CS144 lab0 笔记 📒

如果是 MacBook (with the ARM64 M1 chip)

sudo -i切换为 root 用户

2、输入dhclient -v

再输入ifconfig就可以看到多了一个 ip 地址

有的同学说重启后命令失效，请参考下面的方法： 1、执行vim ~/.bashrc 2、在最后一行添加dhclient -v 3、保存退出 4、执行source ~/.bashrc使其立即生效

Preparations

cs144 官网

Virtual machine setup instructions

Lab_FAQs

origin https://github.com/cs144/sponge (fetch) origin https://github.com/cs144/sponge (push)

cs144@cs144vm:~/sponge/build$ git config --list
user.email=FacundoChan01@gmail.com
user.name=Facundo Chan
core.editor=vim
core.repositoryformatversion=0
core.filemode=true
core.bare=false
core.logallrefupdates=true
remote.origin.url=https://github.com/cs144/sponge
remote.origin.fetch=+refs/heads/*:refs/remotes/origin/*
branch.master.remote=origin
branch.master.merge=refs/heads/master
branch.lab0-startercode.remote=origin
branch.lab0-startercode.merge=refs/heads/lab0-startercode
branch.lab1-startercode.remote=origin
branch.lab1-startercode.merge=refs/heads/lab1-startercode
branch.lab2-startercode.remote=origin
branch.lab2-startercode.merge=refs/heads/lab2-startercode

推荐使用：vscode + ssh 连接虚拟机

Lab Checkpoint 0: networking warmup

2.1 Fetch a Web page

$ telnet cs144.keithw.org http
Trying 104.196.238.229...
Connected to cs144.keithw.org.
Escape character is '^]'.

输入下面的内容（太慢可能会关闭，可以先输入好后复制粘贴）。Hit the Enter key two times

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

HTTP/1.1 200 OK
Date: Fri, 28 Oct 2022 16:55:15 GMT
Server: Apache
Last-Modified: Thu, 13 Dec 2018 15:45:29 GMT
ETag: "e-57ce93446cb64"
Accept-Ranges: bytes
Content-Length: 14
Connection: close
Content-Type: text/plain

Hello, CS144!
Connection closed by foreign host.

2.3 Listening and connecting

可能出现下面的错误：

cs144@cs144vm:~/sponge/build$ netcat -v -l -p 9090
netcat: getnameinfo: Temporary failure in name resolution

The problem could be with the DNS resolver. Try updating the namespace in /etc/resolv.conf as follows.

nameserver 8.8.8.8

3.4 Writing webget

void get_URL(const string &host, const string &path) {
    // Your code here.

    // initialize variables
    TCPSocket Tsocket;
    Address addr = Address(host, "http");

    Tsocket.connect(addr);
    // Write a string, possibly blocking until all is written
    string msg = "GET " + path + " HTTP/1.1\r\n" +
                 "Host: " + host + "\r\n" +
                 "Connection: close\r\n\r\n";
    Tsocket.write(msg);
    // socket.h -> SHUT_RD/WR/RDWR，先用SHUT_WR关闭写，避免服务器等待
    Tsocket.shutdown(SHUT_WR);
    while(!Tsocket.eof()){
        cout << Tsocket.read();
    }
    Tsocket.close();
}

4 An in-memory reliable byte stream

// byte_stream.hh
class ByteStream {
  private:
    // Your code here -- add private members as necessary.

    std::deque<char> _deque{};
    size_t _capacity;
    // size_t _buffer_size;  // == _deque.size() [dynamic]
    size_t _bytes_written;
    size_t _bytes_read;
    // size_t _remaining_capacity;  // _
    bool _input_ended;
    // bool _buffer_empty;
    // bool _eof;  // _buffer_empty && _input_ended

    ...
}

ByteStream::ByteStream(const size_t capacity)
    : _capacity(capacity), _bytes_written(0), _bytes_read(0),
      _input_ended(false)
{
    // DUMMY_CODE(capacity);
}

size_t ByteStream::write(const string &data) {
    // DUMMY_CODE(data);
    size_t input_size = min(remaining_capacity(), data.length());
    for(size_t i = 0; i < input_size; ++i){
        _deque.emplace_back(data[i]);
    }
    _bytes_written += input_size;
    return input_size;
}

//! \param[in] len bytes will be copied from the output side of the buffer
string ByteStream::peek_output(const size_t len) const {
    // DUMMY_CODE(len);
    string output = "";
    size_t output_size = min(buffer_size(), len);
    for(size_t i = 0; i < output_size; ++i){
        output += _deque[i];
    }
    // _bytes_read += output_size; // READ-ONLY!
    return output;
}

//! \param[in] len bytes will be removed from the output side of the buffer
void ByteStream::pop_output(const size_t len) {
    // DUMMY_CODE(len);
    size_t pop_size = min(buffer_size(), len);
    for(size_t i = 0; i < pop_size; ++i){
        _deque.pop_front();
    }
    _bytes_read += pop_size;
}

//! 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) {
    // DUMMY_CODE(len);
    string ret = peek_output(len);
    pop_output(len);
    return ret;
}

void ByteStream::end_input() { _input_ended = true; }

bool ByteStream::input_ended() const { return _input_ended; }

size_t ByteStream::buffer_size() const { return _deque.size(); }

bool ByteStream::buffer_empty() const { return buffer_size() == 0; }

bool ByteStream::eof() const { return buffer_empty() && input_ended(); }

size_t ByteStream::bytes_written() const { return _bytes_written; }

size_t ByteStream::bytes_read() const { return _bytes_read; }

size_t ByteStream::remaining_capacity() const { return _capacity - buffer_size(); }