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/* vi: set sw=4 ts=4: */
/*
* Utility routines.
*
* Copyright (C) 2007 Denys Vlasenko
*
* Licensed under GPLv2, see file LICENSE in this source tree.
*/
#include "libbb.h"
/*
* This asks kernel to let us know dst addr/port of incoming packets
* We don't check for errors here. Not supported == won't be used
*/
void FAST_FUNC
socket_want_pktinfo(int fd UNUSED_PARAM)
{
#ifdef IP_PKTINFO
setsockopt_1(fd, IPPROTO_IP, IP_PKTINFO);
#endif
#if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO)
setsockopt_1(fd, IPPROTO_IPV6, IPV6_PKTINFO);
#endif
}
ssize_t FAST_FUNC
send_to_from(int fd, void *buf, size_t len, int flags,
const struct sockaddr *to,
const struct sockaddr *from,
socklen_t tolen)
{
#ifndef IP_PKTINFO
(void)from; /* suppress "unused from" warning */
return sendto(fd, buf, len, flags, to, tolen);
#else
struct iovec iov[1];
struct msghdr msg;
union {
char cmsg[CMSG_SPACE(sizeof(struct in_pktinfo))];
# if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO)
char cmsg6[CMSG_SPACE(sizeof(struct in6_pktinfo))];
# endif
} u;
struct cmsghdr* cmsgptr;
if (from->sa_family != AF_INET
# if ENABLE_FEATURE_IPV6
&& from->sa_family != AF_INET6
# endif
) {
/* ANY local address */
return sendto(fd, buf, len, flags, to, tolen);
}
/* man recvmsg and man cmsg is needed to make sense of code below */
iov[0].iov_base = buf;
iov[0].iov_len = len;
memset(&u, 0, sizeof(u));
memset(&msg, 0, sizeof(msg));
msg.msg_name = (void *)(struct sockaddr *)to; /* or compiler will annoy us */
msg.msg_namelen = tolen;
msg.msg_iov = iov;
msg.msg_iovlen = 1;
msg.msg_control = &u;
msg.msg_controllen = sizeof(u);
msg.msg_flags = flags;
cmsgptr = CMSG_FIRSTHDR(&msg);
if (to->sa_family == AF_INET && from->sa_family == AF_INET) {
struct in_pktinfo *pktptr;
cmsgptr->cmsg_level = IPPROTO_IP;
cmsgptr->cmsg_type = IP_PKTINFO;
cmsgptr->cmsg_len = CMSG_LEN(sizeof(struct in_pktinfo));
pktptr = (struct in_pktinfo *)(CMSG_DATA(cmsgptr));
/*pktptr->ipi_ifindex = 0; -- already done by memset(u...) */
/* In general, CMSG_DATA() can be unaligned, but in this case
* we know for sure it is sufficiently aligned:
* CMSG_FIRSTHDR simply returns &u above,
* and CMSG_DATA returns &u + size_t + int + int.
* Thus direct assignment is ok:
*/
pktptr->ipi_spec_dst = ((struct sockaddr_in*)from)->sin_addr;
}
# if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO)
else if (to->sa_family == AF_INET6 && from->sa_family == AF_INET6) {
struct in6_pktinfo *pktptr;
cmsgptr->cmsg_level = IPPROTO_IPV6;
cmsgptr->cmsg_type = IPV6_PKTINFO;
cmsgptr->cmsg_len = CMSG_LEN(sizeof(struct in6_pktinfo));
pktptr = (struct in6_pktinfo *)(CMSG_DATA(cmsgptr));
/* pktptr->ipi6_ifindex = 0; -- already done by memset(u...) */
pktptr->ipi6_addr = ((struct sockaddr_in6*)from)->sin6_addr;
}
# endif
msg.msg_controllen = cmsgptr->cmsg_len;
return sendmsg(fd, &msg, flags);
#endif
}
/* NB: this will never set port# in 'to'!
* _Only_ IP/IPv6 address part of 'to' is _maybe_ modified.
* Typical usage is to preinit 'to' with "default" value
* before calling recv_from_to(). */
ssize_t FAST_FUNC
recv_from_to(int fd, void *buf, size_t len, int flags,
struct sockaddr *from, struct sockaddr *to,
socklen_t sa_size)
{
#ifndef IP_PKTINFO
(void)to; /* suppress "unused to" warning */
return recvfrom(fd, buf, len, flags, from, &sa_size);
#else
/* man recvmsg and man cmsg is needed to make sense of code below */
struct iovec iov[1];
union {
char cmsg[CMSG_SPACE(sizeof(struct in_pktinfo))];
# if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO)
char cmsg6[CMSG_SPACE(sizeof(struct in6_pktinfo))];
# endif
} u;
struct cmsghdr *cmsgptr;
struct msghdr msg;
ssize_t recv_length;
iov[0].iov_base = buf;
iov[0].iov_len = len;
memset(&msg, 0, sizeof(msg));
msg.msg_name = (struct sockaddr *)from;
msg.msg_namelen = sa_size;
msg.msg_iov = iov;
msg.msg_iovlen = 1;
msg.msg_control = &u;
msg.msg_controllen = sizeof(u);
recv_length = recvmsg(fd, &msg, flags);
if (recv_length < 0)
return recv_length;
# define to4 ((struct sockaddr_in*)to)
# define to6 ((struct sockaddr_in6*)to)
/* Here we try to retrieve destination IP and memorize it */
for (cmsgptr = CMSG_FIRSTHDR(&msg);
cmsgptr != NULL;
cmsgptr = CMSG_NXTHDR(&msg, cmsgptr)
) {
if (cmsgptr->cmsg_level == IPPROTO_IP
&& cmsgptr->cmsg_type == IP_PKTINFO
) {
const int IPI_ADDR_OFF = offsetof(struct in_pktinfo, ipi_addr);
to->sa_family = AF_INET;
/*# define pktinfo(cmsgptr) ( (struct in_pktinfo*)(CMSG_DATA(cmsgptr)) )*/
/*to4->sin_addr = pktinfo(cmsgptr)->ipi_addr; - may be unaligned */
memcpy(&to4->sin_addr, (char*)(CMSG_DATA(cmsgptr)) + IPI_ADDR_OFF, sizeof(to4->sin_addr));
/*to4->sin_port = 123; - this data is not supplied by kernel */
break;
}
# if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO)
if (cmsgptr->cmsg_level == IPPROTO_IPV6
&& cmsgptr->cmsg_type == IPV6_PKTINFO
) {
const int IPI6_ADDR_OFF = offsetof(struct in6_pktinfo, ipi6_addr);
to->sa_family = AF_INET6;
/*# define pktinfo(cmsgptr) ( (struct in6_pktinfo*)(CMSG_DATA(cmsgptr)) )*/
/*to6->sin6_addr = pktinfo(cmsgptr)->ipi6_addr; - may be unaligned */
memcpy(&to6->sin6_addr, (char*)(CMSG_DATA(cmsgptr)) + IPI6_ADDR_OFF, sizeof(to6->sin6_addr));
/*to6->sin6_port = 123; */
break;
}
# endif
}
return recv_length;
#endif
}
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