CODEWITHSUNDEEP
cdockertcp
S7_0
S7_0

Reputation: 1183

C application server/client doesn't work in docker container

I'm a newbie with Docker. I write a server/client (very simple) application which both of them run in the same container.

I'm working on OSX and it work perfectly when I connect the client to the server.

However, I can't connect my client to my server. Here's my code:

client.c:

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

int main(int argc, char *argv[])
{
    int sockfd = 0, n = 0;
    char recvBuff[1024];
    struct sockaddr_in serv_addr;

    if(argc != 2) {
      printf("\n Usage: %s <ip of server> \n",argv[0]);
      return 1;
    }
    memset(recvBuff, '0',sizeof(recvBuff));
    if((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
      printf("\n Error : Could not create socket \n");
      return 1;
    }
    memset(&serv_addr, '0', sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_port = htons(5000);
    if(inet_pton(AF_INET, argv[1], &serv_addr.sin_addr)<=0) {
      printf("\n inet_pton error occured\n");
      return 1;
    }

   int connect_value = connect(sockfd, (struct sockaddr *)&serv_addr, sizeof(serv_addr));
   if (connect_value < 0) {
     printf("Value of connect_value %d\n", connect_value);
     fprintf(stderr, "Value of errno: %d\n", errno);
     return (1);
   }

    while ( (n = read(sockfd, recvBuff, sizeof(recvBuff)-1)) > 0){
      recvBuff[n] = 0;
      if(fputs(recvBuff, stdout) == EOF)
        printf("\n Error : Fputs error\n");
    }
    if(n < 0)
      printf("\n Read error \n");
    return 0;
}

server.c

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

int main(int argc, char *argv[])
{
    int listenfd = 0, connfd = 0;
    struct sockaddr_in serv_addr;

    char sendBuff[1025];
    time_t ticks;

    listenfd = socket(AF_INET, SOCK_STREAM, 0);
    memset(&serv_addr, '0', sizeof(serv_addr));
    memset(sendBuff, '0', sizeof(sendBuff));

    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
    serv_addr.sin_port = htons(5000);

    bind(listenfd, (struct sockaddr*)&serv_addr, sizeof(serv_addr));

    listen(listenfd, 10);

    while(1)
    {
        connfd = accept(listenfd, (struct sockaddr*)NULL, NULL);

        ticks = time(NULL);
        snprintf(sendBuff, sizeof(sendBuff), "%.24s\r\n", ctime(&ticks));
        write(connfd, sendBuff, strlen(sendBuff));

        close(connfd);
        sleep(1);
     }
}

the command line I use to launch my container:

docker run -it --security-opt seccomp=unconfined --mount type=bind,src=/Users/steven/Documents/eip/firmware_coit,dst=/bidon 987steven/eip_linux bash

I compile and run with the following way:

gcc server.c -o server && ./server

gcc client.c -o client && ./client 127.0.0.1

Error : Connect Failed Value of

connect_value -1

Value of errno: 111

I tried to figured out by myself before post on SO but most of the topic and read about:

But didn't find anything that could solve my problem.

Just to be clear that I have a very few knowledge in network in general and newbie in docker. Please feel free to ask if you node additional information from me. Thanks

Upvotes: 1

Views: 1012

Answers (1)

S7_0
S7_0

Reputation: 1183

Problem solve !

I used to launch my container with the following way:

 docker run -it --security-opt seccomp=unconfined --mount type=bind,src=/Users/steven/Documents/eip/firmware_coit,dst=/bidon 987steven/eip_linux bash

But I only need to add to the command line:

--net="host"

Alternatively you can run a docker container with network settings set to host. Such a container will share the network stack with the docker host and from the container point of view, localhost (or 127.0.0.1) will refer to the docker host.

Source: From inside of a Docker container, how do I connect to the localhost of the machine?

Upvotes: 1

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