IPAddressToStringWithPort(const uint8_t* address,
                                                  size_t address_len,
                                                  uint16_t port);
 
 // Same as IPAddressToString() but for an IPAddressNumber.
 NET_EXPORT std::string IPAddressToString(const IPAddressNumber& addr);
 
 // Same as IPAddressToStringWithPort() but for an IPAddressNumber.
 NET_EXPORT std::string IPAddressToStringWithPort(const IPAddressNumber& addr,
                                                  uint16_t port);
@@ skipping 55 matching lines @@
 // Returns number of matching initial bits between the addresses |a1| and |a2|.
 unsigned CommonPrefixLength(const IPAddressNumber& a1,
                             const IPAddressNumber& a2);
 
 // Computes the number of leading 1-bits in |mask|.
 unsigned MaskPrefixLength(const IPAddressNumber& mask);
 
 }  // namespace net
 
 #endif  // NET_BASE_IP_ADDRESS_NUMBER_H_