phunix/minix/lib/libc/sys/accept.c
David van Moolenbroek c38dbb97aa Prepare for switch to native BSD socket API
Currently, the BSD socket API is implemented in libc, translating the
API calls to character driver operations underneath.  This approach
has several issues:

- it is inefficient, as most character driver operations are specific
  to the socket type, thus requiring that each operation start by
  bruteforcing the socket protocol family and type of the given file
  descriptor using several system calls;
- it requires that libc itself be changed every time system support
  for a new protocol is added;
- various parts of the libc implementations violate the asynchronous
  signal safety POSIX requirements.

In order to resolve all these issues at once, the plan is to turn the
BSD socket calls into system calls, thus making the BSD socket API the
"native" ABI, removing the complexity from libc and instead letting
VFS deal with the socket calls.

The overall change is going to break all networking functionality. In
order to smoothen the transition, this patch introduces the fifteen
new BSD socket system calls, and makes libc try these first before
falling back on the old behavior.  For now, the VFS implementations of
the new calls fail such that libc will always use the fallback cases.
Later on, when we introduce the actual implementation of the native
BSD socket calls, all statically linked programs will automatically
use the new ABI, thus limiting actual application breakage.

In other words: by itself, this patch does nothing, except add a bit
of transitional overhead that will disappear in the future.  The
largest part of the patch is concerned with adding full support for
the new BSD socket system calls to trace(1) - this early addition has
the advantage of making system call tracing output of several socket
calls much more readable already.

Both the system call interfaces and the trace(1) support have already
been tested using code that will be committed later on.

Change-Id: I3460812be50c78be662d857f9d3d6840f3ca917f
2016-02-23 14:34:05 +00:00

163 lines
3.3 KiB
C

#include <sys/cdefs.h>
#include "namespace.h"
#include <lib.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <net/netlib.h>
#include <net/gen/in.h>
#include <net/gen/tcp.h>
#include <net/gen/tcp_io.h>
#include <net/gen/udp.h>
#include <net/gen/udp_io.h>
static int _tcp_accept(int sock, struct sockaddr *__restrict address,
socklen_t *__restrict address_len);
static int _uds_accept(int sock, struct sockaddr *__restrict address,
socklen_t *__restrict address_len);
/*
* Accept a connection on a listening socket, creating a new socket.
*/
static int
__accept(int fd, struct sockaddr * __restrict address,
socklen_t * __restrict address_len)
{
message m;
int r;
if (address != NULL && address_len == NULL) {
errno = EFAULT;
return -1;
}
memset(&m, 0, sizeof(m));
m.m_lc_vfs_sockaddr.fd = fd;
m.m_lc_vfs_sockaddr.addr = (vir_bytes)address;
m.m_lc_vfs_sockaddr.addr_len = (address != NULL) ? *address_len : 0;
if ((r = _syscall(VFS_PROC_NR, VFS_ACCEPT, &m)) < 0)
return -1;
if (address != NULL)
*address_len = m.m_vfs_lc_socklen.len;
return r;
}
int accept(int sock, struct sockaddr *__restrict address,
socklen_t *__restrict address_len)
{
int r;
nwio_udpopt_t udpopt;
r = __accept(sock, address, address_len);
if (r != -1 || errno != ENOTSOCK)
return r;
r= _tcp_accept(sock, address, address_len);
if (r != -1 || errno != ENOTTY)
return r;
r= _uds_accept(sock, address, address_len);
if (r != -1 || errno != ENOTTY)
return r;
/* Unfortunately, we have to return EOPNOTSUPP for a socket that
* does not support accept (such as a UDP socket) and ENOTSOCK for
* filedescriptors that do not refer to a socket.
*/
r= ioctl(sock, NWIOGUDPOPT, &udpopt);
if (r == 0 || (r == -1 && errno != ENOTTY)) {
/* UDP socket */
errno= EOPNOTSUPP;
return -1;
}
errno = ENOTSOCK;
return -1;
}
static int _tcp_accept(int sock, struct sockaddr *__restrict address,
socklen_t *__restrict address_len)
{
int r, s1, t_errno;
tcp_cookie_t cookie;
s1= open(TCP_DEVICE, O_RDWR);
if (s1 == -1)
return s1;
r= ioctl(s1, NWIOGTCPCOOKIE, &cookie);
if (r == -1)
{
t_errno= errno;
close(s1);
errno= t_errno;
return -1;
}
r= ioctl(sock, NWIOTCPACCEPTTO, &cookie);
if (r == -1)
{
t_errno= errno;
close(s1);
errno= t_errno;
return -1;
}
if (address != NULL)
getpeername(s1, address, address_len);
return s1;
}
static int _uds_accept(int sock, struct sockaddr *__restrict address,
socklen_t *__restrict address_len)
{
int s1;
int r;
struct sockaddr_un uds_addr;
socklen_t len;
memset(&uds_addr, '\0', sizeof(struct sockaddr_un));
r= ioctl(sock, NWIOGUDSADDR, &uds_addr);
if (r == -1) {
return r;
}
if (uds_addr.sun_family != AF_UNIX) {
errno= EINVAL;
return -1;
}
len= *address_len;
if (len > sizeof(struct sockaddr_un))
len = sizeof(struct sockaddr_un);
memcpy(address, &uds_addr, len);
*address_len= len;
s1= open(UDS_DEVICE, O_RDWR);
if (s1 == -1)
return s1;
/* Copy file descriptor flags from the listening socket. */
fcntl(s1, F_SETFL, fcntl(sock, F_GETFL));
r= ioctl(s1, NWIOSUDSACCEPT, address);
if (r == -1) {
int ioctl_errno = errno;
close(s1);
errno = ioctl_errno;
return r;
}
return s1;
}