Initial QSfera import

Server/vendor/github.com/opencloud-eu/icap-client/conn.go

@@ -0,0 +1,109 @@
+package icapclient
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"io"
+	"net"
+	"sync"
+	"time"
+)
+
+// ICAPConnConfig is the configuration for the icap connection.
+type ICAPConnConfig struct {
+	// Timeout is the maximum amount of time a connection will be kept open
+	Timeout time.Duration
+}
+
+// ICAPConn manages the transport layer for ICAP protocol.
+type ICAPConn struct {
+	tcp     net.Conn
+	mu      sync.Mutex
+	timeout time.Duration
+}
+
+// NewICAPConn creates a new connection configuration.
+func NewICAPConn(conf ICAPConnConfig) (*ICAPConn, error) {
+	return &ICAPConn{
+		timeout: conf.Timeout,
+	}, nil
+}
+
+// Connect connects to the ICAP server.
+func (c *ICAPConn) Connect(ctx context.Context, address string) error {
+	dialer := net.Dialer{Timeout: c.timeout}
+	conn, err := dialer.DialContext(ctx, "tcp", address)
+	if err != nil {
+		return err
+	}
+	c.tcp = conn
+
+	if c.timeout > 0 {
+		deadline := time.Now().Add(c.timeout)
+		if err := c.tcp.SetDeadline(deadline); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+// Send sends a request to the ICAP server and reads the response.
+func (c *ICAPConn) Send(in []byte) ([]byte, error) {
+	if !c.ok() {
+		return nil, ErrInvalidConnection
+	}
+
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	_, err := c.tcp.Write(in)
+	if err != nil {
+		return nil, err
+	}
+
+	var data []byte
+	buf := make([]byte, 4096)
+	for {
+		n, err := c.tcp.Read(buf)
+		if err != nil && !errors.Is(err, io.EOF) {
+			return nil, err
+		}
+
+		if errors.Is(err, io.EOF) || n == 0 {
+			break
+		}
+
+		data = append(data, buf[:n]...)
+
+		// Protocol checks for message termination
+		{
+			if bytes.Equal(data, []byte(icap100ContinueMsg)) {
+				break
+			}
+
+			if bytes.HasSuffix(data, []byte(doubleCRLF)) {
+				break
+			}
+
+			if bytes.Contains(data, []byte(icap204NoModsMsg)) {
+				break
+			}
+		}
+	}
+
+	return data, nil
+}
+
+// Close closes the TCP connection.
+func (c *ICAPConn) Close() error {
+	if !c.ok() {
+		return ErrInvalidConnection
+	}
+	return c.tcp.Close()
+}
+
+func (c *ICAPConn) ok() bool {
+	return c != nil && c.tcp != nil
+}