To an alias address, or in a multihoming environment, the internal dgram
server may respond from a different address than the destination address sent by the client. To solve this problem, I introduce sendfromto() and recvfromto() so that the server can reply from the correct address, i.e., the destination address used in the request. This change also has the aspect of a reference implementation using the RECVDSTADDR and PKTINFO socket options.
This commit is contained in:
ryo
parent
ec30234b88
commit
223f9ca45a
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@ -1,4 +1,4 @@
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/* $NetBSD: inetd.c,v 1.138 2021/10/12 22:51:28 rillig Exp $ */
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/* $NetBSD: inetd.c,v 1.139 2021/10/17 04:14:49 ryo Exp $ */
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/*-
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* Copyright (c) 1998, 2003 The NetBSD Foundation, Inc.
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@ -66,7 +66,7 @@ __COPYRIGHT("@(#) Copyright (c) 1983, 1991, 1993, 1994\
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#if 0
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static char sccsid[] = "@(#)inetd.c 8.4 (Berkeley) 4/13/94";
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#else
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__RCSID("$NetBSD: inetd.c,v 1.138 2021/10/12 22:51:28 rillig Exp $");
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__RCSID("$NetBSD: inetd.c,v 1.139 2021/10/17 04:14:49 ryo Exp $");
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#endif
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#endif /* not lint */
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@ -269,6 +269,11 @@ size_t changes;
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struct servtab *servtab;
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static ssize_t recvfromto(int, void * restrict, size_t, int,
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struct sockaddr * restrict, socklen_t * restrict,
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struct sockaddr * restrict, socklen_t * restrict);
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static ssize_t sendfromto(int, const void *, size_t, int,
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const struct sockaddr *, socklen_t, const struct sockaddr *, socklen_t);
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static void chargen_dg(int, struct servtab *);
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static void chargen_stream(int, struct servtab *);
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static void daytime_dg(int, struct servtab *);
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@ -809,6 +814,26 @@ setsockopt(fd, SOL_SOCKET, opt, &on, (socklen_t)sizeof(on))
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if (sep->se_socktype == SOCK_STREAM)
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listen(sep->se_fd, 10);
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/* for internal dgram, setsockopt() is required for recvfromto() */
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if (sep->se_socktype == SOCK_DGRAM && sep->se_bi != NULL) {
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switch (sep->se_family) {
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case AF_INET:
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if (setsockopt(sep->se_fd, IPPROTO_IP,
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IP_RECVDSTADDR, &on, sizeof(on)) < 0)
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syslog(LOG_ERR,
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"setsockopt (IP_RECVDSTADDR): %m");
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break;
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#ifdef INET6
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case AF_INET6:
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if (setsockopt(sep->se_fd, IPPROTO_IPV6,
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IPV6_RECVPKTINFO, &on, sizeof(on)) < 0)
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syslog(LOG_ERR,
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"setsockopt (IPV6_RECVPKTINFO): %m");
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break;
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#endif
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}
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}
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/* Set the accept filter, if specified. To be done after listen.*/
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if (sep->se_accf.af_name[0] != 0 && setsockopt(sep->se_fd, SOL_SOCKET,
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SO_ACCEPTFILTER, &sep->se_accf,
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@ -954,6 +979,189 @@ bump_nofile(void)
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return;
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}
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/*
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* In order to get the destination address (`to') with recvfromto(),
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* IP_RECVDSTADDR or IP_RECVPKTINFO for AF_INET, or IPV6_RECVPKTINFO
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* for AF_INET6, must be enabled with setsockopt(2).
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*
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* .sin_port and .sin6_port in 'to' are always stored as zero.
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* If necessary, extract them using getsockname(2).
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*/
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static ssize_t
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recvfromto(int s, void * restrict buf, size_t len, int flags,
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struct sockaddr * restrict from, socklen_t * restrict fromlen,
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struct sockaddr * restrict to, socklen_t * restrict tolen)
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{
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struct msghdr msg;
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struct iovec vec;
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struct cmsghdr *cmsg;
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struct sockaddr_storage ss;
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char cmsgbuf[1024];
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ssize_t rc;
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if (to == NULL)
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return recvfrom(s, buf, len, flags, from, fromlen);
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if (tolen == NULL || fromlen == NULL) {
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errno = EFAULT;
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return -1;
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}
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vec.iov_base = buf;
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vec.iov_len = len;
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msg.msg_name = from;
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msg.msg_namelen = *fromlen;
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msg.msg_iov = &vec;
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msg.msg_iovlen = 1;
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msg.msg_control = cmsgbuf;
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msg.msg_controllen = sizeof(cmsgbuf);
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rc = recvmsg(s, &msg, flags);
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if (rc < 0)
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return rc;
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*fromlen = msg.msg_namelen;
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memset(&ss, 0, sizeof(ss));
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for (cmsg = (struct cmsghdr *)CMSG_FIRSTHDR(&msg); cmsg != NULL;
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cmsg = (struct cmsghdr *)CMSG_NXTHDR(&msg, cmsg)) {
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if (cmsg->cmsg_level == IPPROTO_IP &&
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cmsg->cmsg_type == IP_RECVDSTADDR) {
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struct in_addr *dst = (struct in_addr *)CMSG_DATA(cmsg);
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struct sockaddr_in *sin = (struct sockaddr_in *)&ss;
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sin->sin_len = sizeof(*sin);
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sin->sin_family = AF_INET;
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sin->sin_addr = *dst;
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break;
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}
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if (cmsg->cmsg_level == IPPROTO_IP &&
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cmsg->cmsg_type == IP_PKTINFO) {
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struct in_pktinfo *pi =
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(struct in_pktinfo *)CMSG_DATA(cmsg);
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struct sockaddr_in *sin = (struct sockaddr_in *)&ss;
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sin->sin_len = sizeof(*sin);
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sin->sin_family = AF_INET;
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sin->sin_addr = pi->ipi_addr;
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break;
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}
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#ifdef INET6
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if (cmsg->cmsg_level == IPPROTO_IPV6 &&
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cmsg->cmsg_type == IPV6_PKTINFO) {
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struct in6_pktinfo *pi6 =
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(struct in6_pktinfo *)CMSG_DATA(cmsg);
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struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)&ss;
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sin6->sin6_len = sizeof(*sin6);
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sin6->sin6_family = AF_INET6;
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sin6->sin6_addr = pi6->ipi6_addr;
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if (IN6_IS_ADDR_LINKLOCAL(&sin6->sin6_addr) ||
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IN6_IS_ADDR_MC_LINKLOCAL(&sin6->sin6_addr))
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sin6->sin6_scope_id = pi6->ipi6_ifindex;
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else
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sin6->sin6_scope_id = 0;
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break;
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}
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#endif /* INET6 */
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}
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socklen_t sslen = (*tolen < ss.ss_len) ? *tolen : ss.ss_len;
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if (sslen > 0)
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memcpy(to, &ss, sslen);
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*tolen = sslen;
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return rc;
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}
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/*
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* When sending, the source port is selected as the one bind(2)'ed
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* to the socket.
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* .sin_port and .sin6_port in `from' are always ignored.
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*/
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static ssize_t
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sendfromto(int s, const void *buf, size_t len, int flags,
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const struct sockaddr *from, socklen_t fromlen,
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const struct sockaddr *to, socklen_t tolen)
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{
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struct msghdr msg;
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struct iovec vec;
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struct cmsghdr *cmsg;
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char cmsgbuf[256];
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__CTASSERT(sizeof(cmsgbuf) > CMSG_SPACE(sizeof(struct in_pktinfo)));
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#ifdef INET6
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__CTASSERT(sizeof(cmsgbuf) > CMSG_SPACE(sizeof(struct in6_pktinfo)));
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#endif
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if (from == NULL || fromlen == 0)
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return sendto(s, buf, len, flags, to, tolen);
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vec.iov_base = __UNCONST(buf);
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vec.iov_len = len;
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msg.msg_name = __UNCONST(to);
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msg.msg_namelen = tolen;
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msg.msg_iov = &vec;
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msg.msg_iovlen = 1;
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msg.msg_control = cmsgbuf;
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msg.msg_controllen = 0;
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if (fromlen < 2) { /* sa_len + sa_family */
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errno = EINVAL;
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return -1;
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}
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cmsg = (struct cmsghdr *)cmsgbuf;
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if (from->sa_family == AF_INET) {
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const struct sockaddr_in *from4 =
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(const struct sockaddr_in *)from;
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struct in_pktinfo *pi;
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if (fromlen != sizeof(struct sockaddr_in) ||
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from4->sin_family != AF_INET) {
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errno = EINVAL;
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return -1;
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}
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msg.msg_controllen += CMSG_SPACE(sizeof(struct in_pktinfo));
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cmsg->cmsg_len = CMSG_LEN(sizeof(struct in_pktinfo));
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cmsg->cmsg_level = IPPROTO_IP;
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cmsg->cmsg_type = IP_PKTINFO;
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pi = (struct in_pktinfo *)CMSG_DATA(cmsg);
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pi->ipi_addr = from4->sin_addr;
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pi->ipi_ifindex = 0;
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#ifdef INET6
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} else if (from->sa_family == AF_INET6) {
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const struct sockaddr_in6 *from6 =
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(const struct sockaddr_in6 *)from;
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struct in6_pktinfo *pi6;
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if (fromlen != sizeof(struct sockaddr_in6) ||
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from6->sin6_family != AF_INET6) {
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errno = EINVAL;
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return -1;
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}
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msg.msg_controllen += CMSG_SPACE(sizeof(struct in6_pktinfo));
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cmsg->cmsg_len = CMSG_LEN(sizeof(struct in6_pktinfo));
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cmsg->cmsg_level = IPPROTO_IPV6;
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cmsg->cmsg_type = IPV6_PKTINFO;
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pi6 = (struct in6_pktinfo *)CMSG_DATA(cmsg);
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pi6->ipi6_addr = from6->sin6_addr;
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if (IN6_IS_ADDR_LINKLOCAL(&from6->sin6_addr) ||
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IN6_IS_ADDR_MC_LINKLOCAL(&from6->sin6_addr)) {
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pi6->ipi6_ifindex = from6->sin6_scope_id;
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} else {
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pi6->ipi6_ifindex = 0;
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}
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#endif /* INET6 */
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} else {
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return sendto(s, buf, len, flags, to, tolen);
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}
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return sendmsg(s, &msg, flags);
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}
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/*
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* Internet services provided internally by inetd:
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*/
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@ -978,16 +1186,20 @@ echo_dg(int s, struct servtab *sep) /* Echo service -- echo data back */
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{
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char buffer[BUFSIZE];
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ssize_t i;
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socklen_t size;
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struct sockaddr_storage ss;
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struct sockaddr *sa;
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socklen_t rsize, lsize;
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struct sockaddr_storage remote, local;
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struct sockaddr *lsa, *rsa;
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sa = (struct sockaddr *)(void *)&ss;
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size = sizeof(ss);
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if ((i = recvfrom(s, buffer, sizeof(buffer), 0, sa, &size)) < 0)
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rsa = (struct sockaddr *)(void *)&remote;
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lsa = (struct sockaddr *)(void *)&local;
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rsize = sizeof(remote);
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lsize = sizeof(local);
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if ((i = recvfromto(s, buffer, sizeof(buffer), 0,
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rsa, &rsize, lsa, &lsize)) < 0)
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return;
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if (port_good_dg(sa))
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(void) sendto(s, buffer, (size_t)i, 0, sa, size);
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if (port_good_dg(rsa))
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(void) sendfromto(s, buffer, (size_t)i, 0,
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lsa, lsize, rsa, rsize);
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}
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/* ARGSUSED */
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@ -1062,11 +1274,11 @@ chargen_stream(int s, struct servtab *sep) /* Character generator */
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static void
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chargen_dg(int s, struct servtab *sep) /* Character generator */
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{
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struct sockaddr_storage ss;
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struct sockaddr *sa;
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struct sockaddr_storage remote, local;
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struct sockaddr *rsa, *lsa;
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static char *rs;
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size_t len;
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socklen_t size;
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socklen_t rsize, lsize;
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char text[LINESIZ+2];
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if (endring == 0) {
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@ -1074,12 +1286,15 @@ chargen_dg(int s, struct servtab *sep) /* Character generator */
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rs = ring;
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}
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sa = (struct sockaddr *)(void *)&ss;
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size = sizeof(ss);
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if (recvfrom(s, text, sizeof(text), 0, sa, &size) < 0)
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rsa = (struct sockaddr *)(void *)&remote;
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lsa = (struct sockaddr *)(void *)&local;
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rsize = sizeof(remote);
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lsize = sizeof(local);
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if (recvfromto(s, text, sizeof(text), 0,
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rsa, &rsize, lsa, &lsize) < 0)
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return;
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if (!port_good_dg(sa))
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if (!port_good_dg(rsa))
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return;
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if ((len = (size_t)(endring - rs)) >= LINESIZ)
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@ -1092,7 +1307,7 @@ chargen_dg(int s, struct servtab *sep) /* Character generator */
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rs = ring;
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text[LINESIZ] = '\r';
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text[LINESIZ + 1] = '\n';
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(void) sendto(s, text, sizeof(text), 0, sa, size);
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(void) sendfromto(s, text, sizeof(text), 0, lsa, lsize, rsa, rsize);
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}
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/*
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@ -1132,18 +1347,21 @@ void
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machtime_dg(int s, struct servtab *sep)
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{
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uint32_t result;
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struct sockaddr_storage ss;
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struct sockaddr *sa;
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socklen_t size;
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struct sockaddr_storage remote, local;
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struct sockaddr *rsa, *lsa;
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socklen_t rsize, lsize;
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sa = (struct sockaddr *)(void *)&ss;
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size = sizeof(ss);
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if (recvfrom(s, &result, sizeof(result), 0, sa, &size) < 0)
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rsa = (struct sockaddr *)(void *)&remote;
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lsa = (struct sockaddr *)(void *)&local;
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rsize = sizeof(remote);
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lsize = sizeof(local);
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if (recvfromto(s, &result, sizeof(result), 0,
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rsa, &rsize, lsa, &lsize) < 0)
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return;
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if (!port_good_dg(sa))
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if (!port_good_dg(rsa))
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return;
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result = machtime();
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(void)sendto(s, &result, sizeof(result), 0, sa, size);
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(void)sendfromto(s, &result, sizeof(result), 0, lsa, lsize, rsa, rsize);
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}
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/* ARGSUSED */
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@ -1168,21 +1386,24 @@ daytime_dg(int s, struct servtab *sep)
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{
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char buffer[256];
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time_t clk;
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struct sockaddr_storage ss;
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struct sockaddr *sa;
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socklen_t size;
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struct sockaddr_storage remote, local;
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struct sockaddr *rsa, *lsa;
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socklen_t rsize, lsize;
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int len;
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clk = time((time_t *) 0);
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sa = (struct sockaddr *)(void *)&ss;
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size = sizeof(ss);
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if (recvfrom(s, buffer, sizeof(buffer), 0, sa, &size) < 0)
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rsa = (struct sockaddr *)(void *)&remote;
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lsa = (struct sockaddr *)(void *)&local;
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rsize = sizeof(remote);
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lsize = sizeof(local);
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if (recvfromto(s, buffer, sizeof(buffer), 0,
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rsa, &rsize, lsa, &lsize) < 0)
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return;
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if (!port_good_dg(sa))
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if (!port_good_dg(rsa))
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return;
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len = snprintf(buffer, sizeof buffer, "%.24s\r\n", ctime(&clk));
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(void) sendto(s, buffer, (size_t)len, 0, sa, size);
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(void) sendfromto(s, buffer, (size_t)len, 0, lsa, lsize, rsa, rsize);
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}
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static void
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Loading…
Reference in New Issue