RE: Obtaining client host IP before accept()
On 18-Jun-99 Sheldon Hearn wrote: Will the IP address of the client host ever enter buf[] if the accept() is _not_ uncommented? I don't need portability, since this is for use within the FreeBSD inetd exclusively. Well if you CAN'T do it in FreeBSD, is there an OS we can copy the API from that DOES do it? (Providing it isn't too braindamaged of course.. :) --- Daniel O'Connor software and network engineer for Genesis Software - http://www.gsoft.com.au The nice thing about standards is that there are so many of them to choose from. -- Andrew Tanenbaum pgprZseCOU2BE.pgp Description: PGP signature
Re: Obtaining client host IP before accept()
Will the IP address of the client host ever enter buf[] if the accept() is _not_ uncommented? I don't need portability, since this is for use within the FreeBSD inetd exclusively. Well if you CAN'T do it in FreeBSD, is there an OS we can copy the API from that DOES do it? (Providing it isn't too braindamaged of course.. :) There is an API that can do it: System V Release 4 Streams and TLI (Transport Layer Interface). TLI is not based on systems calls doing the job. It is based on message transfer between the user and some kernel entity. Incoming calls are indicated by sending a T_CONN_IND message (connect indication) to the user process. Then the user process opens a second TLI stream (like using the socket() system call) and sends a T_CONN_CON message (connect confirmation) to the kernel entity. The TLI API is based on OSI. It doesn't provide much more functionality than BSD sockets. Two APIs for the same task isn't very useful. So you should better hack the BSD sockets to fit your needs. A similar functionality in BSD-world would be: (1) use recvfrom() instead of accept() on the socket TLI: use getmsg() to receive the T_CONN_IND (2) create a new socket using socket() TLI: use open() to open a new stream (3) accept the connection using an ioctl() TLI: send T_CONN_CON to accept the connection or (2) reject the connection using an ioctl() TLI: send T_DISCON_REQ to reject the connection Here's an overview of the TLI messages: TLI (user) TLI (kernel)BSD socket T_INFO_REQ T_INFO_ACK - T_BIND_REQ T_BIND_ACK bind() T_UNBIND_REQ- - T_OPTMGMT_REQ T_OPTMGMT_ACK setsockopt() - T_ERROR_ACK errno T_CONN_REQ T_CONN_RES connect() T_CONN_CON T_CONN_IND accept() T_DISCON_REQ- shutdown() - T_DISCON_INDerrno T_ORDREL_REQ- shutdown() T_DATA_REQ - send() / sendto() / write() - T_DATA_IND recv() / recvfrom() / read() T_EXDATA_REQ- send() / sendto() - T_EXDATA_INDrecv() / recvfrom() T_UNITDATA_REQ - send() / sendto() / write() - T_UNITDATA_IND recv() / recvfrom() / read() - T_UDERROR_IND recv() / recvfrom() / read() errno ; Bodo -- Bodo Rüskamp, b...@rueskamp.com, 51°55' N 7°41' E (1) Elvis is alive. (2) Dinosaurs too. http://www.lochness.scotland.net/camera.htm (3) The next millenium starts on January 1st 2000. To Unsubscribe: send mail to majord...@freebsd.org with unsubscribe freebsd-hackers in the body of the message
Obtaining client host IP before accept()
Hi folks,
I found a thread in the freebsd-hackers archive from 1997 that covered
my question, but the answers didn't nail it down to a yes or no
satisfactorily.
We could save ourselves a lot of angst in the work we're doing on inetd
if we could determine the client IP address of a TCP socket before
calling accept(). Alternatively, we'd love a way to accept() without
acknowledging a connection, so that the connection request could be left
for a child that expected to do its own socket() and bind() calls.
My take on the previous thread is that this is impossible in userland.
I'd appreciate it someone who knows the answer for a fact could look at
the code below and answer the following question:
Will the IP address of the client host ever enter buf[] if the
accept() is _not_ uncommented?
I don't need portability, since this is for use within the FreeBSD inetd
exclusively.
Thanks,
Sheldon.
#include err.h
#include errno.h
#include netdb.h
#include stdio.h
#include unistd.h
#include netinet/in.h
#include arpa/inet.h
#include sys/param.h
#include sys/types.h
#include sys/socket.h
/*
* Use an arbitrary port that you know isn't in use on the system. I
* don't run ircd, so this is safe for me.
*/
#define LISTEN_PORT (6667)
#define BUFSIZE (1500)
int
main(void)
{
int ctl;
int peek;
int i = 1;
int port = LISTEN_PORT;
char buf[BUFSIZE];
struct sockaddr_in server_addr;
struct sockaddr_in client_addr;
struct in_addr bind_address;
struct msghdr msg;
if ((ctl = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) 0)
err(errno, error creating socket);
printf(socket number %d created\n, ctl);
if (setsockopt(ctl, SOL_SOCKET, SO_REUSEADDR, (char *)i, sizeof(i)))
err(errno, error setsockopt(SO_REUSEADDR): );
if (setsockopt(ctl, SOL_SOCKET, SO_REUSEPORT, (char *)i, sizeof(i)))
err(errno, error setsockopt(SO_REUSEPORT): );
printf(setsockopt(SO_REUSEADDR|SO_REUSEPORT) successful\n);
bind_address.s_addr = htonl(INADDR_ANY);
server_addr.sin_family = AF_INET;
server_addr.sin_addr = bind_address;
server_addr.sin_port = htons(port);
if (bind(ctl, (struct sockaddr *)server_addr, sizeof(server_addr)))
err(errno, error (%d) bind(%lu:%d), errno,
server_addr.sin_addr.s_addr, port);
printf(bound to port %d\n, port);
if (listen(ctl, 0))
err(errno, error listening: );
printf(listening...\n);
/*
i = sizeof(client_addr);
if (peek = accept(ctl, (struct sockaddr *)client_addr, i) 0)
err(errno, accept() failed: );
printf(connection accepted from %s\n,
inet_ntoa(client_addr.sin_addr));
*/
msg.msg_name = (void *)server_addr;
msg.msg_namelen = sizeof(server_addr);
msg.msg_iovlen = 0;
msg.msg_control = (caddr_t)buf;
msg.msg_controllen = 1;
while (recvmsg(ctl, msg, MSG_PEEK) 0) {
warn(recvmsg failed: );
printf(msg_flags = %i\n, msg.msg_flags);
sleep(2);
}
printf(recvmsg successful, wtf?\n);
close(ctl);
/*
close(peek);
*/
return(0);
}
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