Original Post
In the process of learning winsock, I am trying to create a very basic winsock program that will allow me to connect to an ip address and a port and receive data and issue commands.
My program connects to the server, it starts a loop that retrieves the information first in case the server sends something immediately like an smtp server, and then allows me to send a command.
My problem is that after I send a command it locks up. When I did the debugging with dev-cpp it shows that its locking up when the loop begins again and i issue the recv function again.
Enclosed is the code. Can anyone please give me an idea of what I am doing wrong.
Thanks in advance and code below.
Code:
#include <stdio.h>
#include <winsock2.h>
#include <string.h>
void printerror(char *);
int main(int argc, char *argv[]) {
WSADATA wsa;
SOCKET s;
struct sockaddr_in target;
struct hostent *rhost;
char sbuffer[500];
char rbuffer[500];
int rbytesReceived,sbytesSent;
int iostate = 1;
rbytesReceived = sbytesSent = 0;
if(argc != 3) {
printf("Syntax: telnet ipaddress port\n");
return 1;
}
if((atoi(argv[2])) > 65536) {
printf("Port must be between 1 and 65536");
return 1;
}
if(WSAStartup(MAKEWORD(2,2),&wsa)) {
printerror("WSAStartup()");
return 1;
}
rhost = gethostbyname(argv[1]);
if(rhost == NULL) {
printerror("gethostbyname()");
return 1;
}
s = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
if(s == INVALID_SOCKET) {
printerror("socket()");
WSACleanup();
return 1;
}
target.sin_family = AF_INET;
target.sin_port = htons(atoi(argv[2]));
target.sin_addr.s_addr = inet_addr(inet_ntoa(*(LPIN_ADDR) *(rhost->h_addr_list)));
memset(&(target.sin_zero),''\0'',8);
if(connect(s,(struct sockaddr*) ⌖,sizeof(struct sockaddr)) == -1) {
printerror("connect()");
closesocket(s);
WSACleanup();
return 1;
}
do {
memset(sbuffer,''\0'',500); // To null out the buffer. Not sure if its needed.
memset(rbuffer,''\0'',500);
rbytesReceived = recv(s,rbuffer,sizeof(rbuffer),0);
if(rbytesReceived == SOCKET_ERROR) {
printerror("recv()");
closesocket(s);
WSACleanup();
return 1;
}
rbuffer[rbytesReceived]=''\0'';
puts(rbuffer);
gets(sbuffer); // Ask for input.
sbytesSent = send(s,sbuffer,sizeof(strlen(sbuffer)),0);
if(sbytesSent == SOCKET_ERROR) {
printerror("send()");
closesocket(s);
WSACleanup();
return 1;
}
} while(strcmp(sbuffer,"quit")); // If input is quit, exit program.
closesocket(s);
WSACleanup();
return 0;
}
void printerror(char *function) {
LPVOID lpMsgBuf;
FormatMessage(
FORMAT_MESSAGE_ALLOCATE_BUFFER |
FORMAT_MESSAGE_FROM_SYSTEM |
FORMAT_MESSAGE_IGNORE_INSERTS,
NULL,
WSAGetLastError(),
MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), // Default language
(LPTSTR) &lpMsgBuf,
0,
NULL) ;
printf("Error in %s:\n%s\n",function,(LPCTSTR)lpMsgBuf);
LocalFree( lpMsgBuf );
}
but please not that this is still a bad system because it doesnt recieve any data while its waiting for your input