connectd: Track sodium_fd for Mac tests

On Mac most tests report BROKEN because sodium creating an untracked fd pointing to /dev/random. dev_report_fd’s finds it at tear down and reports a BROKEN message.

Tracking the fd used by sodium allows us to squeltch this message and make tests more usable on Mac.

While we’re here we added the fd mode to the log to help with future rogue fd issues.

ChangeLog-None

connectd/connectd.c

@@ -50,6 +50,7 @@
 #include <unistd.h>
 #include <wire/wire_io.h>
 #include <wire/wire_sync.h>
+#include <sys/stat.h>
 
 /*~ We are passed two file descriptors when exec'ed from `lightningd`: the
  * first is a connection to `hsmd`, which we need for the cryptographic
@@ -1393,6 +1394,9 @@ setup_listeners(const tal_t *ctx,
 }
 
 
+static void dev_report_fds(struct daemon *daemon, const u8 *msg);
+
+
 /*~ Parse the incoming connect init message from lightningd ("master") and
  * assign config variables to the daemon; it should be the first message we
  * get. */
@@ -1957,6 +1961,28 @@ static const char *try_tal_name(const tal_t *ctx, const void *p)
 	return tal_fmt(ctx, "%p", p);
 }
 
+static char *fd_mode_str(int fd)
+{
+	struct stat finfo;
+	if (0 != fstat(fd, &finfo))
+		return "invalid fd";
+	if (S_ISBLK(finfo.st_mode))
+		return "block special";
+	if (S_ISCHR(finfo.st_mode))
+		return "char special";
+	if (S_ISDIR(finfo.st_mode))
+		return "directory";
+	if (S_ISFIFO(finfo.st_mode))
+		return "fifo or socket";
+	if (S_ISREG(finfo.st_mode))
+		return "regular file";
+	if (S_ISLNK(finfo.st_mode))
+		return "symbolic link";
+	if (S_ISSOCK(finfo.st_mode))
+		return "socket";
+	return "unknown";
+}
+
 static void dev_report_fds(struct daemon *daemon, const u8 *msg)
 {
 	for (int fd = 3; fd < 4096; fd++) {
@@ -1981,9 +2007,14 @@ static void dev_report_fds(struct daemon *daemon, const u8 *msg)
 			status_info("dev_report_fds: %i -> gossip_store", fd);
 			continue;
 		}
+		if (fd == daemon->sodium_fd) {
+			status_info("dev_report_fds: %i -> sodium fd", fd);
+			continue;
+		}
 		c = io_have_fd(fd, &listener);
 		if (!c) {
-			status_broken("dev_report_fds: %i open but unowned?", fd);
+			status_broken("dev_report_fds: %i open but unowned? fd"
+				      " mode: %s", fd, fd_mode_str(fd));
 			continue;
 		} else if (listener) {
 			l = (void *)c;
@@ -2154,12 +2185,20 @@ int main(int argc, char *argv[])
 {
 	struct daemon *daemon;
 	bool developer;
+	struct stat finfo;
+	int sodium_fd;
 
 	setup_locale();
 
 	/* Common subdaemon setup code. */
 	developer = subdaemon_setup(argc, argv);
 
+	/* Check if lib-sodium is using fd 5 and it looks like /dev/random */
+	sodium_fd = -1;
+	if(!isatty(5) && errno == ENOTTY && 0 == fstat(5, &finfo))
+		if (S_ISCHR(finfo.st_mode) && !finfo.st_size)
+			sodium_fd = 5;
+
 	/* Allocate and set up our simple top-level structure. */
 	daemon = tal(NULL, struct daemon);
 	daemon->developer = developer;
@@ -2171,6 +2210,7 @@ int main(int argc, char *argv[])
 	list_head_init(&daemon->connecting);
 	timers_init(&daemon->timers, time_mono());
 	daemon->gossip_store_fd = -1;
+	daemon->sodium_fd = sodium_fd;
 	daemon->shutting_down = false;
 	daemon->dev_suppress_gossip = false;
 

connectd/connectd.h

@@ -182,6 +182,9 @@ struct daemon {
 	/* If non-zero, port to listen for websocket connections. */
 	u16 websocket_port;
 
+	/* If lib-sodium keeps a fd open to /dev/random, we track it here. */
+	int sodium_fd;
+
 	/* The gossip_store */
 	int gossip_store_fd;
 	size_t gossip_store_end;