Rust Web 全栈开发（二）：构建 HTTP Server

Rust Web 全栈开发（二）：构建 HTTP Server

• [Rust Web 全栈开发（二）：构建 HTTP Server](#Rust Web 全栈开发（二）：构建 HTTP Server)
• • 创建成员包/库：httpserver、http
  • [解析 HTTP 请求](#解析 HTTP 请求)
  • • [HTTP 请求的构成](#HTTP 请求的构成)
    • [构建 HttpRequest](#构建 HttpRequest)
  • [构建 HTTP 响应](#构建 HTTP 响应)
  • • [HTTP 响应的构成](#HTTP 响应的构成)
    • [构建 HttpResponse](#构建 HttpResponse)
    • • lib

Rust Web 全栈开发（二）：构建 HTTP Server

参考视频：https://www.bilibili.com/video/BV1RP4y1G7KF

Web Server 的消息流动图：

Server：监听 TCP 字节流

Router：接收 HTTP 请求，并决定调用哪个 Handler

Handler：处理 HTTP 请求，构建 HTTP 响应

HTTP Library：

• 解释字节流，把它转换为 HTTP 请求
• 把 HTTP 响应转换回字节流

构建步骤：

1. 解析 HTTP 请求消息
2. 构建 HTTP 响应消息
3. 路由与 Handler
4. 测试 Web Server

创建成员包/库：httpserver、http

在原项目下新建成员包 httpserver、成员库 http：

cargo new httpserver
cargo new --lib http

在工作区内运行 cargo new 会自动将新创建的包添加到工作区内 Cargo.toml 的 [workspace] 定义中的 members 键中，如下所示：

在 http 成员库的 src 目录下新建两个文件：httprequest.rs、httpresponse.rs。

此时，我们可以通过运行 cargo build 来构建工作区。项目目录下的文件应该是这样的：

├── Cargo.lock
├── Cargo.toml
├── httpserver
│   ├── Cargo.toml
│   └── src
│       └── main.rs
├── http
│   ├── Cargo.toml
│   └── src
│       └── lib.rs
│       └── httprequest.rs
│       └── httpresponse.rs
├── tcpclient
│   ├── Cargo.toml
│   └── src
│       └── main.rs
├── tcpserver
│   ├── Cargo.toml
│   └── src
│       └── main.rs
└── target

解析 HTTP 请求

HTTP 请求的构成

HTTP 请求报文由 3 部分组成：请求行、请求头、请求体。

构建 HttpRequest

3 个数据结构：

名称	类型	描述
HttpRequest	struct	表示 HTTP 请求
Method	enum	指定所允许的 HTTP 方法
Version	enum	指定所允许的 HTTP 版本

以上 3 个数据结构都需要实现的 3 个 trait：

名称	描述
From<&str>	用于把传进来的字符串切片转换为 HttpRequest
Debug	打印调试信息
PartialEq	用于解析和自动化测试脚本里做比较

打开 http 成员库中的 httprequest.rs，编写代码：

use std::collections::HashMap;

#[derive(Debug, PartialEq)]
pub enum Method {
    Get,
    Post,
    Uninitialized,
}
impl From<&str> for Method {
    fn from(s: &str) -> Method {
        match s {
            "GET" => Method::Get,
            "POST" => Method::Post,
            _ => Method::Uninitialized,
        }
    }
}

#[derive(Debug, PartialEq)]
pub enum Version {
    V1_1,
    V2_0,
    Uninitialized,
}

impl From<&str> for Version {
    fn from(s: &str) -> Version {
        match s {
            "HTTP/1.1" => Version::V1_1,
            _ => Version::Uninitialized,
        }
    }
}

#[derive(Debug, PartialEq)]
pub enum Resource {
    Path(String),
}

#[derive(Debug)]
pub struct HttpRequest {
    pub method: Method,
    pub resource: Resource,
    pub version: Version,
    pub headers: HashMap<String, String>,
    pub body: String,
}

impl From<String> for HttpRequest {
    fn from(request: String) -> HttpRequest {
        let mut parsed_method = Method::Uninitialized;
        let mut parsed_resource = Resource::Path("".to_string());
        let mut parsed_version =  Version::V1_1;
        let mut parsed_headers = HashMap::new();
        let mut parsed_body = "";

        for line in request.lines() {
            if line.contains("HTTP") {
                let (method, resource, version) = process_request_line(line);
                parsed_method = method;
                parsed_resource = resource;
                parsed_version = version;
            } else if line.contains(":") {
                let (key, value) = process_header_line(line);
                parsed_headers.insert(key, value);
            } else if line.len() == 0 {

            } else {
                parsed_body = line;
            }
        }

        HttpRequest {
            method: parsed_method,
            resource: parsed_resource,
            version: parsed_version,
            headers: parsed_headers,
            body: parsed_body.to_string(),
        }
    }
}

fn process_header_line(s: &str) -> (String, String) {
    let mut header_items = s.split(":");
    let mut key = String::from("");
    let mut value = String::from("");

    if  let Some(k) = header_items.next() {
        key = k.to_string();
    }
    if let Some(v) = header_items.next() {
        value = v.to_string();
    }

    (key, value)
}

fn process_request_line(s: &str) -> (Method, Resource, Version) {
    let mut words = s.split_whitespace();
    let method = words.next().unwrap();
    let resource = words.next().unwrap();
    let version = words.next().unwrap();

    (
        method.into(),
        Resource::Path(resource.to_string()),
        version.into()
    )
}

#[cfg(test)]
mod test {
    use super::*;

    #[test]
    fn test_method_into() {
        let method: Method = "GET".into();
        assert_eq!(method, Method::Get);
    }

    #[test]
    fn test_version_into() {
        let version: Version = "HTTP/1.1".into();
        assert_eq!(version, Version::V1_1);
    }

    #[test]
    fn test_read_http() {
        let s = String::from("GET /greeting HTTP/1.1\r\nHost: localhost:3000\r\nUser-Agent: curl/7.71.1\r\nAccept: */*\r\n\r\n");

        let mut headers_excepted = HashMap::new();
        headers_excepted.insert("Host".into(), " localhost".into());
        headers_excepted.insert("Accept".into(), " */*".into());
        headers_excepted.insert("User-Agent".into(), " curl/7.71.1".into());

        let request: HttpRequest = s.into();

        assert_eq!(request.method, Method::Get);
        assert_eq!(request.resource, Resource::Path("/greeting".to_string()));
        assert_eq!(request.version, Version::V1_1);
        assert_eq!(request.headers, headers_excepted);
    }
}

运行命令 cargo test -p http，测试 http 成员库。

3 个测试都通过了：

构建 HTTP 响应

HTTP 响应的构成

HTTP 响应报文由 3 部分组成：响应行、响应头、响应体。

构建 HttpResponse

HttpResponse 需要实现的方法或 trait：

名称	描述
Default trait	指定成员的默认值
From trait	将 HttpResponse 转化为 String
new()	使用默认值创建一个新的 HttpResponse 结构体
getter 方法	获取 HttpResponse 成员变量的值
send_response()	构建响应，将原始字节通过 TCP 传送

打开 http 成员库中的 httpresponse.rs，编写代码：

use std::collections::HashMap;
use std::io::{Result, Write};

#[derive(Debug, PartialEq, Clone)]
pub struct HttpResponse<'a> {
    version: &'a str,
    status_code: &'a str,
    status_text: &'a str,
    headers: Option<HashMap<&'a str, &'a str>>,
    body: Option<String>,
}

impl<'a> Default for HttpResponse<'a> {
    fn default() -> Self {
        Self {
            version: "HTTP/1.1".into(),
            status_code: "200".into(),
            status_text: "OK".into(),
            headers: None,
            body: None,
        }
    }
}

impl<'a> From<HttpResponse<'a>> for String {
    fn from(response: HttpResponse) -> String {
        let res = response.clone();
        format!(
            "{} {} {}\r\n{}Content-Length: {}\r\n\r\n{}",
            &res.version(),
            &res.status_code(),
            &res.status_text(),
            &res.headers(),
            &response.body.unwrap().len(),
            &res.body(),
        )
    }
}

impl<'a> HttpResponse<'a> {
    pub fn new(
        status_code: &'a str,
        headers: Option<HashMap<&'a str, &'a str>>,
        body: Option<String>,
    ) -> HttpResponse<'a> {
        let mut response: HttpResponse<'a> = HttpResponse::default();
        if status_code != "200" {
            response.status_code = status_code.into();
        }
        response.status_text = match response.status_code {
            // 消息
            "100" => "Continue".into(),
            "101" => "Switching Protocols".into(),
            "102" => "Processing".into(),
            // 成功
            "200" => "OK".into(),
            "201" => "Created".into(),
            "202" => "Accepted".into(),
            "203" => "Non-Authoritative Information".into(),
            "204" => "No Content".into(),
            "205" => "Reset Content".into(),
            "206" => "Partial Content".into(),
            "207" => "Multi-Status".into(),
            // 重定向
            "300" => "Multiple Choices".into(),
            "301" => "Moved Permanently".into(),
            "302" => "Move Temporarily".into(),
            "303" => "See Other".into(),
            "304" => "Not Modified".into(),
            "305" => "Use Proxy".into(),
            "306" => "Switch Proxy".into(),
            "307" => "Temporary Redirect".into(),
            // 请求错误
            "400" => "Bad Request".into(),
            "401" => "Unauthorized".into(),
            "402" => "Payment Required".into(),
            "403" => "Forbidden".into(),
            "404" => "Not Found".into(),
            "405" => "Method Not Allowed".into(),
            "406" => "Not Acceptable".into(),
            "407" => "Proxy Authentication Required".into(),
            "408" => "Request Timeout".into(),
            "409" => "Conflict".into(),
            "410" => "Gone".into(),
            "411" => "Length Required".into(),
            "412" => "Precondition Failed".into(),
            "413" => "Request Entity Too Large".into(),
            "414" => "Request-URI Too Long".into(),
            "415" => "Unsupported Media Type".into(),
            "416" => "Requested Range Not Satisfiable".into(),
            "417" => "Expectation Failed".into(),
            "421" => "Misdirected Request".into(),
            "422" => "Unprocessable Entity".into(),
            "423" => "Locked".into(),
            "424" => "Failed Dependency".into(),
            "425" => "Too Early".into(),
            "426" => "Upgrade Required".into(),
            "449" => "Retry With".into(),
            "451" => "Unavailable For Legal Reasons".into(),
            // 服务器错误
            "500" => "Internal Server Error".into(),
            "501" => "Not Implemented".into(),
            "502" => "Bad Gateway".into(),
            "503" => "Service Unavailable".into(),
            "504" => "Gateway Timeout".into(),
            "505" => "HTTP Version Not Supported".into(),
            "506" => "Variant Also Negotiates".into(),
            "507" => "Insufficient Storage".into(),
            "509" => "Bandwidth Limit Exceeded".into(),
            "510" => "Not Extended".into(),
            "600" => "Unparseable Response Headers".into(),
            _ => "Not Found".into(),
        };
        response.headers = match &headers {
            Some(_h) => headers,
            None => {
                let mut header = HashMap::new();
                header.insert("Content-Type", "text/html");
                Some(header)
            }
        };
        response.body = body;

        response
    }

    fn version(&self) -> &str {
        self.version
    }

    fn status_code(&self) -> &str {
        self.status_code
    }

    fn  status_text(&self) -> &str {
        self.status_text
    }

    fn headers(&self) -> String {
        let map = self.headers.clone().unwrap();
        let mut headers_string = "".into();
        for (key, value) in map.iter() {
            headers_string = format!("{headers_string}{}:{}\r\n", key, value);
        }

        headers_string
    }

    fn body(&self) -> &str {
        match &self.body {
            Some(b) => b.as_str(),
            None => "",
        }
    }

    pub fn send_response(&self, write_stream: &mut impl Write) -> Result<()> {
        let response = self.clone();
        let response_string: String = String::from(response);
        let _ = write!(write_stream, "{}", response_string);

        Ok(())
    }
}

#[cfg(test)]
mod test {
    use super::*;

    #[test]
    fn test_response_struct_creation_200() {
        let response_actual = HttpResponse::new(
            "200",
            None,
            Some("xxxx".into()),
        );
        let response_excepted = HttpResponse {
            version: "HTTP/1.1",
            status_code: "200",
            status_text: "OK",
            headers: {
                let mut h = HashMap::new();
                h.insert("Content-Type", "text/html");
                Some(h)
            },
            body: Some("xxxx".into()),
        };

        assert_eq!(response_actual, response_excepted);
    }

    #[test]
    fn test_response_struct_creation_404() {
        let response_actual = HttpResponse::new(
            "404",
            None,
            Some("xxxx".into()),
        );
        let response_excepted = HttpResponse {
            version: "HTTP/1.1",
            status_code: "404",
            status_text: "Not Found",
            headers: {
                let mut h = HashMap::new();
                h.insert("Content-Type", "text/html");
                Some(h)
            },
            body: Some("xxxx".into()),
        };

        assert_eq!(response_actual, response_excepted);
    }

    #[test]
    fn test_http_response_creation() {
        let response_excepted = HttpResponse {
            version: "HTTP/1.1",
            status_code: "404",
            status_text: "Not Found",
            headers: {
                let mut h = HashMap::new();
                h.insert("Content-Type", "text/html");
                Some(h)
            },
            body: Some("xxxx".into()),
        };

        let http_string: String = response_excepted.into();
        let actual_string = 
            "HTTP/1.1 404 Not Found\r\nContent-Type:text/html\r\nContent-Length: 4\r\n\r\nxxxx";

        assert_eq!(http_string, actual_string);
    }
}

运行命令 cargo test -p http，测试 http 成员库。

现在一共有 6 个测试，都通过了：

lib

打开 http 成员库中的 lib.rs，编写代码：

pub mod httprequest;
pub mod httpresponse;