create mini http client

go.mod

@@ -0,0 +1,3 @@
+module git.3crabs.ru/VLADIMIR/net
+
+go 1.20

http/client.go

@@ -0,0 +1,87 @@
+package http
+
+import (
+	"bufio"
+	"errors"
+	"fmt"
+	"io"
+	"net"
+	"strconv"
+	"strings"
+)
+
+func Do(method string, url string) (*Response, error) {
+	path := "/"
+	arr := strings.Split(url, "/")
+	if len(arr) == 2 {
+		path = arr[1]
+	}
+	if !strings.HasPrefix(path, "/") {
+		path = "/" + path
+	}
+
+	conn, err := net.Dial("tcp", arr[0])
+	if err != nil {
+		return nil, errors.New("connect " + arr[0])
+	}
+	defer conn.Close()
+
+	WriteRequest(conn, method, path, "HTTP/1.0")
+	return ReadResponse(conn)
+}
+
+func WriteRequest(w io.Writer, method string, path string, httpVersion string) {
+	fmt.Fprintf(w, "%s %s %s\r\n\r\n", method, path, httpVersion)
+}
+
+func ReadResponse(r io.Reader) (*Response, error) {
+	response := &Response{}
+
+	b := bufio.NewReader(r)
+
+	status, err := b.ReadString('\n')
+	if err != nil {
+		return response, errors.New("read status")
+	}
+	arr := strings.Split(status, " ")
+	response.StatusCode, err = strconv.Atoi(arr[1])
+	if err != nil {
+		return response, errors.New("read status code")
+	}
+
+	headerStr := ""
+	for {
+		headerStr, err = b.ReadString('\n')
+		if err != nil {
+			return response, errors.New("read header")
+		}
+		if headerStr == "\r\n" {
+			break
+		}
+		arr := strings.Split(headerStr, ": ")
+		value := strings.TrimSpace(arr[1])
+		response.Headers = append(response.Headers, &Header{Name: arr[0], Value: value})
+	}
+
+	contentTypeHeader, err := response.GetHeader("Content-Length")
+	if err != nil {
+		return response, errors.New("get Content-Length")
+	}
+	length, err := strconv.Atoi(contentTypeHeader.Value)
+	if err != nil {
+		return response, errors.New("read Content-Length")
+	}
+
+	body := make([]byte, 0, length)
+
+	for i := 0; i < length; i++ {
+		r, err := b.ReadByte()
+		if err != nil {
+			return response, errors.New("read body")
+		}
+		body = append(body, r)
+	}
+	response.Body = body
+
+	return response, nil
+}

http/header.go

@@ -0,0 +1,6 @@
+package http
+
+type Header struct {
+	Name  string
+	Value string
+}

http/response.go

@@ -0,0 +1,24 @@
+package http
+
+import (
+	"errors"
+)
+
+var (
+	ErrHeaderNotFound = errors.New("header not found")
+)
+
+type Response struct {
+	StatusCode int
+	Headers    []*Header
+	Body       []byte
+}
+
+func (r *Response) GetHeader(name string) (*Header, error) {
+	for _, h := range r.Headers {
+		if h.Name == name {
+			return h, nil
+		}
+	}
+	return nil, ErrHeaderNotFound
+}

test_client/main.go

@@ -0,0 +1,15 @@
+package main
+
+import (
+	"fmt"
+
+	"git.3crabs.ru/VLADIMIR/net/http"
+)
+
+func main() {
+	r, err := http.Do("GET", "127.0.0.1:8081")
+	if err != nil {
+		panic(err)
+	}
+	fmt.Println(r.StatusCode, string(r.Body))
+}

test_server/main.go

@@ -0,0 +1,14 @@
+package main
+
+import (
+	"fmt"
+	"net/http"
+)
+
+func main() {
+	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+		fmt.Fprintf(w, "Hello World!")
+		w.WriteHeader(200)
+	})
+	http.ListenAndServe(":8081", nil)
+}