Quartz 4

cs144-lab0：网络热身

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cs144-lab0：网络热身

lab0.pdf

项目实现：https://github.com/hyperv0id/cs144

1-环境搭建

1.1-wsl安装

  1. 开启wsl2：https://docs.microsoft.com/en-us/windows/wsl/install

  2. 安装Linux环境：

    1. Ubuntu：https://ubuntu.com/tutorials/install-ubuntu-on-wsl2-on-windows-10
    2. 从包中安装：https://docs.microsoft.com/zh-cn/windows/wsl/install#ways-to-run-multiple-linux-distributions-with-wsl

  3. 安装课程依赖：https://stanford.edu/class/cs144/vm_howto/vm-howto-iso.html#install_packages

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2-网络实验

2.1-获取网页

在终端输入命令：这个命令表示使用telnet给网页发送http请求

telnet cs144.keithw.org http

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显示成这样就表示连接成功，不过我们还得配置请求头：

GET /hello HTTP/1.1
Host: cs144.keithw.org
Connection: close

回车两次，会出现下列内容，如果超时了再试一次

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如果手速过慢会失败，这时可以将header保存为文件，使用管道传输给telnet

cat lab0_2.1.in - | telnet cs144.keithw.org http # 从 lab0_2.1.in 文件中读取数据并自动输入到telnet

作业:

现在您已经知道如何手动获取Web页面，向我们展示您可以!使用上述技术获取URL http://cs144.keithw.org/lab0/sunetid，将sunetid替换为您自己的主SUNet ID。你会在“X-Your-Code-Is:”的标题中收到一个密码。保存您的SUNet ID和代码，以便写入您的记录。

telnet cs144.keithw.org http

GET /lab0/43998848 HTTP/1.1 Host: cs144.keithw.org Connection: close

输出：

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2.2-发送邮件

这个需要斯坦福学生身份

2.3-双工通信

打开两个终端，先后分别输入

netcat -v -l -p 9090
telnet localhost 9090

这分别表示在创建服务器并监听9090端口，和连接9090端口，成功效果如下

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这时两边已经建立通信，可以对话了

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3-系统socket

下面我们将编写获取网页的小程序

3.1-启动代码

1 - 克隆项目地址

git clone https://github.com/cs144/sponge

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2 - 构建项目

cd sponge
mkdir build
cd build
cmake ..
make -j4

3.2-C++

3.3-sponge项目文档

  1. 文档地址：https://cs144.github.io/doc/lab0

  2. 特别注意FileDescriptor，Socket，TCPSocket和Address类。(注意，套接字是FileDescriptor的一种类型，TCPSocket是套接字的一种类型。)

  3. 阅读头文件： file_descriptor.hh、socket.hh、address.hh

3.4-实现webget方法

void get_URL(const string &host, const string &path) {
    
    // 1. 建立 TCP 连接
 
    Address addr(host, "http");
    TCPSocket sc; // 创建 TCP 连接对象
    sc.connect(addr); // 连接到远程地址
 
    // Your code here.
 
    // You will need to connect to the "http" service on
    // the computer whose name is in the "host" string,
    // then request the URL path given in the "path" string.
    
    // 2. 发送HTTP请求
    string msg = "GET " + path + " HTTP/1.1\r\n"; //注意必须以 \r\n 结尾
    msg += "Host: "+host+"\r\n";
    msg += "Connection: closed\r\n\r\n";
    sc.write(msg);
    sc.shutdown(SHUT_WR); // 表示不在向对方传输信息
 
    // Then you'll need to print out everything the server sends back,
    // (not just one call to read() -- everything) until you reach
    // the "eof" (end of file).
 
    // 3. 从服务端接收消息
    while (!sc.eof())
    {
        cout << sc.read();
    }
 
    // 4. 关闭 TCP 连接
    sc.close(); 
 
    // cerr << "Function called: get_URL(" << host << ", " << path << ").\n";
    // cerr << "Warning: get_URL() has not been implemented yet.\n";
}
// ./apps/webget cs144.keithw.org /hello 
// make check_webget

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4-内存可靠的字节流

头文件

#ifndef SPONGE_LIBSPONGE_BYTE_STREAM_HH
#define SPONGE_LIBSPONGE_BYTE_STREAM_HH
 
#include <string>
#include<deque>
 
//! \brief An in-order byte stream.
 
//! Bytes are written on the "input" side and read from the "output"
//! side.  The byte stream is finite: the writer can end the input,
//! and then no more bytes can be written.
class ByteStream {
  private:
    // Your code here -- add private members as necessary.
 
    // Hint: This doesn't need to be a sophisticated data structure at
    // all, but if any of your tests are taking longer than a second,
    // that's a sign that you probably want to keep exploring
    // different approaches.
 
    std::deque<char> _buf = {}; // 数据流对象
    size_t _capa = 0; // 容量大小
    size_t nread = 0, nwrite = 0; //读写字符数
    
    bool is_end = false; // 是否结束
 
    bool _error{};  //!< Flag indicating that the stream suffered an error.
 
  public:
//...
}

源文件

#include "byte_stream.hh"
 
// Dummy implementation of a flow-controlled in-memory byte stream.
 
// For Lab 0, please replace with a real implementation that passes the
// automated checks run by `make check_lab0`.
 
// You will need to add private members to the class declaration in `byte_stream.hh`
 
template <typename... Targs>
void DUMMY_CODE(Targs &&... /* unused */) {}
 
using namespace std;
 
ByteStream::ByteStream(const size_t capacity) { 
    _capa = capacity;
    nwrite = 0;
    nread = 0;
}
 
size_t ByteStream::write(const string &data) {
    size_t nadd = min(_capa - _buf.size(), data.length());
    this->nwrite += nadd;
    for (size_t i = 0; i < nadd; i++)
    {
        _buf.push_back(data[i]);
    }
    
    return nadd;
}
 
//! \param[in] len bytes will be copied from the output side of the buffer
string ByteStream::peek_output(const size_t len) const {
    size_t length = min(len, _buf.size());
 
    return string().assign(_buf.begin(), _buf.begin()+length);
}
 
//! \param[in] len bytes will be removed from the output side of the buffer
void ByteStream::pop_output(const size_t len) { 
    size_t length = min(len, _buf.size());
    this->nread += length;
    while(length--)
    {
        _buf.pop_front();
    }
}
 
//! Read (i.e., copy and then pop) the next "len" bytes of the stream
//! \param[in] len bytes will be popped and returned
//! \returns a string
std::string ByteStream::read(const size_t len) {
    string msg = peek_output(len);
    pop_output(len);
 
    return msg;
}
 
void ByteStream::end_input() {this->is_end = true;}
 
bool ByteStream::input_ended() const { return is_end; }
 
size_t ByteStream::buffer_size() const { return _buf.size(); }
 
bool ByteStream::buffer_empty() const { return _buf.empty(); }
 
bool ByteStream::eof() const { return _buf.empty() && is_end; }
 
size_t ByteStream::bytes_written() const { return nwrite; }
 
size_t ByteStream::bytes_read() const { return nread; }
 
size_t ByteStream::remaining_capacity() const { return _capa - _buf.size(); }

功能测试

更新代码并测试

make
make check_lab0

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存档

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