diff --git a/windows_chat.c b/windows_chat.c
index 3967cfc..531e6c3 100644
--- a/windows_chat.c
+++ b/windows_chat.c
@@ -2,98 +2,78 @@
 #include <string.h>
 #include <winsock2.h>
 #include <ws2tcpip.h>
-
-#include "common.h"
+#include <windows.h>
 
 #pragma comment(lib, "ws2_32.lib")
 
-void send_with_stopwait(SOCKET sock,
-                        struct sockaddr_in6 *peer,
-                        struct packet *pkt)
-{
-    int len = sizeof(*peer);
+#include "common.h"
 
-    while (1) {
-        sendto(sock, (char *)pkt, sizeof(*pkt), 0,
-               (struct sockaddr *)peer, len);
+#define LOCAL_PORT 9001
+#define PEER_PORT  9000
+#define TIMEOUT_MS 500
 
-        fd_set fds;
-        FD_ZERO(&fds);
-        FD_SET(sock, &fds);
-
-        TIMEVAL tv;
-        tv.tv_sec = TIMEOUT_SEC;
-        tv.tv_usec = 0;
-
-        int ret = select(0, &fds, NULL, NULL, &tv);
-        if (ret > 0) {
-            struct packet ack;
-            recvfrom(sock, (char *)&ack, sizeof(ack), 0, NULL, NULL);
-            if (ack.type == TYPE_ACK && ack.seq == pkt->seq) {
-                return;
-            }
-        }
-        printf("[timeout] retransmit\n");
-    }
-}
-
-int main(int argc, char *argv[])
-{
+int main(int argc, char *argv[]) {
     if (argc != 2) {
-        printf("用法: %s <对方IPv6地址>\n", argv[0]);
+        printf("Usage: %s <Ubuntu IPv6>\n", argv[0]);
         return 1;
     }
 
     WSADATA wsa;
-    WSAStartup(MAKEWORD(2, 2), &wsa);
+    WSAStartup(MAKEWORD(2,2), &wsa);
 
     SOCKET sock = socket(AF_INET6, SOCK_DGRAM, 0);
 
-    struct sockaddr_in6 local = {0};
+    struct sockaddr_in6 local;
+    memset(&local, 0, sizeof(local));
     local.sin6_family = AF_INET6;
+    local.sin6_port = htons(LOCAL_PORT);
     local.sin6_addr = in6addr_any;
-    local.sin6_port = htons(PORT);
-    bind(sock, (struct sockaddr *)&local, sizeof(local));
 
-    struct sockaddr_in6 peer = {0};
+    bind(sock, (struct sockaddr*)&local, sizeof(local));
+
+    struct sockaddr_in6 peer;
+    memset(&peer, 0, sizeof(peer));
     peer.sin6_family = AF_INET6;
-    peer.sin6_port = htons(PORT);
+    peer.sin6_port = htons(PEER_PORT);
     inet_pton(AF_INET6, argv[1], &peer.sin6_addr);
 
-    uint8_t send_seq = 0;
-    uint8_t recv_seq = 0;
-    struct packet pkt, rcv;
+    int timeout = TIMEOUT_MS;
+    setsockopt(sock, SOL_SOCKET, SO_RCVTIMEO,
+               (char*)&timeout, sizeof(timeout));
 
-    printf("Windows UDP IPv6 Stop-Wait Chat\n");
+    uint8_t seq = 0;
+    char input[DATA_LEN];
 
     while (1) {
-        fd_set fds;
-        FD_ZERO(&fds);
-        FD_SET(sock, &fds);
-        TIMEVAL tv = {0, 100000};
+        printf("You: ");
+        fflush(stdout);
+        fgets(input, sizeof(input), stdin);
 
-        if (select(0, &fds, NULL, NULL, &tv) > 0) {
-            recvfrom(sock, (char *)&rcv, sizeof(rcv), 0, NULL, NULL);
-            if (rcv.type == TYPE_DATA) {
-                if (rcv.seq == recv_seq) {
-                    printf("\npeer: %s\n", rcv.payload);
-                    recv_seq ^= 1;
-                }
-                rcv.type = TYPE_ACK;
-                sendto(sock, (char *)&rcv, sizeof(rcv), 0,
-                       (struct sockaddr *)&peer, sizeof(peer));
+        packet_t pkt = {0};
+        pkt.type = TYPE_DATA;
+        pkt.seq = seq;
+        pkt.length = strlen(input);
+        memcpy(pkt.data, input, pkt.length);
+
+        while (1) {
+            sendto(sock, (char*)&pkt, sizeof(pkt), 0,
+                   (struct sockaddr*)&peer, sizeof(peer));
+
+            packet_t ack;
+            struct sockaddr_in6 from;
+            int fromlen = sizeof(from);
+
+            int n = recvfrom(sock, (char*)&ack, sizeof(ack), 0,
+                             (struct sockaddr*)&from, &fromlen);
+
+            if (n > 0 && ack.type == TYPE_ACK && ack.seq == seq) {
+                break;
             }
+
+            Sleep(TIMEOUT_MS);
         }
 
-        printf(">> ");
-        if (!fgets(pkt.payload, sizeof(pkt.payload), stdin))
-            break;
-
-        pkt.seq = send_seq;
-        pkt.type = TYPE_DATA;
-
-        send_with_stopwait(sock, &peer, &pkt);
-        send_seq ^= 1;
+        seq ^= 1;
     }
 
     closesocket(sock);