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tcpsvd,udpsvd: make them NOMMU-capable

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inetd: make udp nowait work

function                                             old     new   delta
inetd_main                                          1797    2036    +239
tcpudpsvd_main                                      1839    1973    +134
xsetenv_plain                                          -      39     +39
xsetenv_proto                                         23      40     +17
bump_nofile                                          169     170      +1
sig_term_handler                                      72      69      -3
sig_child_handler                                    239     233      -6
connection_status                                     37      31      -6
parse_one_line                                      1102    1092     -10
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 4/4 up/down: 430/-25)           Total: 405 bytes
   text    data     bss     dec     hex filename
 798437     661    7428  806526   c4e7e busybox_old
 798734     661    7428  806823   c4fa7 busybox_unstripped
This commit is contained in:
Denis Vlasenko
2008-03-17 08:35:44 +00:00
parent 9f153f610f
commit aefed941c2
3 changed files with 198 additions and 140 deletions
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101
networking/inetd.c
View File

@ -130,8 +130,13 @@
* tening service socket, and must accept at least one connection request
* before exiting. Such a server would normally accept and process incoming
* connection requests until a timeout.
*
* In short: "stream" can be "wait" or "nowait"; "dgram" must be "wait".
*/
/* Despite of above doc saying that dgram services must use "wait",
* "udp nowait" servers are implemented in busyboxed inetd.
* IPv6 addresses are also implemented. However, they may look ugly -
* ":::service..." means "address '::' (IPv6 wildcard addr)":"service"...
* You have to put "tcp6"/"udp6" in protocol field to select IPv6.
*/
/* Here's the scoop concerning the user[:group] feature:
@ -832,9 +837,6 @@ static NOINLINE servtab_t *parse_one_line(void)
if (sep->se_socktype == SOCK_DGRAM) {
if (sep->se_proto_no == IPPROTO_TCP)
goto parse_err;
/* "udp nowait" is a small fork bomb :) */
if (!sep->se_wait)
goto parse_err;
}
/* check if the hostname specifier is a comma separated list
@ -1195,7 +1197,7 @@ int inetd_main(int argc, char **argv)
for (;;) {
int ready_fd_cnt;
int ctrl, accepted_fd;
int ctrl, accepted_fd, new_udp_fd;
fd_set readable;
if (maxsock < 0)
@ -1220,12 +1222,43 @@ int inetd_main(int argc, char **argv)
ready_fd_cnt--;
ctrl = sep->se_fd;
accepted_fd = -1;
if (!sep->se_wait && sep->se_socktype == SOCK_STREAM) {
ctrl = accepted_fd = accept(sep->se_fd, NULL, NULL);
if (ctrl < 0) {
if (errno != EINTR)
bb_perror_msg("accept (for %s)", sep->se_service);
continue;
new_udp_fd = -1;
if (!sep->se_wait) {
if (sep->se_socktype == SOCK_STREAM) {
ctrl = accepted_fd = accept(sep->se_fd, NULL, NULL);
if (ctrl < 0) {
if (errno != EINTR)
bb_perror_msg("accept (for %s)", sep->se_service);
continue;
}
}
/* "nowait" udp */
if (sep->se_socktype == SOCK_DGRAM
&& sep->se_family != AF_UNIX
) {
/* How udp "nowait" works:
* child peeks at (received and buffered by kernel) UDP packet,
* performs connect() on the socket so that it is linked only
* to this peer. But this also affects parent, because descriptors
* are shared after fork() a-la dup(). When parent performs
* select(), it will see this descriptor connected to the peer (!)
* and still readable, will act on it and mess things up
* (can create many copies of same child, etc).
* Parent must create and use new socket instead. */
new_udp_fd = socket(sep->se_family, SOCK_DGRAM, 0);
if (new_udp_fd < 0) { /* error: eat packet, forget about it */
udp_err:
recv(sep->se_fd, line, LINE_SIZE, MSG_DONTWAIT);
continue;
}
setsockopt_reuseaddr(new_udp_fd);
/* TODO: better do bind after vfork in parent,
* so that we don't have two wildcard bound sockets
* even for a brief moment? */
if (bind(new_udp_fd, &sep->se_lsa->u.sa, sep->se_lsa->len) < 0) {
close(new_udp_fd);
goto udp_err;
}
}
}
@ -1283,10 +1316,15 @@ int inetd_main(int argc, char **argv)
if (pid > 0) { /* parent */
if (sep->se_wait) {
/* tcp wait: we passed listening socket to child,
* will wait for child to terminate */
sep->se_wait = pid;
remove_fd_from_set(sep->se_fd);
/* we passed listening socket to child,
* will wait for child to terminate */
}
if (new_udp_fd >= 0) {
/* udp nowait: child connected the socket,
* we created and will use new, unconnected one */
xmove_fd(new_udp_fd, sep->se_fd);
}
restore_sigmask(&omask);
maybe_close(accepted_fd);
@ -1313,39 +1351,20 @@ int inetd_main(int argc, char **argv)
#endif
/* child */
setsid();
#if 0
/* This does not work.
* Actually, it _almost_ works. The idea behind it is: child
* can peek at (already received and buffered by kernel) UDP packet,
* and perform connect() on the socket so that it is linked only
* to this peer. But this also affects parent, because descriptors
* are shared after fork() a-la dup(). When parent returns to
* select(), it will see this descriptor attached to the peer (!)
* and likely still readable, will act on it and mess things up
* (can create many copies of same child, etc).
* If child will create new socket instead, then bind() and
* connect() it to peer's address, descriptor aliasing problem
* is solved, but first packet cannot be "transferred" to the new
* socket. It is not a problem if child can account for this,
* but our child will exec - and exec'ed program does not know
* about this "lost packet" problem! Pity... */
/* "nowait" udp[6]. Hmmm... */
if (!sep->se_wait
&& sep->se_socktype == SOCK_DGRAM
&& sep->se_family != AF_UNIX
) {
/* "nowait" udp */
if (new_udp_fd >= 0) {
len_and_sockaddr *lsa = xzalloc_lsa(sep->se_family);
/* peek at the packet and remember peer addr */
int r = recvfrom(ctrl, NULL, 0, MSG_PEEK|MSG_DONTWAIT,
&lsa->u.sa, &lsa->len);
if (r >= 0)
/* make this socket "connected" to peer addr:
* only packets from this peer will be recv'ed,
* and bare write()/send() will work on it */
connect(ctrl, &lsa->u.sa, lsa->len);
if (r < 0)
goto do_exit1;
/* make this socket "connected" to peer addr:
* only packets from this peer will be recv'ed,
* and bare write()/send() will work on it */
connect(ctrl, &lsa->u.sa, lsa->len);
free(lsa);
}
#endif
/* prepare env and exec program */
pwd = getpwnam(sep->se_user);
if (pwd == NULL) {