165 lines
4.5 KiB
C
165 lines
4.5 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* Utility routines.
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*
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* Copyright (C) 2007 Denis Vlasenko
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*
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* Licensed under GPL version 2, see file LICENSE in this tarball for details.
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*/
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#include "libbb.h"
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/*
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* This asks kernel to let us know dst addr/port of incoming packets
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* We don't check for errors here. Not supported == won't be used
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*/
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void
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socket_want_pktinfo(int fd)
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{
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#ifdef IP_PKTINFO
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setsockopt(fd, IPPROTO_IP, IP_PKTINFO, &const_int_1, sizeof(int));
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#endif
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#if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO)
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setsockopt(fd, IPPROTO_IPV6, IPV6_PKTINFO, &const_int_1, sizeof(int));
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#endif
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}
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#ifdef UNUSED
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ssize_t
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send_to_from(int fd, void *buf, size_t len, int flags,
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const struct sockaddr *from, const struct sockaddr *to,
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socklen_t tolen)
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{
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#ifndef IP_PKTINFO
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return sendto(fd, buf, len, flags, to, tolen);
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#else
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struct iovec iov[1];
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struct msghdr msg;
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char cbuf[sizeof(struct in_pktinfo)
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#if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO)
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| sizeof(struct in6_pktinfo) /* (a|b) is poor man's max(a,b) */
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#endif
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];
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struct cmsghdr* cmsgptr;
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if (from->sa_family != AF_INET
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#if ENABLE_FEATURE_IPV6
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&& from->sa_family != AF_INET6
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#endif
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) {
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/* ANY local address */
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return sendto(fd, buf, len, flags, to, tolen);
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}
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/* man recvmsg and man cmsg is needed to make sense of code below */
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iov[0].iov_base = buf;
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iov[0].iov_len = len;
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memset(cbuf, 0, sizeof(cbuf));
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memset(&msg, 0, sizeof(msg));
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msg.msg_name = (void *)(struct sockaddr *)to; /* or compiler will annoy us */
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msg.msg_namelen = tolen;
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msg.msg_iov = iov;
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msg.msg_iovlen = 1;
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msg.msg_control = cbuf;
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msg.msg_controllen = sizeof(cbuf);
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msg.msg_flags = flags;
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cmsgptr = CMSG_FIRSTHDR(&msg);
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if (to->sa_family == AF_INET && from->sa_family == AF_INET) {
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struct in_pktinfo *pktptr;
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cmsgptr->cmsg_level = IPPROTO_IP;
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cmsgptr->cmsg_type = IP_PKTINFO;
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cmsgptr->cmsg_len = CMSG_LEN(sizeof(struct in_pktinfo));
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pktptr = (struct in_pktinfo *)(CMSG_DATA(cmsgptr));
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/* pktptr->ipi_ifindex = 0; -- already done by memset(cbuf...) */
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pktptr->ipi_spec_dst = ((struct sockaddr_in*)from)->sin_addr;
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}
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#if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO)
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else if (to->sa_family == AF_INET6 && from->sa_family == AF_INET6) {
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struct in6_pktinfo *pktptr;
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cmsgptr->cmsg_level = IPPROTO_IPV6;
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cmsgptr->cmsg_type = IPV6_PKTINFO;
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cmsgptr->cmsg_len = CMSG_LEN(sizeof(struct in6_pktinfo));
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pktptr = (struct in6_pktinfo *)(CMSG_DATA(cmsgptr));
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/* pktptr->ipi6_ifindex = 0; -- already done by memset(cbuf...) */
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pktptr->ipi6_addr = ((struct sockaddr_in6*)from)->sin6_addr;
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}
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#endif
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return sendmsg(fd, &msg, flags);
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#endif
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}
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#endif /* UNUSED */
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/* NB: this will never set port# in 'to'!
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* _Only_ IP/IPv6 address part of 'to' is _maybe_ modified.
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* Typical usage is to preinit 'to' with "default" value
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* before calling recv_from_to(). */
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ssize_t
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recv_from_to(int fd, void *buf, size_t len, int flags,
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struct sockaddr *from, struct sockaddr *to,
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socklen_t sa_size)
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{
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#ifndef IP_PKTINFO
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return recvfrom(fd, buf, len, flags, from, &sa_size);
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#else
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/* man recvmsg and man cmsg is needed to make sense of code below */
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struct iovec iov[1];
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union {
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char cmsg[CMSG_SPACE(sizeof(struct in_pktinfo))];
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char cmsg6[CMSG_SPACE(sizeof(struct in6_pktinfo))];
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} u;
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struct cmsghdr *cmsgptr;
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struct msghdr msg;
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socklen_t recv_length;
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iov[0].iov_base = buf;
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iov[0].iov_len = len;
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memset(&msg, 0, sizeof(msg));
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msg.msg_name = (struct sockaddr *)from;
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msg.msg_namelen = sa_size;
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msg.msg_iov = iov;
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msg.msg_iovlen = 1;
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msg.msg_control = &u;
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msg.msg_controllen = sizeof(u);
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recv_length = recvmsg(fd, &msg, flags);
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if (recv_length < 0)
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return recv_length;
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/* Here we try to retrieve destination IP and memorize it */
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for (cmsgptr = CMSG_FIRSTHDR(&msg);
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cmsgptr != NULL;
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cmsgptr = CMSG_NXTHDR(&msg, cmsgptr)
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) {
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if (cmsgptr->cmsg_level == IPPROTO_IP
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&& cmsgptr->cmsg_type == IP_PKTINFO
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) {
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#define pktinfo(cmsgptr) ( (struct in_pktinfo*)(CMSG_DATA(cmsgptr)) )
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to->sa_family = AF_INET;
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((struct sockaddr_in*)to)->sin_addr = pktinfo(cmsgptr)->ipi_addr;
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/* ((struct sockaddr_in*)to)->sin_port = 123; */
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#undef pktinfo
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break;
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}
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#if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO)
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if (cmsgptr->cmsg_level == IPPROTO_IPV6
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&& cmsgptr->cmsg_type == IPV6_PKTINFO
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) {
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#define pktinfo(cmsgptr) ( (struct in6_pktinfo*)(CMSG_DATA(cmsgptr)) )
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to->sa_family = AF_INET6;
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((struct sockaddr_in6*)to)->sin6_addr = pktinfo(cmsgptr)->ipi6_addr;
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/* ((struct sockaddr_in6*)to)->sin6_port = 123; */
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#undef pktinfo
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break;
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}
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#endif
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}
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return recv_length;
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#endif
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}
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