LinuxQuestions.org - Can anyone please help to make server.c for non-blocking I/O for TCP socket programming?

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Can anyone please help to make server.c for non-blocking I/O for TCP socket programming?

Can anyone please help to make server.c for non-blocking I/O for TCP socket programming? I am trying to make multiple clients to connect to this server. I have tried the following code:

Code:

#include <stdio.h> 

#include <netdb.h> 

#include <netinet/in.h> 

#include <stdlib.h> 

#include <string.h> 

#include <sys/socket.h> 

#include <sys/types.h> 

#include <unistd.h> // read(), write(), close()

#include <arpa/inet.h>

#include <fcntl.h>

#define MAX 80 

#define PORT 8080 

#define SA struct sockaddr 



void func(int connfd) 

{ 

        char buff[MAX]; 

        int n; 

        // infinite loop for chat 

        for (;;) { 

                bzero(buff, MAX); 



                // read the message from client and copy it in buffer 

                read(connfd, buff, sizeof(buff)); 

                // print buffer which contains the client contents 

                printf("From client: %s\t To client : ", buff); 

                bzero(buff, MAX); 

                n = 0; 

                // copy server message in the buffer 

                while ((buff[n++] = getchar()) != '\n') 

                        ; 



                // and send that buffer to client 

                write(connfd, buff, sizeof(buff)); 



                // if msg contains "Exit" then server exit and chat ended. 

                if (strncmp("exit", buff, 4) == 0) { 

                        printf("Server Exit...\n"); 

                        break; 

                } 

        } 

} 



// Driver function 

int main() 

{ 

        int sockfd, connfd;

    socklen_t len; 

        struct sockaddr_in servaddr, cli; 



        // socket create and verification 

        sockfd = socket(AF_INET, SOCK_STREAM, 0); 

        if (sockfd == -1) { 

                printf("socket creation failed...\n"); 

                exit(0); 

        } 

        else

                printf("Socket successfully created..\n");

        

        

        int flags = fcntl(sockfd, F_GETFL, 0);

        flags |= O_NONBLOCK;

        int status = fcntl(sockfd, F_SETFL, flags);

        //printf("status: %d\n", status);



        bzero(&servaddr, sizeof(servaddr)); 



        // assign IP, PORT 

        servaddr.sin_family = AF_INET; 

        servaddr.sin_addr.s_addr = htonl(INADDR_ANY); 

    //servaddr.sin_addr.s_addr = inet_addr("192.168.1.103"); 

        servaddr.sin_port = htons(PORT); 



        // Binding newly created socket to given IP and verification 

        if ((bind(sockfd, (SA*)&servaddr, sizeof(servaddr))) != 0) { 

                printf("socket bind failed...\n"); 

                exit(0); 

        } 

        else

                printf("Socket successfully binded..\n"); 



        // Now server is ready to listen and verification 

        if ((listen(sockfd, 5)) != 0) { 

                printf("Listen failed...\n"); 

                exit(0); 

        } 

        else

                printf("Server listening..\n"); 

        len = sizeof(cli); 



        while(1) {

                // Accept the data packet from client and verification 

                connfd = accept(sockfd, (SA*)&cli, &len); 

                if (connfd < 0) { 

                        printf("server accept failed...\n"); 

                        exit(0); 

                } 

                else

                        printf("server accept the client...\n"); 



                // Function for chatting between client and server 

                func(connfd); 

        }

        close(sockfd); 

}

I have got the output like this:

Code:

Socket successfully created..

Socket successfully binded..

Server listening..

server accept failed...

Print `errno` and `strerror(errno)`.

The best I can tell you need to change this...,

Code:

connfd = accept(sockfd, (SA*)&cli, &len);

Instead of me trying to rewrite this, here, a working example, you rewrite it.

Code:

//gcc BindPort.c -o BindPort



#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <unistd.h>

#include <sys/types.h>

#include <sys/socket.h>

#include <netinet/in.h>



void error(const char *msg) {

    perror(msg);

    exit(1);

}



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

{

    int sockfd, newsockfd, portno;

    socklen_t clilen;

    char buffer[256];

    struct sockaddr_in serv_addr, cli_addr;

    int n;

    

    if (argc < 2) {

        fprintf(stderr,"ERROR, no port provided\n");

        exit(1);

    }

    

    sockfd = socket(AF_INET, SOCK_STREAM, 0);

    

    if (sockfd < 0)

        error("ERROR opening socket");

        

    bzero((char *) &serv_addr, sizeof(serv_addr));

    portno = atoi(argv[1]);

    serv_addr.sin_family = AF_INET;

    serv_addr.sin_addr.s_addr = INADDR_ANY;

    serv_addr.sin_port = htons(portno);

    

    if (bind(sockfd, (struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0)

        error("ERROR on binding");

        

    listen(sockfd,5);

    clilen = sizeof(cli_addr);

    newsockfd = accept(sockfd, (struct sockaddr *) &cli_addr, &clilen);

    

    if (newsockfd < 0)

        error("ERROR on accept");

        

    bzero(buffer,256);

    n = read(newsockfd,buffer,255);

    

    if (n < 0) 

        error("ERROR reading from socket");

        

    printf("Here is the message: %s\n",buffer);

    n = write(newsockfd,"I got your message",18);

    

    if (n < 0) error("ERROR writing to socket");

        close(newsockfd);

        

    close(sockfd);

    return 0;

}

Compiled, ran executable, Opened a web browser to http://127.0.0.1:8100/

Code:

gcc BindPort.c -o BindPort



./BindPort 8100



Here is the message: GET / HTTP/1.1

Host: 127.0.0.1:8100

Connection: keep-alive

Upgrade-Insecure-Requests: 1

User-Agent: Mozilla/5.0 (iPhone; CPU iPhone OS 17_4 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) CriOS/123.0.6312.52 Mobile/15E148 Safari/604.1