13.2 readv & writev 函数

ch13/peek_recv.c

@@ -0,0 +1,60 @@
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <arpa/inet.h>
+
+#define BUF_SIZE 30
+void error_handling(char *message);
+
+int main(int argc, char *argv[])
+{
+    int acpt_sock, recv_sock;
+    struct sockaddr_in acpt_adr, recv_adr;
+    int str_len, state;
+    socklen_t recv_adr_sz;
+    char buf[BUF_SIZE];
+    if (argc != 2)
+    {
+        printf("Usage : %s <port>\n", argv[0]);
+        exit(1);
+    }
+    acpt_sock = socket(PF_INET, SOCK_STREAM, 0);
+    memset(&acpt_adr, 0, sizeof(acpt_adr));
+    acpt_adr.sin_family = AF_INET;
+    acpt_adr.sin_addr.s_addr = htonl(INADDR_ANY);
+    acpt_adr.sin_port = htons(atoi(argv[1]));
+
+    if (bind(acpt_sock, (struct sockaddr *)&acpt_adr, sizeof(acpt_adr)) == -1)
+        error_handling("bind() error");
+    listen(acpt_sock, 5);
+
+    recv_adr_sz = sizeof(recv_adr);
+    recv_sock = accept(acpt_sock, (struct sockaddr *)&recv_adr, &recv_adr_sz);
+
+    while (1)
+    {
+        //保证就算不存在待读取数据也不会阻塞
+        str_len = recv(recv_sock, buf, sizeof(buf) - 1, MSG_PEEK | MSG_DONTWAIT);
+        if (str_len > 0)
+            break;
+    }
+
+    buf[str_len] = 0;
+    printf("Buffering %d bytes : %s \n", str_len, buf);
+    //再次调用 recv 函数，这一次没有设置任何可选项，所以可以直接从缓冲区读出
+    str_len = recv(recv_sock, buf, sizeof(buf) - 1, 0);
+    buf[str_len] = 0;
+    printf("Read again: %s \n", buf);
+    close(acpt_sock);
+    close(recv_sock);
+    return 0;
+}
+
+void error_handling(char *message)
+{
+    fputs(message, stderr);
+    fputc('\n', stderr);
+    exit(1);
+}

ch13/peek_send.c

@@ -0,0 +1,37 @@
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <arpa/inet.h>
+void error_handling(char *message);
+
+int main(int argc, char *argv[])
+{
+    int sock;
+    struct sockaddr_in send_adr;
+    if (argc != 3)
+    {
+        printf("Usage : %s <IP> <port>\n", argv[0]);
+        exit(1);
+    }
+    sock = socket(PF_INET, SOCK_STREAM, 0);
+    memset(&send_adr, 0, sizeof(send_adr));
+    send_adr.sin_family = AF_INET;
+    send_adr.sin_addr.s_addr = inet_addr(argv[1]);
+    send_adr.sin_port = htons(atoi(argv[2]));
+
+    if (connect(sock, (struct sockaddr *)&send_adr, sizeof(send_adr)) == -1)
+        error_handling("connect() error");
+
+    write(sock, "123", strlen("123"));
+    close(sock);
+    return 0;
+}
+
+void error_handling(char *message)
+{
+    fputs(message, stderr);
+    fputc('\n', stderr);
+    exit(1);
+}