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/* ----------------------------------------------------------------------- *
*
* Copyright 2001-2006 H. Peter Anvin - All Rights Reserved
*
* This program is free software available under the same license
* as the "OpenBSD" operating system, distributed at
* http://www.openbsd.org/.
*
* ----------------------------------------------------------------------- */
/*
* recvfrom.c
*
* Emulate recvfrom() using recvmsg(), but try to capture the local address
* since some TFTP clients consider it an error to get the reply from another
* IP address than the request was sent to.
*
*/
#include "config.h" /* Must be included first! */
#include "common/tftpsubs.h"
#include "recvfrom.h"
#ifdef HAVE_MACHINE_PARAM_H
#include <machine/param.h> /* Needed on some versions of FreeBSD */
#endif
#if defined(HAVE_RECVMSG) && defined(HAVE_MSGHDR_MSG_CONTROL)
#include <sys/uio.h>
#ifdef IP_PKTINFO
# ifndef HAVE_STRUCT_IN_PKTINFO
# ifdef __linux__
/* Assume this version of glibc simply lacks the definition */
struct in_pktinfo {
int ipi_ifindex;
struct in_addr ipi_spec_dst;
struct in_addr ipi_addr;
};
# else
# undef IP_PKTINFO /* No definition, no way to get it */
# endif
# endif
#endif
#ifndef CMSG_LEN
# define CMSG_LEN(size) (sizeof(struct cmsghdr) + (size))
#endif
#ifndef CMSG_SPACE
# define CMSG_SPACE(size) (sizeof(struct cmsghdr) + (size))
#endif
/*
* Check to see if this is a valid local address, meaning that we can
* legally bind to it.
*/
static int address_is_local(const union sock_addr *addr)
{
union sock_addr sa1, sa2;
int sockfd = -1;
int e;
int rv = 0;
socklen_t addrlen;
memcpy(&sa1, addr, sizeof sa1);
/* Multicast or universal broadcast address? */
if (sa1.sa.sa_family == AF_INET) {
if (ntohl(sa1.si.sin_addr.s_addr) >= (224UL << 24))
return 0;
sa1.si.sin_port = 0; /* Any port */
}
#ifdef HAVE_IPV6
else if (sa1.sa.sa_family == AF_INET6) {
if (IN6_IS_ADDR_MULTICAST(&sa1.s6.sin6_addr))
return 0;
sa1.s6.sin6_port = 0; /* Any port */
}
#endif
else
return 0;
sockfd = socket(sa1.sa.sa_family, SOCK_DGRAM, 0);
if (sockfd < 0)
goto err;
if (bind(sockfd, &sa1.sa, SOCKLEN(&sa1)))
goto err;
addrlen = SOCKLEN(addr);
if (getsockname(sockfd, (struct sockaddr *)&sa2, &addrlen))
goto err;
if (sa1.sa.sa_family != sa2.sa.sa_family)
goto err;
if (sa2.sa.sa_family == AF_INET)
rv = sa1.si.sin_addr.s_addr == sa2.si.sin_addr.s_addr;
#ifdef HAVE_IPV6
else if (sa2.sa.sa_family == AF_INET6)
rv = IN6_ARE_ADDR_EQUAL(&sa1.s6.sin6_addr, &sa2.s6.sin6_addr);
#endif
else
rv = 0;
err:
e = errno;
if (sockfd >= 0)
close(sockfd);
errno = e;
return rv;
}
static void normalize_ip6_compat(union sock_addr *myaddr)
{
#ifdef HAVE_IPV6
static const uint8_t ip6_compat_prefix[12] =
{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xff, 0xff };
struct sockaddr_in in;
if (myaddr->sa.sa_family == AF_INET6 &&
!memcmp(&myaddr->s6.sin6_addr, ip6_compat_prefix,
sizeof ip6_compat_prefix)) {
bzero(&in, sizeof in);
in.sin_family = AF_INET;
in.sin_port = myaddr->s6.sin6_port;
memcpy(&in.sin_addr, (const char *)&myaddr->s6.sin6_addr +
sizeof ip6_compat_prefix, sizeof in.sin_addr);
memcpy(&myaddr->si, &in, sizeof in);
}
#else
(void)myaddr;
#endif
}
int
myrecvfrom(int s, void *buf, int len, unsigned int flags,
union sock_addr *from, union sock_addr *myaddr)
{
struct msghdr msg;
struct iovec iov;
int n;
struct cmsghdr *cmptr;
union {
struct cmsghdr cm;
#ifdef IP_PKTINFO
char control[CMSG_SPACE(sizeof(struct in_addr)) +
CMSG_SPACE(sizeof(struct in_pktinfo))];
#else
char control[CMSG_SPACE(sizeof(struct in_addr))];
#endif
#ifdef HAVE_IPV6
#ifdef HAVE_STRUCT_IN6_PKTINFO
char control6[CMSG_SPACE(sizeof(struct in6_addr)) +
CMSG_SPACE(sizeof(struct in6_pktinfo))];
#else
char control6[CMSG_SPACE(sizeof(struct in6_addr))];
#endif
#endif
} control_un;
int on = 1;
#ifdef IP_PKTINFO
struct in_pktinfo pktinfo;
#endif
#ifdef HAVE_STRUCT_IN6_PKTINFO
struct in6_pktinfo pktinfo6;
#endif
/* Try to enable getting the return address */
#ifdef IP_RECVDSTADDR
if (from->sa.sa_family == AF_INET)
setsockopt(s, IPPROTO_IP, IP_RECVDSTADDR, &on, sizeof(on));
#endif
#ifdef IP_PKTINFO
if (from->sa.sa_family == AF_INET)
setsockopt(s, IPPROTO_IP, IP_PKTINFO, &on, sizeof(on));
#endif
#ifdef HAVE_IPV6
#ifdef IPV6_RECVPKTINFO
if (from->sa.sa_family == AF_INET6)
setsockopt(s, IPPROTO_IPV6, IPV6_RECVPKTINFO, &on, sizeof(on));
#endif
#endif
bzero(&msg, sizeof msg); /* Clear possible system-dependent fields */
msg.msg_control = control_un.control;
msg.msg_controllen = sizeof(control_un);
msg.msg_flags = 0;
msg.msg_name = &from->sa;
msg.msg_namelen = sizeof(*from);
iov.iov_base = buf;
iov.iov_len = len;
msg.msg_iov = &iov;
msg.msg_iovlen = 1;
if ((n = recvmsg(s, &msg, flags)) < 0)
return n; /* Error */
if (myaddr) {
bzero(myaddr, sizeof(*myaddr));
myaddr->sa.sa_family = from->sa.sa_family;
if (msg.msg_controllen < sizeof(struct cmsghdr) ||
(msg.msg_flags & MSG_CTRUNC))
return n; /* No information available */
for (cmptr = CMSG_FIRSTHDR(&msg); cmptr != NULL;
cmptr = CMSG_NXTHDR(&msg, cmptr)) {
if (from->sa.sa_family == AF_INET) {
myaddr->sa.sa_family = AF_INET;
#ifdef IP_RECVDSTADDR
if (cmptr->cmsg_level == IPPROTO_IP &&
cmptr->cmsg_type == IP_RECVDSTADDR) {
memcpy(&myaddr->si.sin_addr, CMSG_DATA(cmptr),
sizeof(struct in_addr));
}
#endif
#ifdef IP_PKTINFO
if (cmptr->cmsg_level == IPPROTO_IP &&
cmptr->cmsg_type == IP_PKTINFO) {
memcpy(&pktinfo, CMSG_DATA(cmptr),
sizeof(struct in_pktinfo));
memcpy(&myaddr->si.sin_addr, &pktinfo.ipi_addr,
sizeof(struct in_addr));
}
#endif
}
#ifdef HAVE_IPV6
else if (from->sa.sa_family == AF_INET6) {
myaddr->sa.sa_family = AF_INET6;
#ifdef IP6_RECVDSTADDR
if (cmptr->cmsg_level == IPPROTO_IPV6 &&
cmptr->cmsg_type == IPV6_RECVDSTADDR )
memcpy(&myaddr->s6.sin6_addr, CMSG_DATA(cmptr),
sizeof(struct in6_addr));
#endif
#ifdef HAVE_STRUCT_IN6_PKTINFO
if (cmptr->cmsg_level == IPPROTO_IPV6 &&
(
#ifdef IPV6_RECVPKTINFO
cmptr->cmsg_type == IPV6_RECVPKTINFO ||
#endif
cmptr->cmsg_type == IPV6_PKTINFO)) {
memcpy(&pktinfo6, CMSG_DATA(cmptr),
sizeof(struct in6_pktinfo));
memcpy(&myaddr->s6.sin6_addr, &pktinfo6.ipi6_addr,
sizeof(struct in6_addr));
}
#endif
}
#endif
}
normalize_ip6_compat(myaddr);
/* If the address is not a valid local address,
* then bind to any address...
*/
if (address_is_local(myaddr) != 1) {
if (myaddr->sa.sa_family == AF_INET)
((struct sockaddr_in *)myaddr)->sin_addr.s_addr = INADDR_ANY;
#ifdef HAVE_IPV6
else if (myaddr->sa.sa_family == AF_INET6)
memset(&myaddr->s6.sin6_addr, 0, sizeof(struct in6_addr));
#endif
}
}
normalize_ip6_compat(from);
return n;
}
#else /* pointless... */
int
myrecvfrom(int s, void *buf, int len, unsigned int flags,
union sock_addr *from, union sock_addr *myaddr)
{
/* There is no way we can get the local address, fudge it */
socklen_t fromlen = sizeof(*from);
bzero(myaddr, sizeof(*myaddr));
myaddr->sa.sa_family = from->sa.sa_family;
sa_set_port(myaddr, htons(IPPORT_TFTP));
return recvfrom(s, buf, len, flags, from, &fromlen);
}
#endif
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