C套接字recv()错误处理

Question

我有一个关于套接字中的recv()函数的问题(在linux Raspberri Pi上)

为什么我的程序停止在:

if ((numbytes = recv(fd, odp, 100, 0)) == -1) {
    printf("\n error while test recv 1");
    perror("recv");
    reconnect = 1;
}

是的，出现错误:“资源暂时不可用”

当我看到:printf("\n 测试接收 1 时出错");

我想处理稍后所做的重新连接。但我在终端窗口上看到我的程序停止在:

测试接收1时出错

我尝试过:

信号(SIGPIPE, SIG_IGN);

比:

信号(SIGPIPE, my_function);

但它停在任一处。

一些代码:

int main(int argc, char *argv[])
{

while(1) {          

    if(reconnect){
        close(fd);
        fd = createSocket(argv[1]);
        reconnect=0;
    }

reconnect = connectionTest(fd);

}


int connectionTest(int *fd) {

  numbytes=send(fd, buf, 100,0);

  if ((numbytes = recv(fd, reply, 100, 0)) == -1) {
/* HERE IT STOPS */
    perror("recv");
    printf("\n error while test recv 1");

    reconnect = 1;

  }

    return reconnect;
}

int createSocket(char *server_addr){

 int sockfd;
 struct addrinfo hints, *servinfo, *p;
 int rv;
 char s[INET6_ADDRSTRLEN];
 int set = 1;

signal(SIGPIPE, SIG_IGN);

printf("connect to: %s", server_addr); 

    memset(&hints, 0, sizeof hints);
    hints.ai_family = AF_UNSPEC;
    hints.ai_socktype = SOCK_STREAM;

    if ((rv = getaddrinfo(server_addr, PORT, &hints, &servinfo)) != 0) {
        fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv));
        return 1;
    }

    // loop through all the results and connect to the first we can
    for(p = servinfo; p != NULL; p = p->ai_next) {
        if ((sockfd = socket(p->ai_family, p->ai_socktype,
                p->ai_protocol)) == -1) {
            perror("client: socket");
            continue;
        }
        else printf("socketd created! \n");

    int set = 1;
setsockopt(sockfd, SOL_SOCKET, MSG_NOSIGNAL, (void *)&set, sizeof(int));

      if (setsockopt( sockfd, SOL_SOCKET, SO_KEEPALIVE, (void *)&set, sizeof(int)) < 0 )
      perror("setsockopt failed \n");

struct timeval timeout;
  timeout.tv_sec = 4;
  timeout.tv_usec = 0;


      if (setsockopt(sockfd, SOL_SOCKET, SO_RCVTIMEO, (char *)&timeout, sizeof(timeout)) < 0 ) 
      perror("setsockopt failed \n");

      if (setsockopt(sockfd, SOL_SOCKET, SO_SNDTIMEO, (char *)&timeout, sizeof(timeout)) < 0 ) 
      perror("setsockopt failed \n");

      printf("Try to connect \n");
      if (connect(sockfd, p->ai_addr, p->ai_addrlen) == -1) {
        close(sockfd);
        perror("client: connect");
      }
      else {
        printf("i have connection");
        break;
     }
   }

printf("next1");  

    if (p == NULL) {
        fprintf(stderr, "client: failed to connect\n");
        return 2;
    }

    inet_ntop(p->ai_family, get_in_addr((struct sockaddr *)p->ai_addr),
            s, sizeof s);
    printf("client: connecting to %s\n", s);
    freeaddrinfo(servinfo); // all done with this structure

return  sockfd;
}

Answer 1

read() 应不返回 EPIPE。

如果针对已被另一方 shutdown() 甚至 close()d 的连接发出 write()无论如何，发布过程都会出错。

发出SIGPIPE，如果没有处理也没有被阻止，进程将终止。如果 SIGPIPE 被处理或阻止，write() 应返回 -1 并将 errno 设置为 EPIPE.