Making a socket that only exits if exit message is received - c

Question

#include <io.h>
#include <stdio.h>
#include <winsock2.h>
#include <string.h>
#define MY_PORT 8989
#define MAXBUF 256
//function prototype
int exitmsg(const char *a, const char *b);
int main(int argc, char *argv[]){
WSADATA wsa;
SOCKET sockfd ,clientfd; //define 2 sockets
struct sockaddr_in self;
char buffer[MAXBUF];
printf("\nInitialising Winsock...");
if (WSAStartup(MAKEWORD(2,2),&wsa) != 0){
printf("Failed. Error Code : %d",WSAGetLastError());
return 1;
}
printf("Initialised.\n");
/*---create streaming socket---*/
if ( (sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0 ){
perror("Socket");
exit(errno);
}
printf("Socket created.\n");
/*---initialize address/port structure---*/
/* bzero(&self, sizeof(self));*/
self.sin_family = AF_INET;
self.sin_port = htons(MY_PORT);
self.sin_addr.s_addr = INADDR_ANY;
/*---assign a port number to the socket---*/
if ((bind(sockfd, (struct sockaddr*)&self, sizeof(self)))!=0){
perror("socket--bind");
exit(errno);
}
puts("Bind done");
/*---make it a "listening socket"---*/
if ((listen(sockfd, 20))!=0){
perror("socket--listen");
exit(errno);
}
puts("Waiting for incoming connections...");
/*---forever... ---*/
while (1){
struct sockaddr_in client_addr;
int addrlen=sizeof(client_addr), checking;
/*---accept a connection (creating a data pipe)---*/
clientfd= accept(sockfd, (struct sockaddr*)&client_addr, &addrlen);
char test[20]="exit server";
int loop=0, len=strlen(buffer);
char temp; //temporary holds character to swap
int length= recv(clientfd, buffer, MAXBUF, 0);
// handle multiple requests
do {
//from server 1
for(int i=0; i<len; i++){
if(buffer[i]>=65 && buffer[i]<=90){ // check ascii value
buffer[i]= buffer[i]+32; // if uppercase thn change
}
}
//check if client want to exit
checking= exitmsg(test, buffer);
if (checking==1){
printf("Message to exit received. \n");
}
else{
//reverse
len--; // start from 0
while (loop<len){
temp=buffer[loop];
buffer[loop]=buffer[len];
buffer[len]=temp;
loop++;
len--;
}
//outputs
//ip and host port
char *ipadd=inet_ntoa(client_addr.sin_addr);
printf("IP address: %s \nPORT: %d\n", ipadd, ntohs(client_addr.sin_port));
printf("Length of message: %d\n", length);
//send back
send(clientfd, buffer, strlen(buffer), 0);
}
length= recv(clientfd, buffer, MAXBUF, 0)>0;
}while (length>0);
/*---close connection---*/
close(clientfd);
}
/*---clean up (should never get here!)---*/
close(sockfd);
WSACleanup();
return 0;
}
int exitmsg(const char *a, const char *b){
for(; (*a!='\0' && *b!='\0'); a++, b++){
if(*a==*b){
return 1;
}
}
return 0;
}
I tried to look for several references online and came up with this, however my server doesn't work as intended. Currently sends back only reverses first 3 letters string with a letter missing and secondly the original string with two characters missing. I'm using port 8989 with a passive Telnet connection. All pointers to understand what's happening would be useful as I'm very new to this.
I'm also attempting to print the ip address, port number and length of buffer for each connection made.
I'm trying to make the server handle multiple requests from a single client, however I'm wondering whether it's even possible....