krb5 commit: Move pktinfo functions into a new file
Greg Hudson
ghudson at mit.edu
Wed Feb 17 15:38:00 EST 2016
https://github.com/krb5/krb5/commit/b6396a5f7c720f51bb7daaf8624324d49163babb
commit b6396a5f7c720f51bb7daaf8624324d49163babb
Author: Sarah Day <sarahday at mit.edu>
Date: Wed Feb 10 12:42:47 2016 -0500
Move pktinfo functions into a new file
Move the functions set_pktinfo(), recv_from_to(), and send_to_from()
out of net_server.c into a new file udppktinfo.c. The function
setup_udp_pktinfo_ports() will now always try to set the pktinfo
option for the socket on UDP wildcard sockets, and will fallback to
binding to the individual addresses at runtime when pktinfo isn't
supported.
src/lib/apputils/Makefile.in | 5 +-
src/lib/apputils/net-server.c | 290 +++-------------------------------------
src/lib/apputils/udppktinfo.c | 296 +++++++++++++++++++++++++++++++++++++++++
src/lib/apputils/udppktinfo.h | 59 ++++++++
4 files changed, 377 insertions(+), 273 deletions(-)
diff --git a/src/lib/apputils/Makefile.in b/src/lib/apputils/Makefile.in
index d7fe336..686a0ee 100644
--- a/src/lib/apputils/Makefile.in
+++ b/src/lib/apputils/Makefile.in
@@ -12,7 +12,7 @@ SED = sed
##DOS##XTRA=
##DOS##OBJFILE=$(OUTPRE)apputils.lst
-STLIBOBJS=net-server.o @LIBOBJS@
+STLIBOBJS=net-server.o udppktinfo.o @LIBOBJS@
LIBBASE=apputils
all-unix:: all-liblinks
@@ -24,7 +24,8 @@ LINTFILES= daemon.c
LIBOBJS=$(OUTPRE)daemon.$(OBJEXT)
SRCS= $(srcdir)/daemon.c \
- $(srcdir)/net-server.c
+ $(srcdir)/net-server.c \
+ $(srcdir)/udppktinfo.c
@libpriv_frag@
@lib_frag@
diff --git a/src/lib/apputils/net-server.c b/src/lib/apputils/net-server.c
index 12f3570..3dcc67c 100644
--- a/src/lib/apputils/net-server.c
+++ b/src/lib/apputils/net-server.c
@@ -60,6 +60,8 @@
#include "net-server.h"
#include <signal.h>
+#include "udppktinfo.h"
+
/* XXX */
#define KDC5_NONET (-1779992062L)
@@ -96,43 +98,6 @@ setv6only(int sock, int value)
}
#endif
-/* Use RFC 3542 API below, but fall back from IPV6_RECVPKTINFO to
- IPV6_PKTINFO for RFC 2292 implementations. */
-#ifndef IPV6_RECVPKTINFO
-#define IPV6_RECVPKTINFO IPV6_PKTINFO
-#endif
-/* Parallel, though not standardized. */
-#ifndef IP_RECVPKTINFO
-#define IP_RECVPKTINFO IP_PKTINFO
-#endif
-
-static int
-set_pktinfo(int sock, int family)
-{
- int sockopt = 1;
- int option = 0, proto = 0;
-
- switch (family) {
-#if defined(IP_PKTINFO) && defined(HAVE_STRUCT_IN_PKTINFO)
- case AF_INET:
- proto = IPPROTO_IP;
- option = IP_RECVPKTINFO;
- break;
-#endif
-#if defined(IPV6_PKTINFO) && defined(HAVE_STRUCT_IN6_PKTINFO)
- case AF_INET6:
- proto = IPPROTO_IPV6;
- option = IPV6_RECVPKTINFO;
- break;
-#endif
- default:
- return EINVAL;
- }
- if (setsockopt(sock, proto, option, &sockopt, sizeof(sockopt)))
- return errno;
- return 0;
-}
-
static const char *
paddr(struct sockaddr *sa)
{
@@ -806,55 +771,29 @@ setup_rpc_listener_ports(struct socksetup *data)
return 0;
}
-#if defined(CMSG_SPACE) && defined(HAVE_STRUCT_CMSGHDR) && \
- (defined(IP_PKTINFO) || defined(IPV6_PKTINFO))
-union pktinfo {
-#ifdef HAVE_STRUCT_IN6_PKTINFO
- struct in6_pktinfo pi6;
-#endif
-#ifdef HAVE_STRUCT_IN_PKTINFO
- struct in_pktinfo pi4;
-#endif
- char c;
-};
-
static int
setup_udp_port_1(struct socksetup *data, struct sockaddr *addr, int pktinfo);
static void
setup_udp_pktinfo_ports(struct socksetup *data)
{
-#ifdef IP_PKTINFO
- {
- struct sockaddr_in sa;
- int r;
-
- memset(&sa, 0, sizeof(sa));
- sa.sin_family = AF_INET;
- r = setup_udp_port_1(data, (struct sockaddr *)&sa, 4);
- if (r == 0)
- data->do_ipv4_udp_all = FALSE;
- }
-#endif
-#ifdef IPV6_PKTINFO
- {
- struct sockaddr_in6 sa;
- int r;
-
- memset(&sa, 0, sizeof(sa));
- sa.sin6_family = AF_INET6;
- r = setup_udp_port_1(data, (struct sockaddr *)&sa, 6);
- if (r == 0)
- data->do_ipv6_udp_all = FALSE;
- }
-#endif
-}
-#else /* no pktinfo compile-time support */
-static void
-setup_udp_pktinfo_ports(struct socksetup *data)
-{
+ struct sockaddr_in sa;
+ struct sockaddr_in6 sa6;
+ int r;
+
+ memset(&sa, 0, sizeof(sa));
+ sa.sin_family = AF_INET;
+ r = setup_udp_port_1(data, (struct sockaddr *)&sa, 4);
+ if (r == 0)
+ data->do_ipv4_udp_all = FALSE;
+
+ memset(&sa6, 0, sizeof(sa6));
+ sa6.sin6_family = AF_INET6;
+ r = setup_udp_port_1(data, (struct sockaddr *)&sa6, 6);
+ if (r == 0)
+ data->do_ipv6_udp_all = FALSE;
+
}
-#endif
static int
setup_udp_port_1(struct socksetup *data, struct sockaddr *addr, int pktinfo)
@@ -869,10 +808,6 @@ setup_udp_port_1(struct socksetup *data, struct sockaddr *addr, int pktinfo)
return 1;
setnbio(sock);
-#if !(defined(CMSG_SPACE) && defined(HAVE_STRUCT_CMSGHDR) && \
- (defined(IP_PKTINFO) || defined(IPV6_PKTINFO)))
- assert(pktinfo == 0);
-#endif
if (pktinfo) {
r = set_pktinfo(sock, addr->sa_family);
if (r) {
@@ -1135,193 +1070,6 @@ init_addr(krb5_fulladdr *faddr, struct sockaddr *sa)
}
}
-/*
- * This holds whatever additional information might be needed to
- * properly send back to the client from the correct local address.
- *
- * In this case, we only need one datum so far: On Mac OS X, the
- * kernel doesn't seem to like sending from link-local addresses
- * unless we specify the correct interface.
- */
-
-union aux_addressing_info {
- int ipv6_ifindex;
-};
-
-static int
-recv_from_to(int s, void *buf, size_t len, int flags,
- struct sockaddr *from, socklen_t *fromlen,
- struct sockaddr *to, socklen_t *tolen,
- union aux_addressing_info *auxaddr)
-{
-#if (!defined(IP_PKTINFO) && !defined(IPV6_PKTINFO)) || !defined(CMSG_SPACE)
- if (to && tolen) {
- /* Clobber with something recognizeable in case we try to use
- the address. */
- memset(to, 0x40, *tolen);
- *tolen = 0;
- }
-
- return recvfrom(s, buf, len, flags, from, fromlen);
-#else
- int r;
- struct iovec iov;
- char cmsg[CMSG_SPACE(sizeof(union pktinfo))];
- struct cmsghdr *cmsgptr;
- struct msghdr msg;
-
- if (!to || !tolen)
- return recvfrom(s, buf, len, flags, from, fromlen);
-
- /* Clobber with something recognizeable in case we can't extract
- the address but try to use it anyways. */
- memset(to, 0x40, *tolen);
-
- iov.iov_base = buf;
- iov.iov_len = len;
- memset(&msg, 0, sizeof(msg));
- msg.msg_name = from;
- msg.msg_namelen = *fromlen;
- msg.msg_iov = &iov;
- msg.msg_iovlen = 1;
- msg.msg_control = cmsg;
- msg.msg_controllen = sizeof(cmsg);
-
- r = recvmsg(s, &msg, flags);
- if (r < 0)
- return r;
- *fromlen = msg.msg_namelen;
-
- /* On Darwin (and presumably all *BSD with KAME stacks),
- CMSG_FIRSTHDR doesn't check for a non-zero controllen. RFC
- 3542 recommends making this check, even though the (new) spec
- for CMSG_FIRSTHDR says it's supposed to do the check. */
- if (msg.msg_controllen) {
- cmsgptr = CMSG_FIRSTHDR(&msg);
- while (cmsgptr) {
-#ifdef IP_PKTINFO
- if (cmsgptr->cmsg_level == IPPROTO_IP
- && cmsgptr->cmsg_type == IP_PKTINFO
- && *tolen >= sizeof(struct sockaddr_in)) {
- struct in_pktinfo *pktinfo;
- memset(to, 0, sizeof(struct sockaddr_in));
- pktinfo = (struct in_pktinfo *)CMSG_DATA(cmsgptr);
- ((struct sockaddr_in *)to)->sin_addr = pktinfo->ipi_addr;
- ((struct sockaddr_in *)to)->sin_family = AF_INET;
- *tolen = sizeof(struct sockaddr_in);
- return r;
- }
-#endif
-#if defined(IPV6_PKTINFO) && defined(HAVE_STRUCT_IN6_PKTINFO)
- if (cmsgptr->cmsg_level == IPPROTO_IPV6
- && cmsgptr->cmsg_type == IPV6_PKTINFO
- && *tolen >= sizeof(struct sockaddr_in6)) {
- struct in6_pktinfo *pktinfo;
- memset(to, 0, sizeof(struct sockaddr_in6));
- pktinfo = (struct in6_pktinfo *)CMSG_DATA(cmsgptr);
- ((struct sockaddr_in6 *)to)->sin6_addr = pktinfo->ipi6_addr;
- ((struct sockaddr_in6 *)to)->sin6_family = AF_INET6;
- *tolen = sizeof(struct sockaddr_in6);
- auxaddr->ipv6_ifindex = pktinfo->ipi6_ifindex;
- return r;
- }
-#endif
- cmsgptr = CMSG_NXTHDR(&msg, cmsgptr);
- }
- }
- /* No info about destination addr was available. */
- *tolen = 0;
- return r;
-#endif
-}
-
-static int
-send_to_from(int s, void *buf, size_t len, int flags,
- const struct sockaddr *to, socklen_t tolen,
- const struct sockaddr *from, socklen_t fromlen,
- union aux_addressing_info *auxaddr)
-{
-#if (!defined(IP_PKTINFO) && !defined(IPV6_PKTINFO)) || !defined(CMSG_SPACE)
- return sendto(s, buf, len, flags, to, tolen);
-#else
- struct iovec iov;
- struct msghdr msg;
- struct cmsghdr *cmsgptr;
- char cbuf[CMSG_SPACE(sizeof(union pktinfo))];
-
- if (from == 0 || fromlen == 0 || from->sa_family != to->sa_family) {
- use_sendto:
- return sendto(s, buf, len, flags, to, tolen);
- }
-
- iov.iov_base = buf;
- iov.iov_len = len;
- /* Truncation? */
- if (iov.iov_len != len)
- return EINVAL;
- memset(cbuf, 0, sizeof(cbuf));
- memset(&msg, 0, sizeof(msg));
- msg.msg_name = (void *) to;
- msg.msg_namelen = tolen;
- msg.msg_iov = &iov;
- msg.msg_iovlen = 1;
- msg.msg_control = cbuf;
- /* CMSG_FIRSTHDR needs a non-zero controllen, or it'll return NULL
- on Linux. */
- msg.msg_controllen = sizeof(cbuf);
- cmsgptr = CMSG_FIRSTHDR(&msg);
- msg.msg_controllen = 0;
-
- switch (from->sa_family) {
-#if defined(IP_PKTINFO)
- case AF_INET:
- if (fromlen != sizeof(struct sockaddr_in))
- goto use_sendto;
- cmsgptr->cmsg_level = IPPROTO_IP;
- cmsgptr->cmsg_type = IP_PKTINFO;
- cmsgptr->cmsg_len = CMSG_LEN(sizeof(struct in_pktinfo));
- {
- struct in_pktinfo *p = (struct in_pktinfo *)CMSG_DATA(cmsgptr);
- const struct sockaddr_in *from4 = (const struct sockaddr_in *)from;
- p->ipi_spec_dst = from4->sin_addr;
- }
- msg.msg_controllen = CMSG_SPACE(sizeof(struct in_pktinfo));
- break;
-#endif
-#if defined(IPV6_PKTINFO) && defined(HAVE_STRUCT_IN6_PKTINFO)
- case AF_INET6:
- if (fromlen != sizeof(struct sockaddr_in6))
- goto use_sendto;
- cmsgptr->cmsg_level = IPPROTO_IPV6;
- cmsgptr->cmsg_type = IPV6_PKTINFO;
- cmsgptr->cmsg_len = CMSG_LEN(sizeof(struct in6_pktinfo));
- {
- struct in6_pktinfo *p = (struct in6_pktinfo *)CMSG_DATA(cmsgptr);
- const struct sockaddr_in6 *from6 =
- (const struct sockaddr_in6 *)from;
- p->ipi6_addr = from6->sin6_addr;
- /*
- * Because of the possibility of asymmetric routing, we
- * normally don't want to specify an interface. However,
- * Mac OS X doesn't like sending from a link-local address
- * (which can come up in testing at least, if you wind up
- * with a "foo.local" name) unless we do specify the
- * interface.
- */
- if (IN6_IS_ADDR_LINKLOCAL(&from6->sin6_addr))
- p->ipi6_ifindex = auxaddr->ipv6_ifindex;
- /* otherwise, already zero */
- }
- msg.msg_controllen = CMSG_SPACE(sizeof(struct in6_pktinfo));
- break;
-#endif
- default:
- goto use_sendto;
- }
- return sendmsg(s, &msg, flags);
-#endif
-}
-
struct udp_dispatch_state {
void *handle;
const char *prog;
@@ -1332,7 +1080,7 @@ struct udp_dispatch_state {
socklen_t daddr_len;
struct sockaddr_storage saddr;
struct sockaddr_storage daddr;
- union aux_addressing_info auxaddr;
+ aux_addressing_info auxaddr;
krb5_data request;
char pktbuf[MAX_DGRAM_SIZE];
};
diff --git a/src/lib/apputils/udppktinfo.c b/src/lib/apputils/udppktinfo.c
new file mode 100644
index 0000000..383b474
--- /dev/null
+++ b/src/lib/apputils/udppktinfo.c
@@ -0,0 +1,296 @@
+/* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */
+/*
+ * Copyright 2016 by the Massachusetts Institute of Technology.
+ * All Rights Reserved.
+ *
+ * Export of this software from the United States of America may
+ * require a specific license from the United States Government.
+ * It is the responsibility of any person or organization contemplating
+ * export to obtain such a license before exporting.
+ *
+ * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
+ * distribute this software and its documentation for any purpose and
+ * without fee is hereby granted, provided that the above copyright
+ * notice appear in all copies and that both that copyright notice and
+ * this permission notice appear in supporting documentation, and that
+ * the name of M.I.T. not be used in advertising or publicity pertaining
+ * to distribution of the software without specific, written prior
+ * permission. Furthermore if you modify this software you must label
+ * your software as modified software and not distribute it in such a
+ * fashion that it might be confused with the original M.I.T. software.
+ * M.I.T. makes no representations about the suitability of
+ * this software for any purpose. It is provided "as is" without express
+ * or implied warranty.
+ */
+
+#include "udppktinfo.h"
+
+#include <netinet/in.h>
+#include <sys/socket.h>
+
+/* Use RFC 3542 API below, but fall back from IPV6_RECVPKTINFO to IPV6_PKTINFO
+ * for RFC 2292 implementations. */
+#ifndef IPV6_RECVPKTINFO
+#define IPV6_RECVPKTINFO IPV6_PKTINFO
+#endif
+
+/* Parallel, though not standardized. */
+#if !defined(IP_RECVPKTINFO) && defined(IP_PKTINFO)
+#define IP_RECVPKTINFO IP_PKTINFO
+#endif /* IP_RECVPKTINFO */
+
+#if defined(CMSG_SPACE) && defined(HAVE_STRUCT_CMSGHDR) && \
+(defined(IP_PKTINFO) || defined(IPV6_PKTINFO))
+union pktinfo {
+#ifdef HAVE_STRUCT_IN6_PKTINFO
+ struct in6_pktinfo pi6;
+#endif
+#ifdef HAVE_STRUCT_IN_PKTINFO
+ struct in_pktinfo pi4;
+#endif
+ char c;
+};
+#endif
+
+/*
+ * Set pktinfo option on a socket. Takes a socket and the socket address family
+ * as arguments.
+ *
+ * Returns 0 on success, EINVAL if pktinfo is not supported for the address
+ * family.
+ */
+krb5_error_code
+set_pktinfo(int sock, int family)
+{
+ int sockopt = 1;
+ int option = 0, proto = 0;
+
+ switch (family) {
+#if defined(IP_PKTINFO) && defined(HAVE_STRUCT_IN_PKTINFO)
+ case AF_INET:
+ proto = IPPROTO_IP;
+ option = IP_RECVPKTINFO;
+ break;
+#endif
+#if defined(IPV6_PKTINFO) && defined(HAVE_STRUCT_IN6_PKTINFO)
+ case AF_INET6:
+ proto = IPPROTO_IPV6;
+ option = IPV6_RECVPKTINFO;
+ break;
+#endif
+ default:
+ return EINVAL;
+ }
+ if (setsockopt(sock, proto, option, &sockopt, sizeof(sockopt)))
+ return errno;
+ return 0;
+}
+
+/*
+ * Receive a message from a socket.
+ *
+ * Arguments:
+ * socket
+ * buf - The buffer to store the message in.
+ * len - buf length
+ * flags
+ * from - Set to the address that sent the message
+ * fromlen
+ * to - Set to the address that the message was sent to if possible.
+ * May not be set in certain cases such as if pktinfo support is
+ * missing. May be NULL.
+ * tolen
+ * auxaddr - Miscellaneous address information.
+ *
+ * Returns 0 on success, otherwise an error code.
+ */
+krb5_error_code
+recv_from_to(int socket, void *buf, size_t len, int flags,
+ struct sockaddr *from, socklen_t *fromlen,
+ struct sockaddr *to, socklen_t *tolen,
+ aux_addressing_info *auxaddr)
+
+{
+#if (!defined(IP_PKTINFO) && !defined(IPV6_PKTINFO)) || !defined(CMSG_SPACE)
+ if (to && tolen) {
+ /* Clobber with something recognizeable in case we try to use
+ * the address. */
+ memset(to, 0x40, *tolen);
+ *tolen = 0;
+ }
+
+ return recvfrom(socket, buf, len, flags, from, fromlen);
+#else
+ int r;
+ struct iovec iov;
+ char cmsg[CMSG_SPACE(sizeof(union pktinfo))];
+ struct cmsghdr *cmsgptr;
+ struct msghdr msg;
+
+ if (!to || !tolen)
+ return recvfrom(socket, buf, len, flags, from, fromlen);
+
+ /* Clobber with something recognizeable in case we can't extract
+ * the address but try to use it anyways. */
+ memset(to, 0x40, *tolen);
+
+ iov.iov_base = buf;
+ iov.iov_len = len;
+ memset(&msg, 0, sizeof(msg));
+ msg.msg_name = from;
+ msg.msg_namelen = *fromlen;
+ msg.msg_iov = &iov;
+ msg.msg_iovlen = 1;
+ msg.msg_control = cmsg;
+ msg.msg_controllen = sizeof(cmsg);
+
+ r = recvmsg(socket, &msg, flags);
+ if (r < 0)
+ return r;
+ *fromlen = msg.msg_namelen;
+
+ /* On Darwin (and presumably all *BSD with KAME stacks),
+ * CMSG_FIRSTHDR doesn't check for a non-zero controllen. RFC
+ * 3542 recommends making this check, even though the (new) spec
+ * for CMSG_FIRSTHDR says it's supposed to do the check. */
+ if (msg.msg_controllen) {
+ cmsgptr = CMSG_FIRSTHDR(&msg);
+ while (cmsgptr) {
+#ifdef IP_PKTINFO
+ if (cmsgptr->cmsg_level == IPPROTO_IP
+ && cmsgptr->cmsg_type == IP_PKTINFO
+ && *tolen >= sizeof(struct sockaddr_in)) {
+ struct in_pktinfo *pktinfo;
+ memset(to, 0, sizeof(struct sockaddr_in));
+ pktinfo = (struct in_pktinfo *)CMSG_DATA(cmsgptr);
+ ((struct sockaddr_in *)to)->sin_addr = pktinfo->ipi_addr;
+ ((struct sockaddr_in *)to)->sin_family = AF_INET;
+ *tolen = sizeof(struct sockaddr_in);
+ return r;
+ }
+#endif
+#if defined(IPV6_PKTINFO) && defined(HAVE_STRUCT_IN6_PKTINFO)
+ if (cmsgptr->cmsg_level == IPPROTO_IPV6
+ && cmsgptr->cmsg_type == IPV6_PKTINFO
+ && *tolen >= sizeof(struct sockaddr_in6)) {
+ struct in6_pktinfo *pktinfo;
+ memset(to, 0, sizeof(struct sockaddr_in6));
+ pktinfo = (struct in6_pktinfo *)CMSG_DATA(cmsgptr);
+ ((struct sockaddr_in6 *)to)->sin6_addr = pktinfo->ipi6_addr;
+ ((struct sockaddr_in6 *)to)->sin6_family = AF_INET6;
+ *tolen = sizeof(struct sockaddr_in6);
+ auxaddr->ipv6_ifindex = pktinfo->ipi6_ifindex;
+ return r;
+ }
+#endif
+ cmsgptr = CMSG_NXTHDR(&msg, cmsgptr);
+ }
+ }
+ /* No info about destination addr was available. */
+ *tolen = 0;
+ return r;
+#endif
+}
+
+/*
+ * Send a message to an address.
+ *
+ * Arguments:
+ * socket
+ * buf - The message to send.
+ * len - buf length
+ * flags
+ * to - The address to send the message to.
+ * tolen
+ * from - The address to attempt to send the message from. May be NULL.
+ * fromlen
+ * auxaddr - Miscellaneous address information.
+ *
+ * Returns 0 on success, otherwise an error code.
+ */
+krb5_error_code
+send_to_from(int socket, void *buf, size_t len, int flags,
+ const struct sockaddr *to, socklen_t tolen,
+ const struct sockaddr *from, socklen_t fromlen,
+ aux_addressing_info *auxaddr)
+{
+#if (!defined(IP_PKTINFO) && !defined(IPV6_PKTINFO)) || !defined(CMSG_SPACE)
+ return sendto(socket, buf, len, flags, to, tolen);
+#else
+ struct iovec iov;
+ struct msghdr msg;
+ struct cmsghdr *cmsgptr;
+ char cbuf[CMSG_SPACE(sizeof(union pktinfo))];
+
+ if (from == 0 || fromlen == 0 || from->sa_family != to->sa_family) {
+use_sendto:
+ return sendto(socket, buf, len, flags, to, tolen);
+ }
+
+ iov.iov_base = buf;
+ iov.iov_len = len;
+ /* Truncation? */
+ if (iov.iov_len != len)
+ return EINVAL;
+ memset(cbuf, 0, sizeof(cbuf));
+ memset(&msg, 0, sizeof(msg));
+ msg.msg_name = (void *)to;
+ msg.msg_namelen = tolen;
+ msg.msg_iov = &iov;
+ msg.msg_iovlen = 1;
+ msg.msg_control = cbuf;
+ /* CMSG_FIRSTHDR needs a non-zero controllen, or it'll return NULL
+ * on Linux. */
+ msg.msg_controllen = sizeof(cbuf);
+ cmsgptr = CMSG_FIRSTHDR(&msg);
+ msg.msg_controllen = 0;
+
+ switch (from->sa_family) {
+#if defined(IP_PKTINFO)
+ case AF_INET:
+ if (fromlen != sizeof(struct sockaddr_in))
+ goto use_sendto;
+ cmsgptr->cmsg_level = IPPROTO_IP;
+ cmsgptr->cmsg_type = IP_PKTINFO;
+ cmsgptr->cmsg_len = CMSG_LEN(sizeof(struct in_pktinfo));
+ {
+ struct in_pktinfo *p = (struct in_pktinfo *)CMSG_DATA(cmsgptr);
+ const struct sockaddr_in *from4 = (const struct sockaddr_in *)from;
+ p->ipi_spec_dst = from4->sin_addr;
+ }
+ msg.msg_controllen = CMSG_SPACE(sizeof(struct in_pktinfo));
+ break;
+#endif
+#if defined(IPV6_PKTINFO) && defined(HAVE_STRUCT_IN6_PKTINFO)
+ case AF_INET6:
+ if (fromlen != sizeof(struct sockaddr_in6))
+ goto use_sendto;
+ cmsgptr->cmsg_level = IPPROTO_IPV6;
+ cmsgptr->cmsg_type = IPV6_PKTINFO;
+ cmsgptr->cmsg_len = CMSG_LEN(sizeof(struct in6_pktinfo));
+ {
+ struct in6_pktinfo *p = (struct in6_pktinfo *)CMSG_DATA(cmsgptr);
+ const struct sockaddr_in6 *from6 =
+ (const struct sockaddr_in6 *)from;
+ p->ipi6_addr = from6->sin6_addr;
+ /*
+ * Because of the possibility of asymmetric routing, we
+ * normally don't want to specify an interface. However,
+ * Mac OS X doesn't like sending from a link-local address
+ * (which can come up in testing at least, if you wind up
+ * with a "foo.local" name) unless we do specify the
+ * interface.
+ */
+ if (IN6_IS_ADDR_LINKLOCAL(&from6->sin6_addr))
+ p->ipi6_ifindex = auxaddr->ipv6_ifindex;
+ /* otherwise, already zero */
+ }
+ msg.msg_controllen = CMSG_SPACE(sizeof(struct in6_pktinfo));
+ break;
+#endif
+ default:
+ goto use_sendto;
+ }
+ return sendmsg(socket, &msg, flags);
+#endif
+}
diff --git a/src/lib/apputils/udppktinfo.h b/src/lib/apputils/udppktinfo.h
new file mode 100644
index 0000000..af37028
--- /dev/null
+++ b/src/lib/apputils/udppktinfo.h
@@ -0,0 +1,59 @@
+/* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */
+/*
+ * Copyright 2016 by the Massachusetts Institute of Technology.
+ * All Rights Reserved.
+ *
+ * Export of this software from the United States of America may
+ * require a specific license from the United States Government.
+ * It is the responsibility of any person or organization contemplating
+ * export to obtain such a license before exporting.
+ *
+ * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
+ * distribute this software and its documentation for any purpose and
+ * without fee is hereby granted, provided that the above copyright
+ * notice appear in all copies and that both that copyright notice and
+ * this permission notice appear in supporting documentation, and that
+ * the name of M.I.T. not be used in advertising or publicity pertaining
+ * to distribution of the software without specific, written prior
+ * permission. Furthermore if you modify this software you must label
+ * your software as modified software and not distribute it in such a
+ * fashion that it might be confused with the original M.I.T. software.
+ * M.I.T. makes no representations about the suitability of
+ * this software for any purpose. It is provided "as is" without express
+ * or implied warranty.
+ */
+
+#ifndef UDPPKTINFO_H
+#define UDPPKTINFO_H
+
+#include "k5-int.h"
+
+/*
+ * This holds whatever additional information might be needed to
+ * properly send back to the client from the correct local address.
+ *
+ * In this case, we only need one datum so far: On Mac OS X, the
+ * kernel doesn't seem to like sending from link-local addresses
+ * unless we specify the correct interface.
+ */
+typedef union aux_addressing_info
+{
+ int ipv6_ifindex;
+} aux_addressing_info;
+
+krb5_error_code
+set_pktinfo(int socket, int family);
+
+krb5_error_code
+recv_from_to(int socket, void *buf, size_t len, int flags,
+ struct sockaddr *from, socklen_t *fromlen,
+ struct sockaddr *to, socklen_t *tolen,
+ aux_addressing_info *auxaddr);
+
+krb5_error_code
+send_to_from(int socket, void *buf, size_t len, int flags,
+ const struct sockaddr *to, socklen_t tolen,
+ const struct sockaddr *from, socklen_t fromlen,
+ aux_addressing_info *auxaddr);
+
+#endif /* UDPPKTINFO_H */
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