使用select

Question

服务器正在接受客户端，但未收到任何消息。这是我的服务器代码：

服务器：

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


//Socket Creation
int socketFile(){
    int Socket = socket(AF_INET, SOCK_STREAM, 0);
    if(Socket == -1){
        perror("Socket Error\n");
        exit(1);
    }
    else
        printf("Successfullly Connected to Socket: %d\n",Socket);

    return Socket;
}

int bindFile(int Socket, const struct sockaddr * receiver, int len){
    int Bind = bind(Socket, receiver, len);
    if(Bind == -1){
        perror("Bind Error\n");
        exit(1);
    }
    else
        printf("Successfullly Connected with Bind number: %d\n", Bind);
}

int listenFile(int Socket, int n){
    int listen1 = listen(Socket, n);
    if(listen1 == -1){
        perror("listen Error\n");
        exit(1);
    }
    else
        printf("Successfully Connected with no Listen Error\n");
}

int acceptFile(int Socket, struct sockaddr * receiver, socklen_t addrlen){
    int accept1 = accept(Socket, (struct sockaddr *)&receiver, &addrlen);
    if(accept1 == -1){
        perror("accept Error\n");
        exit(1);
    }
    else
        printf("Successfully Accepted with Data Socket number: %d\n", accept1);
}


void clearBuffer(char* b, int len) {
    int i;
    for (i = 0; i < len; i++)
        b[i] = '\0';
    sleep(0.1);
}

int main(int abcd, char *args[]) {
    //Socket
    int Socket = socketFile();

    //Struct for Receiver
    struct sockaddr_in receiver, sender;
    receiver.sin_family = AF_INET;
    receiver.sin_port = htons(atoi(args[1]));
    receiver.sin_addr.s_addr = inet_addr("127.0.0.1");
    int addrlength = sizeof(sender);
    socklen_t senderLength;

    //Bind
    int Bind = bindFile(Socket, (const struct sockaddr *)&receiver, addrlength);

    //Listen
    int Listen = listenFile(Socket, 5);

    char buffer[21];
    clearBuffer(buffer, 20);
    int message, set = 0, Select, client[30], max_client = 30, i, max_set = Socket;
    fd_set readfds, fds;
    struct timeval timeout;

    for(i = 0; i < max_client; i++){
        client[i] = 0;
    }

    //Clear & Add
    FD_ZERO(&fds);
    FD_SET(Socket, &fds);
    bool stop = false;

    while(!stop) {

        readfds = fds;
        Select = select(max_set +1, &readfds, NULL, NULL, NULL);

        if (Select == -1) {
          perror("Select");
          break;
        }

        if(FD_ISSET(Socket, &readfds)) {
            if(set < max_client) {
            client[set] = acceptFile(Socket,(struct sockaddr *) &sender, senderLength);
            FD_SET(client[set], &fds);

            if(client[set] > max_set)
                max_set = client[set];

            set++;
        }
    }

    for(i = 0; i < set; i++) {
        if(FD_ISSET(client[i], &readfds)){
            message = recv(client[i], buffer, 20, 0);
            buffer[message] = '\0';
            printf("%s\n", buffer);
        }
    }

}

  close(Socket);
  return 0;
}

客户端部分还可以，但是连接到服务器并发送第一条消息后，服务器将无法接收该消息。 我在处理错误时遇到很多麻烦。因此，请纠正错误。

Answer 1

您应该启用所有警告。然后，您会立即看到原因：acceptFile不返回任何内容，因此client[set]被设置为垃圾。