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elinks/src/main/interlink.c

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/* Inter-instances internal communication socket interface */
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h> /* OS/2 needs this after sys/types.h */
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
/* struct timeval */
#ifdef HAVE_SYS_TIME_H
#include <sys/time.h>
#endif
#ifdef HAVE_TIME_H
#include <time.h>
#endif
/* Blame BSD for position of this includes. */
#ifdef HAVE_NETINET_IN_H
#include <netinet/in.h>
#endif
#ifdef HAVE_SYS_SELECT_H
#include <sys/select.h>
#endif
#ifdef HAVE_SYS_SOCKET_H
#include <sys/socket.h> /* OS/2 needs this after sys/types.h */
#endif
#ifdef HAVE_SYS_UN_H
#include <sys/un.h>
#endif
#ifdef HAVE_ARPA_INET_H
#include <arpa/inet.h>
#endif
#include "elinks.h"
#include "config/home.h"
#include "intl/gettext/libintl.h"
#include "main/interlink.h"
#include "main/select.h"
#include "osdep/osdep.h"
#include "util/conv.h"
#include "util/error.h"
#include "util/memory.h"
#include "util/string.h"
/* Testing purpose. Do not remove. */
/* At some point zas added experimental support for interlinking
* ELinks' over a TCP socket. However, it was removed due to some
* unsettled security related questions. More info in:
*
* src/config/options.c (1.233 -> 1.234)
* src/network/interlink.c (1.54 -> 1.55)
*
* The log message:
*
* Experimental remote mode is now (almost) functionnal. To test define
* ELINKS_REMOTE in setup.h, compile elinks, add a second ip to your
* machine or use a second machine, then launch elinks -listen
* <your_first_ip> on one side, and elinks -remote <your_first_ip> on the
* second side. There is many things to improve, and it may not function as
* you hope it does, but feel free to provide enhancements. Note this
* feature may disappear soon if none is interested in. Please report
* issues/comments/ideas/bugs on #elinks.
*/
#if 0
#undef CONFIG_TCP_INTERLINK
#endif
/* Common to both AF_UNIX and AF_INET stuff. */
struct socket_info {
struct sockaddr *addr;
int size;
int fd;
};
/* Accepted socket info */
static struct socket_info s_info_accept;
/* Listening socket info */
static struct socket_info s_info_listen;
/* Connect socket info */
static struct socket_info s_info_connect;
/* Type of address requested (for get_address()) */
enum addr_type {
ADDR_IP_CLIENT,
ADDR_IP_SERVER,
ADDR_ANY_SERVER,
};
#ifndef CONFIG_TCP_INTERLINK
/*** Unix file socket for internal communication. ***/
/* Compute socket file path and allocate space for it.
* It returns 0 on error (in this case, there's no need
* to free anything).
* It returns 1 on success. */
static int
get_sun_path(struct string *sun_path)
{
assert(sun_path);
if_assert_failed return 0;
if (!elinks_home) return 0;
if (!init_string(sun_path)) return 0;
add_to_string(sun_path, elinks_home);
add_to_string(sun_path, ELINKS_SOCK_NAME);
add_long_to_string(sun_path,
get_cmd_opt_int("session-ring"));
return 1;
}
/* @type is ignored here => always local. */
static int
get_address(struct socket_info *info, enum addr_type type)
{
struct sockaddr_un *addr = NULL;
int sun_path_freespace;
struct string path;
assert(info);
if_assert_failed return -1;
if (!get_sun_path(&path)) return -1;
/* Linux defines that as:
* #define UNIX_PATH_MAX 108
* struct sockaddr_un {
* sa_family_t sun_family;
* char sun_path[UNIX_PATH_MAX];
* };
*
* UNIX_PATH_MAX is not defined on all systems, so we'll use sizeof().
*/
/* Following code may need to be changed if at some time the
* struct sockaddr_un mess is fixed. For now, i tried to make it
* sure and portable.
*
* Extract from glibc documentation:
* char sun_path[108]
* This is the file name to use.
* Incomplete: Why is 108 a magic number?
* RMS suggests making this a zero-length array and tweaking the example
* following to use alloca to allocate an appropriate amount of storage
* based on the length of the filename.
*
* But at this day (2003/06/18) it seems there's no implementation of such
* thing.
* If it was the case, then following code will always generate an error.
* --Zas
*/
sun_path_freespace = sizeof(addr->sun_path) - (path.length + 1);
if (sun_path_freespace < 0) {
INTERNAL("Socket path name '%s' is too long: %d >= %zu",
path.source, path.length, sizeof(addr->sun_path));
goto free_and_error;
}
addr = mem_calloc(1, sizeof(*addr));
if (!addr) goto free_and_error;
memcpy(addr->sun_path, path.source, path.length); /* ending '\0' is done by calloc() */
done_string(&path);
addr->sun_family = AF_UNIX;
info->addr = (struct sockaddr *) addr;
/* The size of the address is the offset of the start of the filename,
* plus its length, plus one for the terminating null byte (well, this
* last byte may or not be needed it depends of....).
* Alternatively we can use SUN_LEN() macro but this one is not always
* defined nor always defined in the same way. --Zas */
info->size = sizeof(*addr) - sun_path_freespace;
return AF_UNIX;
free_and_error:
done_string(&path);
mem_free_if(addr);
return -1;
}
static int
alloc_address(struct socket_info *info)
{
struct sockaddr_un *sa;
assert(info);
if_assert_failed return 0;
/* calloc() is safer there. */
sa = mem_calloc(1, sizeof(*sa));
if (!sa) return 0;
info->addr = (struct sockaddr *) sa;
info->size = sizeof(*sa);
return 1;
}
static void
unlink_unix(struct sockaddr *addr)
{
assert(addr);
if_assert_failed return;
unlink(((struct sockaddr_un *) addr)->sun_path);
}
#define setsock_reuse_addr(fd)
#else /* CONFIG_TCP_INTERLINK */
/*** TCP socket for internal communication. ***/
/* FIXME: IPv6 support. */
/* These may not be defined in netinet/in.h on some systems. */
#ifndef INADDR_LOOPBACK
#define INADDR_LOOPBACK ((struct in_addr) 0x7f000001)
#endif
#ifndef IPPORT_USERRESERVED
#define IPPORT_USERRESERVED 5000
#endif
/* @type is not used for now, and is ignored, it will
* be used in remote mode feature. */
static int
get_address(struct socket_info *info, enum addr_type type)
{
struct sockaddr_in *sin;
uint16_t port;
assert(info);
if_assert_failed return -1;
/* Each ring is bind to ELINKS_PORT + ring number. */
port = ELINKS_PORT + get_cmd_opt_int("session-ring");
if (port < IPPORT_USERRESERVED)
return -1; /* Just in case of... */
sin = mem_calloc(1, sizeof(*sin));
if (!sin) return -1;
sin->sin_family = AF_INET;
sin->sin_port = htons(port);
sin->sin_addr.s_addr = htonl(INADDR_LOOPBACK);
info->addr = (struct sockaddr *) sin;
info->size = sizeof(*sin);
return AF_INET;
}
static int
alloc_address(struct socket_info *info)
{
struct sockaddr_in *sa;
assert(info);
if_assert_failed return 0;
/* calloc() is safer there. */
sa = mem_calloc(1, sizeof(*sa));
if (!sa) return 0;
info->addr = (struct sockaddr *) sa;
info->size = sizeof(*sa);
return 1;
}
#if defined(SOL_SOCKET) && defined(SO_REUSEADDR)
static void
setsock_reuse_addr(int fd)
{
int reuse_addr = 1;
setsockopt(fd, SOL_SOCKET, SO_REUSEADDR,
(void *) &reuse_addr, sizeof(reuse_addr));
}
#else
#define setsock_reuse_addr(fd)
#endif
#define unlink_unix(s)
#endif /* CONFIG_TCP_INTERLINK */
/* Max. number of bind attempts. */
#define MAX_BIND_TRIES 3
/* Base delay in useconds between bind attempts.
* We will sleep that time on first attempt, then
* 2 * delay, then 3 * delay .... */
#define BIND_TRIES_DELAY 100000
/* Number of connections in listen backlog. */
#define LISTEN_BACKLOG 100
/* Max. number of connect attempts. */
#define MAX_CONNECT_TRIES 3
/* Base delay in useconds between connect attempts. */
#define CONNECT_TRIES_DELAY 50000
static void
report_af_unix_error(unsigned char *function, int error)
{
ERROR(gettext("The call to %s failed: %d (%s)"),
function, error, (unsigned char *) strerror(error));
}
/* Called when we receive a connection on listening socket. */
static void
af_unix_connection(struct socket_info *info)
{
int ns;
int l;
assert(info);
if_assert_failed return;
l = info->size;
memset(info->addr, 0, l);
ns = accept(info->fd, info->addr, &l);
if (ns < 0) {
report_af_unix_error("accept()", errno);
return;
}
init_term(ns, ns);
set_highpri();
}
/* usleep() is not portable, so we use this replacement.
* TODO: move it to somewhere. */
void
elinks_usleep(unsigned long useconds)
{
struct timeval delay;
fd_set dummy;
FD_ZERO(&dummy);
delay.tv_sec = 0;
delay.tv_usec = useconds;
select(0, &dummy, &dummy, &dummy, &delay);
}
/* Listen on socket for internal ELinks communication.
* Returns -1 on error
* or listened file descriptor on success. */
static int
bind_to_af_unix(void)
{
mode_t saved_mask = umask(0177);
int attempts = 0;
int af = get_address(&s_info_listen, ADDR_IP_SERVER);
if (af == -1) goto free_and_error;
while (1) {
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s_info_listen.fd = socket(af, SOCK_STREAM, 0);
if (s_info_listen.fd == -1) {
report_af_unix_error("socket()", errno);
goto free_and_error;
}
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setsock_reuse_addr(s_info_listen.fd);
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if (bind(s_info_listen.fd, s_info_listen.addr, s_info_listen.size) >= 0)
break;
if (errno != EADDRINUSE)
report_af_unix_error("bind()", errno);
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++attempts;
if (attempts == MAX_BIND_TRIES)
unlink_unix(s_info_listen.addr);
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if (attempts > MAX_BIND_TRIES)
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goto free_and_error;
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elinks_usleep(BIND_TRIES_DELAY * attempts);
close(s_info_listen.fd);
}
/* Listen and accept. */
if (!alloc_address(&s_info_accept))
goto free_and_error;
s_info_accept.fd = s_info_listen.fd;
if (listen(s_info_listen.fd, LISTEN_BACKLOG)) {
report_af_unix_error("listen()", errno);
goto free_and_error;
}
set_handlers(s_info_listen.fd, (void (*)(void *)) af_unix_connection,
NULL, NULL, &s_info_accept);
umask(saved_mask);
return s_info_listen.fd;
free_and_error:
done_interlink();
umask(saved_mask);
return -1;
}
/* Connect to an listening socket for internal ELinks communication.
* Returns -1 on error
* or file descriptor on success. */
static int
connect_to_af_unix(void)
{
int attempts = 0;
int af = get_address(&s_info_connect, ADDR_IP_CLIENT);
while (af != -1 && attempts++ < MAX_CONNECT_TRIES) {
int saved_errno;
s_info_connect.fd = socket(af, SOCK_STREAM, 0);
if (s_info_connect.fd == -1) {
report_af_unix_error("socket()", errno);
break;
}
if (connect(s_info_connect.fd, s_info_connect.addr,
s_info_connect.size) >= 0)
return s_info_connect.fd;
saved_errno = errno;
close(s_info_connect.fd);
if (saved_errno != ECONNREFUSED && saved_errno != ENOENT) {
report_af_unix_error("connect()", errno);
break;
}
elinks_usleep(CONNECT_TRIES_DELAY * attempts);
}
mem_free_set(&s_info_connect.addr, NULL);
return -1;
}
static void safe_close(int *fd) {
if (*fd == -1) return;
close(*fd);
*fd = -1;
}
/* Free all allocated memory and close all descriptors if
* needed. */
void
done_interlink(void)
{
/* We test for addr != NULL since
* if it was not allocated then fd is not
* initialized and we don't want to close
* fd 0 ;). --Zas */
if (s_info_listen.addr) {
safe_close(&s_info_listen.fd);
unlink_unix(s_info_listen.addr);
mem_free(s_info_listen.addr);
s_info_listen.addr = NULL;
}
if (s_info_connect.addr) {
safe_close(&s_info_connect.fd);
mem_free(s_info_connect.addr);
s_info_connect.addr = NULL;
}
if (s_info_accept.addr) {
safe_close(&s_info_accept.fd);
mem_free(s_info_accept.addr);
s_info_accept.addr = NULL;
}
}
/* Initialize sockets for internal ELinks communication.
* If connect succeeds it returns file descriptor,
* else it tries to bind and listen on a socket, and
* return -1
*/
int
init_interlink(void)
{
int fd = connect_to_af_unix();
if (fd != -1) return fd;
bind_to_af_unix();
return -1;
}
#undef MAX_BIND_TRIES
#undef BIND_TRIES_DELAY
#undef LISTEN_BACKLOG
#undef MAX_CONNECT_TRIES
#undef CONNECT_TRIES_DELAY