From: Witold Kręcicki <wpk@isc.org>
Date: Tue, 3 Dec 2019 18:48:10 +0000 (+0100)
Subject: netmgr:
X-Git-Tag: v9.15.7~20^2~12
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0bf74ac79284688c0b1cefbf8972235a75ee51e6;p=thirdparty%2Fbind9.git

netmgr:
 - make tcp listening IPC pipe name saner
 - put the pipe in /tmp on unices
 - add pid to the pipe name to avoid conflicts between processes
 - fsync directory in which the pipe resides to make sure that the
   child threads will see it and be able to open it
---

diff --git a/lib/isc/netmgr/netmgr-int.h b/lib/isc/netmgr/netmgr-int.h
index e882f3586bf..1d7b09db328 100644
--- a/lib/isc/netmgr/netmgr-int.h
+++ b/lib/isc/netmgr/netmgr-int.h
@@ -339,7 +339,7 @@ struct isc_nmsocket {
 
 	/*% Used to transfer listening TCP sockets to children */
 	uv_pipe_t		ipc;
-	char			ipc_pipe_name[32];
+	char			ipc_pipe_name[64];
 	atomic_int_fast32_t	schildren;
 
 	/*% Extra data allocated at the end of each isc_nmhandle_t */
diff --git a/lib/isc/netmgr/netmgr.c b/lib/isc/netmgr/netmgr.c
index ab9f956b221..1216918d26d 100644
--- a/lib/isc/netmgr/netmgr.c
+++ b/lib/isc/netmgr/netmgr.c
@@ -44,9 +44,9 @@
 ISC_THREAD_LOCAL int isc__nm_tid_v = ISC_NETMGR_TID_UNKNOWN;
 
 #ifdef WIN32
-#define NAMED_PIPE_PREFIX "\\\\.\\pipe\\named-ipc"
+#define NAMED_PIPE_PATTERN "\\\\.\\pipe\\named-%d-%u.pipe"
 #else
-#define NAMED_PIPE_PREFIX ".named-ipc"
+#define NAMED_PIPE_PATTERN "/tmp/named-%d-%u.pipe"
 #endif
 
 static void
@@ -840,14 +840,14 @@ isc__nmsocket_init(isc_nmsocket_t *sock, isc_nm_t *mgr,
 	}
 
 	/*
-	 * XXXWPK Maybe it should be in tmp, maybe it should not
-	 * be random?
+	 * Use a random number in the named pipe name. Also add getpid()
+	 * to the name to make sure we don't get a conflict between
+	 * different unit tests running at the same time, where the PRNG
+	 * is initialized to a constant seed.
 	 */
-	strcpy(sock->ipc_pipe_name, NAMED_PIPE_PREFIX);
-	for (int i = strlen(sock->ipc_pipe_name); i < 31; i++) {
-		sock->ipc_pipe_name[i] = isc_random8() % 24 + 'a';
-	}
-	sock->ipc_pipe_name[31] = '\0';
+	snprintf(sock->ipc_pipe_name, sizeof(sock->ipc_pipe_name),
+		 NAMED_PIPE_PATTERN, getpid(), isc_random32());
+	sock->ipc_pipe_name[sizeof(sock->ipc_pipe_name) - 1] = '\0';
 
 	isc_mutex_init(&sock->lock);
 	isc_condition_init(&sock->cond);
diff --git a/lib/isc/netmgr/tcp.c b/lib/isc/netmgr/tcp.c
index 22d21d57bb4..8a9eac74f1c 100644
--- a/lib/isc/netmgr/tcp.c
+++ b/lib/isc/netmgr/tcp.c
@@ -10,6 +10,7 @@
  */
 
 #include <unistd.h>
+#include <libgen.h>
 #include <uv.h>
 
 #include <isc/atomic.h>
@@ -203,6 +204,25 @@ isc_nm_listentcp(isc_nm_t *mgr, isc_nmiface_t *iface,
 	}
 }
 
+#ifndef WIN32
+/*
+ * Run fsync() on the directory containing a socket's IPC pipe, to
+ * ensure that all threads can see the pipe.
+ */
+static void
+syncdir(const isc_nmsocket_t *sock) {
+	 char *pipe = isc_mem_strdup(sock->mgr->mctx, sock->ipc_pipe_name);
+	 int fd = open(dirname(pipe), O_RDONLY);
+
+	 RUNTIME_CHECK(fd >= 0);
+
+	 isc_mem_free(sock->mgr->mctx, pipe);
+
+	 fsync(fd);
+	 close(fd);
+}
+#endif
+
 /*
  * For TCP listening, we create a single socket, bind it, and then
  * pass it to `ncpu` child sockets - the passing is done over IPC.
@@ -274,7 +294,17 @@ isc__nm_async_tcplisten(isc__networker_t *worker, isc__netievent_t *ievent0) {
 	r = uv_listen((uv_stream_t *) &sock->ipc, sock->nchildren,
 		      ipc_connection_cb);
 	INSIST(r == 0);
-
+#ifndef WIN32
+	/*
+	 * On Unices a child thread might not see the pipe yet;
+	 * that happened quite often in unit tests on FreeBSD.
+	 * Syncing the directory ensures that the pipe is visible
+	 * to everyone.
+	 * This isn't done on Windows because named pipes exist
+	 * within a different namespace, not on VFS.
+	 */
+	syncdir(sock);
+#endif
 	/*
 	 * We launch n 'tcpchildlistener' that will receive
 	 * sockets to be listened on over ipc.