C#如何解析http报文

2020-01-24 01:34:25

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下面通过一段内容有文字说明有代码分析，并附有展示图供大家学习。

要解析HTTP报文，需要实现以下操作：

读取HTTP报头提供的各种属性
分析属性值，从中获取内容编码和字符集编码
将报头数据和内容进行分离
判断内容是否文本还是二进制，如果是二进制的则不进行处理
如果内容是文本，按报头中提供的内容编码和字符集编码进行解压缩和解码
目前没有找到.Net框架内置的解析方法，理论上HttpClient等类在内部应该已经实现了解析，但不知为何没有公开这些处理方法。（亦或是我没找到）

那么只能自己来解析这些数据了。

我们先来看看这个经过gzip压缩的文本内容的HTTP报文：

这里提供一个老外写的简陋的解析类（已经过修改，原代码中存在一些严重BUG）：

public enum HTTPHeaderField{ Accept = 0, Accept_Charset = 1, Accept_Encoding = 2, Accept_Language = 3, Accept_Ranges = 4, Authorization = 5, Cache_Control = 6, Connection = 7, Cookie = 8, Content_Length = 9, Content_Type = 10, Date = 11, Expect = 12, From = 13, Host = 14, If_Match = 15, If_Modified_Since = 16, If_None_Match = 17, If_Range = 18, If_Unmodified_Since = 19, Max_Forwards = 20, Pragma = 21, Proxy_Authorization = 22, Range = 23, Referer = 24, TE = 25, Upgrade = 26, User_Agent = 27, Via = 28, Warn = 29, Age = 30, Allow = 31, Content_Encoding = 32, Content_Language = 33, Content_Location = 34, Content_Disposition = 35, Content_MD5 = 36, Content_Range = 37, ETag = 38, Expires = 39, Last_Modified = 40, Location = 41, Proxy_Authenticate = 42, Refresh = 43, Retry_After = 44, Server = 45, Set_Cookie = 46, Trailer = 47, Transfer_Encoding = 48, Vary = 49, Warning = 50, WWW_Authenticate = 51};class HTTPHeader{ #region PROPERTIES private string[] m_StrHTTPField = new string[52]; private byte[] m_byteData = new byte[4096]; public string[] HTTPField {  get { return m_StrHTTPField; }  set { m_StrHTTPField = value; } } public byte[] Data {  get { return m_byteData; }  set { m_byteData = value; } } #endregion // convertion System.Text.ASCIIEncoding encoding = new System.Text.ASCIIEncoding(); #region CONSTRUCTEUR /// <summary> /// Constructeur par défaut - non utilisé /// </summary> private HTTPHeader() { } public HTTPHeader(byte[] ByteHTTPRequest) {  string HTTPRequest = encoding.GetString(ByteHTTPRequest);  try  {   int IndexHeaderEnd;   string Header;   // Si la taille de requête est supérieur ou égale à 1460, alors toutes la chaine est l'entête http   if (HTTPRequest.Length <= 1460)    Header = HTTPRequest;   else   {    IndexHeaderEnd = HTTPRequest.IndexOf("/r/n/r/n");    Header = HTTPRequest.Substring(0, IndexHeaderEnd);    Data = ByteHTTPRequest.Skip(IndexHeaderEnd + 4).ToArray();   }   HTTPHeaderParse(Header);  }  catch (Exception)  { } } #endregion #region METHODES private void HTTPHeaderParse(string Header) {  #region HTTP HEADER REQUEST & RESPONSE  HTTPHeaderField HHField;  string HTTPfield, buffer;  int Index;  foreach (int IndexHTTPfield in Enum.GetValues(typeof(HTTPHeaderField)))  {   HHField = (HTTPHeaderField)IndexHTTPfield;   HTTPfield = "/n" + HHField.ToString().Replace('_', '-') + ": "; //Ajout de /n devant pour éviter les doublons entre cookie et set_cookie   // Si le champ n'est pas présent dans la requête, on passe au champ suivant   Index = Header.IndexOf(HTTPfield);   if (Index == -1)    continue;   buffer = Header.Substring(Index + HTTPfield.Length);   Index = buffer.IndexOf("/r/n");   if (Index == -1)    m_StrHTTPField[IndexHTTPfield] = buffer.Trim();   else    m_StrHTTPField[IndexHTTPfield] = buffer.Substring(0, Index).Trim();   //Console.WriteLine("Index = " + IndexHTTPfield + " | champ = " + HTTPfield.Substring(1) + " " + m_StrHTTPField[IndexHTTPfield]);  }  // Affichage de tout les champs  /*for (int j = 0; j < m_StrHTTPField.Length; j++)  {   HHField = (HTTPHeaderField)j;   Console.WriteLine("m_StrHTTPField[" + j + "]; " + HHField + " = " + m_StrHTTPField[j]);  }  */  #endregion } #endregion}

编写以下代码以实现解析文件：

class Program{ static void Main(string[] args) {  SRART: Console.WriteLine("输入待解析的HTTP报文数据文件完整路径：");  var filename = Console.ReadLine();  try  {   FileStream fs = new FileStream(filename, FileMode.Open);   BinaryReader br = new BinaryReader(fs);   var data = br.ReadBytes((int)fs.Length);   var header = new HTTPHeader(data);   var x = 0;   foreach (var f in header.HTTPField)   {    if (!String.IsNullOrEmpty(f))    {     Console.WriteLine($"[{x:00}] - {(HTTPHeaderField) x} : {f}");    }    x++;   }   Console.WriteLine($"总数据尺寸{fs.Length}字节，实际数据尺寸{header.Data.Length}字节");   Console.WriteLine(Encoding.UTF8.GetString(header.Data));   Console.WriteLine();   br.Close();   fs.Close();    }  catch (Exception e)  {   Console.WriteLine(e);  }  goto SRART; }}

这里还未实现gzip解压缩和字符解码，直接用UTF8解码输出的。（需要时再写吧，都是体力活儿~）

效果图展示：