client-udp.c

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

#define BUFLEN 2048

int main(int argc, char *argv[])
{
    struct sockaddr_in myaddr, remaddr;
    int sockfd, i;
    char *server = "127.0.0.1", *message;
    char buf[BUFLEN];
    socklen_t addrlen = sizeof(remaddr);

    if((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) > 0)
    {
        printf("socket created.");
    }

    memset((char *)&myaddr, 0, sizeof(myaddr));
    myaddr.sin_family = AF_INET;
    myaddr.sin_addr.s_addr = htonl(INADDR_ANY);
    myaddr.sin_port = htons(0);

    if(bind(sockfd, (struct sockaddr *)&myaddr, sizeof(myaddr)) < 0)
    {
        perror("bind failed");
        return 0;
    }

    memset((char *)&remaddr, 0, sizeof(remaddr));
    remaddr.sin_family = AF_INET;
    remaddr.sin_port = htons(9303);

    if(inet_aton(server, &remaddr.sin_addr) == 0)
    {
        perror("inet_aton() failed\n");
        exit(1);
    }


    printf("what do you want to send?\n");
    scanf("%s",buf);
    sprintf(buf,"%s",buf);
    if (sendto(sockfd, buf, strlen(buf), 0, (struct sockaddr *)&remaddr, sizeof(remaddr))==-1)
	perror("sendto() failed");
    printf("Now receiving..");
    if (recvfrom(sockfd, buf, strlen(buf), 0, (struct sockaddr *)&remaddr, &addrlen))
	perror("recvfrom() failed");

    close(sockfd);
    return 0;
}