Add code to read and discard incoming packets on fallback socket

6 files changed, 82 insertions, 2 deletions

diff --git a/common/dispatch.c b/common/dispatch.c
index bc9ebe11..5c278ea1 100644
--- a/common/dispatch.c
+++ b/common/dispatch.c
@@ -280,7 +280,10 @@ void dispatch ()
 	for (l = interfaces; l; l = l -> next) {
 		++nfds;
 	}
-	fds = (struct pollfd *)malloc (nfds * sizeof (struct pollfd));
+#ifdef USE_FALLBACK
+	++nfds;
+#endif
+	fds = (struct pollfd *)malloc ((nfds) * sizeof (struct pollfd));
 	if (!fds)
 		error ("Can't allocate poll structures.");
 
@@ -292,6 +295,13 @@ void dispatch ()
 		++i;
 	}
 
+#ifdef USE_FALLBACK
+	fds [i].fd = fallback_interface.wfdesc;
+	fds [i].events = POLLIN;
+	fds [i].revents = 0;
+	++i;
+#endif
+
 	do {
 		/* Wait for a packet or a timeout... XXX */
 		count = poll (fds, nfds, -1);
@@ -310,6 +320,10 @@ void dispatch ()
 			fds [i].revents = 0;
 			got_one (l);
 		}
+#ifdef USE_FALLBACK
+		if (fds [i].revents & POLLIN)
+			fallback_discard (&fallback_interface);
+#endif
 	} while (1);
 }
 #else
@@ -337,6 +351,12 @@ void dispatch ()
 			if (l -> rfdesc > max)
 				max = l -> rfdesc;
 		}
+#ifdef USE_FALLBACK
+		FD_SET (fallback_interface.wfdesc, &r);
+		FD_SET (fallback_interface.wfdesc, &w);
+		if (fallback_interface.wfdesc > max)
+				max = fallback_interface.wfdesc;
+#endif
 
 		/* Wait for a packet or a timeout... XXX */
 		count = select (max + 1, &r, &w, &x, (struct timeval *)0);
@@ -353,6 +373,10 @@ void dispatch ()
 				continue;
 			got_one (l);
 		}
+#ifdef USE_FALLBACK
+		if (FD_ISSET (fallback_interface.wfdesc, &r))
+			fallback_discard (&fallback_interface);
+#endif
 	} while (1);
 }
 #endif /* USE_POLL */
diff --git a/common/socket.c b/common/socket.c
index 2ce80452..56c84ddc 100644
--- a/common/socket.c
+++ b/common/socket.c
@@ -182,3 +182,18 @@ size_t receive_packet (interface, buf, len, from, hfrom)
 			 (struct sockaddr *)from, &flen);
 }
 #endif /* USE_SOCKET_RECEIVE */
+
+#ifdef USE_SOCKET_FALLBACK
+/* This just reads in a packet and silently discards it. */
+
+size_t fallback_discard (interface)
+	struct interface_info *interface;
+{
+	char buf [1540];
+	struct sockaddr_in from;
+	int flen = sizeof from;
+
+	return recvfrom (interface -> wfdesc, buf, sizeof buf, 0,
+			 (struct sockaddr *)&from, &flen);
+}
+#endif /* USE_SOCKET_RECEIVE */
diff --git a/dhcpd.h b/dhcpd.h
index 1856f343..9081d9bf 100644
--- a/dhcpd.h
+++ b/dhcpd.h
@@ -401,6 +401,7 @@ size_t send_fallback PROTO ((struct interface_info *,
 			   struct packet *, struct dhcp_packet *, size_t, 
 			   struct in_addr,
 			   struct sockaddr_in *, struct hardware *));
+size_t fallback_discard PROTO ((struct interface_info *));
 #endif
 
 #ifdef USE_SOCKET_SEND
diff --git a/dispatch.c b/dispatch.c
index bc9ebe11..5c278ea1 100644
--- a/dispatch.c
+++ b/dispatch.c
@@ -280,7 +280,10 @@ void dispatch ()
 	for (l = interfaces; l; l = l -> next) {
 		++nfds;
 	}
-	fds = (struct pollfd *)malloc (nfds * sizeof (struct pollfd));
+#ifdef USE_FALLBACK
+	++nfds;
+#endif
+	fds = (struct pollfd *)malloc ((nfds) * sizeof (struct pollfd));
 	if (!fds)
 		error ("Can't allocate poll structures.");
 
@@ -292,6 +295,13 @@ void dispatch ()
 		++i;
 	}
 
+#ifdef USE_FALLBACK
+	fds [i].fd = fallback_interface.wfdesc;
+	fds [i].events = POLLIN;
+	fds [i].revents = 0;
+	++i;
+#endif
+
 	do {
 		/* Wait for a packet or a timeout... XXX */
 		count = poll (fds, nfds, -1);
@@ -310,6 +320,10 @@ void dispatch ()
 			fds [i].revents = 0;
 			got_one (l);
 		}
+#ifdef USE_FALLBACK
+		if (fds [i].revents & POLLIN)
+			fallback_discard (&fallback_interface);
+#endif
 	} while (1);
 }
 #else
@@ -337,6 +351,12 @@ void dispatch ()
 			if (l -> rfdesc > max)
 				max = l -> rfdesc;
 		}
+#ifdef USE_FALLBACK
+		FD_SET (fallback_interface.wfdesc, &r);
+		FD_SET (fallback_interface.wfdesc, &w);
+		if (fallback_interface.wfdesc > max)
+				max = fallback_interface.wfdesc;
+#endif
 
 		/* Wait for a packet or a timeout... XXX */
 		count = select (max + 1, &r, &w, &x, (struct timeval *)0);
@@ -353,6 +373,10 @@ void dispatch ()
 				continue;
 			got_one (l);
 		}
+#ifdef USE_FALLBACK
+		if (FD_ISSET (fallback_interface.wfdesc, &r))
+			fallback_discard (&fallback_interface);
+#endif
 	} while (1);
 }
 #endif /* USE_POLL */
diff --git a/includes/dhcpd.h b/includes/dhcpd.h
index 1856f343..9081d9bf 100644
--- a/includes/dhcpd.h
+++ b/includes/dhcpd.h
@@ -401,6 +401,7 @@ size_t send_fallback PROTO ((struct interface_info *,
 			   struct packet *, struct dhcp_packet *, size_t, 
 			   struct in_addr,
 			   struct sockaddr_in *, struct hardware *));
+size_t fallback_discard PROTO ((struct interface_info *));
 #endif
 
 #ifdef USE_SOCKET_SEND
diff --git a/socket.c b/socket.c
index 2ce80452..56c84ddc 100644
--- a/socket.c
+++ b/socket.c
@@ -182,3 +182,18 @@ size_t receive_packet (interface, buf, len, from, hfrom)
 			 (struct sockaddr *)from, &flen);
 }
 #endif /* USE_SOCKET_RECEIVE */
+
+#ifdef USE_SOCKET_FALLBACK
+/* This just reads in a packet and silently discards it. */
+
+size_t fallback_discard (interface)
+	struct interface_info *interface;
+{
+	char buf [1540];
+	struct sockaddr_in from;
+	int flen = sizeof from;
+
+	return recvfrom (interface -> wfdesc, buf, sizeof buf, 0,
+			 (struct sockaddr *)&from, &flen);
+}
+#endif /* USE_SOCKET_RECEIVE */