Set source IPv6 address on NTP reply

This is needed on systems with multiple IPv6 addresses to reply with
the same source address as the destination address of the NTP request.

diff --git a/configure b/configure
index cf2555f505ecc481613a95719186c706b4729697..3fa76dbb72ded24b907d613da0776954502cabba 100755 (executable)
--- a/configure
+++ b/configure
@@ -360,6 +360,15 @@ if [ $feat_ipv6 = "1" ] && \
     return !inet_ntop(AF_INET6, &n.sin6_addr.s6_addr, p, sizeof(p));'
 then
   add_def HAVE_IPV6
+  if ! test_code 'in6_pktinfo' 'sys/socket.h netinet/in.h' '' '' '
+    return sizeof(struct in6_pktinfo);'
+  then
+    if test_code 'in6_pktinfo with _GNU_SOURCE' 'sys/socket.h netinet/in.h' \
+      '-D_GNU_SOURCE' '' 'return sizeof(struct in6_pktinfo);'
+    then
+      add_def _GNU_SOURCE
+    fi
+  fi
 fi
 
 if [ $feat_pps = "1" ] && \

diff --git a/ntp_io.c b/ntp_io.c
index 9bad2bca5cb7d22d17852e517a69d9886fb1513e..7fdff425cce54befc78ca92a70d20e0e88557a3c 100644 (file)
--- a/ntp_io.c
+++ b/ntp_io.c
@@ -159,6 +159,16 @@ prepare_socket(int family)
       LOG(LOGS_ERR, LOGF_NtpIO, "Could not request IPV6_V6ONLY socket option");
     }
 #endif
+
+#ifdef IPV6_RECVPKTINFO
+    if (setsockopt(sock_fd, IPPROTO_IPV6, IPV6_RECVPKTINFO, (char *)&on_off, sizeof(on_off)) < 0) {
+      LOG(LOGS_ERR, LOGF_NtpIO, "Could not request IPv6 packet info socket option");
+    }
+#elif defined(IPV6_PKTINFO)
+    if (setsockopt(sock_fd, IPPROTO_IPV6, IPV6_PKTINFO, (char *)&on_off, sizeof(on_off)) < 0) {
+      LOG(LOGS_ERR, LOGF_NtpIO, "Could not request IPv6 packet info socket option");
+    }
+#endif
   }
 #endif
 
@@ -345,6 +355,17 @@ read_from_socket(void *anything)
       }
 #endif
 
+#ifdef IPV6_PKTINFO
+      if (cmsg->cmsg_level == IPPROTO_IPV6 && cmsg->cmsg_type == IPV6_PKTINFO) {
+        struct in6_pktinfo ipi;
+
+        memcpy(&ipi, CMSG_DATA(cmsg), sizeof(ipi));
+        memcpy(&remote_addr.local_ip_addr.addr.in6, &ipi.ipi6_addr.s6_addr,
+            sizeof (remote_addr.local_ip_addr.addr.in6));
+        remote_addr.local_ip_addr.family = IPADDR_INET6;
+      }
+#endif
+
 #ifdef SO_TIMESTAMP
       if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SO_TIMESTAMP) {
         struct timeval tv;
@@ -445,6 +466,25 @@ send_packet(void *packet, int packetlen, NTP_Remote_Address *remote_addr)
   }
 #endif
 
+#ifdef IPV6_PKTINFO
+  if (remote_addr->local_ip_addr.family == IPADDR_INET6) {
+    struct cmsghdr *cmsg;
+    struct in6_pktinfo *ipi;
+
+    cmsg = CMSG_FIRSTHDR(&msg);
+    memset(cmsg, 0, CMSG_SPACE(sizeof(struct in6_pktinfo)));
+    cmsglen += CMSG_SPACE(sizeof(struct in6_pktinfo));
+
+    cmsg->cmsg_level = IPPROTO_IPV6;
+    cmsg->cmsg_type = IPV6_PKTINFO;
+    cmsg->cmsg_len = CMSG_LEN(sizeof(struct in6_pktinfo));
+
+    ipi = (struct in6_pktinfo *) CMSG_DATA(cmsg);
+    memcpy(&ipi->ipi6_addr.s6_addr, &remote_addr->local_ip_addr.addr.in6,
+        sizeof(ipi->ipi6_addr.s6_addr));
+  }
+#endif
+
 #if 0
     LOG(LOGS_INFO, LOGF_NtpIO, "sending to %s:%d from %s",
         UTI_IPToString(&remote_addr->ip_addr), remote_addr->port, UTI_IPToString(&remote_addr->local_ip_addr));