Hi all,
Thank you for your reply.
- You recommened me that use netcat. But what for ? (debugging, sending
test email vs vs ...) Can you explain a bit more please ?
- As you said i added the code error handling. But when i run this poc code
and try to send email postfix again says me "451 4.3.0 Error: queue file
write error" and wait rcpt to : x...@xxx.com. All i need is send mail
through 10025/tcp and send it through 10026/tcp. So i can see smtp traffic
before-queue postfix method.
Actually i have explored example code but i havent seen. So i don't know
how i can debug and fix this. I try to develop program running before-queue
postfix method.
Best regards.
New code is below
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <unistd.h>
#include <time.h>
#include <errno.h>
#include <fcntl.h>
#define PORT 10025
#define REMOTE_PORT 10026
#define REMOTE_IP "0.0.0.0"
#define TRUE 1
void exitsys(const char *msg);
int main(int argc, const char **argv)
{
int addr_len, result, yes = 1;
int server_sock = 0, client_sock = 0, sock_fd = 0;
char buff[1025];
struct sockaddr_in server_addr, client_addr, remote_addr;
fd_set read_fds;
struct timeval timeout;
timeout.tv_sec = 1; // seconds
timeout.tv_usec = 0;
if ((server_sock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0)
exitsys("socket");
if (setsockopt(server_sock, SOL_SOCKET, SO_REUSEADDR, &yes,
sizeof(int)) == -1)
exitsys("setsockopt");
memset(buff, 0x0, sizeof(buff));
memset(&server_addr, 0x0, sizeof(server_addr));
memset(&client_addr, 0x0, sizeof(client_addr));
memset(&remote_addr, 0x0, sizeof(remote_addr));
server_addr.sin_family = AF_INET;
server_addr.sin_port = htons(PORT);
server_addr.sin_addr.s_addr = htonl(INADDR_ANY);
remote_addr.sin_family = AF_INET;
remote_addr.sin_port = htons(REMOTE_PORT);
if ((bind(server_sock, (struct sockaddr*)&server_addr,
sizeof(server_addr))) < 0)
exitsys("bind");
if (fcntl(server_sock, F_SETFL, O_NONBLOCK) < 0)
exitsys("fcntl");
if (listen(server_sock, 8) < 0)
exitsys("listen");
while (TRUE) {
if ( (select(server_sock, NULL, NULL, NULL, &timeout)) > 0)
{
addr_len = sizeof(client_addr);
if ( (client_sock = accept(server_sock, (struct
sockaddr *)&client_addr, &addr_len)) < 0 )
exitsys("accept-1");
if ( ( sock_fd = socket(AF_INET, SOCK_STREAM, 0)) <
0 )
exitsys("socket");
inet_pton(AF_INET, REMOTE_IP,
&remote_addr.sin_addr);
connect(sock_fd, (struct sockaddr *)&remote_addr,
sizeof(remote_addr));
if ( fcntl(client_sock, F_SETFL, O_NONBLOCK) < 0)
exitsys("fcntl");
while (TRUE) {
if ( (select(client_sock, NULL, NULL, NULL,
&timeout)) > 0 ) {
result = recv(client_sock, buff,
sizeof(buff), 0);
if (result > 0)
send(sock_fd, buff,
(sizeof(buff)-1), 0);
else
printf("YOK\n");
}
}
shutdown(client_sock, SHUT_RDWR);
close(server_sock);
close(client_sock);
close(sock_fd);
}
}
return 0;
}
void exitsys(const char *msg)
{
perror(msg);
exit(EXIT_FAILURE);
}
On Wed, Apr 23, 2014 at 4:59 PM, Wietse Venema <wie...@porcupine.org> wrote:
> G?khan Alkan:
> > I try to develop poc code for postfix content filtering. All i need is
> read
> > the 10025/tcp and send all data which i can read to 10026/tcp. Below is
> my
> > poc code. But i try to send email it doesn't work and postfix show me
> "451
> > 4.3.0 Error: queue file write error".
>
> I recommend that you use netcat.
>
> Wietse
>
> > fcntl(server_sock, F_SETFL, O_NONBLOCK);
>
> What if fcntl() reports an error?
>
> > fcntl(client_sock, F_SETFL, O_NONBLOCK);
>
> client_sock is still zero here.
>
> What if fcntl() reports an error?
>
> > client_sock = accept(server_sock, (struct sockaddr
> > *)&client_addr, &addr_len);
>
> What if accept() reports an error? It will always return -1 because
> server_sock is non-blocking. Thus, client_sock will always be -1.
>
> > sock_fd = socket(AF_INET, SOCK_STREAM, 0);
>
> What if socket() reports an error?
>
> > while(1) {
> > result = recv(client_sock, buff, sizeof(buff),0 );
>
> What if recv() reports an error? At this point, client_sock is
> -1 because accept() reported an error. See above.
>
> > inet_pton(AF_INET, REMOTE_IP, &remote_addr.sin_addr);
> > connect(sock_fd, (struct sockaddr *)&remote_addr,
> > sizeof(remote_addr));
>
> What if connect() reports an error?
>
> > send(sock_fd, buff, (sizeof(buff)-1), 0);
>
> What if send() reports an error?
>
> > }
>
> The above program loops forever in while(1).
>
> > shutdown(client_sock, SHUT_RDWR);
>
> What if shutdown() reports an error? At this point client_sock is -1
> because accept() reported an error. See above.
>
> > close(server_sock);
> > close(client_sock);
> > close(sock_fd);
>
> Wietse
>
--
----------------------
Gökhan ALKAN
