diff --git a/src/tlcp.c b/src/tlcp.c
index 363d3289..e961c444 100644
--- a/src/tlcp.c
+++ b/src/tlcp.c
@@ -983,33 +983,41 @@ int tlcp_send_client_key_exchange(TLS_CONNECT *conn)
 {
 	uint8_t enced_pre_master_secret[SM2_MAX_CIPHERTEXT_SIZE];
 	size_t enced_pre_master_secret_len;
+	int ret;
 
 	tls_trace("send ClientKeyExchange\n");
 
-	if (tls_pre_master_secret_generate(conn->pre_master_secret, TLS_protocol_tlcp) != 1) {
-		error_print();
-		return -1;
+	if (!conn->recordlen) {
+		if (tls_pre_master_secret_generate(conn->pre_master_secret, TLS_protocol_tlcp) != 1) {
+			error_print();
+			return -1;
+		}
+
+		if (sm2_encrypt(&conn->server_enc_key.u.sm2_key, conn->pre_master_secret, 48,
+				enced_pre_master_secret, &enced_pre_master_secret_len) != 1
+			|| tls_record_set_handshake_client_key_exchange_pke(conn->record, &conn->recordlen,
+				enced_pre_master_secret, enced_pre_master_secret_len) != 1) {
+			error_print();
+			tls_send_alert(conn, TLS_alert_internal_error);
+			return -1;
+		}
+		tlcp_record_print(stderr, 0, 0, conn->record, conn->recordlen);
+
+		if (digest_update(&conn->dgst_ctx, conn->record + 5, conn->recordlen - 5) != 1) {
+			error_print();
+			return -1;
+		}
+		tls_handshake_digest_print(stderr, 0, 0, "ClientKeyExchange", &conn->dgst_ctx);
 	}
 
-	if (sm2_encrypt(&conn->server_enc_key.u.sm2_key, conn->pre_master_secret, 48,
-			enced_pre_master_secret, &enced_pre_master_secret_len) != 1
-		|| tls_record_set_handshake_client_key_exchange_pke(conn->record, &conn->recordlen,
-			enced_pre_master_secret, enced_pre_master_secret_len) != 1) {
-		error_print();
-		tls_send_alert(conn, TLS_alert_internal_error);
-		return -1;
-	}
-	tlcp_record_print(stderr, 0, 0, conn->record, conn->recordlen);
-	if (tls_record_send(conn->record, conn->recordlen, conn->sock) != 1) {
-		error_print();
-		return -1;
+	if ((ret = tls_send_record(conn)) != 1) {
+		if (ret != TLS_ERROR_SEND_AGAIN) {
+			error_print();
+		}
+		return ret;
 	}
 
-	if (digest_update(&conn->dgst_ctx, conn->record + 5, conn->recordlen - 5) != 1) {
-		error_print();
-		return -1;
-	}
-	tls_handshake_digest_print(stderr, 0, 0, "ClientKeyExchange", &conn->dgst_ctx);
+	tls_clean_record(conn);
 
 	if (tlcp_generate_keys(conn) != 1) {
 		error_print();
@@ -2059,11 +2067,18 @@ int tlcp_recv_client_key_exchange(TLS_CONNECT *conn)
 	size_t enced_pms_len;
 	size_t pre_master_secret_len;
 	X509_KEY *enc_key;
+	int ret;
 
 	tls_trace("recv ClientKeyExchange\n");
 
-	if (tls_record_recv(conn->record, &conn->recordlen, conn->sock) != 1
-		|| tls_record_protocol(conn->record) != TLS_protocol_tlcp) {
+	if ((ret = tls_recv_record(conn)) != 1) {
+		if (ret != TLS_ERROR_RECV_AGAIN) {
+			error_print();
+		}
+		return ret;
+	}
+
+	if (tls_record_protocol(conn->record) != TLS_protocol_tlcp) {
 		error_print();
 		tls_send_alert(conn, TLS_alert_unexpected_message);
 		return -1;
@@ -2501,75 +2516,45 @@ int tlcp_server_handshake(TLS_CONNECT *conn)
 int tlcp_do_connect(TLS_CONNECT *conn)
 {
 	int ret;
-	fd_set rfds;
-	fd_set wfds;
 
 	// 应该把protocol_version的初始化放在这里
 
-	conn->handshake_state = TLS_state_client_hello;
-	//sm3_init(&conn->sm3_ctx);
-
-	while (1) {
-
-		ret = tlcp_client_handshake(conn);
-		if (ret == 1) {
-			break;
-
-		} else if (ret == TLS_ERROR_SEND_AGAIN) {
-			FD_ZERO(&rfds);
-			FD_ZERO(&wfds);
-			FD_SET(conn->sock, &rfds);
-			select(conn->sock + 1, &rfds, &wfds, NULL, NULL);
-
-		} else if (ret == TLS_ERROR_RECV_AGAIN) {
-			FD_ZERO(&rfds);
-			FD_ZERO(&wfds);
-			FD_SET(conn->sock, &wfds);
-			select(conn->sock + 1, &rfds, &wfds, NULL, NULL);
-
-		} else {
-			error_print();
-			return -1;
-		}
+	if (conn->handshake_state == TLS_state_handshake_over) {
+		return 1;
 	}
 
-	return 1;
+	if (conn->handshake_state == TLS_state_handshake_init) {
+		conn->handshake_state = TLS_state_client_hello;
+	}
+
+	ret = tlcp_client_handshake(conn);
+	if (ret == 1
+		|| ret == TLS_ERROR_RECV_AGAIN
+		|| ret == TLS_ERROR_SEND_AGAIN) {
+		return ret;
+	}
+	error_print();
+	return -1;
 }
 
 int tlcp_do_accept(TLS_CONNECT *conn)
 {
 	int ret;
-	fd_set rfds;
-	fd_set wfds;
 
-	conn->handshake_state = TLS_state_client_hello;
-
-	//sm3_init(&conn->sm3_ctx);
-
-	while (1) {
-
-		ret = tlcp_server_handshake(conn);
-
-		if (ret == 1) {
-			break;
-
-		} else if (ret == TLS_ERROR_SEND_AGAIN) {
-			FD_ZERO(&rfds);
-			FD_ZERO(&wfds);
-			FD_SET(conn->sock, &rfds);
-			select(conn->sock + 1, &rfds, &wfds, NULL, NULL);
-
-		} else if (ret == TLS_ERROR_RECV_AGAIN) {
-			FD_ZERO(&rfds);
-			FD_ZERO(&wfds);
-			FD_SET(conn->sock, &wfds);
-			select(conn->sock + 1, &rfds, &wfds, NULL, NULL);
-
-		} else {
-			error_print();
-			return -1;
-		}
+	if (conn->handshake_state == TLS_state_handshake_over) {
+		return 1;
 	}
 
-	return 1;
+	if (conn->handshake_state == TLS_state_handshake_init) {
+		conn->handshake_state = TLS_state_client_hello;
+	}
+
+	ret = tlcp_server_handshake(conn);
+	if (ret == 1
+		|| ret == TLS_ERROR_RECV_AGAIN
+		|| ret == TLS_ERROR_SEND_AGAIN) {
+		return ret;
+	}
+	error_print();
+	return -1;
 }
diff --git a/src/tls12.c b/src/tls12.c
index 5485544d..2efb145b 100644
--- a/src/tls12.c
+++ b/src/tls12.c
@@ -3783,77 +3783,45 @@ int tls12_server_handshake(TLS_CONNECT *conn)
 int tls12_do_connect(TLS_CONNECT *conn)
 {
 	int ret;
-	fd_set rfds;
-	fd_set wfds;
 
-	conn->handshake_state = TLS_state_client_hello;
-	//sm3_init(&conn->sm3_ctx);
-
-
-	digest_init(&conn->dgst_ctx, DIGEST_sm3());
-
-	while (1) {
-
-		ret = tls12_client_handshake(conn);
-		if (ret == 1) {
-			break;
-
-		} else if (ret == TLS_ERROR_SEND_AGAIN) {
-			FD_ZERO(&rfds);
-			FD_ZERO(&wfds);
-			FD_SET(conn->sock, &wfds);
-			select(conn->sock + 1, &rfds, &wfds, NULL, NULL);
-
-		} else if (ret == TLS_ERROR_RECV_AGAIN) {
-			FD_ZERO(&rfds);
-			FD_ZERO(&wfds);
-			FD_SET(conn->sock, &rfds);
-			select(conn->sock + 1, &rfds, &wfds, NULL, NULL);
-
-		} else {
-			error_print();
-			return -1;
-		}
+	if (conn->handshake_state == TLS_state_handshake_over) {
+		return 1;
 	}
 
-	return 1;
+	if (conn->handshake_state == TLS_state_handshake_init) {
+		conn->handshake_state = TLS_state_client_hello;
+		digest_init(&conn->dgst_ctx, DIGEST_sm3());
+	}
+
+	ret = tls12_client_handshake(conn);
+	if (ret == 1
+		|| ret == TLS_ERROR_RECV_AGAIN
+		|| ret == TLS_ERROR_SEND_AGAIN) {
+		return ret;
+	}
+	error_print();
+	return -1;
 }
 
 int tls12_do_accept(TLS_CONNECT *conn)
 {
 	int ret;
-	fd_set rfds;
-	fd_set wfds;
 
-	conn->handshake_state = TLS_state_client_hello;
-
-	//sm3_init(&conn->sm3_ctx);
-	digest_init(&conn->dgst_ctx, DIGEST_sm3());
-
-	while (1) {
-
-		ret = tls12_server_handshake(conn);
-
-		if (ret == 1) {
-			break;
-
-		} else if (ret == TLS_ERROR_SEND_AGAIN) {
-			FD_ZERO(&rfds);
-			FD_ZERO(&wfds);
-			FD_SET(conn->sock, &rfds);
-			select(conn->sock + 1, &rfds, &wfds, NULL, NULL);
-
-		} else if (ret == TLS_ERROR_RECV_AGAIN) {
-			FD_ZERO(&rfds);
-			FD_ZERO(&wfds);
-			FD_SET(conn->sock, &wfds);
-			select(conn->sock + 1, &rfds, &wfds, NULL, NULL);
-
-		} else {
-			error_print();
-			return -1;
-		}
+	if (conn->handshake_state == TLS_state_handshake_over) {
+		return 1;
 	}
 
-	return 1;
+	if (conn->handshake_state == TLS_state_handshake_init) {
+		conn->handshake_state = TLS_state_client_hello;
+		digest_init(&conn->dgst_ctx, DIGEST_sm3());
+	}
+
+	ret = tls12_server_handshake(conn);
+	if (ret == 1
+		|| ret == TLS_ERROR_RECV_AGAIN
+		|| ret == TLS_ERROR_SEND_AGAIN) {
+		return ret;
+	}
+	error_print();
+	return -1;
 }
diff --git a/tools/tlcp_client.c b/tools/tlcp_client.c
index c3071ac2..4c8079b9 100644
--- a/tools/tlcp_client.c
+++ b/tools/tlcp_client.c
@@ -54,6 +54,53 @@ static const char *help =
 "\n";
 
 
+static int set_socket_nonblocking(tls_socket_t sock)
+{
+#ifdef WIN32
+	u_long mode = 1;
+	if (ioctlsocket(sock, FIONBIO, &mode) != 0) {
+		error_print();
+		return -1;
+	}
+#else
+	int flags;
+	if ((flags = fcntl(sock, F_GETFL)) < 0
+		|| fcntl(sock, F_SETFL, flags | O_NONBLOCK) < 0) {
+		error_print();
+		return -1;
+	}
+#endif
+	return 1;
+}
+
+static int do_handshake_select(TLS_CONNECT *conn)
+{
+	int ret;
+	fd_set rfds;
+	fd_set wfds;
+
+	for (;;) {
+		ret = tls_do_handshake(conn);
+		if (ret == 1) {
+			return 1;
+		}
+		FD_ZERO(&rfds);
+		FD_ZERO(&wfds);
+		if (ret == TLS_ERROR_RECV_AGAIN) {
+			FD_SET(conn->sock, &rfds);
+		} else if (ret == TLS_ERROR_SEND_AGAIN) {
+			FD_SET(conn->sock, &wfds);
+		} else {
+			error_print();
+			return -1;
+		}
+		if (select((int)(conn->sock + 1), &rfds, &wfds, NULL, NULL) < 0) {
+			error_print();
+			return -1;
+		}
+	}
+}
+
 int tlcp_client_main(int argc, char *argv[])
 {
 	int ret = -1;
@@ -317,7 +364,12 @@ bad:
 		goto end;
 	}
 
-	if (tls_do_handshake(&conn) != 1) {
+	if (set_socket_nonblocking(sock) != 1) {
+		error_print();
+		goto end;
+	}
+
+	if (do_handshake_select(&conn) != 1) {
 		fprintf(stderr, "%s: error\n", prog);
 		goto end;
 	}
@@ -359,6 +411,7 @@ bad:
 		for (;;) {
 			int rv;
 
+			len = sizeof(buf);
 			rv = tls_recv(&conn, (uint8_t *)buf, sizeof(buf), &len);
 
 			if (rv == 1) {
@@ -367,11 +420,26 @@ bad:
 			} else if (rv == 0) {
 				fprintf(stderr, "%s: TLCP connection is closed by remote host\n", prog);
 				goto end;
-			} else if (rv == -EAGAIN) {
-				// when timeout, tls_recv return -EAGAIN (-11)
-				tls_shutdown(&conn);
-				ret = 0;
-				goto end;
+			} else if (rv == -EAGAIN
+				|| rv == TLS_ERROR_RECV_AGAIN
+				|| rv == TLS_ERROR_SEND_AGAIN) {
+				fd_set fds;
+				struct timeval timeout;
+				int sel;
+
+				timeout.tv_sec = TIMEOUT_SECONDS;
+				timeout.tv_usec = 0;
+				FD_ZERO(&fds);
+				FD_SET(conn.sock, &fds);
+				sel = select(conn.sock + 1, &fds, NULL, NULL, &timeout);
+				if (sel < 0) {
+					fprintf(stderr, "%s: select error\n", prog);
+					goto end;
+				} else if (sel == 0) {
+					tls_shutdown(&conn);
+					ret = 0;
+					goto end;
+				}
 			} else {
 				fprintf(stderr, "%s: tls_recv error\n", prog);
 				goto end;
@@ -432,6 +500,7 @@ bad:
 		if (FD_ISSET(conn.sock, &fds)) {
 			int rv;
 
+			len = sizeof(buf);
 			rv = tls_recv(&conn, (uint8_t *)buf, sizeof(buf), &len);
 
 			if (rv == 1) {
@@ -440,10 +509,10 @@ bad:
 			} else if (rv == 0) {
 				fprintf(stderr, "Connection closed by remote host\n");
 				goto end;
-			} else if (rv == -EAGAIN) {
-				// should not happen
-				error_print();
-				goto end;
+			} else if (rv == -EAGAIN
+				|| rv == TLS_ERROR_RECV_AGAIN
+				|| rv == TLS_ERROR_SEND_AGAIN) {
+				continue;
 			} else {
 				error_print();
 				fprintf(stderr, "%s: tls_recv error\n", prog);
diff --git a/tools/tlcp_server.c b/tools/tlcp_server.c
index fda0c29a..c06a7ed1 100644
--- a/tools/tlcp_server.c
+++ b/tools/tlcp_server.c
@@ -34,6 +34,53 @@ static const char *help =
 #include "tlcp_help.h"
 "\n";
 
+static int set_socket_nonblocking(tls_socket_t sock)
+{
+#ifdef WIN32
+	u_long mode = 1;
+	if (ioctlsocket(sock, FIONBIO, &mode) != 0) {
+		error_print();
+		return -1;
+	}
+#else
+	int flags;
+	if ((flags = fcntl(sock, F_GETFL)) < 0
+		|| fcntl(sock, F_SETFL, flags | O_NONBLOCK) < 0) {
+		error_print();
+		return -1;
+	}
+#endif
+	return 1;
+}
+
+static int do_handshake_select(TLS_CONNECT *conn)
+{
+	int ret;
+	fd_set rfds;
+	fd_set wfds;
+
+	for (;;) {
+		ret = tls_do_handshake(conn);
+		if (ret == 1) {
+			return 1;
+		}
+		FD_ZERO(&rfds);
+		FD_ZERO(&wfds);
+		if (ret == TLS_ERROR_RECV_AGAIN) {
+			FD_SET(conn->sock, &rfds);
+		} else if (ret == TLS_ERROR_SEND_AGAIN) {
+			FD_SET(conn->sock, &wfds);
+		} else {
+			error_print();
+			return -1;
+		}
+		if (select((int)(conn->sock + 1), &rfds, &wfds, NULL, NULL) < 0) {
+			error_print();
+			return -1;
+		}
+	}
+}
+
 int tlcp_server_main(int argc , char **argv)
 {
 	int ret = 1;
@@ -207,7 +254,12 @@ restart:
 		return -1;
 	}
 
-	if (tls_do_handshake(&conn) != 1) {
+	if (set_socket_nonblocking(conn_sock) != 1) {
+		error_print();
+		return -1;
+	}
+
+	if (do_handshake_select(&conn) != 1) {
 		error_print();
 		return -1;
 	}
@@ -216,10 +268,24 @@ restart:
 
 		int rv;
 		size_t sentlen;
+		fd_set fds;
 
 		do {
+			FD_ZERO(&fds);
+			FD_SET(conn.sock, &fds);
+
+			if (select((int)(conn.sock + 1), &fds, NULL, NULL, NULL) < 0) {
+				fprintf(stderr, "%s: select failed\n", prog);
+				goto end;
+			}
+
 			len = sizeof(buf);
 			if ((rv = tls_recv(&conn, (uint8_t *)buf, sizeof(buf), &len)) != 1) {
+				if (rv == -EAGAIN
+					|| rv == TLS_ERROR_RECV_AGAIN
+					|| rv == TLS_ERROR_SEND_AGAIN) {
+					continue;
+				}
 				if (rv < 0) fprintf(stderr, "%s: recv failure\n", prog);
 				else fprintf(stderr, "%s: Disconnected by remote\n", prog);
 
diff --git a/tools/tls12_client.c b/tools/tls12_client.c
index 45c73f9e..83238f1f 100644
--- a/tools/tls12_client.c
+++ b/tools/tls12_client.c
@@ -49,6 +49,53 @@ static const char *help =
 #include "tls12_help.h"
 "\n";
 
+static int set_socket_nonblocking(tls_socket_t sock)
+{
+#ifdef WIN32
+	u_long mode = 1;
+	if (ioctlsocket(sock, FIONBIO, &mode) != 0) {
+		error_print();
+		return -1;
+	}
+#else
+	int flags;
+	if ((flags = fcntl(sock, F_GETFL)) < 0
+		|| fcntl(sock, F_SETFL, flags | O_NONBLOCK) < 0) {
+		error_print();
+		return -1;
+	}
+#endif
+	return 1;
+}
+
+static int do_handshake_select(TLS_CONNECT *conn)
+{
+	int ret;
+	fd_set rfds;
+	fd_set wfds;
+
+	for (;;) {
+		ret = tls_do_handshake(conn);
+		if (ret == 1) {
+			return 1;
+		}
+		FD_ZERO(&rfds);
+		FD_ZERO(&wfds);
+		if (ret == TLS_ERROR_RECV_AGAIN) {
+			FD_SET(conn->sock, &rfds);
+		} else if (ret == TLS_ERROR_SEND_AGAIN) {
+			FD_SET(conn->sock, &wfds);
+		} else {
+			error_print();
+			return -1;
+		}
+		if (select((int)(conn->sock + 1), &rfds, &wfds, NULL, NULL) < 0) {
+			error_print();
+			return -1;
+		}
+	}
+}
+
 int tls12_client_main(int argc, char *argv[])
 {
 	int ret = -1;
@@ -298,7 +345,12 @@ bad:
 		goto end;
 	}
 
-	if (tls_do_handshake(&conn) != 1) {
+	if (set_socket_nonblocking(sock) != 1) {
+		error_print();
+		goto end;
+	}
+
+	if (do_handshake_select(&conn) != 1) {
 		fprintf(stderr, "%s: error\n", prog);
 		goto end;
 	}
@@ -334,8 +386,16 @@ bad:
 
 		if (FD_ISSET(conn.sock, &fds)) {
 			for (;;) {
+				int rv;
+
 				memset(buf, 0, sizeof(buf));
-				if (tls_recv(&conn, (uint8_t *)buf, sizeof(buf), &len) != 1) {
+				len = sizeof(buf);
+				if ((rv = tls_recv(&conn, (uint8_t *)buf, sizeof(buf), &len)) != 1) {
+					if (rv == -EAGAIN
+						|| rv == TLS_ERROR_RECV_AGAIN
+						|| rv == TLS_ERROR_SEND_AGAIN) {
+						break;
+					}
 					goto end;
 				}
 				fwrite(buf, 1, len, stdout);
diff --git a/tools/tls12_server.c b/tools/tls12_server.c
index 9f6e70be..822625aa 100644
--- a/tools/tls12_server.c
+++ b/tools/tls12_server.c
@@ -40,6 +40,53 @@ static const char *help =
 "\n";
 
 
+static int set_socket_nonblocking(tls_socket_t sock)
+{
+#ifdef WIN32
+	u_long mode = 1;
+	if (ioctlsocket(sock, FIONBIO, &mode) != 0) {
+		error_print();
+		return -1;
+	}
+#else
+	int flags;
+	if ((flags = fcntl(sock, F_GETFL)) < 0
+		|| fcntl(sock, F_SETFL, flags | O_NONBLOCK) < 0) {
+		error_print();
+		return -1;
+	}
+#endif
+	return 1;
+}
+
+static int do_handshake_select(TLS_CONNECT *conn)
+{
+	int ret;
+	fd_set rfds;
+	fd_set wfds;
+
+	for (;;) {
+		ret = tls_do_handshake(conn);
+		if (ret == 1) {
+			return 1;
+		}
+		FD_ZERO(&rfds);
+		FD_ZERO(&wfds);
+		if (ret == TLS_ERROR_RECV_AGAIN) {
+			FD_SET(conn->sock, &rfds);
+		} else if (ret == TLS_ERROR_SEND_AGAIN) {
+			FD_SET(conn->sock, &wfds);
+		} else {
+			error_print();
+			return -1;
+		}
+		if (select((int)(conn->sock + 1), &rfds, &wfds, NULL, NULL) < 0) {
+			error_print();
+			return -1;
+		}
+	}
+}
+
 int tls12_server_main(int argc , char **argv)
 {
 	int ret = 1;
@@ -302,7 +349,12 @@ restart:
 		goto end;
 	}
 
-	if (tls_do_handshake(&conn) != 1) {
+	if (set_socket_nonblocking(conn_sock) != 1) {
+		error_print();
+		goto end;
+	}
+
+	if (do_handshake_select(&conn) != 1) {
 		error_print();
 		goto end;
 	}
@@ -311,10 +363,24 @@ restart:
 
 		int rv;
 		size_t sentlen;
+		fd_set fds;
 
 		do {
+			FD_ZERO(&fds);
+			FD_SET(conn.sock, &fds);
+
+			if (select((int)(conn.sock + 1), &fds, NULL, NULL, NULL) < 0) {
+				fprintf(stderr, "%s: select failed\n", prog);
+				goto end;
+			}
+
 			len = sizeof(buf);
 			if ((rv = tls_recv(&conn, (uint8_t *)buf, sizeof(buf), &len)) != 1) {
+				if (rv == -EAGAIN
+					|| rv == TLS_ERROR_RECV_AGAIN
+					|| rv == TLS_ERROR_SEND_AGAIN) {
+					continue;
+				}
 				if (rv < 0) fprintf(stderr, "%s: recv failure\n", prog);
 				else fprintf(stderr, "%s: Disconnected by remote\n", prog);