why Imap server send different output? - c

Question

Network programming problem regarding imap-client. I am using Dovecod localhost for imap. When I use telnet to check the connection it work perfectly but when C use my C-code to check the connection server send me different output.
The C-code only get error for my loopback ip, it works perfectly when I use different ip to execute the programs.
Here is the output difference screenshot
this is the output diffrence while using telnet and c-code
I tried to change the code little bit but the error give same.
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <sys/socket.h>
#include <resolv.h>
#include <stdlib.h>
#define PORT_TIME 13
#define PORT_IMAP 143
#define MAXBUF 1024
int main(int argc,char *argv[])
{
int sockfd;
int n;
struct sockaddr_in dest;
char buffer[MAXBUF],p[MAXBUF],q[MAXBUF];
/*---Open socket for streaming---*/
if ( (sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0 )
{
perror("Socket");
exit(errno);
}
/*---Initialize server address/port struct---*/
bzero(&dest, sizeof(dest));
dest.sin_family = AF_INET;
dest.sin_port = htons(PORT_IMAP);
if ( inet_aton(argv[1], &dest.sin_addr) == 0 )
{
perror(argv[1]);
exit(errno);
}
if ( connect(sockfd, (struct sockaddr*)&dest, sizeof(dest)) != 0 )
{
perror("Connect ");
exit(errno);
}
else
{
printf("Connected to %s\n",argv[1]);
}
bzero(buffer, MAXBUF);
recv(sockfd, buffer, sizeof(buffer), 0);
printf("%s", buffer);
bzero(buffer,MAXBUF);
bzero(p,MAXBUF);
bzero(q,MAXBUF);
printf(" Name: ");
scanf("%[^\n]%*c",q);
printf(" Password: ");
fgets(p,MAXBUF,stdin);
strcat(buffer,"a1 LOGIN ");
strcat(buffer,q);
strcat(buffer," ");
strcat(buffer,p);
printf("%s",buffer);
if(write(sockfd,buffer,sizeof(buffer))<0)
perror("error on writing");
bzero(buffer, MAXBUF);
recv(sockfd, buffer, sizeof(buffer), 0);
printf("%s", buffer);
bzero(buffer,MAXBUF);
strncpy(buffer,"a2 LIST \"\" \"*\"\r\n",16);
printf("%s",buffer);
if(write(sockfd,buffer,16)<0)
perror("error on writing");
bzero(buffer, MAXBUF);
recv(sockfd, buffer, MAXBUF, 0);
printf("%s", buffer);
close(sockfd);
return 0;
}
When i receive from server it should get me "a2 OK" according to my c-code but it get me "* OK"

Answer 1

The IMAP server is required to do some things in response to your commands, but not forbidden from doing other things.
Most importantly, it can react to incoming mail independently of what commands you send, and its output depends both on the commands you send and those other events to which it also reacts.
Some IMAP servers send occasional * OK whatever for no particular reason, just to keep NAT middleboxes from closing the connection. I don't know why your server sent that * OK, but it's permitted. The server has to eventually send a2 OK, but it can send zero, one, two or 500 * OK responses first. (* OK just means "not an error, not related to any command".)