implemented HTTP 1.0/1.1 server

.gitignore

@@ -1,3 +1,4 @@
 /serveg.toml
 /serveg
 bin/
+__debug_bin*

cmd/serveg/main.go

@@ -22,29 +22,27 @@ func run() int {
 
 	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
 
-	configPath := *flag.String("config", "serveg.toml", "path to config file")
+	configPath := flag.String("config", "serveg.toml", "path to config file")
 	flag.Parse()
 
-	conf, err := server.ParseOrCreateConfig(configPath)
+	conf, err := server.ParseOrCreateConfig(*configPath)
 	if err != nil {
+		logger.Error("can't parse config: ", err)
+		return 1
+	}
+
+	srv := server.Server{Conf: conf}
+	if err := srv.StartGoroutine(); err != nil {
 		logger.Error(err)
 		return 1
 	}
 
-	errCh := make(chan error, 1)
-	go func() { errCh <- server.Serve(conf) }()
-	logger.Info("server started")
-
-	select {
-	// server failed to start
-	case err := <-errCh:
-		logger.Error(err)
-		return 1
 	// got SIGINT/SIGTERM
-	case <-ctx.Done():
-		stop() // restore default behaviour: a second Ctrl+C kills immediately
-		logger.Info("shutting down")
-	}
+	<-ctx.Done()
+	stop() // restore default behaviour: a second Ctrl+C kills immediately
+	logger.Info("shutting down")
+	// waits for server stop
+	srv.Stop()
 
 	return 0
 }

internal/http/Connection.go

@@ -0,0 +1,38 @@
+package http
+
+import (
+	"bufio"
+	"net"
+	sh "serveg/internal/string_helper"
+	"strings"
+)
+
+const maxHeaderBytes = 16 * 1024
+const initialWriteBufCap = 512
+
+type mapStrStr map[string]string
+type HeadersMap map[string]string
+
+type Connection struct {
+	socket *net.TCPConn
+	r      *bufio.Reader
+	wbuf   sh.StringBuilder
+}
+
+func NewConnection(socket *net.TCPConn) *Connection {
+	return &Connection{
+		socket: socket,
+		r:      bufio.NewReaderSize(socket, maxHeaderBytes),
+		wbuf:   sh.StringBuilder{Buf: make([]byte, 0, initialWriteBufCap)},
+	}
+}
+
+func HeaderValueContains(sourceSplit []string, target string) bool {
+	for _, v := range sourceSplit {
+		v = strings.TrimSpace(v)
+		if strings.EqualFold(v, target) {
+			return true
+		}
+	}
+	return false
+}

internal/http/Request.go

@@ -0,0 +1,172 @@
+package http
+
+import (
+	"net/url"
+	sh "serveg/internal/string_helper"
+	"strings"
+)
+
+type Request struct {
+	Method   string
+	Protocol string
+	// url-encoded characters (%D0), query params (?v=123)
+	PathRaw     string
+	Path        string
+	QueryParams mapStrStr
+	// keys are in lower case
+	// duplicate keys are joined with ", "
+	Headers HeadersMap
+	// if true, don't close connection after response
+	WantsKeepAlive bool
+}
+
+// Read request (body not supported)
+// Returns valid request pointer. If err != nil, req is partially parsed.
+// It doesn't enforce "Host" header because i don't need it in this project.
+//
+//	if httpErr, ok := errors.AsType[*http.HttpError](err); ok {
+//		// Request is malformed, socket buffer contains unread garbage data.
+//		// Send error code and close connection.
+//	} else {
+//		// something bad happened with the connection, just close it
+//	}
+func (conn *Connection) ReadRequest() (req *Request, err error) {
+	req = new(Request)
+	var readN int
+	// METHOD /path HTTP/ver
+	if err = conn.readFirstLine(req, &readN); err != nil {
+		return
+	}
+	// key: value
+	// ...
+	// empty line
+	if err = conn.readHeaders(req, &readN); err != nil {
+		return
+	}
+
+	// This server doesn't accept request bodies.
+	// Reject connection rather than desync the stream.
+	contentLength := req.Headers["content-length"]
+	transferEncoding := req.Headers["transfer-encoding"]
+	if (contentLength != "" && contentLength != "0") ||
+		transferEncoding != "" {
+		err = NewHttpError(StatusBadRequest,
+			"request bodies are not supported")
+	}
+
+	// set WantsKeepAlive
+	connectionStrSplit := strings.Split(req.Headers["connection"], ",")
+	if req.Protocol == "HTTP/1.0" {
+		req.WantsKeepAlive = HeaderValueContains(connectionStrSplit, "keep-alive")
+	} else {
+		req.WantsKeepAlive = !HeaderValueContains(connectionStrSplit, "close")
+	}
+
+	return
+}
+
+func (conn *Connection) readLineBelowLimit(readN *int) (string, error) {
+	// read up to maxHeaderBytes
+	slice, notLineEnd, err := conn.r.ReadLine()
+	if err != nil {
+		// something is wrong with tcp socket
+		return "", err
+	}
+	if notLineEnd {
+		// buffer end was reached but no '\n' found
+		return "", NewHttpError(StatusBadRequest, "line end not found")
+	}
+
+	*readN += len(slice) + 1 // \n
+	if *readN > maxHeaderBytes {
+		return "", NewHttpError(StatusRequestHeaderFieldsTooLarge,
+			"headers too large")
+	}
+
+	return strings.TrimRight(string(slice), " \r\n"), nil
+}
+
+func (conn *Connection) readFirstLine(req *Request, readN *int) error {
+	line, err := conn.readLineBelowLimit(readN)
+	if err != nil {
+		return err
+	}
+	// skip one empty line
+	// some clients send it between requests
+	if line == "" {
+		line, err = conn.readLineBelowLimit(readN)
+		if err != nil {
+			return err
+		}
+	}
+
+	parts := strings.Split(line, " ")
+	if len(parts) != 3 || !strings.HasPrefix(parts[2], "HTTP/") {
+		return NewHttpError(StatusBadRequest,
+			"malformed request line '"+line+"'")
+	}
+	req.Method = parts[0]
+	// url-encoded characters (%D0), query params (?v=123)
+	req.PathRaw = parts[1]
+	req.Protocol = parts[2]
+
+	if req.Protocol != "HTTP/1.0" && req.Protocol != "HTTP/1.1" {
+		return NewHttpError(StatusHTTPVersionNotSupported,
+			"request protocol not supported: "+req.Protocol)
+	}
+
+	u, err := url.ParseRequestURI(req.PathRaw)
+	if err != nil {
+		return NewHttpError(StatusBadRequest, err.Error())
+	}
+
+	req.Path = sh.ResolveSafePath(u.Path)
+	if req.Path == "" {
+		return NewHttpError(StatusForbidden,
+			"unsafe request path '"+u.Path+"'")
+	}
+	req.QueryParams = make(mapStrStr)
+	for key, values := range u.Query() {
+		req.QueryParams[key] = values[0]
+	}
+
+	return nil
+}
+
+func (conn *Connection) readHeaders(req *Request, readN *int) error {
+	req.Headers = make(HeadersMap)
+	for {
+		line, err := conn.readLineBelowLimit(readN)
+		if err != nil {
+			return err
+		}
+		// empty line means end of headers
+		if line == "" {
+			break
+		}
+
+		i := strings.IndexByte(line, ':')
+		if i < 1 {
+			return NewHttpError(StatusBadRequest,
+				"not a header line '"+line+"'")
+		}
+		key := line[:i]
+		firstB, lastB := key[0], key[i-1]
+		if firstB == ' ' || firstB == '\t' ||
+			lastB == ' ' || lastB == '\t' {
+			return NewHttpError(StatusBadRequest,
+				"header name must not start or end with space")
+		}
+		key = strings.ToLower(key)
+
+		// val can be empty
+		val := strings.TrimSpace(line[i+1:])
+		// if header repeats, join values with ", "
+		existing := req.Headers[key]
+		if existing != "" {
+			val = existing + ", " + val
+		}
+		req.Headers[key] = val
+	}
+	return nil
+}

internal/http/Response.go

@@ -0,0 +1,150 @@
+package http
+
+import (
+	"errors"
+	"io"
+	"net"
+	sh "serveg/internal/string_helper"
+	"strconv"
+	"strings"
+	"time"
+)
+
+type responseBodyType uint8
+
+const (
+	responseBodyEmpty = responseBodyType(iota)
+	responseBodySmall
+	responseBodyBig
+)
+
+const TextPlain = "text/plain; charset=utf-8"
+
+type Response struct {
+	Status    StatusCode
+	Headers   HeadersMap // keys are in lower case
+	omitBody  bool       // don't add body and content-* headers for HEAD request
+	bodyType  responseBodyType
+	bodySmall []byte      // small body is sent in one write() call with headers
+	bodyBig   io.WriterTo // big body, sent as multiple write() calls to socket
+}
+
+const TimeFormat = "Mon, 02 Jan 2006 15:04:05 GMT"
+
+func (conn *Connection) CreateResponse(
+	status StatusCode, req *Request, wantsClose bool,
+) *Response {
+	res := &Response{
+		Status: status,
+		Headers: HeadersMap{
+			"date": time.Now().UTC().Format(TimeFormat),
+		},
+	}
+
+	res.omitBody = req.Method == "HEAD"
+	if !res.omitBody &&
+		status >= 200 &&
+		status != StatusNoContent &&
+		status != StatusNotModified {
+		// content-length 0 is mandatory for most responses
+		res.Headers["content-length"] = "0"
+	}
+
+	if wantsClose || !req.WantsKeepAlive {
+		res.Headers["connection"] = "close"
+	} else if req.Protocol == "HTTP/1.0" {
+		res.Headers["connection"] = "keep-alive"
+	}
+
+	return res
+}
+
+func (res *Response) AttachBodySmall(body []byte, contentType string) {
+	if res.omitBody {
+		return
+	}
+
+	if res.bodyType != responseBodyEmpty {
+		panic("response already has body")
+	}
+	res.bodyType = responseBodySmall
+	res.bodySmall = body
+	lenStr := strconv.FormatUint(uint64(len(body)), 10)
+	res.Headers["content-length"] = lenStr
+	res.Headers["content-type"] = contentType
+}
+func (res *Response) AttachBodySmallStr(body string, contentType string) {
+	res.AttachBodySmall(sh.UnsafeGetStrBytes(body), contentType)
+}
+
+func (res *Response) AttachBodyBig(body io.WriterTo,
+	size uint64, contentType string) {
+
+	if res.omitBody {
+		return
+	}
+	if res.bodyType != responseBodyEmpty {
+		panic("response already has body")
+	}
+	res.bodyType = responseBodyBig
+	res.bodyBig = body
+	lenStr := strconv.FormatUint(size, 10)
+	res.Headers["content-length"] = lenStr
+	res.Headers["content-type"] = contentType
+}
+
+var ErrInvalidHeader = errors.New("http: header key or value contains CR or LF")
+
+func (conn *Connection) SendResponse(res *Response) error {
+	sb := &conn.wbuf
+	sb.Reset()
+
+	// first line
+	// space before \r\n is required by standard
+	sb.AddS("HTTP/1.1 ").AddU(uint64(res.Status)).AddS(" \r\n")
+
+	// headers
+	for k, v := range res.Headers {
+		// prevent response splitting / header injection
+		if strings.ContainsAny(k, "\r\n:") || strings.ContainsAny(v, "\r\n") {
+			return ErrInvalidHeader
+		}
+		sb.AddS(k).AddS(": ").AddS(v).AddS("\r\n")
+	}
+	// empty line
+	sb.AddS("\r\n")
+
+	switch res.bodyType {
+	case responseBodyEmpty:
+		// net.Conn.Write follows the io.Writer contract: it returns a non-nil
+		// error whenever n < len(p), so no loop is needed.
+		if _, err := conn.socket.Write(conn.wbuf.Buf); err != nil {
+			return err
+		}
+	case responseBodySmall:
+		// write headers and body in one socket.Write() call
+		bbb := net.Buffers{sb.Buf, res.bodySmall}
+		if _, err := bbb.WriteTo(conn.socket); err != nil {
+			return err
+		}
+	case responseBodyBig:
+		// write headers, then write big body
+		if _, err := conn.socket.Write(conn.wbuf.Buf); err != nil {
+			return err
+		}
+		if _, err := res.bodyBig.WriteTo(conn.socket); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func (conn *Connection) SendErrorResponse(
+	httpErr *HttpError, req *Request, wantsClose bool,
+) error {
+
+	res := conn.CreateResponse(httpErr.Status, req, wantsClose)
+	// attach error message if method allows
+	res.AttachBodySmallStr(httpErr.Error(), TextPlain)
+	return conn.SendResponse(res)
+}

internal/http/StatusCodes.go

@@ -0,0 +1,220 @@
+package http
+
+import (
+	"strconv"
+)
+
+type StatusCode uint16
+
+func (c StatusCode) String() string {
+	numStr := strconv.FormatUint(uint64(c), 10)
+	return statusText(c) + " (" + numStr + ")"
+}
+
+/// Copied from /usr/lib/go/src/net/http/status.go
+/// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// HTTP status codes as registered with IANA.
+// See: https://www.iana.org/assignments/http-status-codes/http-status-codes.xhtml
+const (
+	StatusContinue           StatusCode = 100 // RFC 9110, 15.2.1
+	StatusSwitchingProtocols StatusCode = 101 // RFC 9110, 15.2.2
+	StatusProcessing         StatusCode = 102 // RFC 2518, 10.1
+	StatusEarlyHints         StatusCode = 103 // RFC 8297
+
+	StatusOK                   StatusCode = 200 // RFC 9110, 15.3.1
+	StatusCreated              StatusCode = 201 // RFC 9110, 15.3.2
+	StatusAccepted             StatusCode = 202 // RFC 9110, 15.3.3
+	StatusNonAuthoritativeInfo StatusCode = 203 // RFC 9110, 15.3.4
+	StatusNoContent            StatusCode = 204 // RFC 9110, 15.3.5
+	StatusResetContent         StatusCode = 205 // RFC 9110, 15.3.6
+	StatusPartialContent       StatusCode = 206 // RFC 9110, 15.3.7
+	StatusMultiStatus          StatusCode = 207 // RFC 4918, 11.1
+	StatusAlreadyReported      StatusCode = 208 // RFC 5842, 7.1
+	StatusIMUsed               StatusCode = 226 // RFC 3229, 10.4.1
+
+	StatusMultipleChoices   StatusCode = 300 // RFC 9110, 15.4.1
+	StatusMovedPermanently  StatusCode = 301 // RFC 9110, 15.4.2
+	StatusFound             StatusCode = 302 // RFC 9110, 15.4.3
+	StatusSeeOther          StatusCode = 303 // RFC 9110, 15.4.4
+	StatusNotModified       StatusCode = 304 // RFC 9110, 15.4.5
+	StatusUseProxy          StatusCode = 305 // RFC 9110, 15.4.6
+	_                       StatusCode = 306 // RFC 9110, 15.4.7 (Unused)
+	StatusTemporaryRedirect StatusCode = 307 // RFC 9110, 15.4.8
+	StatusPermanentRedirect StatusCode = 308 // RFC 9110, 15.4.9
+
+	StatusBadRequest                   StatusCode = 400 // RFC 9110, 15.5.1
+	StatusUnauthorized                 StatusCode = 401 // RFC 9110, 15.5.2
+	StatusPaymentRequired              StatusCode = 402 // RFC 9110, 15.5.3
+	StatusForbidden                    StatusCode = 403 // RFC 9110, 15.5.4
+	StatusNotFound                     StatusCode = 404 // RFC 9110, 15.5.5
+	StatusMethodNotAllowed             StatusCode = 405 // RFC 9110, 15.5.6
+	StatusNotAcceptable                StatusCode = 406 // RFC 9110, 15.5.7
+	StatusProxyAuthRequired            StatusCode = 407 // RFC 9110, 15.5.8
+	StatusRequestTimeout               StatusCode = 408 // RFC 9110, 15.5.9
+	StatusConflict                     StatusCode = 409 // RFC 9110, 15.5.10
+	StatusGone                         StatusCode = 410 // RFC 9110, 15.5.11
+	StatusLengthRequired               StatusCode = 411 // RFC 9110, 15.5.12
+	StatusPreconditionFailed           StatusCode = 412 // RFC 9110, 15.5.13
+	StatusRequestEntityTooLarge        StatusCode = 413 // RFC 9110, 15.5.14
+	StatusRequestURITooLong            StatusCode = 414 // RFC 9110, 15.5.15
+	StatusUnsupportedMediaType         StatusCode = 415 // RFC 9110, 15.5.16
+	StatusRequestedRangeNotSatisfiable StatusCode = 416 // RFC 9110, 15.5.17
+	StatusExpectationFailed            StatusCode = 417 // RFC 9110, 15.5.18
+	StatusTeapot                       StatusCode = 418 // RFC 9110, 15.5.19 (Unused)
+	StatusMisdirectedRequest           StatusCode = 421 // RFC 9110, 15.5.20
+	StatusUnprocessableEntity          StatusCode = 422 // RFC 9110, 15.5.21
+	StatusLocked                       StatusCode = 423 // RFC 4918, 11.3
+	StatusFailedDependency             StatusCode = 424 // RFC 4918, 11.4
+	StatusTooEarly                     StatusCode = 425 // RFC 8470, 5.2.
+	StatusUpgradeRequired              StatusCode = 426 // RFC 9110, 15.5.22
+	StatusPreconditionRequired         StatusCode = 428 // RFC 6585, 3
+	StatusTooManyRequests              StatusCode = 429 // RFC 6585, 4
+	StatusRequestHeaderFieldsTooLarge  StatusCode = 431 // RFC 6585, 5
+	StatusUnavailableForLegalReasons   StatusCode = 451 // RFC 7725, 3
+
+	StatusInternalServerError           StatusCode = 500 // RFC 9110, 15.6.1
+	StatusNotImplemented                StatusCode = 501 // RFC 9110, 15.6.2
+	StatusBadGateway                    StatusCode = 502 // RFC 9110, 15.6.3
+	StatusServiceUnavailable            StatusCode = 503 // RFC 9110, 15.6.4
+	StatusGatewayTimeout                StatusCode = 504 // RFC 9110, 15.6.5
+	StatusHTTPVersionNotSupported       StatusCode = 505 // RFC 9110, 15.6.6
+	StatusVariantAlsoNegotiates         StatusCode = 506 // RFC 2295, 8.1
+	StatusInsufficientStorage           StatusCode = 507 // RFC 4918, 11.5
+	StatusLoopDetected                  StatusCode = 508 // RFC 5842, 7.2
+	StatusNotExtended                   StatusCode = 510 // RFC 2774, 7
+	StatusNetworkAuthenticationRequired StatusCode = 511 // RFC 6585, 6
+)
+
+func statusText(c StatusCode) string {
+	switch c {
+	case StatusContinue:
+		return "Continue"
+	case StatusSwitchingProtocols:
+		return "Switching Protocols"
+	case StatusProcessing:
+		return "Processing"
+	case StatusEarlyHints:
+		return "Early Hints"
+	case StatusOK:
+		return "OK"
+	case StatusCreated:
+		return "Created"
+	case StatusAccepted:
+		return "Accepted"
+	case StatusNonAuthoritativeInfo:
+		return "Non-Authoritative Information"
+	case StatusNoContent:
+		return "No Content"
+	case StatusResetContent:
+		return "Reset Content"
+	case StatusPartialContent:
+		return "Partial Content"
+	case StatusMultiStatus:
+		return "Multi-Status"
+	case StatusAlreadyReported:
+		return "Already Reported"
+	case StatusIMUsed:
+		return "IM Used"
+	case StatusMultipleChoices:
+		return "Multiple Choices"
+	case StatusMovedPermanently:
+		return "Moved Permanently"
+	case StatusFound:
+		return "Found"
+	case StatusSeeOther:
+		return "See Other"
+	case StatusNotModified:
+		return "Not Modified"
+	case StatusUseProxy:
+		return "Use Proxy"
+	case StatusTemporaryRedirect:
+		return "Temporary Redirect"
+	case StatusPermanentRedirect:
+		return "Permanent Redirect"
+	case StatusBadRequest:
+		return "Bad Request"
+	case StatusUnauthorized:
+		return "Unauthorized"
+	case StatusPaymentRequired:
+		return "Payment Required"
+	case StatusForbidden:
+		return "Forbidden"
+	case StatusNotFound:
+		return "Not Found"
+	case StatusMethodNotAllowed:
+		return "Method Not Allowed"
+	case StatusNotAcceptable:
+		return "Not Acceptable"
+	case StatusProxyAuthRequired:
+		return "Proxy Authentication Required"
+	case StatusRequestTimeout:
+		return "Request Timeout"
+	case StatusConflict:
+		return "Conflict"
+	case StatusGone:
+		return "Gone"
+	case StatusLengthRequired:
+		return "Length Required"
+	case StatusPreconditionFailed:
+		return "Precondition Failed"
+	case StatusRequestEntityTooLarge:
+		return "Request Entity Too Large"
+	case StatusRequestURITooLong:
+		return "Request URI Too Long"
+	case StatusUnsupportedMediaType:
+		return "Unsupported Media Type"
+	case StatusRequestedRangeNotSatisfiable:
+		return "Requested Range Not Satisfiable"
+	case StatusExpectationFailed:
+		return "Expectation Failed"
+	case StatusTeapot:
+		return "I'm a teapot"
+	case StatusMisdirectedRequest:
+		return "Misdirected Request"
+	case StatusUnprocessableEntity:
+		return "Unprocessable Entity"
+	case StatusLocked:
+		return "Locked"
+	case StatusFailedDependency:
+		return "Failed Dependency"
+	case StatusTooEarly:
+		return "Too Early"
+	case StatusUpgradeRequired:
+		return "Upgrade Required"
+	case StatusPreconditionRequired:
+		return "Precondition Required"
+	case StatusTooManyRequests:
+		return "Too Many Requests"
+	case StatusRequestHeaderFieldsTooLarge:
+		return "Request Header Fields Too Large"
+	case StatusUnavailableForLegalReasons:
+		return "Unavailable For Legal Reasons"
+	case StatusInternalServerError:
+		return "Internal Server Error"
+	case StatusNotImplemented:
+		return "Not Implemented"
+	case StatusBadGateway:
+		return "Bad Gateway"
+	case StatusServiceUnavailable:
+		return "Service Unavailable"
+	case StatusGatewayTimeout:
+		return "Gateway Timeout"
+	case StatusHTTPVersionNotSupported:
+		return "HTTP Version Not Supported"
+	case StatusVariantAlsoNegotiates:
+		return "Variant Also Negotiates"
+	case StatusInsufficientStorage:
+		return "Insufficient Storage"
+	case StatusLoopDetected:
+		return "Loop Detected"
+	case StatusNotExtended:
+		return "Not Extended"
+	case StatusNetworkAuthenticationRequired:
+		return "Network Authentication Required"
+	default:
+		return "INVALID STATUS CODE"
+	}
+}

internal/http/errors.go

@@ -0,0 +1,14 @@
+package http
+
+type HttpError struct {
+	Status StatusCode
+	Msg    string
+}
+
+func (e *HttpError) Error() string {
+	return e.Status.String() + ": " + e.Msg
+}
+
+func NewHttpError(code StatusCode, msg string) *HttpError {
+	return &HttpError{Status: code, Msg: msg}
+}

internal/log/log.go

@@ -37,6 +37,7 @@ package log
 import (
 	"fmt"
 	"os"
+	sh "serveg/internal/string_helper"
 	"sync"
 	"time"
 )
@@ -164,9 +165,9 @@ func buildMessage(context string, severity Severity, a ...any) message {
 	return message{text, color}
 }
 
-func (msg message) print() {
+func (msg *message) print() {
 	SetColorFg(msg.color)
-	if _, err := os.Stdout.Write([]byte(msg.text)); err != nil {
+	if _, err := os.Stdout.Write(sh.UnsafeGetStrBytes(msg.text)); err != nil {
 		panic(err)
 	}
 }

internal/server/Config.go

@@ -1,23 +1,21 @@
 package server
 
 import (
-	"encoding"
 	"errors"
 	"fmt"
 	"io/fs"
-	"net"
 	"os"
 
 	"github.com/BurntSushi/toml"
 )
 
+// TODO: add example config file
 type Config struct {
-	Port uint16 `toml:"port"`
-	Ip   IP     `toml:"ip"`
+	Addr string `toml:"address"`
 }
 
 func ReadConfig(path string) (*Config, error) {
-	var config = new(Config)
+	var config = DefaultConfig()
 	tomlMeta, err := toml.DecodeFile(path, config)
 	if err != nil {
 		return nil, err
@@ -33,8 +31,7 @@ func ReadConfig(path string) (*Config, error) {
 
 func DefaultConfig() *Config {
 	return &Config{
-		Port: 8080,
-		Ip:   IP{net.IPv4(127, 0, 0, 1)},
+		Addr: "127.0.0.1:8080",
 	}
 }
 
@@ -62,20 +59,3 @@ func WriteConfig(config *Config, path string) (err error) {
 	enc.Indent = "    " // 4
 	return enc.Encode(config)
 }
-
-type IP struct {
-	net.IP
-}
-
-var _ encoding.TextUnmarshaler = (*IP)(nil)
-var _ encoding.TextMarshaler = IP{}
-
-func (a *IP) UnmarshalText(text []byte) error {
-	s := string(text)
-	ip := net.ParseIP(s)
-	if ip == nil {
-		return errors.New("can't parse '" + s + "' as IP address")
-	}
-	a.IP = ip
-	return nil
-}

internal/server/Server.go

@@ -1,59 +1,139 @@
 package server
 
 import (
+	"errors"
+	"io"
 	"net"
+	"os"
+	"serveg/internal/http"
 	"serveg/internal/log"
 	"strconv"
+	"sync"
+	"syscall"
 	"time"
 )
 
-func Serve(conf *Config) error {
-	logger := log.LoggerContext{Name: "server"}
-	addr := net.JoinHostPort(conf.Ip.String(), strconv.Itoa(int(conf.Port)))
+type Server struct {
+	Conf     *Config
+	listener net.Listener
+	logger   log.LoggerContext
+	wg       sync.WaitGroup
+}
 
-	logger.Info("listening at", addr)
-	srv, err := net.Listen("tcp", addr)
-	if err != nil {
-		return err
+func (srv *Server) StartGoroutine() (err error) {
+	srv.logger = log.LoggerContext{Name: "server"}
+	srv.logger.Info("listening at ", srv.Conf.Addr)
+	srv.listener, err = net.Listen("tcp", srv.Conf.Addr)
+	if err == nil {
+		srv.wg.Go(srv.serve)
 	}
-	defer func() { _ = srv.Close() }()
+	return
+}
 
+func (srv *Server) serve() {
+	srv.logger.Info("server started")
 	for i := int64(0); ; i++ {
-		conn, err := srv.Accept()
+		conn, err := srv.listener.Accept()
 		if err != nil {
-			logger.Warn(err)
+			if errors.Is(err, net.ErrClosed) {
+				srv.logger.Info("listener socket closed")
+				return
+			}
+			srv.logger.Warn(err)
 			continue
 		}
-		go handleConnection(conn, i)
+		// TODO: add connection to map. SetDeadline(Now()) in Stop().
+		// srv.wg.Go(func() { handleConnection(conn.(*net.TCPConn), i) })
+		go handleConnection(conn.(*net.TCPConn), i)
 	}
 }
 
-func handleConnection(conn net.Conn, n int64) {
+func (srv *Server) Stop() {
+	srv.logger.Info("stopping server")
+	_ = srv.listener.Close()
+	srv.wg.Wait()
+}
+
+func handleConnection(socket *net.TCPConn, n int64) {
 	logger := log.LoggerContext{Name: "conn-" + strconv.FormatInt(n, 10)}
 	defer func() {
 		if r := recover(); r != nil {
 			logger.Error("panic: ", r)
 		}
-		_ = conn.Close()
+		_ = socket.Close()
+		logger.Info("connection closed")
 	}()
 
-	buf := make([]byte, 4096)
-
+	conn := http.NewConnection(socket)
 	for {
-		if err := conn.SetDeadline(time.Now().Add(30 * time.Second)); err != nil {
-			logger.Warn(err)
-			break
-		}
-		n, err := conn.Read(buf)
+		err := socket.SetDeadline(time.Now().Add(30 * time.Second))
 		if err != nil {
 			logger.Warn(err)
-			break
+			return
 		}
-		msgBytes := buf[:n]
-		logger.Info("msg: `", string(msgBytes), "`")
-		if _, err := conn.Write(msgBytes); err != nil {
-			logger.Warn(err)
-			break
+
+		req, err := conn.ReadRequest()
+		if err != nil {
+			logConnError(logger, err)
+
+			if httpErr, ok := errors.AsType[*http.HttpError](err); ok {
+				// return error code to client
+				logger.Info("sending error response")
+				// req is partially parsed, may use fields
+				if err = conn.SendErrorResponse(httpErr, req, true); err != nil {
+					logger.Warn("can't send error response")
+					return
+				}
+			}
+			// close the connection
+			logger.Info("lingering close")
+			lingeringClose(socket)
+			return
+		}
+		logger.Info(req.Method, " ", req.Path, " ", req.Protocol,
+			"\nHeaders: ", req.Headers)
+
+		resBody := "Hi\n" + time.Now().Format(time.DateTime)
+
+		res := conn.CreateResponse(http.StatusOK, req, false)
+		res.AttachBodySmallStr(resBody, http.TextPlain)
+		logger.Info("sending response: ", res.Status,
+			"\nHeaders: ", res.Headers)
+		err = conn.SendResponse(res)
+		if err != nil {
+			logConnError(logger, err)
+			return
+		}
+
+		// it is set by CreateResponse
+		if res.Headers["connection"] == "close" {
+			logger.Info("lingering close")
+			lingeringClose(socket)
+			return
 		}
 	}
 }
+
+func logConnError(logger log.LoggerContext, err error) {
+	if errors.Is(err, os.ErrDeadlineExceeded) {
+		logger.Info("time out")
+	} else if errors.Is(err, io.EOF) ||
+		errors.Is(err, syscall.EPIPE) ||
+		errors.Is(err, syscall.ECONNRESET) {
+
+		logger.Info("closed by client")
+	} else {
+		logger.Warn(err)
+	}
+}
+
+// lingeringClose: shut down our side, then drain the client's unread data,
+// so close() doesn't send RST and destroy the response before it's read.
+// Limits: 500 ms, 32 KB
+func lingeringClose(socket *net.TCPConn) {
+	if socket.CloseWrite() != nil {
+		return
+	}
+	_ = socket.SetReadDeadline(time.Now().Add(500 * time.Millisecond))
+	_, _ = io.Copy(io.Discard, io.LimitReader(socket, 32*1024))
+}

internal/string_helper/StringBuilder.go

@@ -0,0 +1,117 @@
+package string_helper
+
+import (
+	"io"
+	"slices"
+	"strconv"
+	"unicode/utf8"
+)
+
+type StringBuilder struct {
+	// allocate it with size of estimated output
+	Buf []byte
+}
+
+// compile-time interface checks
+var (
+	_ io.Writer       = (*StringBuilder)(nil)
+	_ io.StringWriter = (*StringBuilder)(nil)
+	_ io.ByteWriter   = (*StringBuilder)(nil)
+)
+
+// Write implements [io.Writer]. It never returns an error.
+func (b *StringBuilder) Write(p []byte) (int, error) {
+	b.Buf = append(b.Buf, p...)
+	return len(p), nil
+}
+
+// WriteString implements [io.StringWriter]. It never returns an error.
+func (b *StringBuilder) WriteString(s string) (int, error) {
+	b.Buf = append(b.Buf, s...)
+	return len(s), nil
+}
+
+// WriteByte implements [io.ByteWriter]. It never returns an error.
+func (b *StringBuilder) WriteByte(c byte) error {
+	b.Buf = append(b.Buf, c)
+	return nil
+}
+
+// Reset empties the builder but keeps the allocated capacity for reuse.
+func (b *StringBuilder) Reset() { b.Buf = b.Buf[:0] }
+
+// Grow ensures there is room for at least n more bytes
+func (b *StringBuilder) Grow(n int) { b.Buf = slices.Grow(b.Buf, n) }
+
+func (b *StringBuilder) Len() int { return len(b.Buf) }
+
+func (b *StringBuilder) AddS(v string) *StringBuilder {
+	b.Buf = append(b.Buf, v...)
+	return b
+}
+
+func (b *StringBuilder) AddB(v byte) *StringBuilder {
+	b.Buf = append(b.Buf, v)
+	return b
+}
+
+func (b *StringBuilder) AddR(v rune) *StringBuilder {
+	b.Buf = utf8.AppendRune(b.Buf, v)
+	return b
+}
+
+func (b *StringBuilder) AddBool(v bool) *StringBuilder {
+	b.Buf = strconv.AppendBool(b.Buf, v)
+	return b
+}
+
+// numberBase: 2 <= base <= 36
+func (b *StringBuilder) AddIExt(v int64, numberBase int) *StringBuilder {
+	b.Buf = strconv.AppendInt(b.Buf, v, numberBase)
+	return b
+}
+func (b *StringBuilder) AddI(v int64) *StringBuilder   { return b.AddIExt(v, 10) }
+func (b *StringBuilder) AddI32(v int32) *StringBuilder { return b.AddI(int64(v)) }
+func (b *StringBuilder) AddI16(v int16) *StringBuilder { return b.AddI(int64(v)) }
+func (b *StringBuilder) AddI8(v int8) *StringBuilder   { return b.AddI(int64(v)) }
+
+// numberBase: 2 <= base <= 36
+func (b *StringBuilder) AddUExt(v uint64, numberBase int) *StringBuilder {
+	b.Buf = strconv.AppendUint(b.Buf, v, numberBase)
+	return b
+}
+func (b *StringBuilder) AddU(v uint64) *StringBuilder   { return b.AddUExt(v, 10) }
+func (b *StringBuilder) AddU32(v uint32) *StringBuilder { return b.AddU(uint64(v)) }
+func (b *StringBuilder) AddU16(v uint16) *StringBuilder { return b.AddU(uint64(v)) }
+func (b *StringBuilder) AddU8(v uint8) *StringBuilder   { return b.AddU(uint64(v)) }
+
+// fmtChar: see [strconv.FormatFloat]
+// precision: number of digits after . (-1 for max precision)
+func (b *StringBuilder) AddF32Ext(v float32, fmtChar byte, precision int) *StringBuilder {
+	b.Buf = strconv.AppendFloat(b.Buf, float64(v), fmtChar, precision, 32)
+	return b
+}
+func (b *StringBuilder) AddF32(v float32) *StringBuilder {
+	return b.AddF32Ext(v, 'g', -1)
+}
+
+// fmtChar: see [strconv.FormatFloat]
+// precision: number of digits after . (-1 for max precision)
+func (b *StringBuilder) AddF64Ext(v float64, fmtChar byte, precision int) *StringBuilder {
+	b.Buf = strconv.AppendFloat(b.Buf, v, fmtChar, precision, 64)
+	return b
+}
+func (b *StringBuilder) AddF64(v float64) *StringBuilder {
+	return b.AddF64Ext(v, 'g', -1)
+}
+
+// creates copy of buffer
+func (b *StringBuilder) String() string {
+	return string(b.Buf)
+}
+
+// doesn't copy buffer,
+// so you shouldn't modify b.Buf before using the string
+func (b *StringBuilder) StringUnsafe() string {
+	return UnsafeBytesToStr(b.Buf)
+}

internal/string_helper/path.go

@@ -0,0 +1,104 @@
+package string_helper
+
+import (
+	"strings"
+)
+
+// Returns path cleaned from "./", "/./", "//"
+// or empty string if path is not safe.
+// Path is considered unsafe if it:
+// - contains ".." segments
+// - ends with '.'
+// - contains `\:*?"<>|`
+// - contains windows-restricted names COM, CON, ...
+func ResolveSafePath(decodedPath string) string {
+	var sb StringBuilder
+	sb.Grow(len(decodedPath))
+	var seg string
+	for rest := decodedPath; rest != ""; {
+		seg, rest = nextSegment(rest)
+		if seg == "" || seg == "." {
+			continue
+		}
+		if !isSafeSegment(seg) {
+			return ""
+		}
+		sb.AddB('/')
+		sb.AddS(seg)
+	}
+	if sb.Len() == 0 {
+		return "/"
+	}
+	return sb.StringUnsafe()
+}
+
+// nextSegment splits off the first '/'-separated segment of s.
+func nextSegment(s string) (seg, rest string) {
+	seg, rest, _ = strings.Cut(s, "/")
+	return
+}
+
+// isSafeSegment reports whether a single non-empty path segment is safe to
+// use as a file name.
+func isSafeSegment(seg string) bool {
+	if seg == ".." {
+		return false
+	}
+	// Windows strips trailing dots "a.txt." would open "a.txt"
+	if last := seg[len(seg)-1]; last == '.' {
+		return false
+	}
+	for i := 0; i < len(seg); i++ {
+		c := seg[i]
+		if c < 0x20 || c == 0x7F {
+			return false
+		}
+		// invalid in Windows file names, ':' also selects NTFS streams
+		if strings.IndexByte(`\:*?"<>|`, c) >= 0 {
+			return false
+		}
+	}
+	return !isReservedWindowsName(seg)
+}
+
+// isReservedWindowsName reports whether seg names a Windows device:
+// "CON", "con.txt", "COM1.tar.gz", ...
+func isReservedWindowsName(seg string) bool {
+	base := seg
+	if i := strings.IndexByte(seg, '.'); i >= 0 {
+		base = seg[:i]
+	}
+	switch len(base) {
+	case 3:
+		return asciiEqualUpper(base, "CON") || asciiEqualUpper(base, "PRN") ||
+			asciiEqualUpper(base, "AUX") || asciiEqualUpper(base, "NUL")
+	case 4:
+		prefix := base[:3]
+		return (asciiEqualUpper(prefix, "COM") || asciiEqualUpper(prefix, "LPT")) &&
+			'0' <= base[3] && base[3] <= '9'
+	}
+	return false
+}
+
+// asciiUpper upper-cases ASCII letters only (like std::toupper in the "C" locale).
+func asciiUpper(c byte) byte {
+	if 'a' <= c && c <= 'z' {
+		return c - ('a' - 'A')
+	}
+	return c
+}
+
+// asciiEqualUpper compares s with upper (which must be upper-case ASCII), ignoring
+// ASCII case. Unlike strings.EqualFold it does no Unicode folding, so e.g. the
+// Kelvin sign 'K' (U+212A) does not match 'K'.
+func asciiEqualUpper(s, upper string) bool {
+	if len(s) != len(upper) {
+		return false
+	}
+	for i := 0; i < len(s); i++ {
+		if asciiUpper(s[i]) != upper[i] {
+			return false
+		}
+	}
+	return true
+}

internal/string_helper/unsafe.go

@@ -0,0 +1,13 @@
+package string_helper
+
+import "unsafe"
+
+func UnsafeGetStrBytes(s string) []byte {
+	pointr := unsafe.StringData(s)
+	return unsafe.Slice(pointr, len(s))
+}
+
+func UnsafeBytesToStr(b []byte) string {
+	pointr := unsafe.SliceData(b)
+	return unsafe.String(pointr, len(b))
+}