Replace string matching with syscall error checking for connection resets

lpr_daemon.go

@@ -1,7 +1,6 @@
 package lprlib
 
 import (
-	"context"
 	"errors"
 	"fmt"
 	"io"
@@ -33,10 +32,6 @@ type QueueState func(queue string, list string, long bool) string
 
 type ExternalIDCallbackFunc func() uint64
 
-func init() {
-	rand.Seed(time.Now().UnixMicro())
-}
-
 // LprDaemon structure
 type LprDaemon struct {
 	finishedConns chan *LprConnection
@@ -287,10 +282,6 @@ type LprConnection struct {
 	// SaveName The File name of the new file
 	SaveName string
 
-	// ctx is the lpr daemon's context.
-	// The connection must be closed once the context is canceled.
-	ctx context.Context
-
 	// daemon contains a reference to the LprDaemon
 	daemon *LprDaemon
 
@@ -376,16 +367,27 @@ func (lpr *LprConnection) RunConnection() {
 		}
 		defer traceFile.Close()
 		logDebugf("Created trace file %s", traceFile.Name())
-		traceFile.WriteString(fmt.Sprintf("LPR connection trace %s\n", time.Now()))
+
+		_, err = fmt.Fprintf(traceFile, "LPR connection trace %s\n", time.Now())
+		if err != nil {
+			logErrorf("failed to write to trace file %s: %v", traceFile.Name(), err)
+		}
 	}
 
 	for lpr.Status != Error && lpr.Status != End {
 		command, err := lpr.ReadCommand()
 
 		if traceFile != nil {
-			traceFile.WriteString(fmt.Sprintf("received message %d:\n", len(command)))
+			_, traceErr := fmt.Fprintf(traceFile, "received message %d:\n", len(command))
+			if traceErr != nil {
+				logErrorf("failed to write to trace file %s: %v", traceFile.Name(), traceErr)
+			}
+
 			if err != nil {
-				traceFile.WriteString(fmt.Sprintf("error: %v\n", err))
+				_, traceErr = fmt.Fprintf(traceFile, "error: %v\n", err)
+				if traceErr != nil {
+					logErrorf("failed to write to trace file %s: %v", traceFile.Name(), traceErr)
+				}
 			} else {
 				traceFile.WriteString("-----\n")
 				traceFile.Write(command)

lpr_daemon_test.go

@@ -156,7 +156,7 @@ func TestDaemonLargeFileConnection(t *testing.T) {
 
 	conn := <-lprd.FinishedConnections()
 
-	out, err = ioutil.ReadFile(conn.SaveName)
+	out, err = os.ReadFile(conn.SaveName)
 	if err != nil {
 		t.Error(err)
 	} else {
@@ -243,7 +243,7 @@ func TestDaemonMultipleConnection(t *testing.T) {
 
 	i := 0
 	for conn := range lprd.FinishedConnections() {
-		out, err = ioutil.ReadFile(conn.SaveName)
+		out, err = os.ReadFile(conn.SaveName)
 		if err != nil {
 			t.Error(err)
 		} else {
@@ -288,7 +288,7 @@ func generateTempFile(dir, prefix, text string) (string, error) {
 	var err error
 	var file *os.File
 
-	file, err = ioutil.TempFile(dir, prefix)
+	file, err = os.CreateTemp(dir, prefix)
 	if err != nil {
 		return "", err
 	}
@@ -413,6 +413,9 @@ func TestDaemonClose(t *testing.T) {
 	conn := <-lprd.FinishedConnections()
 	require.Equal(t, End, conn.Status)
 
+	err = os.Remove(conn.SaveName)
+	require.Nil(t, err)
+
 	// no new connection may be opened
 	lprs = LprSend{}
 	err = lprs.Init("127.0.0.1", name, port, "raw", "TestUser", time.Minute)
@@ -457,7 +460,7 @@ func TestDaemonFileSize(t *testing.T) {
 
 	con := <-lprd.FinishedConnections()
 	require.Equal(t, End, con.Status)
-	out, err = ioutil.ReadFile(con.SaveName)
+	out, err = os.ReadFile(con.SaveName)
 	require.Nil(t, err)
 	err = os.Remove(con.SaveName)
 	require.Nil(t, err)
@@ -501,7 +504,7 @@ func TestDaemonFileSize(t *testing.T) {
 
 	con = <-lprd.FinishedConnections()
 	require.Equal(t, End, con.Status)
-	out, err = ioutil.ReadFile(con.SaveName)
+	out, err = os.ReadFile(con.SaveName)
 	require.Nil(t, err)
 	err = os.Remove(con.SaveName)
 	require.Nil(t, err)

lpr_status.go

@@ -5,7 +5,6 @@ import (
 	"fmt"
 	"io"
 	"net"
-	"strings"
 	"time"
 )
 
@@ -99,7 +98,10 @@ func GetStatus(hostname string, port uint16, queue string, long bool, timeout ti
 					opErr := &net.OpError{}
 
 					if errors.As(err, &opErr) {
-						if strings.Contains(opErr.Error(), "connection was forcibly closed by the remote host") || strings.Contains(opErr.Error(), "connection reset by peer") {
+						// Check for connection reset errors at the syscall level
+						// This works cross-platform: ECONNRESET on Unix-like systems,
+						// WSAECONNRESET on Windows
+						if isConnResetErr(opErr) {
 							logDebugf("Ignoring forceful connection closure by server")
 							break
 						}

lpr_status_other.go

@@ -0,0 +1,14 @@
+//go:build !windows
+// +build !windows
+
+package lprlib
+
+import (
+	"errors"
+	"net"
+	"syscall"
+)
+
+func isConnResetErr(err *net.OpError) bool {
+	return errors.Is(err.Err, syscall.ECONNRESET)
+}

lpr_status_windows.go

@@ -0,0 +1,11 @@
+package lprlib
+
+import (
+	"errors"
+	"net"
+	"syscall"
+)
+
+func isConnResetErr(err *net.OpError) bool {
+	return errors.Is(err.Err, syscall.ECONNRESET) || errors.Is(err.Err, syscall.WSAECONNRESET)
+}