Hello:

Should one be able to call connect() again on a tcp
socket after a failed attempt.  The problem that
arises is that the RST handling calls tcp_drop() which
calls tcp_close() which in turn disassociates the socket
from the protocol (in_pcbdetach() etc.).  As such one
currently has to close() and create a new socket.

FWIW, I'm told Linux allows this (haven't confirmed).


Here's a diff on a quick fix that allows this.  I'm not
sure it's the best solution or even if it's worth allowing
at all.  I added the PR_CONNATTCH flag to restrict it
to tcp sockets for now but that may not be required.


Index: kern/uipc_socket.c
===================================================================
RCS file: /cvsroot/src/sys/kern/uipc_socket.c,v
retrieving revision 1.66.4.1
diff -c -r1.66.4.1 uipc_socket.c
*** kern/uipc_socket.c	2002/06/11 01:59:49	1.66.4.1
--- kern/uipc_socket.c	2003/06/17 20:27:12
***************
*** 518,523 ****
--- 518,532 ----
  	if (so->so_options & SO_ACCEPTCONN)
  		return (EOPNOTSUPP);
  	s = splsoftnet();
+ 
+ 	if (so->so_pcb == NULL && (so->so_proto->pr_flags & PR_CONATTCH)) {
+ 		if (error = (*so->so_proto->pr_usrreq)(so, PRU_ATTACH,
+ 		    (struct mbuf *)0, (struct mbuf *)(long)so->so_proto->pr_protocol,
+ 		    (struct mbuf *)0, p)) {
+ 			splx(s);
+ 			return (error);
+ 		}
+ 	}
  	/*
  	 * If protocol is connection-based, can only connect once.
  	 * Otherwise, if connected, try to disconnect first.


To demonstrate the issue:



#include <sys/socket.h>
#include <netinet/in.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <arpa/inet.h>

int
main(void)
{
	int s;
	struct sockaddr_in s_in;

	if ((s = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
		perror("socket");
		return 1;
	}

	memset(&s_in, 0x00, sizeof(s_in));

	s_in.sin_family      = AF_INET;
	s_in.sin_len         = sizeof(s_in);
	s_in.sin_addr.s_addr = inet_addr("127.0.0.1");
	s_in.sin_port        = htons(1234);

	if (connect(s, (struct sockaddr *)&s_in, sizeof(s_in)) != -1) {
		fprintf(stderr, "disable port 1234\n");
		return 1;
	}

	/* Assume discard is working but doesn't matter as it never gets that far */
	s_in.sin_port = htons(9);
	if (connect(s, (struct sockaddr *)&s_in, sizeof(s_in)) == -1) {
		fprintf(stderr, "should this connect() have worked?  errno = %d\n", errno);
		return 1;
	}

	printf("Success?\n");
	return 0;
}