mirror of
https://github.com/topjohnwu/ndk-busybox.git
synced 2024-12-05 02:16:49 +00:00
7cef4817d6
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
186 lines
5.5 KiB
C
186 lines
5.5 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 Denys Vlasenko
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*
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* Licensed under GPLv2, see file LICENSE in this source tree.
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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 FAST_FUNC
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socket_want_pktinfo(int fd UNUSED_PARAM)
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{
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#ifdef IP_PKTINFO
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setsockopt_1(fd, IPPROTO_IP, IP_PKTINFO);
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#endif
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#if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO)
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setsockopt_1(fd, IPPROTO_IPV6, IPV6_PKTINFO);
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#endif
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}
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ssize_t FAST_FUNC
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send_to_from(int fd, void *buf, size_t len, int flags,
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const struct sockaddr *to,
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const struct sockaddr *from,
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socklen_t tolen)
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{
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#ifndef IP_PKTINFO
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(void)from; /* suppress "unused from" warning */
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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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union {
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char cmsg[CMSG_SPACE(sizeof(struct in_pktinfo))];
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# if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO)
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char cmsg6[CMSG_SPACE(sizeof(struct in6_pktinfo))];
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# endif
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} u;
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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(&u, 0, sizeof(u));
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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 = &u;
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msg.msg_controllen = sizeof(u);
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msg.msg_flags = flags;
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cmsgptr = CMSG_FIRSTHDR(&msg);
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/*
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* Users report that to->sa_family can be AF_INET6 too,
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* if "to" was acquired by recv_from_to(). IOW: recv_from_to()
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* was seen showing IPv6 "from" even when the destination
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* of received packet (our local address) was IPv4.
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*/
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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(u...) */
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/* In general, CMSG_DATA() can be unaligned, but in this case
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* we know for sure it is sufficiently aligned:
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* CMSG_FIRSTHDR simply returns &u above,
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* and CMSG_DATA returns &u + size_t + int + int.
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* Thus direct assignment is ok:
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*/
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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(u...) */
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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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msg.msg_controllen = cmsgptr->cmsg_len;
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return sendmsg(fd, &msg, flags);
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#endif
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}
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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 FAST_FUNC
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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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(void)to; /* suppress "unused to" warning */
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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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# if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO)
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char cmsg6[CMSG_SPACE(sizeof(struct in6_pktinfo))];
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# endif
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} u;
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struct cmsghdr *cmsgptr;
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struct msghdr msg;
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ssize_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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# define to4 ((struct sockaddr_in*)to)
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# define to6 ((struct sockaddr_in6*)to)
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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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const int IPI_ADDR_OFF = offsetof(struct in_pktinfo, ipi_addr);
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to->sa_family = AF_INET;
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/*# define pktinfo(cmsgptr) ( (struct in_pktinfo*)(CMSG_DATA(cmsgptr)) )*/
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/*to4->sin_addr = pktinfo(cmsgptr)->ipi_addr; - may be unaligned */
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memcpy(&to4->sin_addr, (char*)(CMSG_DATA(cmsgptr)) + IPI_ADDR_OFF, sizeof(to4->sin_addr));
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/*to4->sin_port = 123; - this data is not supplied by kernel */
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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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const int IPI6_ADDR_OFF = offsetof(struct in6_pktinfo, ipi6_addr);
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to->sa_family = AF_INET6;
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/*# define pktinfo(cmsgptr) ( (struct in6_pktinfo*)(CMSG_DATA(cmsgptr)) )*/
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/*to6->sin6_addr = pktinfo(cmsgptr)->ipi6_addr; - may be unaligned */
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memcpy(&to6->sin6_addr, (char*)(CMSG_DATA(cmsgptr)) + IPI6_ADDR_OFF, sizeof(to6->sin6_addr));
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/*to6->sin6_port = 123; */
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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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