From 85ec7b0f4311dd0ef380b9ffca567f8fe96740f1 Mon Sep 17 00:00:00 2001
From: xinghenLuyus <2593026969@qq.com>
Date: Fri, 26 Dec 2025 14:33:01 +0800
Subject: [PATCH] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=20linux=5Fchat.c?=
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---
 linux_chat.c | 105 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 105 insertions(+)
 create mode 100644 linux_chat.c

diff --git a/linux_chat.c b/linux_chat.c
new file mode 100644
index 0000000..f2b7bb1
--- /dev/null
+++ b/linux_chat.c
@@ -0,0 +1,105 @@
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <arpa/inet.h>
+#include <sys/socket.h>
+#include <sys/select.h>
+
+#include "common.h"
+
+/* 停等协议发送（带超时重传） */
+void send_with_stopwait(int sock,
+                        struct sockaddr_in6 *peer,
+                        struct packet *pkt)
+{
+    socklen_t len = sizeof(*peer);
+
+    while (1) {
+        sendto(sock, pkt, sizeof(*pkt), 0,
+               (struct sockaddr *)peer, len);
+
+        fd_set fds;
+        FD_ZERO(&fds);
+        FD_SET(sock, &fds);
+
+        struct timeval tv;
+        tv.tv_sec = TIMEOUT_SEC;
+        tv.tv_usec = 0;
+
+        int ret = select(sock + 1, &fds, NULL, NULL, &tv);
+        if (ret > 0) {
+            struct packet ack;
+            recvfrom(sock, &ack, sizeof(ack), 0, NULL, NULL);
+            if (ack.type == TYPE_ACK && ack.seq == pkt->seq) {
+                return; // 正确 ACK
+            }
+        }
+        printf("[timeout] retransmit\n");
+    }
+}
+
+int main(int argc, char *argv[])
+{
+    if (argc != 2) {
+        printf("用法: %s <对方IPv6地址>\n", argv[0]);
+        return 1;
+    }
+
+    int sock = socket(AF_INET6, SOCK_DGRAM, 0);
+
+    /* 绑定本地 IPv6 端口 */
+    struct sockaddr_in6 local;
+    memset(&local, 0, sizeof(local));
+    local.sin6_family = AF_INET6;
+    local.sin6_addr = in6addr_any;
+    local.sin6_port = htons(PORT);
+    bind(sock, (struct sockaddr *)&local, sizeof(local));
+
+    /* 对端地址 */
+    struct sockaddr_in6 peer;
+    memset(&peer, 0, sizeof(peer));
+    peer.sin6_family = AF_INET6;
+    peer.sin6_port = htons(PORT);
+    inet_pton(AF_INET6, argv[1], &peer.sin6_addr);
+
+    uint8_t send_seq = 0;
+    uint8_t recv_seq = 0;
+    struct packet pkt, rcv;
+
+    printf("Linux UDP IPv6 Stop-Wait Chat\n");
+
+    while (1) {
+        /* 非阻塞接收 */
+        fd_set fds;
+        FD_ZERO(&fds);
+        FD_SET(sock, &fds);
+        struct timeval tv = {0, 100000};
+
+        if (select(sock + 1, &fds, NULL, NULL, &tv) > 0) {
+            recvfrom(sock, &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, &rcv, sizeof(rcv), 0,
+                       (struct sockaddr *)&peer, sizeof(peer));
+            }
+        }
+
+        /* 发送 */
+        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;
+    }
+
+    close(sock);
+    return 0;
+}