send() socket operation on non-socket - c

Question

While trying to implement a server and client, I noticed that the client was writing to stdout instead
of through the network. I figured out that the file descriptor being returned by connect() is always zero, which explains why it was writing to stdout. But I can not figure out why connect() always returns zero instead of a valid socket. All the articles on the web I found with the same problem were due to precedence issues with wrapping if() around the connect() call. But I haven't done that, any help would be appreciated.
server code
int setUpServer(struct fuzzerObj *ptr, int *firstClient)
{
/* Declarations */
int hostSocket, yes = 1, rtrn, clientfd;
union
{
struct sockaddr_in in;
}address;
/* Create Socket */
hostSocket = socket(AF_INET, SOCK_STREAM, 0);
if(hostSocket < 0)
{
errorHandler("Could not create socket\n", FUNCTION_ID_SET_UP_SERVER);
return -1;
}
/* Reuse Address */
rtrn = setsockopt(hostSocket, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(yes));
if(rtrn < 0)
{
errorHandler("Couldn't Reuse Address\n", FUNCTION_ID_SET_UP_SERVER);
return -1;
}
/* Set Up Struct */
address.in.sin_len = sizeof(address.in);
address.in.sin_family = AF_INET;
address.in.sin_port = htons(BBPORT_NUMBER);
address.in.sin_addr.s_addr = htonl(INADDR_ANY);
memset(address.in.sin_zero, 0, sizeof(address.in.sin_zero));
/* Bind Address to Socket */
rtrn = bind(hostSocket, (struct sockaddr*) &address, address.in.sin_len);
if(rtrn < 0)
{
errorHandler("Can't Bind Address to Socket\n", FUNCTION_ID_SET_UP_SERVER);
return -1;
}
/* listen */
rtrn = listen(hostSocket, ptr->numberOfClients);
if(rtrn < 0)
{
errorHandler("Can't Listen\n", FUNCTION_ID_SET_UP_SERVER);
return -1;
}
while(1)
{
rtrn = acceptClient(hostSocket, &clientfd);
if(rtrn < 0)
{
printf("Can't Accept Client\n");
return -1;
}
break;
}
*firstClient = clientfd;
return 0;
}
client code
#include <CoreFoundation/CoreFoundation.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <netinet/in.h>
#include <stdbool.h>
#include <sys/types.h>
#include <unistd.h>
#include <errno.h>
#define BLACKBOX_PORT 9696
int main(int argc, char *argv[])
{
/* Check To See If an argument was passed */
if(argc < 2)
{
printf("No enough Arguments\n");
return -1;
}
/* Declaration's */
const char *ip = argv[1];
int sockfd, fd, rtrn;
char *outBuf;
struct sockaddr_in servaddr;
/* Get Socket to Connect to Fuzz Server */
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if(sockfd < 0)
{
perror("Can't Create Socket");
return -1;
}
/* Fill Out Struct */
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(BLACKBOX_PORT);
inet_pton(AF_INET, ip, &servaddr.sin_addr);
/* Attempt Connection */
fd = connect(sockfd,(struct sockaddr *)&servaddr, sizeof(servaddr));
if(fd < 0)
{
perror("Can not connect to BlackBox Fuzz server");
return -1;
}
/* Allocate Space in Memory for Outgoing Connection */
rtrn = asprintf(&outBuf, "Mac OSX 10.9\n");
if(rtrn < 0)
{
perror("Copy Error");
return -1;
}
/* Send Data to Fuzzer via Socket */
rtrn = send(fd, outBuf, strlen(outBuf), 0);
if(rtrn < 0)
{
perror("Can't write Data to BlackBox Server");
return -1;
}
free(outBuf);
return 0;
}

Answer 1

Upon successfully calling connect(), the sockfd is connected. The 0 return value indicates that the call is successful. If the value was not 0, it would have indicated an error, and that the connection attempt has failed or is not yet completed (if the connect is non-blocking).
After determining that connect() has succeeded, call send() on the sockfd, not on the return value of the connect() call.
rtrn = send(sockfd, outBuf, strlen(outBuf), 0);