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systemd/src/basic/socket-util.c
Zbigniew Jędrzejewski-Szmek f97b34a629 Rename formats-util.h to format-util.h 
We don't have plural in the name of any other -util files and this
inconsistency trips me up every time I try to type this file name
from memory. "formats-util" is even hard to pronounce.
2016-11-07 10:15:08 -05:00

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/***
This file is part of systemd.
Copyright 2010 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <arpa/inet.h>
#include <errno.h>
#include <limits.h>
#include <net/if.h>
#include <netdb.h>
#include <netinet/ip.h>
#include <poll.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "alloc-util.h"
#include "fd-util.h"
#include "fileio.h"
#include "format-util.h"
#include "log.h"
#include "macro.h"
#include "missing.h"
#include "parse-util.h"
#include "path-util.h"
#include "socket-util.h"
#include "string-table.h"
#include "string-util.h"
#include "strv.h"
#include "user-util.h"
#include "utf8.h"
#include "util.h"
int socket_address_parse(SocketAddress *a, const char *s) {
char *e, *n;
unsigned u;
int r;
assert(a);
assert(s);
zero(*a);
a->type = SOCK_STREAM;
if (*s == '[') {
/* IPv6 in [x:.....:z]:p notation */
e = strchr(s+1, ']');
if (!e)
return -EINVAL;
n = strndupa(s+1, e-s-1);
errno = 0;
if (inet_pton(AF_INET6, n, &a->sockaddr.in6.sin6_addr) <= 0)
return errno > 0 ? -errno : -EINVAL;
e++;
if (*e != ':')
return -EINVAL;
e++;
r = safe_atou(e, &u);
if (r < 0)
return r;
if (u <= 0 || u > 0xFFFF)
return -EINVAL;
a->sockaddr.in6.sin6_family = AF_INET6;
a->sockaddr.in6.sin6_port = htobe16((uint16_t)u);
a->size = sizeof(struct sockaddr_in6);
} else if (*s == '/') {
/* AF_UNIX socket */
size_t l;
l = strlen(s);
if (l >= sizeof(a->sockaddr.un.sun_path))
return -EINVAL;
a->sockaddr.un.sun_family = AF_UNIX;
memcpy(a->sockaddr.un.sun_path, s, l);
a->size = offsetof(struct sockaddr_un, sun_path) + l + 1;
} else if (*s == '@') {
/* Abstract AF_UNIX socket */
size_t l;
l = strlen(s+1);
if (l >= sizeof(a->sockaddr.un.sun_path) - 1)
return -EINVAL;
a->sockaddr.un.sun_family = AF_UNIX;
memcpy(a->sockaddr.un.sun_path+1, s+1, l);
a->size = offsetof(struct sockaddr_un, sun_path) + 1 + l;
} else {
e = strchr(s, ':');
if (e) {
r = safe_atou(e+1, &u);
if (r < 0)
return r;
if (u <= 0 || u > 0xFFFF)
return -EINVAL;
n = strndupa(s, e-s);
/* IPv4 in w.x.y.z:p notation? */
r = inet_pton(AF_INET, n, &a->sockaddr.in.sin_addr);
if (r < 0)
return -errno;
if (r > 0) {
/* Gotcha, it's a traditional IPv4 address */
a->sockaddr.in.sin_family = AF_INET;
a->sockaddr.in.sin_port = htobe16((uint16_t)u);
a->size = sizeof(struct sockaddr_in);
} else {
unsigned idx;
if (strlen(n) > IF_NAMESIZE-1)
return -EINVAL;
/* Uh, our last resort, an interface name */
idx = if_nametoindex(n);
if (idx == 0)
return -EINVAL;
a->sockaddr.in6.sin6_family = AF_INET6;
a->sockaddr.in6.sin6_port = htobe16((uint16_t)u);
a->sockaddr.in6.sin6_scope_id = idx;
a->sockaddr.in6.sin6_addr = in6addr_any;
a->size = sizeof(struct sockaddr_in6);
}
} else {
/* Just a port */
r = safe_atou(s, &u);
if (r < 0)
return r;
if (u <= 0 || u > 0xFFFF)
return -EINVAL;
if (socket_ipv6_is_supported()) {
a->sockaddr.in6.sin6_family = AF_INET6;
a->sockaddr.in6.sin6_port = htobe16((uint16_t)u);
a->sockaddr.in6.sin6_addr = in6addr_any;
a->size = sizeof(struct sockaddr_in6);
} else {
a->sockaddr.in.sin_family = AF_INET;
a->sockaddr.in.sin_port = htobe16((uint16_t)u);
a->sockaddr.in.sin_addr.s_addr = INADDR_ANY;
a->size = sizeof(struct sockaddr_in);
}
}
}
return 0;
}
int socket_address_parse_and_warn(SocketAddress *a, const char *s) {
SocketAddress b;
int r;
/* Similar to socket_address_parse() but warns for IPv6 sockets when we don't support them. */
r = socket_address_parse(&b, s);
if (r < 0)
return r;
if (!socket_ipv6_is_supported() && b.sockaddr.sa.sa_family == AF_INET6) {
log_warning("Binding to IPv6 address not available since kernel does not support IPv6.");
return -EAFNOSUPPORT;
}
*a = b;
return 0;
}
int socket_address_parse_netlink(SocketAddress *a, const char *s) {
int family;
unsigned group = 0;
_cleanup_free_ char *sfamily = NULL;
assert(a);
assert(s);
zero(*a);
a->type = SOCK_RAW;
errno = 0;
if (sscanf(s, "%ms %u", &sfamily, &group) < 1)
return errno > 0 ? -errno : -EINVAL;
family = netlink_family_from_string(sfamily);
if (family < 0)
return -EINVAL;
a->sockaddr.nl.nl_family = AF_NETLINK;
a->sockaddr.nl.nl_groups = group;
a->type = SOCK_RAW;
a->size = sizeof(struct sockaddr_nl);
a->protocol = family;
return 0;
}
int socket_address_verify(const SocketAddress *a) {
assert(a);
switch (socket_address_family(a)) {
case AF_INET:
if (a->size != sizeof(struct sockaddr_in))
return -EINVAL;
if (a->sockaddr.in.sin_port == 0)
return -EINVAL;
if (a->type != SOCK_STREAM && a->type != SOCK_DGRAM)
return -EINVAL;
return 0;
case AF_INET6:
if (a->size != sizeof(struct sockaddr_in6))
return -EINVAL;
if (a->sockaddr.in6.sin6_port == 0)
return -EINVAL;
if (a->type != SOCK_STREAM && a->type != SOCK_DGRAM)
return -EINVAL;
return 0;
case AF_UNIX:
if (a->size < offsetof(struct sockaddr_un, sun_path))
return -EINVAL;
if (a->size > offsetof(struct sockaddr_un, sun_path)) {
if (a->sockaddr.un.sun_path[0] != 0) {
char *e;
/* path */
e = memchr(a->sockaddr.un.sun_path, 0, sizeof(a->sockaddr.un.sun_path));
if (!e)
return -EINVAL;
if (a->size != offsetof(struct sockaddr_un, sun_path) + (e - a->sockaddr.un.sun_path) + 1)
return -EINVAL;
}
}
if (a->type != SOCK_STREAM && a->type != SOCK_DGRAM && a->type != SOCK_SEQPACKET)
return -EINVAL;
return 0;
case AF_NETLINK:
if (a->size != sizeof(struct sockaddr_nl))
return -EINVAL;
if (a->type != SOCK_RAW && a->type != SOCK_DGRAM)
return -EINVAL;
return 0;
default:
return -EAFNOSUPPORT;
}
}
int socket_address_print(const SocketAddress *a, char **ret) {
int r;
assert(a);
assert(ret);
r = socket_address_verify(a);
if (r < 0)
return r;
if (socket_address_family(a) == AF_NETLINK) {
_cleanup_free_ char *sfamily = NULL;
r = netlink_family_to_string_alloc(a->protocol, &sfamily);
if (r < 0)
return r;
r = asprintf(ret, "%s %u", sfamily, a->sockaddr.nl.nl_groups);
if (r < 0)
return -ENOMEM;
return 0;
}
return sockaddr_pretty(&a->sockaddr.sa, a->size, false, true, ret);
}
bool socket_address_can_accept(const SocketAddress *a) {
assert(a);
return
a->type == SOCK_STREAM ||
a->type == SOCK_SEQPACKET;
}
bool socket_address_equal(const SocketAddress *a, const SocketAddress *b) {
assert(a);
assert(b);
/* Invalid addresses are unequal to all */
if (socket_address_verify(a) < 0 ||
socket_address_verify(b) < 0)
return false;
if (a->type != b->type)
return false;
if (socket_address_family(a) != socket_address_family(b))
return false;
switch (socket_address_family(a)) {
case AF_INET:
if (a->sockaddr.in.sin_addr.s_addr != b->sockaddr.in.sin_addr.s_addr)
return false;
if (a->sockaddr.in.sin_port != b->sockaddr.in.sin_port)
return false;
break;
case AF_INET6:
if (memcmp(&a->sockaddr.in6.sin6_addr, &b->sockaddr.in6.sin6_addr, sizeof(a->sockaddr.in6.sin6_addr)) != 0)
return false;
if (a->sockaddr.in6.sin6_port != b->sockaddr.in6.sin6_port)
return false;
break;
case AF_UNIX:
if (a->size <= offsetof(struct sockaddr_un, sun_path) ||
b->size <= offsetof(struct sockaddr_un, sun_path))
return false;
if ((a->sockaddr.un.sun_path[0] == 0) != (b->sockaddr.un.sun_path[0] == 0))
return false;
if (a->sockaddr.un.sun_path[0]) {
if (!path_equal_or_files_same(a->sockaddr.un.sun_path, b->sockaddr.un.sun_path))
return false;
} else {
if (a->size != b->size)
return false;
if (memcmp(a->sockaddr.un.sun_path, b->sockaddr.un.sun_path, a->size) != 0)
return false;
}
break;
case AF_NETLINK:
if (a->protocol != b->protocol)
return false;
if (a->sockaddr.nl.nl_groups != b->sockaddr.nl.nl_groups)
return false;
break;
default:
/* Cannot compare, so we assume the addresses are different */
return false;
}
return true;
}
bool socket_address_is(const SocketAddress *a, const char *s, int type) {
struct SocketAddress b;
assert(a);
assert(s);
if (socket_address_parse(&b, s) < 0)
return false;
b.type = type;
return socket_address_equal(a, &b);
}
bool socket_address_is_netlink(const SocketAddress *a, const char *s) {
struct SocketAddress b;
assert(a);
assert(s);
if (socket_address_parse_netlink(&b, s) < 0)
return false;
return socket_address_equal(a, &b);
}
const char* socket_address_get_path(const SocketAddress *a) {
assert(a);
if (socket_address_family(a) != AF_UNIX)
return NULL;
if (a->sockaddr.un.sun_path[0] == 0)
return NULL;
return a->sockaddr.un.sun_path;
}
bool socket_ipv6_is_supported(void) {
if (access("/proc/net/if_inet6", F_OK) != 0)
return false;
return true;
}
bool socket_address_matches_fd(const SocketAddress *a, int fd) {
SocketAddress b;
socklen_t solen;
assert(a);
assert(fd >= 0);
b.size = sizeof(b.sockaddr);
if (getsockname(fd, &b.sockaddr.sa, &b.size) < 0)
return false;
if (b.sockaddr.sa.sa_family != a->sockaddr.sa.sa_family)
return false;
solen = sizeof(b.type);
if (getsockopt(fd, SOL_SOCKET, SO_TYPE, &b.type, &solen) < 0)
return false;
if (b.type != a->type)
return false;
if (a->protocol != 0) {
solen = sizeof(b.protocol);
if (getsockopt(fd, SOL_SOCKET, SO_PROTOCOL, &b.protocol, &solen) < 0)
return false;
if (b.protocol != a->protocol)
return false;
}
return socket_address_equal(a, &b);
}
int sockaddr_port(const struct sockaddr *_sa) {
union sockaddr_union *sa = (union sockaddr_union*) _sa;
assert(sa);
if (!IN_SET(sa->sa.sa_family, AF_INET, AF_INET6))
return -EAFNOSUPPORT;
return be16toh(sa->sa.sa_family == AF_INET6 ? sa->in6.sin6_port : sa->in.sin_port);
}
int sockaddr_pretty(const struct sockaddr *_sa, socklen_t salen, bool translate_ipv6, bool include_port, char **ret) {
union sockaddr_union *sa = (union sockaddr_union*) _sa;
char *p;
int r;
assert(sa);
assert(salen >= sizeof(sa->sa.sa_family));
switch (sa->sa.sa_family) {
case AF_INET: {
uint32_t a;
a = be32toh(sa->in.sin_addr.s_addr);
if (include_port)
r = asprintf(&p,
"%u.%u.%u.%u:%u",
a >> 24, (a >> 16) & 0xFF, (a >> 8) & 0xFF, a & 0xFF,
be16toh(sa->in.sin_port));
else
r = asprintf(&p,
"%u.%u.%u.%u",
a >> 24, (a >> 16) & 0xFF, (a >> 8) & 0xFF, a & 0xFF);
if (r < 0)
return -ENOMEM;
break;
}
case AF_INET6: {
static const unsigned char ipv4_prefix[] = {
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xFF, 0xFF
};
if (translate_ipv6 &&
memcmp(&sa->in6.sin6_addr, ipv4_prefix, sizeof(ipv4_prefix)) == 0) {
const uint8_t *a = sa->in6.sin6_addr.s6_addr+12;
if (include_port)
r = asprintf(&p,
"%u.%u.%u.%u:%u",
a[0], a[1], a[2], a[3],
be16toh(sa->in6.sin6_port));
else
r = asprintf(&p,
"%u.%u.%u.%u",
a[0], a[1], a[2], a[3]);
if (r < 0)
return -ENOMEM;
} else {
char a[INET6_ADDRSTRLEN];
inet_ntop(AF_INET6, &sa->in6.sin6_addr, a, sizeof(a));
if (include_port) {
r = asprintf(&p,
"[%s]:%u",
a,
be16toh(sa->in6.sin6_port));
if (r < 0)
return -ENOMEM;
} else {
p = strdup(a);
if (!p)
return -ENOMEM;
}
}
break;
}
case AF_UNIX:
if (salen <= offsetof(struct sockaddr_un, sun_path)) {
p = strdup("<unnamed>");
if (!p)
return -ENOMEM;
} else if (sa->un.sun_path[0] == 0) {
/* abstract */
/* FIXME: We assume we can print the
* socket path here and that it hasn't
* more than one NUL byte. That is
* actually an invalid assumption */
p = new(char, sizeof(sa->un.sun_path)+1);
if (!p)
return -ENOMEM;
p[0] = '@';
memcpy(p+1, sa->un.sun_path+1, sizeof(sa->un.sun_path)-1);
p[sizeof(sa->un.sun_path)] = 0;
} else {
p = strndup(sa->un.sun_path, sizeof(sa->un.sun_path));
if (!p)
return -ENOMEM;
}
break;
default:
return -EOPNOTSUPP;
}
*ret = p;
return 0;
}
int getpeername_pretty(int fd, bool include_port, char **ret) {
union sockaddr_union sa;
socklen_t salen = sizeof(sa);
int r;
assert(fd >= 0);
assert(ret);
if (getpeername(fd, &sa.sa, &salen) < 0)
return -errno;
if (sa.sa.sa_family == AF_UNIX) {
struct ucred ucred = {};
/* UNIX connection sockets are anonymous, so let's use
* PID/UID as pretty credentials instead */
r = getpeercred(fd, &ucred);
if (r < 0)
return r;
if (asprintf(ret, "PID "PID_FMT"/UID "UID_FMT, ucred.pid, ucred.uid) < 0)
return -ENOMEM;
return 0;
}
/* For remote sockets we translate IPv6 addresses back to IPv4
* if applicable, since that's nicer. */
return sockaddr_pretty(&sa.sa, salen, true, include_port, ret);
}
int getsockname_pretty(int fd, char **ret) {
union sockaddr_union sa;
socklen_t salen = sizeof(sa);
assert(fd >= 0);
assert(ret);
if (getsockname(fd, &sa.sa, &salen) < 0)
return -errno;
/* For local sockets we do not translate IPv6 addresses back
* to IPv6 if applicable, since this is usually used for
* listening sockets where the difference between IPv4 and
* IPv6 matters. */
return sockaddr_pretty(&sa.sa, salen, false, true, ret);
}
int socknameinfo_pretty(union sockaddr_union *sa, socklen_t salen, char **_ret) {
int r;
char host[NI_MAXHOST], *ret;
assert(_ret);
r = getnameinfo(&sa->sa, salen, host, sizeof(host), NULL, 0,
NI_IDN|NI_IDN_USE_STD3_ASCII_RULES);
if (r != 0) {
int saved_errno = errno;
r = sockaddr_pretty(&sa->sa, salen, true, true, &ret);
if (r < 0)
return r;
log_debug_errno(saved_errno, "getnameinfo(%s) failed: %m", ret);
} else {
ret = strdup(host);
if (!ret)
return -ENOMEM;
}
*_ret = ret;
return 0;
}
int getnameinfo_pretty(int fd, char **ret) {
union sockaddr_union sa;
socklen_t salen = sizeof(sa);
assert(fd >= 0);
assert(ret);
if (getsockname(fd, &sa.sa, &salen) < 0)
return -errno;
return socknameinfo_pretty(&sa, salen, ret);
}
int socket_address_unlink(SocketAddress *a) {
assert(a);
if (socket_address_family(a) != AF_UNIX)
return 0;
if (a->sockaddr.un.sun_path[0] == 0)
return 0;
if (unlink(a->sockaddr.un.sun_path) < 0)
return -errno;
return 1;
}
static const char* const netlink_family_table[] = {
[NETLINK_ROUTE] = "route",
[NETLINK_FIREWALL] = "firewall",
[NETLINK_INET_DIAG] = "inet-diag",
[NETLINK_NFLOG] = "nflog",
[NETLINK_XFRM] = "xfrm",
[NETLINK_SELINUX] = "selinux",
[NETLINK_ISCSI] = "iscsi",
[NETLINK_AUDIT] = "audit",
[NETLINK_FIB_LOOKUP] = "fib-lookup",
[NETLINK_CONNECTOR] = "connector",
[NETLINK_NETFILTER] = "netfilter",
[NETLINK_IP6_FW] = "ip6-fw",
[NETLINK_DNRTMSG] = "dnrtmsg",
[NETLINK_KOBJECT_UEVENT] = "kobject-uevent",
[NETLINK_GENERIC] = "generic",
[NETLINK_SCSITRANSPORT] = "scsitransport",
[NETLINK_ECRYPTFS] = "ecryptfs"
};
DEFINE_STRING_TABLE_LOOKUP_WITH_FALLBACK(netlink_family, int, INT_MAX);
static const char* const socket_address_bind_ipv6_only_table[_SOCKET_ADDRESS_BIND_IPV6_ONLY_MAX] = {
[SOCKET_ADDRESS_DEFAULT] = "default",
[SOCKET_ADDRESS_BOTH] = "both",
[SOCKET_ADDRESS_IPV6_ONLY] = "ipv6-only"
};
DEFINE_STRING_TABLE_LOOKUP(socket_address_bind_ipv6_only, SocketAddressBindIPv6Only);
bool sockaddr_equal(const union sockaddr_union *a, const union sockaddr_union *b) {
assert(a);
assert(b);
if (a->sa.sa_family != b->sa.sa_family)
return false;
if (a->sa.sa_family == AF_INET)
return a->in.sin_addr.s_addr == b->in.sin_addr.s_addr;
if (a->sa.sa_family == AF_INET6)
return memcmp(&a->in6.sin6_addr, &b->in6.sin6_addr, sizeof(a->in6.sin6_addr)) == 0;
return false;
}
int fd_inc_sndbuf(int fd, size_t n) {
int r, value;
socklen_t l = sizeof(value);
r = getsockopt(fd, SOL_SOCKET, SO_SNDBUF, &value, &l);
if (r >= 0 && l == sizeof(value) && (size_t) value >= n*2)
return 0;
/* If we have the privileges we will ignore the kernel limit. */
value = (int) n;
if (setsockopt(fd, SOL_SOCKET, SO_SNDBUFFORCE, &value, sizeof(value)) < 0)
if (setsockopt(fd, SOL_SOCKET, SO_SNDBUF, &value, sizeof(value)) < 0)
return -errno;
return 1;
}
int fd_inc_rcvbuf(int fd, size_t n) {
int r, value;
socklen_t l = sizeof(value);
r = getsockopt(fd, SOL_SOCKET, SO_RCVBUF, &value, &l);
if (r >= 0 && l == sizeof(value) && (size_t) value >= n*2)
return 0;
/* If we have the privileges we will ignore the kernel limit. */
value = (int) n;
if (setsockopt(fd, SOL_SOCKET, SO_RCVBUFFORCE, &value, sizeof(value)) < 0)
if (setsockopt(fd, SOL_SOCKET, SO_RCVBUF, &value, sizeof(value)) < 0)
return -errno;
return 1;
}
static const char* const ip_tos_table[] = {
[IPTOS_LOWDELAY] = "low-delay",
[IPTOS_THROUGHPUT] = "throughput",
[IPTOS_RELIABILITY] = "reliability",
[IPTOS_LOWCOST] = "low-cost",
};
DEFINE_STRING_TABLE_LOOKUP_WITH_FALLBACK(ip_tos, int, 0xff);
bool ifname_valid(const char *p) {
bool numeric = true;
/* Checks whether a network interface name is valid. This is inspired by dev_valid_name() in the kernel sources
* but slightly stricter, as we only allow non-control, non-space ASCII characters in the interface name. We
* also don't permit names that only container numbers, to avoid confusion with numeric interface indexes. */
if (isempty(p))
return false;
if (strlen(p) >= IFNAMSIZ)
return false;
if (STR_IN_SET(p, ".", ".."))
return false;
while (*p) {
if ((unsigned char) *p >= 127U)
return false;
if ((unsigned char) *p <= 32U)
return false;
if (*p == ':' || *p == '/')
return false;
numeric = numeric && (*p >= '0' && *p <= '9');
p++;
}
if (numeric)
return false;
return true;
}
int getpeercred(int fd, struct ucred *ucred) {
socklen_t n = sizeof(struct ucred);
struct ucred u;
int r;
assert(fd >= 0);
assert(ucred);
r = getsockopt(fd, SOL_SOCKET, SO_PEERCRED, &u, &n);
if (r < 0)
return -errno;
if (n != sizeof(struct ucred))
return -EIO;
/* Check if the data is actually useful and not suppressed due
* to namespacing issues */
if (u.pid <= 0)
return -ENODATA;
if (u.uid == UID_INVALID)
return -ENODATA;
if (u.gid == GID_INVALID)
return -ENODATA;
*ucred = u;
return 0;
}
int getpeersec(int fd, char **ret) {
socklen_t n = 64;
char *s;
int r;
assert(fd >= 0);
assert(ret);
s = new0(char, n);
if (!s)
return -ENOMEM;
r = getsockopt(fd, SOL_SOCKET, SO_PEERSEC, s, &n);
if (r < 0) {
free(s);
if (errno != ERANGE)
return -errno;
s = new0(char, n);
if (!s)
return -ENOMEM;
r = getsockopt(fd, SOL_SOCKET, SO_PEERSEC, s, &n);
if (r < 0) {
free(s);
return -errno;
}
}
if (isempty(s)) {
free(s);
return -EOPNOTSUPP;
}
*ret = s;
return 0;
}
int send_one_fd_sa(
int transport_fd,
int fd,
const struct sockaddr *sa, socklen_t len,
int flags) {
union {
struct cmsghdr cmsghdr;
uint8_t buf[CMSG_SPACE(sizeof(int))];
} control = {};
struct msghdr mh = {
.msg_name = (struct sockaddr*) sa,
.msg_namelen = len,
.msg_control = &control,
.msg_controllen = sizeof(control),
};
struct cmsghdr *cmsg;
assert(transport_fd >= 0);
assert(fd >= 0);
cmsg = CMSG_FIRSTHDR(&mh);
cmsg->cmsg_level = SOL_SOCKET;
cmsg->cmsg_type = SCM_RIGHTS;
cmsg->cmsg_len = CMSG_LEN(sizeof(int));
memcpy(CMSG_DATA(cmsg), &fd, sizeof(int));
mh.msg_controllen = CMSG_SPACE(sizeof(int));
if (sendmsg(transport_fd, &mh, MSG_NOSIGNAL | flags) < 0)
return -errno;
return 0;
}
int receive_one_fd(int transport_fd, int flags) {
union {
struct cmsghdr cmsghdr;
uint8_t buf[CMSG_SPACE(sizeof(int))];
} control = {};
struct msghdr mh = {
.msg_control = &control,
.msg_controllen = sizeof(control),
};
struct cmsghdr *cmsg, *found = NULL;
assert(transport_fd >= 0);
/*
* Receive a single FD via @transport_fd. We don't care for
* the transport-type. We retrieve a single FD at most, so for
* packet-based transports, the caller must ensure to send
* only a single FD per packet. This is best used in
* combination with send_one_fd().
*/
if (recvmsg(transport_fd, &mh, MSG_NOSIGNAL | MSG_CMSG_CLOEXEC | flags) < 0)
return -errno;
CMSG_FOREACH(cmsg, &mh) {
if (cmsg->cmsg_level == SOL_SOCKET &&
cmsg->cmsg_type == SCM_RIGHTS &&
cmsg->cmsg_len == CMSG_LEN(sizeof(int))) {
assert(!found);
found = cmsg;
break;
}
}
if (!found) {
cmsg_close_all(&mh);
return -EIO;
}
return *(int*) CMSG_DATA(found);
}
ssize_t next_datagram_size_fd(int fd) {
ssize_t l;
int k;
/* This is a bit like FIONREAD/SIOCINQ, however a bit more powerful. The difference being: recv(MSG_PEEK) will
* actually cause the next datagram in the queue to be validated regarding checksums, which FIONREAD doesn't
* do. This difference is actually of major importance as we need to be sure that the size returned here
* actually matches what we will read with recvmsg() next, as otherwise we might end up allocating a buffer of
* the wrong size. */
l = recv(fd, NULL, 0, MSG_PEEK|MSG_TRUNC);
if (l < 0) {
if (errno == EOPNOTSUPP || errno == EFAULT)
goto fallback;
return -errno;
}
if (l == 0)
goto fallback;
return l;
fallback:
k = 0;
/* Some sockets (AF_PACKET) do not support null-sized recv() with MSG_TRUNC set, let's fall back to FIONREAD
* for them. Checksums don't matter for raw sockets anyway, hence this should be fine. */
if (ioctl(fd, FIONREAD, &k) < 0)
return -errno;
return (ssize_t) k;
}
int flush_accept(int fd) {
struct pollfd pollfd = {
.fd = fd,
.events = POLLIN,
};
int r;
/* Similar to flush_fd() but flushes all incoming connection by accepting them and immediately closing them. */
for (;;) {
int cfd;
r = poll(&pollfd, 1, 0);
if (r < 0) {
if (errno == EINTR)
continue;
return -errno;
} else if (r == 0)
return 0;
cfd = accept4(fd, NULL, NULL, SOCK_NONBLOCK|SOCK_CLOEXEC);
if (cfd < 0) {
if (errno == EINTR)
continue;
if (errno == EAGAIN)
return 0;
return -errno;
}
close(cfd);
}
}
struct cmsghdr* cmsg_find(struct msghdr *mh, int level, int type, socklen_t length) {
struct cmsghdr *cmsg;
assert(mh);
CMSG_FOREACH(cmsg, mh)
if (cmsg->cmsg_level == level &&
cmsg->cmsg_type == type &&
(length == (socklen_t) -1 || length == cmsg->cmsg_len))
return cmsg;
return NULL;
}
int socket_ioctl_fd(void) {
int fd;
/* Create a socket to invoke the various network interface ioctl()s on. Traditionally only AF_INET was good for
* that. Since kernel 4.6 AF_NETLINK works for this too. We first try to use AF_INET hence, but if that's not
* available (for example, because it is made unavailable via SECCOMP or such), we'll fall back to the more
* generic AF_NETLINK. */
fd = socket(AF_INET, SOCK_DGRAM|SOCK_CLOEXEC, 0);
if (fd < 0)
fd = socket(AF_NETLINK, SOCK_RAW|SOCK_CLOEXEC, NETLINK_GENERIC);
if (fd < 0)
return -errno;
return fd;
}
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