UDP Client Segmentation Error - c

Question

Please help! This is due in a few hours and I've had no luck w/ online searches
CODE:
/*
Description:
The client should first send a datagram to the LocationServer.
The LocationServer will be listening on port number 23510 of the host c-lnx001.engr.uiowa.edu.
The message contained in this datagram should be the specified UserID (no null characters, blanks, line-feeds, or other extraneous characters).
The LocationServer will respond with a datagram containing the following information:
[WeatherServer hostname] [WeatherServer port #]
*/
#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h> /* for fprintf */
#include <string.h> /* for memcpy */
#include <strings.h>
#include <netinet/in.h>
#include <netdb.h>
#include <stdlib.h>
#define SIZE 2048
int main(){
struct hostent *hp; /* host information */
struct sockaddr_in servaddr; /* server address */
char *my_message = "laura\0";/*USERID as message to server*/
char *buf_addr;
char *host = "c-lnx001.engr.uiowa.edu\0";
int port = 23510;
int fd;
/* fill in the server's address and data */
//memset((char*)&servaddr, 0, sizeof(servaddr)); ?
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(23510);
/* look up the address of the server given its name */
hp = gethostbyname("c-lnx001.engr.uiowa.edu");
if (!hp) {
fprintf(stderr, "could not obtain address of %s\n", host);
return 0;
}
/* put the host's address into the server address structure */
// DOESN't WORK: memcpy((void *)&servaddr.sin_addr, hp->h_addr_list[0], hp->h_length);
bcopy(hp->h_addr,(char*)&servaddr.sin_addr,hp->h_length);
if((fd = socket(AF_INET,SOCK_DGRAM, 0))<0)
{
exit(2);
}
/* send a message to the server */
if (sendto(fd, my_message, strlen(my_message), 0, (struct sockaddr *)&servaddr, sizeof(servaddr)) < 0)
{
perror("sendto failed");
return 0;
}
int addrlen = sizeof(servaddr);
recvfrom(fd,buf_addr,SIZE,0,(struct sockaddr*)&servaddr,&addrlen);
printf("%s\n", buf_addr);
}

Answer 1

I think your problem is that you're not resetting the serveraddr
Here's a working copy
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#define IP_ADDRESS "127.0.0.1"
#define SERVER_PORT 5060
int main (int argc, char *argv[])
{
int recBytes, clientSocket=socket(AF_INET, SOCK_DGRAM, 0);
char buf[80], msg[]="greeting to server";
const int msgLen = sizeof(msg);
struct sockaddr_in serverAddr;
socklen_t reSize;
memset(&serverAddr, sizeof(struct sockaddr_in), 0);
serverAddr.sin_family = AF_INET;
serverAddr.sin_port = htons(SERVER_PORT);
inet_aton(IP_ADDRESS, &serverAddr.sin_addr);
if(sendto(clientSocket, msg, sizeof(msg), 0, (struct sockaddr*)&serverAddr, sizeof(serverAddr)) != (sizeof(msg)))
{
perror("sendto");
return -1;
}
reSize = sizeof(struct sockaddr);
if((recBytes = recvfrom(clientSocket, buf, sizeof(buf)-1, 0, (struct sockaddr*)&serverAddr, &reSize)) == -1)
{
perror("recvfrom");
return -1;
}
buf[recBytes]='\0';
printf("%s\n", buf);
return 0;
}