refactor: 将 example 路径重构为 examples

examples/simpliest_tcp_loop.cpp

@@ -0,0 +1,71 @@
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <unistd.h>
+#include <cstring>
+#include <iostream>
+
+int main()
+{
+    int sock_fd = socket(
+        AF_INET,     /* IPv4 */
+        SOCK_STREAM, /* TCP */
+        0 /* File Descriptor */);
+    if (sock_fd < 0)
+    {
+        perror("socket create error");
+        return 1;
+    }
+
+    int opt = 1;
+    setsockopt(sock_fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));
+
+    sockaddr_in addr{};                /* Internet socket address */
+    addr.sin_family = AF_INET;         /* IPv4 */
+    addr.sin_port = htons(8080);       /* Port */
+    addr.sin_addr.s_addr = INADDR_ANY; /* listen all */
+
+    if (bind(sock_fd, (sockaddr *)&addr, sizeof(addr))) /* Bind file descriptor with socket address. */
+    {
+        perror("bind address error");
+        return 1;
+    }
+    if (listen(sock_fd, SOMAXCONN /* Max wait queue that system allows. */)) /* Listen the file descriptor */
+    {
+        perror("set listen queue error");
+        return 1;
+    }
+
+    puts("Server listening on port 8080...");
+
+    int client_fd = 0;
+    while (true)
+    {
+        if (client_fd < 0)
+        {
+            perror("accept socket error");
+            continue;
+        }
+        else if (client_fd == 0)
+        {
+            client_fd = accept(sock_fd, nullptr, nullptr); /* Accept from client */
+            if (client_fd > 0)
+                printf("New client connected: %d\n", client_fd);
+            continue;
+        }
+
+        char buf[1024];
+        memset(buf, 0, sizeof(buf));
+        ssize_t n = read(client_fd, buf, sizeof(buf)); /* Get data length */
+        if (n > 0)
+        {
+            if (!memcmp("exit", buf, 4))
+                break;
+            write(client_fd, buf, n); /* Echo data into buffer */
+            printf(buf);
+        }
+    }
+
+    close(client_fd);
+    close(sock_fd);
+    return 0;
+}