| /* vi: set sw=4 ts=4: */ |
| /* |
| * Utility routines. |
| * |
| * Copyright (C) 2007 Denys Vlasenko |
| * |
| * Licensed under GPL version 2, see file LICENSE in this tarball for details. |
| */ |
| #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) |
| { |
| #ifdef IP_PKTINFO |
| setsockopt(fd, IPPROTO_IP, IP_PKTINFO, &const_int_1, sizeof(int)); |
| #endif |
| #if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO) |
| setsockopt(fd, IPPROTO_IPV6, IPV6_PKTINFO, &const_int_1, sizeof(int)); |
| #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 |
| } |