Created scp.go image_scp_test.go and podman-image-scp.1.md

added functionality for image secure copying from local to remote.
Also moved system connection add code around a bit so functions within that file
can be used by scp.

Signed-off-by: cdoern <cdoern@redhat.com>

vendor/github.com/dtylman/scp/msg.go

@@ -0,0 +1,121 @@
+package scp
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"strconv"
+	"strings"
+)
+
+const (
+	//CopyMessage Copy Message Opcode
+	CopyMessage = 'C'
+	//ErrorMessage Error OpCode
+	ErrorMessage = 0x1
+	//WarnMessage Warning Opcode
+	WarnMessage = 0x2
+)
+
+//Message is scp control message
+type Message struct {
+	Type     byte
+	Error    error
+	Mode     string
+	Size     int64
+	FileName string
+}
+
+func (m *Message) readByte(reader io.Reader) (byte, error) {
+	buff := make([]byte, 1)
+	_, err := io.ReadFull(reader, buff)
+	if err != nil {
+		return 0, err
+	}
+	return buff[0], nil
+
+}
+
+func (m *Message) readOpCode(reader io.Reader) error {
+	var err error
+	m.Type, err = m.readByte(reader)
+	return err
+}
+
+//ReadError reads an error message
+func (m *Message) ReadError(reader io.Reader) error {
+	msg, err := ioutil.ReadAll(reader)
+	if err != nil {
+		return err
+	}
+	m.Error = errors.New(strings.TrimSpace(string(msg)))
+	return nil
+}
+
+func (m *Message) readLine(reader io.Reader) (string, error) {
+	line := ""
+	b, err := m.readByte(reader)
+	if err != nil {
+		return "", err
+	}
+	for b != 10 {
+		line += string(b)
+		b, err = m.readByte(reader)
+		if err != nil {
+			return "", err
+		}
+	}
+	return line, nil
+}
+
+func (m *Message) readCopy(reader io.Reader) error {
+	line, err := m.readLine(reader)
+	if err != nil {
+		return err
+	}
+	parts := strings.Split(line, " ")
+	if len(parts) < 2 {
+		return errors.New("Invalid copy line: " + line)
+	}
+	m.Mode = parts[0]
+	m.Size, err = strconv.ParseInt(parts[1], 10, 0)
+	if err != nil {
+		return err
+	}
+	m.FileName = parts[2]
+	return nil
+}
+
+//ReadFrom reads message from reader
+func (m *Message) ReadFrom(reader io.Reader) (int64, error) {
+	err := m.readOpCode(reader)
+	if err != nil {
+		return 0, err
+	}
+	switch m.Type {
+	case CopyMessage:
+		err = m.readCopy(reader)
+		if err != nil {
+			return 0, err
+		}
+	case ErrorMessage, WarnMessage:
+		err = m.ReadError(reader)
+		if err != nil {
+			return 0, err
+		}
+	default:
+		return 0, fmt.Errorf("Unsupported opcode: %v", m.Type)
+	}
+	return m.Size, nil
+}
+
+//NewMessageFromReader constructs a new message from a data in reader
+func NewMessageFromReader(reader io.Reader) (*Message, error) {
+	m := new(Message)
+	_, err := m.ReadFrom(reader)
+	if err != nil {
+		return nil, err
+	}
+	return m, nil
+}