Implemented conn.go and hanshake.go + unit tests

handshake.go

@@ -0,0 +1,118 @@
+package ownwire_sdk
+
+import (
+	"context"
+	"encoding/base64"
+	"fmt"
+	"time"
+)
+
+type SessionState struct {
+	SessionId       string
+	ClientPubKeyB64 string
+
+	ServerPubKeyB64 string
+	SaltB64         string
+
+	SharedKey      [32]byte
+	SessionIdBytes [16]byte
+
+	SeqOut   uint64
+	SeqInMax uint64
+}
+
+type Handshaker struct {
+	Timeout       time.Duration
+	GenClientKeyF func() (Keypair, error)
+}
+
+func (h Handshaker) EnsureDefaults() Handshaker {
+	if h.Timeout == 0 {
+		h.Timeout = 10 * time.Second
+	}
+	if h.GenClientKeyF == nil {
+		h.GenClientKeyF = GenClientKey
+	}
+	return h
+}
+
+func (h Handshaker) Run(ctx context.Context, conn Conn, resume_session_id string) (SessionState, []string, error) {
+	h = h.EnsureDefaults()
+
+	timeout_ctx, cancel := context.WithTimeout(ctx, h.Timeout)
+	defer cancel()
+
+	keypair, err := h.GenClientKeyF()
+	if err != nil {
+		return SessionState{}, nil, err
+	}
+
+	client_pub_b64 := base64.StdEncoding.EncodeToString(keypair.ClientPub)
+
+	if resume_session_id != "" {
+		open_cmd := fmt.Sprintf("/open:%s:%s", resume_session_id, client_pub_b64)
+		if err := conn.WriteText(timeout_ctx, open_cmd); err != nil {
+			return SessionState{}, nil, err
+		}
+	} else {
+		create_cmd := fmt.Sprintf("/create:%s", client_pub_b64)
+		if err := conn.WriteText(timeout_ctx, create_cmd); err != nil {
+			return SessionState{}, nil, err
+		}
+	}
+
+	pending := make([]string, 0, 8)
+
+	for {
+		line, err := conn.ReadText(timeout_ctx)
+		if err != nil {
+			return SessionState{}, nil, err
+		}
+
+		if len(line) >= 9 && line[:9] == "/session:" {
+			parsed, err := ParseSessionInit(line)
+			if err != nil {
+				return SessionState{}, nil, err
+			}
+
+			server_pub_raw, err := base64.StdEncoding.DecodeString(parsed.ServerPubKeyB64)
+			if err != nil {
+				return SessionState{}, nil, fmt.Errorf("invalid server pubkey base64: %w", err)
+			}
+
+			salt_raw, err := base64.StdEncoding.DecodeString(parsed.SaltB64)
+			if err != nil {
+				return SessionState{}, nil, fmt.Errorf("invalid salt base64: %w", err)
+			}
+
+			shared_key, err := DeriveSharedKey(parsed.SessionId, keypair.ClientPriv, server_pub_raw, salt_raw)
+			if err != nil {
+				return SessionState{}, nil, err
+			}
+
+			session_id_bytes, err := ParseUUIDBytes(parsed.SessionId)
+			if err != nil {
+				return SessionState{}, nil, err
+			}
+
+			out := SessionState{
+				SessionId:       parsed.SessionId,
+				ClientPubKeyB64: client_pub_b64,
+
+				ServerPubKeyB64: parsed.ServerPubKeyB64,
+				SaltB64:         parsed.SaltB64,
+
+				SharedKey:      shared_key,
+				SessionIdBytes: session_id_bytes,
+
+				SeqOut:   parsed.SeqInMax,
+				SeqInMax: parsed.SeqOut,
+			}
+
+			return out, pending, nil
+		}
+
+		pending = append(pending, line)
+	}
+}
+