Ndtyjky

I'm currently learning network programming in university and programmed a server. As we need this one for further progress I need to reuse the code every time. There is a random function with an error I don't really get because on the linux pcs at university everything compiles well only my mac which I do all my homework shows this error.

#include <stdio.h>

#include <stdlib.h>

#include <unistd.h>

#include <errno.h>

#include <string.h>

#include <sys/types.h>

#include <sys/socket.h>

#include <netinet/in.h>

#include <netdb.h>

#include <arpa/inet.h>

#include <sys/wait.h>

#include <signal.h>

#include <time.h>

//#define PORT "3490"  // the port users will be connecting to

#define BACKLOG 10   // how many pending connections queue will hold





int random(int min, int max){

      srand ( time(NULL) ); 

      return min + rand() / (RAND_MAX / (max - min + 1) + 1);

    }





void sigchld_handler(int s)

{

    // waitpid() might overwrite errno, so we save and restore it:

    int saved_errno = errno;

    while(waitpid(-1, NULL, WNOHANG) > 0);

    errno = saved_errno;

}

// get sockaddr, IPv4 or IPv6:

void *get_in_addr(struct sockaddr *sa)

{

    if (sa->sa_family == AF_INET) {

        return &(((struct sockaddr_in*)sa)->sin_addr);

    }

    return &(((struct sockaddr_in6*)sa)->sin6_addr);

}

int main(int argc, char *argv)

{

    int sockfd, new_fd;  // listen on sock_fd, new connection on new_fd

    struct addrinfo hints, *servinfo, *p;

    struct sockaddr_storage their_addr; // connector's address information

    socklen_t sin_size;

    struct sigaction sa;

    int yes=1;

    char s[INET6_ADDRSTRLEN];

    int rv;

    //int linetoread;



    if (argc != 3) {

        fprintf(stderr,"usage: server port txtfilen");

        exit(1);

    }



    FILE* fp;

    char buffer[255];

    int i = 0;

    char rnd[200][255];

    int fixed;



    fp = fopen(argv[2], "r");



    while(fgets(buffer, 255, (FILE*) fp)) {

        //printf("%sn", buffer);

        for (int j = 0; j < 255; j++){

          rnd[i][j] = buffer[j];

        }

        i++;

    }



    fclose(fp);

    //printf("number of lines: %dn", i);

    //linetoread = rand() % i;

    //printf("%dn", random(0,i));



    memset(&hints, 0, sizeof hints);

    hints.ai_family = AF_UNSPEC;

    hints.ai_socktype = SOCK_STREAM;

    hints.ai_flags = AI_PASSIVE; // use my IP

    if ((rv = getaddrinfo(NULL, argv[1], &hints, &servinfo)) != 0) {

        fprintf(stderr, "getaddrinfo: %sn", gai_strerror(rv));

        return 1;

    }

    // loop through all the results and bind 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("server: socket");

            continue;

        }

        if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &yes,

                sizeof(int)) == -1) {

            perror("setsockopt");

            exit(1);

        }

        if (bind(sockfd, p->ai_addr, p->ai_addrlen) == -1) {

            close(sockfd);

            perror("server: bind");

            continue;

        }

        break;

    }

    freeaddrinfo(servinfo); // all done with this structure

    if (p == NULL)  {

        fprintf(stderr, "server: failed to bindn");

        exit(1);

    }

    if (listen(sockfd, BACKLOG) == -1) {

        perror("listen");

        exit(1);

    }

    sa.sa_handler = sigchld_handler; // reap all dead processes

    sigemptyset(&sa.sa_mask);

    sa.sa_flags = SA_RESTART;

    if (sigaction(SIGCHLD, &sa, NULL) == -1) {

        perror("sigaction");

        exit(1);

    }

    printf("server: waiting for connections...n");

    while(1) {  // main accept() loop

        sin_size = sizeof their_addr;

        new_fd = accept(sockfd, (struct sockaddr *)&their_addr, &sin_size);

        if (new_fd == -1) {

            perror("accept");

            continue;

        }

        inet_ntop(their_addr.ss_family,

            get_in_addr((struct sockaddr *)&their_addr),

            s, sizeof s);

        printf("server: got connection from %sn", s);

        if (!fork()) { // this is the child process

            close(sockfd); // child doesn't need the listener

            fixed = random(0,i-1);

            //printf("line: %dn", fixed);

            if (send(new_fd, rnd[fixed], strlen(rnd[fixed]), 0) == -1)

                perror("send");

            close(new_fd);

            exit(0);

        }

        close(new_fd);  // parent doesn't need this

    }

    return 0;

}       

Error on my mac:

server.c:16:5: error: conflicting types for 'random'

int random(int min, int max){

    ^

/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.13.sdk/usr/include/stdlib.h:233:7: note: 

      previous declaration is here

long     random(void) __swift_unavailable("Use arc4random instead.");

         ^

server.c:132:19: error: too many arguments to function call, expected 0, have 2

                        fixed = random(0,i-1);

                                ~~~~~~ ^~~~~

/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.13.sdk/usr/include/stdlib.h:233:1: note: 

      'random' declared here

long     random(void) __swift_unavailable("Use arc4random instead.");

^

2 errors generated.

random() is a known function name. change it to something else and it will work.