Linux网络编程之简单TCP客户端服务器端实现

下面的 代码有两个问题：
server 端code：

#include <sys/socket.h>
#include <stdio.h>
#include <stdlib.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <string.h>
#include <unistd.h>
int main()
{
    int listenfd = 0;
    **if (listenfd = socket(AF_INET, SOCK_STREAM, 0) == -1)**
    {
        perror("socket error\n");
        exit(1);
    }
    printf("creat socket success\n");
    struct sockaddr_in seraddr;
    memset(&seraddr, 0, sizeof(seraddr));
    seraddr.sin_family = AF_INET;
    seraddr.sin_port = htons(51888);
    seraddr.sin_addr.s_addr = inet_addr("127.0.0.1");
    if (bind(listenfd, (struct sockaddr *)&seraddr,sizeof(seraddr)) < 0)
    {
        perror("bind error\n");
        exit(1);
    }
    printf("bind success\n");
    if (listen(listenfd, 50) < 0)
    {
        perror("listen error\n");
        exit(1);
    }
    printf("listen success\n");
    struct sockaddr_in peer_addr;
    socklen_t addr_len = sizeof(peer_addr);
    memset(&peer_addr, 0, sizeof(peer_addr));
    int conid;
    if ((conid = accept(listenfd, (struct sockaddr *)&peer_addr, &addr_len)) < 0)
    {
        perror("listen error\n");
        exit(1);
    }
    printf("accept success\n");
       printf("peer address is %s, port is %d\n", inet_ntoa(peer_addr.sin_addr),ntohs(peer_addr.sin_port));
    char recbuf[1024];
    while (1)
    {
        memset(recbuf, 0, sizeof(recbuf));
        int ret = read(conid, recbuf, sizeof(recbuf));
        if (ret == 0)
        {
            printf ("client has closed\n");
            break;
        }
        printf ("receive data is %s, length is %d\n", recbuf, ret);
        send(conid, recbuf, ret, 0);
        printf ("send data is %s to client,length is %d\n", recbuf, ret);
    }
    close(listenfd);
    close(conid);

    return 0;
}

TCP client 端 code：

#include <sys/socket.h>
#include <stdio.h>
#include <stdlib.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <string.h>
#include <unistd.h>

int main()
{
    int confd = 0;
    if((confd = socket(AF_INET, SOCK_STREAM, 0)) == -1)
    {
        perror("socket error\n");
        exit(1);
    }
    printf("create socket success\n");
    struct sockaddr_in seraddr;
    memset(&seraddr, 0, sizeof(seraddr));
    seraddr.sin_family = AF_INET;
    seraddr.sin_port = htons(51888);
    seraddr.sin_addr.s_addr = inet_addr("127.0.0.1");
    if (connect(confd, (struct sockaddr *)&seraddr, sizeof(seraddr)) < 0)
       {
        perror("connect error\n");
        exit(1);
    }
    printf ("connect to server success\n");
    char sendbuf[1024] = {0};
    char recbuf[1024] = {0};
    while (fgets(sendbuf, sizeof(sendbuf), stdin) != NULL)
    {
        write(confd, sendbuf, strlen(sendbuf));
        read(confd, recbuf, **strlen**(recbuf));
        printf ("receive data:%s\n", recbuf);
        memset(sendbuf, 0, sizeof(sendbuf));
        memset(recbuf, 0, sizeof(recbuf));
    }
    close(confd);
    return 0;
}

问题1：
运行 server 端应该会报下面的错误：
Socket operation on non-socket
原因是 建立socket 这句 if(listenfd = socket(AF_INET, SOCK_STREAM, 0) == -1)
等号的优先级比比较符低，所以 listenfd 永远等于 false，从而导致后面bind 了一个 非法 socket。
问题2：
调试过程中发现 Client 收不到 server发送端发送端数据。
最后调查发现是 client 端 调用 read函数时
read(confd, recbuf, strlen(recbuf));
recbuf 的string length 恒为0， 所以接收不到数据。