Asp.Net Core get client IP

不废话，直接上代码，你懂得。

public string GetRequestIP(bool tryUseXForwardHeader = true)
{
string ip = null;

// todo support new "Forwarded" header (2014) https://en.wikipedia.org/wiki/X-Forwarded-For

if (tryUseXForwardHeader)
ip = GetHeaderValueAs<string>("X-Forwarded-For").SplitCsv().FirstOrDefault();

// RemoteIpAddress is always null in DNX RC1 Update1 (bug).
if (ip.IsNullOrWhitespace() && _httpContextAccessor.HttpContext?.Connection?.RemoteIpAddress != null)
ip = _httpContextAccessor.HttpContext.Connection.RemoteIpAddress.ToString();

if (ip.IsNullOrWhitespace())
ip = GetHeaderValueAs<string>("REMOTE_ADDR");

// _httpContextAccessor.HttpContext?.Request?.Host this is the local host.

if (ip.IsNullOrWhitespace())
throw new Exception("Unable to determine caller's IP.");

return ip;
}

public T GetHeaderValueAs<T>(string headerName)
{
StringValues values;

if (_httpContextAccessor.HttpContext?.Request?.Headers?.TryGetValue(headerName, out values) ?? false)
{
string rawValues = values.ToString();   // writes out as Csv when there are multiple.

if (!rawValues.IsNullOrEmpty())
return (T)Convert.ChangeType(values.ToString(), typeof(T));
}
return default(T);
}

public static List<string> SplitCsv(this string csvList, bool nullOrWhitespaceInputReturnsNull = false)
{
if (string.IsNullOrWhiteSpace(csvList))
return nullOrWhitespaceInputReturnsNull ? null : new List<string>();

return csvList
.TrimEnd(',')
.Split(',')
.AsEnumerable<string>()
.Select(s => s.Trim())
.ToList();
}

public static bool IsNullOrWhitespace(this string s)
{
return String.IsNullOrWhiteSpace(s);
}