content-length 怎么用

Posted 2023-05-12

参考技术A 1、Content-Length如果存在并且有效的话，则必须和消息内容的传输长度完全一致。（经过测试，如果过短则会截断，过长则会导致超时。）
2、如果存在Transfer-Encoding（重点是chunked），则在header中不能有Content-Length，有也会被忽视。
3、如果采用短连接，则直接可以通过服务器关闭连接来确定消息的传输长度。（这个很容易懂）
结合HTTP协议其他的特点，比如说Http1.1之前的不支持keep alive。那么可以得出以下结论：
1、在Http 1.0及之前版本中，content-length字段可有可无。
2、在http1.1及之后版本。如果是keep alive，则content-length和chunk必然是二选一。若是非keep alive，则和http1.0一样。content-length可有可无。本回答被提问者采纳

服务器提交了协议冲突. Section=ResponseHeader Detail=“Content-Length”标题值无效

C# 采集金碧坊网站数据时出现该异常，导致无法获取网页源码
The server committed a protocol violation. Section=ResponseHeader Detail='Content-Length' header value is invalid

参考技术A 网上大部分都是在app.Config配置里设置useUnsafeHeaderParsing：

<?xml version="1.0"?>
<configuration>
<system.net>
<settings>
<httpWebRequest useUnsafeHeaderParsing="true" />
</settings>
</system.net>
</configuration>

这个方法证明可行，但是想了下，很多朋友都很不喜欢一个小小的程序因为这个事带上个配置文件，总感觉心里毛毛的。要是在程序里解决多好。于是乎又花了点时间，在一个国外的论坛里找到了解决方案，用了反射，直接操作System.Net.Configuration.SettingsSectionInternal类下的私有字段。虽然反射会带来性能上的影响，但是这里貌似没有更好的办法，因为不能操作一个封装好的私有变量。 参考技术B The server committed a protocol violation

One of the issues involving XML-RPC.NET that turns up fairly frequently is when the library throws an instance of System.Net.WebException with the message ""The server committed a protocol violation". This usually occurs because from .NET 1.1 SP1 onwards the parsing of HTTP responses became much more strict, as a security measure to prevent attacks which exploit malformed HTTP status lines and headers. The strict behaviour can be switched off via the application config file:

<?xml version ="1.0"?>
<configuration>
<system.net>
<settings>
<httpWebRequest useUnsafeHeaderParsing="true" />
</settings>
</system.net>
</configuration>

From .NET 2.0 this behaviour can be configured programmatically using the HttpWebRequestElement useUnsafeHeaderParsing property. At first when I read about this I assumed it was a property that can be set dynamically at runtime, for example in the same way as the HttpWebRequest KeepAlive property. But in fact its used in the new 2.0 configuration infrastructure to set the value in the config file (although once you do this the new value applies to the current running application as well as any apps launched afterwards. The new configuration infrastructure is pretty complex but this code seems to work ok:

Configuration config = ConfigurationManager.OpenExeConfiguration(
ConfigurationUserLevel.None);
SettingsSection section = (SettingsSection)config.GetSection(
"system.net/settings");
section.HttpWebRequest.UseUnsafeHeaderParsing = false;
config.Save();

ConfigurationUserLevel.None specifies that the configuration file in the same directory as the executable should be modified so this file has to be writable. The other options PerUserRoaming and PerUserRoamingAndLocal can be used in different scenarios.
Finally, I found the code below in a post on the .NET Framework Networking and Communication forum. This uses reflection to set the private field useUnsafeHeaderParsing to true and as a result may not be suitable in all scenarios where the relevant code access security permission is not available. (Note: add System.Configuration.dll as a reference to your project.)

public static bool SetAllowUnsafeHeaderParsing()

//Get the assembly that contains the internal class
Assembly aNetAssembly = Assembly.GetAssembly(
typeof(System.Net.Configuration.SettingsSection));
if (aNetAssembly != null)

//Use the assembly in order to get the internal type for
// the internal class
Type aSettingsType = aNetAssembly.GetType(
"System.Net.Configuration.SettingsSectionInternal");
if (aSettingsType != null)

//Use the internal static property to get an instance
// of the internal settings class. If the static instance
// isn't created allready the property will create it for us.
object anInstance = aSettingsType.InvokeMember("Section",
BindingFlags.Static | BindingFlags.GetProperty
| BindingFlags.NonPublic, null, null, new object[] );
if (anInstance != null)

//Locate the private bool field that tells the
// framework is unsafe header parsing should be
// allowed or not
FieldInfo aUseUnsafeHeaderParsing = aSettingsType.GetField(
"useUnsafeHeaderParsing",
BindingFlags.NonPublic | BindingFlags.Instance);
if (aUseUnsafeHeaderParsing != null)

aUseUnsafeHeaderParsing.SetValue(anInstance, true);
return true;




return false;
本回答被提问者采纳