busybox/networking/isrv.c

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/* vi: set sw=4 ts=4: */
/*
* Generic non-forking server infrastructure.
* Intended to make writing telnetd-type servers easier.
*
* Copyright (C) 2007 Denys Vlasenko
*
* Licensed under GPLv2, see file LICENSE in this source tree.
*/
#include "libbb.h"
#include "isrv.h"
#define DEBUG 0
#if DEBUG
#define DPRINTF(args...) bb_error_msg(args)
#else
#define DPRINTF(args...) ((void)0)
#endif
/* Helpers */
/* Opaque structure */
struct isrv_state_t {
short *fd2peer; /* one per registered fd */
void **param_tbl; /* one per registered peer */
/* one per registered peer; doesn't exist if !timeout */
time_t *timeo_tbl;
int (*new_peer)(isrv_state_t *state, int fd);
time_t curtime;
int timeout;
int fd_count;
int peer_count;
int wr_count;
fd_set rd;
fd_set wr;
};
#define FD2PEER (state->fd2peer)
#define PARAM_TBL (state->param_tbl)
#define TIMEO_TBL (state->timeo_tbl)
#define CURTIME (state->curtime)
#define TIMEOUT (state->timeout)
#define FD_COUNT (state->fd_count)
#define PEER_COUNT (state->peer_count)
#define WR_COUNT (state->wr_count)
/* callback */
void isrv_want_rd(isrv_state_t *state, int fd)
{
FD_SET(fd, &state->rd);
}
/* callback */
void isrv_want_wr(isrv_state_t *state, int fd)
{
if (!FD_ISSET(fd, &state->wr)) {
WR_COUNT++;
FD_SET(fd, &state->wr);
}
}
/* callback */
void isrv_dont_want_rd(isrv_state_t *state, int fd)
{
FD_CLR(fd, &state->rd);
}
/* callback */
void isrv_dont_want_wr(isrv_state_t *state, int fd)
{
if (FD_ISSET(fd, &state->wr)) {
WR_COUNT--;
FD_CLR(fd, &state->wr);
}
}
/* callback */
int isrv_register_fd(isrv_state_t *state, int peer, int fd)
{
int n;
DPRINTF("register_fd(peer:%d,fd:%d)", peer, fd);
if (FD_COUNT >= FD_SETSIZE) return -1;
if (FD_COUNT <= fd) {
n = FD_COUNT;
FD_COUNT = fd + 1;
DPRINTF("register_fd: FD_COUNT %d", FD_COUNT);
FD2PEER = xrealloc(FD2PEER, FD_COUNT * sizeof(FD2PEER[0]));
while (n < fd) FD2PEER[n++] = -1;
}
DPRINTF("register_fd: FD2PEER[%d] = %d", fd, peer);
FD2PEER[fd] = peer;
return 0;
}
/* callback */
void isrv_close_fd(isrv_state_t *state, int fd)
{
DPRINTF("close_fd(%d)", fd);
close(fd);
isrv_dont_want_rd(state, fd);
if (WR_COUNT) isrv_dont_want_wr(state, fd);
FD2PEER[fd] = -1;
if (fd == FD_COUNT-1) {
do fd--; while (fd >= 0 && FD2PEER[fd] == -1);
FD_COUNT = fd + 1;
DPRINTF("close_fd: FD_COUNT %d", FD_COUNT);
FD2PEER = xrealloc(FD2PEER, FD_COUNT * sizeof(FD2PEER[0]));
}
}
/* callback */
int isrv_register_peer(isrv_state_t *state, void *param)
{
int n;
if (PEER_COUNT >= FD_SETSIZE) return -1;
n = PEER_COUNT++;
DPRINTF("register_peer: PEER_COUNT %d", PEER_COUNT);
PARAM_TBL = xrealloc(PARAM_TBL, PEER_COUNT * sizeof(PARAM_TBL[0]));
PARAM_TBL[n] = param;
if (TIMEOUT) {
TIMEO_TBL = xrealloc(TIMEO_TBL, PEER_COUNT * sizeof(TIMEO_TBL[0]));
TIMEO_TBL[n] = CURTIME;
}
return n;
}
static void remove_peer(isrv_state_t *state, int peer)
{
int movesize;
int fd;
DPRINTF("remove_peer(%d)", peer);
fd = FD_COUNT - 1;
while (fd >= 0) {
if (FD2PEER[fd] == peer) {
isrv_close_fd(state, fd);
fd--;
continue;
}
if (FD2PEER[fd] > peer)
FD2PEER[fd]--;
fd--;
}
PEER_COUNT--;
DPRINTF("remove_peer: PEER_COUNT %d", PEER_COUNT);
movesize = (PEER_COUNT - peer) * sizeof(void*);
if (movesize > 0) {
memcpy(&PARAM_TBL[peer], &PARAM_TBL[peer+1], movesize);
if (TIMEOUT)
memcpy(&TIMEO_TBL[peer], &TIMEO_TBL[peer+1], movesize);
}
PARAM_TBL = xrealloc(PARAM_TBL, PEER_COUNT * sizeof(PARAM_TBL[0]));
if (TIMEOUT)
TIMEO_TBL = xrealloc(TIMEO_TBL, PEER_COUNT * sizeof(TIMEO_TBL[0]));
}
static void handle_accept(isrv_state_t *state, int fd)
{
int n, newfd;
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/* suppress gcc warning "cast from ptr to int of different size" */
fcntl(fd, F_SETFL, (int)(ptrdiff_t)(PARAM_TBL[0]) | O_NONBLOCK);
newfd = accept(fd, NULL, 0);
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fcntl(fd, F_SETFL, (int)(ptrdiff_t)(PARAM_TBL[0]));
if (newfd < 0) {
if (errno == EAGAIN) return;
/* Most probably someone gave us wrong fd type
* (for example, non-socket). Don't want
* to loop forever. */
libbb: reduce the overhead of single parameter bb_error_msg() calls Back in 2007, commit 0c97c9d43707 ("'simple' error message functions by Loic Grenie") introduced bb_simple_perror_msg() to allow for a lower overhead call to bb_perror_msg() when only a string was being printed with no parameters. This saves space for some CPU architectures because it avoids the overhead of a call to a variadic function. However there has never been a simple version of bb_error_msg(), and since 2007 many new calls to bb_perror_msg() have been added that only take a single parameter and so could have been using bb_simple_perror_message(). This changeset introduces 'simple' versions of bb_info_msg(), bb_error_msg(), bb_error_msg_and_die(), bb_herror_msg() and bb_herror_msg_and_die(), and replaces all calls that only take a single parameter, or use something like ("%s", arg), with calls to the corresponding 'simple' version. Since it is likely that single parameter calls to the variadic functions may be accidentally reintroduced in the future a new debugging config option WARN_SIMPLE_MSG has been introduced. This uses some macro magic which will cause any such calls to generate a warning, but this is turned off by default to avoid use of the unpleasant macros in normal circumstances. This is a large changeset due to the number of calls that have been replaced. The only files that contain changes other than simple substitution of function calls are libbb.h, libbb/herror_msg.c, libbb/verror_msg.c and libbb/xfuncs_printf.c. In miscutils/devfsd.c, networking/udhcp/common.h and util-linux/mdev.c additonal macros have been added for logging so that single parameter and multiple parameter logging variants exist. The amount of space saved varies considerably by architecture, and was found to be as follows (for 'defconfig' using GCC 7.4): Arm: -92 bytes MIPS: -52 bytes PPC: -1836 bytes x86_64: -938 bytes Note that for the MIPS architecture only an exception had to be made disabling the 'simple' calls for 'udhcp' (in networking/udhcp/common.h) because it made these files larger on MIPS. Signed-off-by: James Byrne <james.byrne@origamienergy.com> Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2019-07-02 15:05:03 +05:30
bb_simple_perror_msg_and_die("accept");
}
DPRINTF("new_peer(%d)", newfd);
n = state->new_peer(state, newfd);
if (n)
remove_peer(state, n); /* unsuccessful peer start */
}
static void handle_fd_set(isrv_state_t *state, fd_set *fds, int (*h)(int, void **))
{
enum { LONG_CNT = sizeof(fd_set) / sizeof(long) };
int fds_pos;
int fd, peer;
/* need to know value at _the beginning_ of this routine */
int fd_cnt = FD_COUNT;
BUILD_BUG_ON(LONG_CNT * sizeof(long) != sizeof(fd_set));
fds_pos = 0;
while (1) {
/* Find next nonzero bit */
while (fds_pos < LONG_CNT) {
if (((long*)fds)[fds_pos] == 0) {
fds_pos++;
continue;
}
/* Found non-zero word */
fd = fds_pos * sizeof(long)*8; /* word# -> bit# */
while (1) {
if (FD_ISSET(fd, fds)) {
FD_CLR(fd, fds);
goto found_fd;
}
fd++;
}
}
break; /* all words are zero */
found_fd:
if (fd >= fd_cnt) { /* paranoia */
DPRINTF("handle_fd_set: fd > fd_cnt?? (%d > %d)",
fd, fd_cnt);
break;
}
DPRINTF("handle_fd_set: fd %d is active", fd);
peer = FD2PEER[fd];
if (peer < 0)
continue; /* peer is already gone */
if (peer == 0) {
handle_accept(state, fd);
continue;
}
DPRINTF("h(fd:%d)", fd);
if (h(fd, &PARAM_TBL[peer])) {
/* this peer is gone */
remove_peer(state, peer);
} else if (TIMEOUT) {
TIMEO_TBL[peer] = monotonic_sec();
}
}
}
static void handle_timeout(isrv_state_t *state, int (*do_timeout)(void **))
{
int n, peer;
peer = PEER_COUNT-1;
/* peer 0 is not checked */
while (peer > 0) {
DPRINTF("peer %d: time diff %d", peer,
(int)(CURTIME - TIMEO_TBL[peer]));
if ((CURTIME - TIMEO_TBL[peer]) >= TIMEOUT) {
DPRINTF("peer %d: do_timeout()", peer);
n = do_timeout(&PARAM_TBL[peer]);
if (n)
remove_peer(state, peer);
}
peer--;
}
}
/* Driver */
void isrv_run(
int listen_fd,
int (*new_peer)(isrv_state_t *state, int fd),
int (*do_rd)(int fd, void **),
int (*do_wr)(int fd, void **),
int (*do_timeout)(void **),
int timeout,
int linger_timeout)
{
isrv_state_t *state = xzalloc(sizeof(*state));
state->new_peer = new_peer;
state->timeout = timeout;
/* register "peer" #0 - it will accept new connections */
isrv_register_peer(state, NULL);
isrv_register_fd(state, /*peer:*/ 0, listen_fd);
isrv_want_rd(state, listen_fd);
/* remember flags to make blocking<->nonblocking switch faster */
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/* (suppress gcc warning "cast from ptr to int of different size") */
PARAM_TBL[0] = (void*)(ptrdiff_t)(fcntl(listen_fd, F_GETFL));
while (1) {
struct timeval tv;
fd_set rd;
fd_set wr;
fd_set *wrp = NULL;
int n;
tv.tv_sec = timeout;
if (PEER_COUNT <= 1)
tv.tv_sec = linger_timeout;
tv.tv_usec = 0;
rd = state->rd;
if (WR_COUNT) {
wr = state->wr;
wrp = &wr;
}
DPRINTF("run: select(FD_COUNT:%d,timeout:%d)...",
FD_COUNT, (int)tv.tv_sec);
n = select(FD_COUNT, &rd, wrp, NULL, tv.tv_sec ? &tv : NULL);
DPRINTF("run: ...select:%d", n);
if (n < 0) {
if (errno != EINTR)
libbb: reduce the overhead of single parameter bb_error_msg() calls Back in 2007, commit 0c97c9d43707 ("'simple' error message functions by Loic Grenie") introduced bb_simple_perror_msg() to allow for a lower overhead call to bb_perror_msg() when only a string was being printed with no parameters. This saves space for some CPU architectures because it avoids the overhead of a call to a variadic function. However there has never been a simple version of bb_error_msg(), and since 2007 many new calls to bb_perror_msg() have been added that only take a single parameter and so could have been using bb_simple_perror_message(). This changeset introduces 'simple' versions of bb_info_msg(), bb_error_msg(), bb_error_msg_and_die(), bb_herror_msg() and bb_herror_msg_and_die(), and replaces all calls that only take a single parameter, or use something like ("%s", arg), with calls to the corresponding 'simple' version. Since it is likely that single parameter calls to the variadic functions may be accidentally reintroduced in the future a new debugging config option WARN_SIMPLE_MSG has been introduced. This uses some macro magic which will cause any such calls to generate a warning, but this is turned off by default to avoid use of the unpleasant macros in normal circumstances. This is a large changeset due to the number of calls that have been replaced. The only files that contain changes other than simple substitution of function calls are libbb.h, libbb/herror_msg.c, libbb/verror_msg.c and libbb/xfuncs_printf.c. In miscutils/devfsd.c, networking/udhcp/common.h and util-linux/mdev.c additonal macros have been added for logging so that single parameter and multiple parameter logging variants exist. The amount of space saved varies considerably by architecture, and was found to be as follows (for 'defconfig' using GCC 7.4): Arm: -92 bytes MIPS: -52 bytes PPC: -1836 bytes x86_64: -938 bytes Note that for the MIPS architecture only an exception had to be made disabling the 'simple' calls for 'udhcp' (in networking/udhcp/common.h) because it made these files larger on MIPS. Signed-off-by: James Byrne <james.byrne@origamienergy.com> Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2019-07-02 15:05:03 +05:30
bb_simple_perror_msg("select");
continue;
}
if (n == 0 && linger_timeout && PEER_COUNT <= 1)
break;
if (timeout) {
time_t t = monotonic_sec();
if (t != CURTIME) {
CURTIME = t;
handle_timeout(state, do_timeout);
}
}
if (n > 0) {
handle_fd_set(state, &rd, do_rd);
if (wrp)
handle_fd_set(state, wrp, do_wr);
}
}
DPRINTF("run: bailout");
/* NB: accept socket is not closed. Caller is to decide what to do */
}