using System;
|
using System.Collections.Generic;
|
|
namespace Alipay.EasySDK.Kernel.Util
|
{
|
/// <summary>
|
/// 待验签原文提取器
|
/// 注：此处不可使用JSON反序列化工具进行提取，会破坏原有格式，对于签名而言差个空格都会验签不通过
|
/// </summary>
|
public class SignContentExtractor
|
{
|
/// <summary>
|
/// 左大括号
|
/// </summary>
|
public const char LEFT_BRACE = '{';
|
|
/// <summary>
|
/// 右大括号
|
/// </summary>
|
public const char RIGHT_BRACE = '}';
|
|
/// <summary>
|
/// 双引号
|
/// </summary>
|
public const char DOUBLE_QUOTES = '"';
|
|
/// <summary>
|
/// 获取待验签的原文
|
/// </summary>
|
/// <param name="body">网关的整体响应字符串</param>
|
/// <param name="method">本次调用的OpenAPI接口名称</param>
|
/// <returns>待验签的原文</returns>
|
public static string GetSignSourceData(string body, string method)
|
{
|
string rootNode = method.Replace(".", "_") + AlipayConstants.RESPONSE_SUFFIX;
|
string errorRootNode = AlipayConstants.ERROR_RESPONSE;
|
|
int indexOfRootNode = body.IndexOf(rootNode, StringComparison.Ordinal);
|
int indexOfErrorRoot = body.IndexOf(errorRootNode, StringComparison.Ordinal);
|
|
string result = null;
|
if (indexOfRootNode > 0)
|
{
|
result = ParseSignSourceData(body, rootNode, indexOfRootNode);
|
}
|
else if (indexOfErrorRoot > 0)
|
{
|
result = ParseSignSourceData(body, errorRootNode, indexOfErrorRoot);
|
}
|
|
return result;
|
}
|
|
private static string ParseSignSourceData(string body, string rootNode, int indexOfRootNode)
|
{
|
int signDataStartIndex = indexOfRootNode + rootNode.Length + 2;
|
int indexOfSign = body.IndexOf("\"" + AlipayConstants.SIGN_FIELD + "\"", StringComparison.Ordinal);
|
if (indexOfSign < 0)
|
{
|
return null;
|
}
|
SignSourceData signSourceData = ExtractSignContent(body, signDataStartIndex);
|
|
//如果提取的待验签原始内容后还有rootNode
|
if (body.LastIndexOf(rootNode, StringComparison.Ordinal) > signSourceData.EndIndex)
|
{
|
throw new Exception("检测到响应报文中有重复的" + rootNode + "，验签失败。");
|
}
|
|
return signSourceData.SourceData;
|
}
|
|
private static SignSourceData ExtractSignContent(string str, int begin)
|
{
|
if (str == null)
|
{
|
return null;
|
}
|
|
int beginIndex = ExtractBeginPosition(str, begin);
|
if (beginIndex >= str.Length)
|
{
|
return null;
|
}
|
|
int endIndex = ExtractEndPosition(str, beginIndex);
|
return new SignSourceData()
|
{
|
SourceData = str.Substring(beginIndex, endIndex - beginIndex),
|
BeginIndex = beginIndex,
|
EndIndex = endIndex
|
};
|
}
|
|
private static int ExtractBeginPosition(string responseString, int begin)
|
{
|
int beginPosition = begin;
|
//找到第一个左大括号（对应响应的是JSON对象的情况：普通调用OpenAPI响应明文）
|
//或者双引号（对应响应的是JSON字符串的情况：加密调用OpenAPI响应Base64串），作为待验签内容的起点
|
while (beginPosition < responseString.Length
|
&& responseString[beginPosition] != LEFT_BRACE
|
&& responseString[beginPosition] != DOUBLE_QUOTES)
|
{
|
++beginPosition;
|
}
|
return beginPosition;
|
}
|
|
private static int ExtractEndPosition(string responseString, int beginPosition)
|
{
|
//提取明文验签内容终点
|
if (responseString[beginPosition] == LEFT_BRACE)
|
{
|
return ExtractJsonObjectEndPosition(responseString, beginPosition);
|
}
|
//提取密文验签内容终点
|
else
|
{
|
return ExtractJsonBase64ValueEndPosition(responseString, beginPosition);
|
}
|
}
|
|
private static int ExtractJsonBase64ValueEndPosition(string responseString, int beginPosition)
|
{
|
for (int index = beginPosition; index < responseString.Length; ++index)
|
{
|
//找到第2个双引号作为终点，由于中间全部是Base64编码的密文，所以不会有干扰的特殊字符
|
if (responseString[index] == DOUBLE_QUOTES && index != beginPosition)
|
{
|
return index + 1;
|
}
|
}
|
//如果没有找到第2个双引号，说明验签内容片段提取失败，直接尝试选取剩余整个响应字符串进行验签
|
return responseString.Length;
|
}
|
|
private static int ExtractJsonObjectEndPosition(string responseString, int beginPosition)
|
{
|
//记录当前尚未发现配对闭合的大括号
|
LinkedList<char> braces = new LinkedList<char>();
|
//记录当前字符是否在双引号中
|
bool inQuotes = false;
|
//记录当前字符前面连续的转义字符个数
|
int consecutiveEscapeCount = 0;
|
//从待验签字符的起点开始遍历后续字符串，找出待验签字符串的终止点，终点即是与起点{配对的}
|
for (int index = beginPosition; index < responseString.Length; ++index)
|
{
|
//提取当前字符
|
char currentChar = responseString[index];
|
|
//如果当前字符是"且前面有偶数个转义标记（0也是偶数）
|
if (currentChar == DOUBLE_QUOTES && consecutiveEscapeCount % 2 == 0)
|
{
|
//是否在引号中的状态取反
|
inQuotes = !inQuotes;
|
}
|
//如果当前字符是{且不在引号中
|
else if (currentChar == LEFT_BRACE && !inQuotes)
|
{
|
//将该{加入未闭合括号中
|
braces.AddLast(LEFT_BRACE);
|
}
|
//如果当前字符是}且不在引号中
|
else if (currentChar == RIGHT_BRACE && !inQuotes)
|
{
|
//弹出一个未闭合括号
|
braces.RemoveLast();
|
//如果弹出后，未闭合括号为空，说明已经找到终点
|
if (braces.Count == 0)
|
{
|
return index + 1;
|
}
|
}
|
|
//如果当前字符是转义字符
|
if (currentChar == '\\')
|
{
|
//连续转义字符个数+1
|
++consecutiveEscapeCount;
|
}
|
else
|
{
|
//连续转义字符个数置0
|
consecutiveEscapeCount = 0;
|
}
|
}
|
|
//如果没有找到配对的闭合括号，说明验签内容片段提取失败，直接尝试选取剩余整个响应字符串进行验签
|
return responseString.Length;
|
}
|
|
/// <summary>
|
/// 从响应字符串中提取到的待验签原始内容
|
/// </summary>
|
public class SignSourceData
|
{
|
/// <summary>
|
/// 待验签原始内容
|
/// </summary>
|
public string SourceData { get; set; }
|
|
/// <summary>
|
/// 待验签原始内容在响应字符串中的起始位置
|
/// </summary>
|
public int BeginIndex { get; set; }
|
|
/// <summary>
|
/// 待验签原始内容在响应字符串中的结束位置
|
/// </summary>
|
public int EndIndex { get; set; }
|
}
|
}
|
}
|
