Basic server
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commit
b740f57488
210
main.go
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210
main.go
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@ -0,0 +1,210 @@
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package main
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import (
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"errors"
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"fmt"
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"io"
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"log"
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"net"
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"os"
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"strings"
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"time"
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)
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type HTTPMethod string
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const (
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HTTPMETHOD_GET HTTPMethod = "GET"
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HTTPMETHOD_POST HTTPMethod = "POST"
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)
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/*
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A request-line begins with a method token, followed by a single space
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(SP), the request-target, another single space (SP), the protocol
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version, and ends with CRLF.
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request-line = method SP request-target SP HTTP-version CRLF
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HTTP-version = HTTP-name "/" DIGIT "." DIGIT
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*/
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type RequestLine struct {
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Method HTTPMethod
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RequestTarget string
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HTTPVersion string
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}
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/*
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The first line of a response message is the status-line, consisting
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of the protocol version, a space (SP), the status code, another
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space, a possibly empty textual phrase describing the status code,
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and ending with CRLF.
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status-line = HTTP-version SP status-code SP reason-phrase CRLF
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*/
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type StatusLine struct {
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}
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/*
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All HTTP/1.1 messages consist of a start-line followed by a sequence
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of octets in a format similar to the Internet Message Format
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[RFC5322]: zero or more header fields (collectively referred to as
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the "headers" or the "header section"), an empty line indicating the
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end of the header section, and an optional message body.
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HTTP-message = start-line
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*( header-field CRLF )
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CRLF
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[ message-body ]
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*/
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type HTTPRequest struct {
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StartLine RequestLine
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}
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type HTTPResponse struct {
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StartLine StatusLine
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}
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func printDiff(s1, s2 string) {
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length := len(s1)
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if len(s2) > length {
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length = len(s2)
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}
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for i := 0; i < length; i++ {
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var char1, char2 byte
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if i < len(s1) {
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char1 = s1[i]
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} else {
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char1 = ' ' // padding for shorter string
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}
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if i < len(s2) {
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char2 = s2[i]
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} else {
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char2 = ' ' // padding for shorter string
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}
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if char1 != char2 {
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fmt.Printf("Difference at index %d: '%c' != '%c'\n", i, char1, char2)
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}
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}
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}
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func ParseHTTPRequest(b []byte) (HTTPRequest, error) {
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ret := HTTPRequest{}
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rs := string(b[:])
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method, rs, found := strings.Cut(rs, " ")
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if !found {
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return ret, errors.New("could not find method in request")
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}
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method = strings.ToUpper(strings.TrimSpace(method))
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ret.StartLine = RequestLine{}
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switch method {
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case string(HTTPMETHOD_GET):
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ret.StartLine.Method = HTTPMETHOD_GET
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case string(HTTPMETHOD_POST):
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ret.StartLine.Method = HTTPMETHOD_POST
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default:
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if method != "GET" {
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result1 := strings.Compare("GET", method)
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fmt.Println(result1)
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fmt.Println(len("GET"), len(method))
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}
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return ret, fmt.Errorf("unsupported method '%s'", method)
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}
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rt, rs, found := strings.Cut(rs, " ")
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if !found {
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return ret, errors.New("could not find target in request")
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}
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ret.StartLine.RequestTarget = rt
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hv, rs, found := strings.Cut(rs, "\r\n")
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if !found {
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return ret, errors.New("could not find http version in request")
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}
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if hv != "HTTP/1.0" && hv != "HTTP/1.1" {
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return ret, fmt.Errorf("unsupported http version %s", hv)
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}
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ret.StartLine.HTTPVersion = hv
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fmt.Println("rm: ", rs)
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return ret, nil
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}
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func main() {
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logger := log.New(os.Stdout, "DWSHTTP", log.LstdFlags)
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l, err := net.Listen("tcp", ":4221")
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if err != nil {
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logger.Fatal(err)
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}
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defer l.Close()
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logger.Print("Started server on 4221")
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for {
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conn, err := l.Accept()
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if err != nil {
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logger.Fatal(err)
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}
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logger.Printf("New connection: %s", conn.RemoteAddr().String())
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go func(c net.Conn) {
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defer c.Close()
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bSize := 0
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rSize := 256
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buf := make([]byte, bSize)
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tmp := make([]byte, rSize)
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err := c.SetReadDeadline(time.Now().Add(time.Second * 5))
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if err != nil {
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logger.Printf("ERROR %s - (%s) %s", c.RemoteAddr().String(), "connsetup", err)
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}
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for {
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n, err := c.Read(tmp)
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if err != nil {
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if err != io.EOF {
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logger.Fatalf("ERROR %s - (%s) %s", c.RemoteAddr().String(), "unexpected error while reading", err)
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}
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break
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}
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buf = append(buf, tmp[:n]...)
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if n > 0 {
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if n < rSize {
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break
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}
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continue
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}
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}
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req, err := ParseHTTPRequest(buf)
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if err != nil {
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logger.Printf("ERROR %s - (%s) %s", c.RemoteAddr().String(), "parsing", err)
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bw, err := c.Write([]byte("HTTP/1.1 500 Internal Server Error\r\n\r\n"))
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if err != nil {
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logger.Printf("ERROR %s - (Could not write err) %s", c.RemoteAddr().String(), err)
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return
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}
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if bw < 1 {
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return
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}
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}
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logger.Printf("%s - %s - %s -> 200", req.StartLine.Method, req.StartLine.HTTPVersion, req.StartLine.RequestTarget)
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bw, err := c.Write([]byte("HTTP/1.1 200 OK\r\n\r\n"))
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if err != nil {
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logger.Printf("ERROR %s - (Could not write err) %s", c.RemoteAddr().String(), err)
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return
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}
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if bw < 1 {
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return
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}
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}(conn)
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}
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}
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