HTTP 报文结构：手写一份原始报文

请求报文                          响应报文
┌─────────────────────────┐      ┌─────────────────────────┐
│ 请求行: 方法 路径 版本      │      │ 状态行: 版本 状态码 原因   │
│ GET /index.html HTTP/1.1 │      │ HTTP/1.1 200 OK          │
├─────────────────────────┤      ├─────────────────────────┤
│ 头部字段（每行一个键值对）  │      │ 头部字段                  │
│ Host: example.com        │      │ Content-Type: text/html  │
│ Accept: text/html        │      │ Content-Length: 1024     │
├─────────────────────────┤      ├─────────────────────────┤
│ 空行（头部结束的标志）      │      │ 空行                     │
├─────────────────────────┤      ├─────────────────────────┤
│ 报文体（可选）             │      │ 报文体                   │
└─────────────────────────┘      └─────────────────────────┘

GET /list/books?page=2 HTTP/1.1
 │        │               │
方法    请求目标         协议版本

python3 -c '
from http.server import BaseHTTPRequestHandler, HTTPServer
 
class Echo(BaseHTTPRequestHandler):
    def do_GET(self):
        body = ("请求行: " + self.requestline + "\n---头部---\n" + str(self.headers)).encode()
        self.send_response(200)
        self.send_header("Content-Type", "text/plain; charset=utf-8")
        self.send_header("Content-Length", str(len(body)))
        self.end_headers()
        self.wfile.write(body)
    def log_message(self, *args):
        pass
 
HTTPServer(("127.0.0.1", 8000), Echo).serve_forever()
' &
for _i in $(seq 1 50); do (exec 3<>/dev/tcp/127.0.0.1/8000) 2>/dev/null && break; sleep 0.1; done
 
# 一个最普通的 GET，再附加一个自定义头
curl -s "http://127.0.0.1:8000/books?page=2" -H "X-Debug: 1"

python3 -c '
import socket, threading
 
def server():
    srv = socket.socket()
    srv.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
    srv.bind(("127.0.0.1", 8001)); srv.listen(1)
    conn, _ = srv.accept()
    raw = conn.recv(65536)
    # repr 让 \r\n 显形
    print("== 收到的原始字节 ==")
    parts = raw.split(b"\r\n")
    for i, line in enumerate(parts):
        if i < len(parts) - 1:
            tag = "   <-- 空行，头部结束" if line == b"" else ""
            print(repr(line + b"\r\n") + tag)
        elif line:
            print(repr(line) + "   <-- 报文体（无 CRLF 结尾）")
    conn.sendall(b"HTTP/1.1 200 OK\r\nContent-Length: 3\r\n\r\nok\n")
    conn.close()
 
threading.Thread(target=server, daemon=True).start()
import time; time.sleep(0.2)
 
import subprocess
subprocess.run(["curl", "-s", "-X", "POST", "http://127.0.0.1:8001/login",
                "-H", "Content-Type: application/json",
                "-d", "{\"user\":\"ada\"}"], check=False)
'

python3 -c '
import socket, threading, time
 
RESP = (b"HTTP/1.1 200 OK\r\n"
        b"Content-Type: text/plain; charset=utf-8\r\n"
        b"X-Handmade: yes\r\n"
        b"Content-Length: 22\r\n"
        b"\r\n"
        b"hand-crafted response\n")
 
def server():
    srv = socket.socket()
    srv.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
    srv.bind(("127.0.0.1", 8002)); srv.listen(1)
    while True:
        conn, _ = srv.accept()
        conn.recv(65536)          # 读掉请求
        conn.sendall(RESP)
        conn.close()
 
threading.Thread(target=server, daemon=True).start()
time.sleep(0.2)
import subprocess
subprocess.run(["curl", "-v", "http://127.0.0.1:8002/"], check=False)
'