From my client I am trying to send a string, the server needs to reverse the characters and send it back to the client.
SERVER CODE::
/******************************************************************
This is a simple example of a server using TCP
*****************************************************************/
/* Library Section */
#include <stdio.h> /* Standard Input and Output */
#include <unistd.h> /* Unix Standard Functions */
#include <string.h> /* Used for bzero */
#include <math.h> /* Math Library used for log10 */
#include <sys/types.h> /* Used for System Data Type Defitions */
#include <sys/socket.h> /* Used for sockets */
#include <netinet/in.h> /* sockaddr_in definition */
#include <arpa/inet.h> /* Internet Sockets */
char* reverse(char s[]);
/* Definitions */
#define SERV_TCP_PORT 10617 /* Port Number */
#define SERV_HOST_ADDR "198.102.147.137" /* IP address for Gimli */
#define BUFFSIZE 500 /* Buffer Size */
int main() {
int sockfd; /* Initial socket descriptor */
int newsockfd; /* Client/Server socket descriptor */
socklen_t client_len; /* Client Socket File Length */
struct sockaddr_in serv_addr; /* Server Address Information */
struct sockaddr_in cli_addr; /* Client Address Information */
char msgbuff[BUFFSIZE]; /* Message Buffer */
char userstring[BUFFSIZE]; /* string from the user */
char* revstring; /* string reversed from the server */
/* Open a TCP socket (an Internet stream socket). */
if ( (sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)/* creating internet socket */
fprintf(stderr, "server: can't open stream socket\n");
/* Bind our local address so that the client can send to us. */
/* First, clear out the structure */
bzero((char *) &serv_addr, sizeof(serv_addr));
serv_addr.sin_family = AF_INET;
serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
serv_addr.sin_port = htons(SERV_TCP_PORT);
if (bind(sockfd, (struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0)
fprintf(stderr, "server: can't bind local address\n");
/* Now, listen for incomming connections. */
listen(sockfd, 5);
printf("The server is now listening for connections\n");
while (1) { /* loop forever */
client_len = sizeof(cli_addr);
/* Accept the client connection */
newsockfd = accept(sockfd, (struct sockaddr *) &cli_addr, &client_len);
if (newsockfd < 0)
fprintf(stderr, "server: accept error");
/* Read string from the socket */
read(newsockfd, userstring, BUFFSIZE);
/*reverse the string */
revstring = reverse(userstring);
/* Write string to the socket */
write(newsockfd, revstring, strlen(revstring));
close(newsockfd); /* We are finished with the socket */
bzero(msgbuff, BUFFSIZE);
} /* END WHILE */
return (0); /* This will never happen since in infinite loop */
}
char* reverse(char s[])
{
int c, i, j;
for (i=0, j=strlen(s)-1; i < j;i++, j--)
{
c = s[i];
s[i] = s [j];
s[j] = c;
}
return s;
}
CLIENT CODE::
/* Library Section */
#include <stdio.h> /* Standard Input and Output */
#include <unistd.h> /* Unix Standard Functions */
#include <math.h> /* Math Library for log function */
#include <string.h> /* Used for bzero */
#include <sys/types.h> /* Used for System Data Type Defitions */
#include <sys/socket.h> /* Used for sockets */
#include <netinet/in.h> /* sockaddr_in definition */
#include <arpa/inet.h> /* Internet Sockets */
/* Definitions */
#define SERV_TCP_PORT 10617 /* Port Number */
#define SERV_HOST_ADDR "198.102.147.137" /* IP address for Gimli */
#define BUFFSIZE 500 /* Buffer Size */
int main() {
int sockfd; /* Initial socket descriptor */
struct sockaddr_in serv_addr; /* Server Address Information */
/*char climsg[BUFFSIZE];*/ /* Client Message */
char userstring; /* String from the user */
char revstring; /* String reversed from the server */
/* Fill in the structure of "serv_addr" with the address of the
* server that we want to connect with.
*/
/* First, zero out the structure. */
bzero((char *) &serv_addr, sizeof(serv_addr));
serv_addr.sin_family = AF_INET;
serv_addr.sin_addr.s_addr = inet_addr(SERV_HOST_ADDR);
serv_addr.sin_port = htons(SERV_TCP_PORT);
/* Open a TCP socket */
if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
fprintf(stderr, "Client: can't open stream socket");
/* Connect to the server */
if (connect(sockfd, (struct sockaddr *) &serv_addr,
sizeof(serv_addr)) < 0)
fprintf(stderr, "Client: can't connect to server");
/* Get string from the user */
printf("Please enter a string to be reversed by the server");
scanf("%s", &userstring);
/* Write string to the socket */
write(sockfd, userstring, strlen(userstring)); /* or size +2 */
/* Read string from the socket */
read(sockfd, revstring, BUFFSIZE);
printf("The string %s reversed is %s\n", userstring, revstring);
close(sockfd);
return (0); /* A zero indicates a normal closure */
}
I can get the server to listen for connections. When I send the message to the server I get a segmentation fault. Some one suggested I have a problem with my reverse function but I can not figure it out.
