/* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */
/*
* Copyright 2016 by the Massachusetts Institute of Technology.
* All Rights Reserved.
*
* Export of this software from the United States of America may
* require a specific license from the United States Government.
* It is the responsibility of any person or organization contemplating
* export to obtain such a license before exporting.
*
* WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
* distribute this software and its documentation for any purpose and
* without fee is hereby granted, provided that the above copyright
* notice appear in all copies and that both that copyright notice and
* this permission notice appear in supporting documentation, and that
* the name of M.I.T. not be used in advertising or publicity pertaining
* to distribution of the software without specific, written prior
* permission. Furthermore if you modify this software you must label
* your software as modified software and not distribute it in such a
* fashion that it might be confused with the original M.I.T. software.
* M.I.T. makes no representations about the suitability of
* this software for any purpose. It is provided "as is" without express
* or implied warranty.
*/
/* macOS requires this define for IPV6_PKTINFO. */
#define __APPLE_USE_RFC_3542
#include "udppktinfo.h"
#include <netinet/in.h>
#include <sys/socket.h>
#if defined(IP_PKTINFO) && defined(HAVE_STRUCT_IN_PKTINFO)
#define HAVE_IP_PKTINFO
#endif
#if defined(IPV6_PKTINFO) && defined(HAVE_STRUCT_IN6_PKTINFO)
#define HAVE_IPV6_PKTINFO
#endif
#if defined(HAVE_IP_PKTINFO) || defined(IP_SENDSRCADDR) || \
defined(HAVE_IPV6_PKTINFO)
#define HAVE_PKTINFO_SUPPORT
#endif
/* Use RFC 3542 API below, but fall back from IPV6_RECVPKTINFO to IPV6_PKTINFO
* for RFC 2292 implementations. */
#if !defined(IPV6_RECVPKTINFO) && defined(IPV6_PKTINFO)
#define IPV6_RECVPKTINFO IPV6_PKTINFO
#endif
/* Parallel, though not standardized. */
#if !defined(IP_RECVPKTINFO) && defined(IP_PKTINFO)
#define IP_RECVPKTINFO IP_PKTINFO
#endif /* IP_RECVPKTINFO */
#if defined(CMSG_SPACE) && defined(HAVE_STRUCT_CMSGHDR) && \
defined(HAVE_PKTINFO_SUPPORT)
union pktinfo {
#ifdef HAVE_STRUCT_IN6_PKTINFO
struct in6_pktinfo pi6;
#endif
#ifdef HAVE_STRUCT_IN_PKTINFO
struct in_pktinfo pi4;
#endif
#ifdef IP_RECVDSTADDR
struct in_addr iaddr;
#endif
char c;
};
#endif /* HAVE_IPV6_PKTINFO && HAVE_STRUCT_CMSGHDR && HAVE_PKTINFO_SUPPORT */
#ifdef HAVE_IP_PKTINFO
#define set_ipv4_pktinfo set_ipv4_recvpktinfo
static inline krb5_error_code
set_ipv4_recvpktinfo(int sock)
{
int sockopt = 1;
return setsockopt(sock, IPPROTO_IP, IP_RECVPKTINFO, &sockopt,
sizeof(sockopt));
}
#elif defined(IP_RECVDSTADDR) /* HAVE_IP_PKTINFO */
#define set_ipv4_pktinfo set_ipv4_recvdstaddr
static inline krb5_error_code
set_ipv4_recvdstaddr(int sock)
{
int sockopt = 1;
return setsockopt(sock, IPPROTO_IP, IP_RECVDSTADDR, &sockopt,
sizeof(sockopt));
}
#else /* HAVE_IP_PKTINFO || IP_RECVDSTADDR */
#define set_ipv4_pktinfo(s) EINVAL
#endif /* HAVE_IP_PKTINFO || IP_RECVDSTADDR */
#ifdef HAVE_IPV6_PKTINFO
#define set_ipv6_pktinfo set_ipv6_recvpktinfo
static inline krb5_error_code
set_ipv6_recvpktinfo(int sock)
{
int sockopt = 1;
return setsockopt(sock, IPPROTO_IPV6, IPV6_RECVPKTINFO, &sockopt,
sizeof(sockopt));
}
#else /* HAVE_IPV6_PKTINFO */
#define set_ipv6_pktinfo(s) EINVAL
#endif /* HAVE_IPV6_PKTINFO */
/*
* Set pktinfo option on a socket. Takes a socket and the socket address family
* as arguments.
*
* Returns 0 on success, EINVAL if pktinfo is not supported for the address
* family.
*/
krb5_error_code
set_pktinfo(int sock, int family)
{
switch (family) {
case AF_INET:
return set_ipv4_pktinfo(sock);
case AF_INET6:
return set_ipv6_pktinfo(sock);
default:
return EINVAL;
}
}
#if defined(HAVE_PKTINFO_SUPPORT) && defined(CMSG_SPACE)
/*
* Check if a socket is bound to a wildcard address.
* Returns 1 if it is, 0 if it's bound to a specific address, or -1 on error
* with errno set to the error.
*/
static int
is_socket_bound_to_wildcard(int sock)
{
struct sockaddr_storage bound_addr;
socklen_t bound_addr_len = sizeof(bound_addr);
struct sockaddr *sa = ss2sa(&bound_addr);
if (getsockname(sock, sa, &bound_addr_len) < 0)
return -1;
if (!sa_is_inet(sa)) {
errno = EINVAL;
return -1;
}
return sa_is_wildcard(sa);
}
#ifdef HAVE_IP_PKTINFO
static inline struct in_pktinfo *
cmsg2pktinfo(struct cmsghdr *cmsgptr)
{
return (struct in_pktinfo *)(void *)CMSG_DATA(cmsgptr);
}
#define check_cmsg_v4_pktinfo check_cmsg_ip_pktinfo
static int
check_cmsg_ip_pktinfo(struct cmsghdr *cmsgptr, struct sockaddr *to,
socklen_t *tolen, aux_addressing_info *auxaddr)
{
struct in_pktinfo *pktinfo;
if (cmsgptr->cmsg_level == IPPROTO_IP &&
cmsgptr->cmsg_type == IP_PKTINFO &&
*tolen >= sizeof(struct sockaddr_in)) {
memset(to, 0, sizeof(struct sockaddr_in));
pktinfo = cmsg2pktinfo(cmsgptr);
sa2sin(to)->sin_addr = pktinfo->ipi_addr;
sa2sin(to)->sin_family = AF_INET;
*tolen = sizeof(struct sockaddr_in);
return 1;
}
return 0;
}
#elif defined(IP_RECVDSTADDR) /* HAVE_IP_PKTINFO */
static inline struct in_addr *
cmsg2sin(struct cmsghdr *cmsgptr)
{
return (struct in_addr *)(void *)CMSG_DATA(cmsgptr);
}
#define check_cmsg_v4_pktinfo check_cmsg_ip_recvdstaddr
static int
check_cmsg_ip_recvdstaddr(struct cmsghdr *cmsgptr, struct sockaddr *to,
socklen_t *tolen, aux_addressing_info * auxaddr)
{
if (cmsgptr->cmsg_level == IPPROTO_IP &&
cmsgptr->cmsg_type == IP_RECVDSTADDR &&
*tolen >= sizeof(struct sockaddr_in)) {
struct in_addr *sin_addr;
memset(to, 0, sizeof(struct sockaddr_in));
sin_addr = cmsg2sin(cmsgptr);
sa2sin(to)->sin_addr = *sin_addr;
sa2sin(to)->sin_family = AF_INET;
*tolen = sizeof(struct sockaddr_in);
return 1;
}
return 0;
}
#else /* HAVE_IP_PKTINFO || IP_RECVDSTADDR */
#define check_cmsg_v4_pktinfo(c, t, l, a) 0
#endif /* HAVE_IP_PKTINFO || IP_RECVDSTADDR */
#ifdef HAVE_IPV6_PKTINFO
static inline struct in6_pktinfo *
cmsg2pktinfo6(struct cmsghdr *cmsgptr)
{
return (struct in6_pktinfo *)(void *)CMSG_DATA(cmsgptr);
}
#define check_cmsg_v6_pktinfo check_cmsg_ipv6_pktinfo
static int
check_cmsg_ipv6_pktinfo(struct cmsghdr *cmsgptr, struct sockaddr *to,
socklen_t *tolen, aux_addressing_info *auxaddr)
{
struct in6_pktinfo *pktinfo;
if (cmsgptr->cmsg_level == IPPROTO_IPV6 &&
cmsgptr->cmsg_type == IPV6_PKTINFO &&
*tolen >= sizeof(struct sockaddr_in6)) {
memset(to, 0, sizeof(struct sockaddr_in6));
pktinfo = cmsg2pktinfo6(cmsgptr);
sa2sin6(to)->sin6_addr = pktinfo->ipi6_addr;
sa2sin6(to)->sin6_family = AF_INET6;
*tolen = sizeof(struct sockaddr_in6);
auxaddr->ipv6_ifindex = pktinfo->ipi6_ifindex;
return 1;
}
return 0;
}
#else /* HAVE_IPV6_PKTINFO */
#define check_cmsg_v6_pktinfo(c, t, l, a) 0
#endif /* HAVE_IPV6_PKTINFO */
static int
check_cmsg_pktinfo(struct cmsghdr *cmsgptr, struct sockaddr *to,
socklen_t *tolen, aux_addressing_info *auxaddr)
{
return check_cmsg_v4_pktinfo(cmsgptr, to, tolen, auxaddr) ||
check_cmsg_v6_pktinfo(cmsgptr, to, tolen, auxaddr);
}
/*
* Receive a message from a socket.
*
* Arguments:
* sock
* buf - The buffer to store the message in.
* len - buf length
* flags
* from - Set to the address that sent the message
* fromlen
* to - Set to the address that the message was sent to if possible.
* May not be set in certain cases such as if pktinfo support is
* missing. May be NULL.
* tolen
* auxaddr - Miscellaneous address information.
*
* Returns 0 on success, otherwise an error code.
*/
krb5_error_code
recv_from_to(int sock, void *buf, size_t len, int flags,
struct sockaddr *from, socklen_t * fromlen,
struct sockaddr *to, socklen_t * tolen,
aux_addressing_info *auxaddr)
{
int r;
struct iovec iov;
char cmsg[CMSG_SPACE(sizeof(union pktinfo))];
struct cmsghdr *cmsgptr;
struct msghdr msg;
/* Don't use pktinfo if the socket isn't bound to a wildcard address. */
r = is_socket_bound_to_wildcard(sock);
if (r < 0)
return errno;
if (!to || !tolen || !r)
return recvfrom(sock, buf, len, flags, from, fromlen);
/* Clobber with something recognizeable in case we can't extract the
* address but try to use it anyways. */
memset(to, 0x40, *tolen);
iov.iov_base = buf;
iov.iov_len = len;
memset(&msg, 0, sizeof(msg));
msg.msg_name = from;
msg.msg_namelen = *fromlen;
msg.msg_iov = &iov;
msg.msg_iovlen = 1;
msg.msg_control = cmsg;
msg.msg_controllen = sizeof(cmsg);
r = recvmsg(sock, &msg, flags);
if (r < 0)
return r;
*fromlen = msg.msg_namelen;
/*
* On Darwin (and presumably all *BSD with KAME stacks), CMSG_FIRSTHDR
* doesn't check for a non-zero controllen. RFC 3542 recommends making
* this check, even though the (new) spec for CMSG_FIRSTHDR says it's
* supposed to do the check.
*/
if (msg.msg_controllen) {
cmsgptr = CMSG_FIRSTHDR(&msg);
while (cmsgptr) {
if (check_cmsg_pktinfo(cmsgptr, to, tolen, auxaddr))
return r;
cmsgptr = CMSG_NXTHDR(&msg, cmsgptr);
}
}
/* No info about destination addr was available. */
*tolen = 0;
return r;
}
#ifdef HAVE_IP_PKTINFO
#define set_msg_from_ipv4 set_msg_from_ip_pktinfo
static krb5_error_code
set_msg_from_ip_pktinfo(struct msghdr *msg, struct cmsghdr *cmsgptr,
struct sockaddr *from, socklen_t fromlen,
aux_addressing_info *auxaddr)
{
struct in_pktinfo *p = cmsg2pktinfo(cmsgptr);
const struct sockaddr_in *from4 = sa2sin(from);
if (fromlen != sizeof(struct sockaddr_in))
return EINVAL;
cmsgptr->cmsg_level = IPPROTO_IP;
cmsgptr->cmsg_type = IP_PKTINFO;
cmsgptr->cmsg_len = CMSG_LEN(sizeof(struct in_pktinfo));
p->ipi_spec_dst = from4->sin_addr;
msg->msg_controllen = CMSG_SPACE(sizeof(struct in_pktinfo));
return 0;
}
#elif defined(IP_SENDSRCADDR) /* HAVE_IP_PKTINFO */
#define set_msg_from_ipv4 set_msg_from_ip_sendsrcaddr
static krb5_error_code
set_msg_from_ip_sendsrcaddr(struct msghdr *msg, struct cmsghdr *cmsgptr,
struct sockaddr *from, socklen_t fromlen,
aux_addressing_info *auxaddr)
{
struct in_addr *sin_addr = cmsg2sin(cmsgptr);
const struct sockaddr_in *from4 = sa2sin(from);
if (fromlen != sizeof(struct sockaddr_in))
return EINVAL;
cmsgptr->cmsg_level = IPPROTO_IP;
cmsgptr->cmsg_type = IP_SENDSRCADDR;
cmsgptr->cmsg_len = CMSG_LEN(sizeof(struct in_addr));
msg->msg_controllen = CMSG_SPACE(sizeof(struct in_addr));
*sin_addr = from4->sin_addr;
return 0;
}
#else /* HAVE_IP_PKTINFO || IP_SENDSRCADDR */
#define set_msg_from_ipv4(m, c, f, l, a) EINVAL
#endif /* HAVE_IP_PKTINFO || IP_SENDSRCADDR */
#ifdef HAVE_IPV6_PKTINFO
#define set_msg_from_ipv6 set_msg_from_ipv6_pktinfo
static krb5_error_code
set_msg_from_ipv6_pktinfo(struct msghdr *msg, struct cmsghdr *cmsgptr,
struct sockaddr *from, socklen_t fromlen,
aux_addressing_info *auxaddr)
{
struct in6_pktinfo *p = cmsg2pktinfo6(cmsgptr);
const struct sockaddr_in6 *from6 = sa2sin6(from);
if (fromlen != sizeof(struct sockaddr_in6))
return EINVAL;
cmsgptr->cmsg_level = IPPROTO_IPV6;
cmsgptr->cmsg_type = IPV6_PKTINFO;
cmsgptr->cmsg_len = CMSG_LEN(sizeof(struct in6_pktinfo));
p->ipi6_addr = from6->sin6_addr;
/*
* Because of the possibility of asymmetric routing, we
* normally don't want to specify an interface. However,
* macOS doesn't like sending from a link-local address
* (which can come up in testing at least, if you wind up
* with a "foo.local" name) unless we do specify the
* interface.
*/
if (IN6_IS_ADDR_LINKLOCAL(&from6->sin6_addr))
p->ipi6_ifindex = auxaddr->ipv6_ifindex;
/* otherwise, already zero */
msg->msg_controllen = CMSG_SPACE(sizeof(struct in6_pktinfo));
return 0;
}
#else /* HAVE_IPV6_PKTINFO */
#define set_msg_from_ipv6(m, c, f, l, a) EINVAL
#endif /* HAVE_IPV6_PKTINFO */
static krb5_error_code
set_msg_from(int family, struct msghdr *msg, struct cmsghdr *cmsgptr,
struct sockaddr *from, socklen_t fromlen,
aux_addressing_info *auxaddr)
{
switch (family) {
case AF_INET:
return set_msg_from_ipv4(msg, cmsgptr, from, fromlen, auxaddr);
case AF_INET6:
return set_msg_from_ipv6(msg, cmsgptr, from, fromlen, auxaddr);
}
return EINVAL;
}
/*
* Send a message to an address.
*
* Arguments:
* sock
* buf - The message to send.
* len - buf length
* flags
* to - The address to send the message to.
* tolen
* from - The address to attempt to send the message from. May be NULL.
* fromlen
* auxaddr - Miscellaneous address information.
*
* Returns 0 on success, otherwise an error code.
*/
krb5_error_code
send_to_from(int sock, void *buf, size_t len, int flags,
const struct sockaddr *to, socklen_t tolen, struct sockaddr *from,
socklen_t fromlen, aux_addressing_info *auxaddr)
{
int r;
struct iovec iov;
struct msghdr msg;
struct cmsghdr *cmsgptr;
char cbuf[CMSG_SPACE(sizeof(union pktinfo))];
/* Don't use pktinfo if the socket isn't bound to a wildcard address. */
r = is_socket_bound_to_wildcard(sock);
if (r < 0)
return errno;
if (from == NULL || fromlen == 0 || from->sa_family != to->sa_family || !r)
goto use_sendto;
iov.iov_base = buf;
iov.iov_len = len;
/* Truncation? */
if (iov.iov_len != len)
return EINVAL;
memset(cbuf, 0, sizeof(cbuf));
memset(&msg, 0, sizeof(msg));
msg.msg_name = (void *)to;
msg.msg_namelen = tolen;
msg.msg_iov = &iov;
msg.msg_iovlen = 1;
msg.msg_control = cbuf;
/* CMSG_FIRSTHDR needs a non-zero controllen, or it'll return NULL on
* Linux. */
msg.msg_controllen = sizeof(cbuf);
cmsgptr = CMSG_FIRSTHDR(&msg);
msg.msg_controllen = 0;
if (set_msg_from(from->sa_family, &msg, cmsgptr, from, fromlen, auxaddr))
goto use_sendto;
return sendmsg(sock, &msg, flags);
use_sendto:
return sendto(sock, buf, len, flags, to, tolen);
}
#else /* HAVE_PKTINFO_SUPPORT && CMSG_SPACE */
krb5_error_code
recv_from_to(int sock, void *buf, size_t len, int flags,
struct sockaddr *from, socklen_t *fromlen,
struct sockaddr *to, socklen_t *tolen,
aux_addressing_info *auxaddr)
{
if (to && tolen) {
/* Clobber with something recognizeable in case we try to use the
* address. */
memset(to, 0x40, *tolen);
*tolen = 0;
}
return recvfrom(sock, buf, len, flags, from, fromlen);
}
krb5_error_code
send_to_from(int sock, void *buf, size_t len, int flags,
const struct sockaddr *to, socklen_t tolen,
struct sockaddr *from, socklen_t fromlen,
aux_addressing_info *auxaddr)
{
return sendto(sock, buf, len, flags, to, tolen);
}
#endif /* HAVE_PKTINFO_SUPPORT && CMSG_SPACE */