From: W.C.A. Wijngaards <wouter@nlnetlabs.nl>
Date: Fri, 26 Jun 2026 13:22:08 +0000 (+0200)
Subject: - auth-load-thread, put create_socketpair and sock_poll_timeout into
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=153accb8ded5038e5ffd76bae5a393afeeccb7ea;p=thirdparty%2Funbound.git

- auth-load-thread, put create_socketpair and sock_poll_timeout into
  util/net_help.h
---

diff --git a/daemon/remote.c b/daemon/remote.c
index 720f0daab..8d424520c 100644
--- a/daemon/remote.c
+++ b/daemon/remote.c
@@ -115,9 +115,6 @@
 #ifdef HAVE_NETDB_H
 #include <netdb.h>
 #endif
-#ifdef HAVE_POLL_H
-#include <poll.h>
-#endif
 
 /* just for portability */
 #ifdef SQ
@@ -4354,92 +4351,6 @@ int remote_control_callback(struct comm_point* c, void* arg, int err,
 	return 0;
 }
 
-/**
- * This routine polls a socket for readiness.
- * @param fd: file descriptor, -1 uses no fd for a timer only.
- * @param timeout: time in msec to wait. 0 means nonblocking test,
- * 	-1 waits blocking for events.
- * @param pollin: check for input event.
- * @param pollout: check for output event.
- * @param event: output variable, set to true if the event happens.
- * 	It is false if there was an error or timeout.
- * @return false is system call failure, also logged.
- */
-static int
-sock_poll_timeout(int fd, int timeout, int pollin, int pollout, int* event)
-{
-	int loopcount = 0;
-	/* Loop if the system call returns an errno to do so, like EINTR. */
-	log_assert(pollin || pollout);
-	while(1) {
-		struct pollfd p, *fds;
-		int nfds, ret;
-		if(++loopcount > IPC_LOOP_MAX) {
-			log_err("sock_poll_timeout: loop");
-			if(event)
-				*event = 0;
-			return 0;
-		}
-		if(fd == -1) {
-			fds = NULL;
-			nfds = 0;
-		} else {
-			fds = &p;
-			nfds = 1;
-			memset(&p, 0, sizeof(p));
-			p.fd = fd;
-#ifndef USE_WINSOCK
-			p.events = POLLERR
-				| POLLHUP
-				;
-#endif
-			if(pollin)
-				p.events |= POLLIN;
-			if(pollout)
-				p.events |= POLLOUT;
-		}
-#ifndef USE_WINSOCK
-		ret = poll(fds, nfds, timeout);
-#else
-		if(fds == NULL) {
-			Sleep(timeout);
-			ret = 0;
-		} else {
-			ret = WSAPoll(fds, nfds, timeout);
-		}
-#endif
-		if(ret == -1) {
-#ifndef USE_WINSOCK
-			if(
-				errno == EINTR || errno == EAGAIN
-#  ifdef EWOULDBLOCK
-				|| errno == EWOULDBLOCK
-#  endif
-			) continue; /* Try again. */
-#endif
-			/* For WSAPoll we only get errors here:
-			 * o WSAENETDOWN
-			 * o WSAEFAULT
-			 * o WSAEINVAL
-			 * o WSAENOBUFS
-			 */
-			log_err("poll: %s", sock_strerror(errno));
-			if(event)
-				*event = 0;
-			return 0;
-		} else if(ret == 0) {
-			/* Timeout */
-			if(event)
-				*event = 0;
-			return 1;
-		}
-		break;
-	}
-	if(event)
-		*event = 1;
-	return 1;
-}
-
 /** fast reload convert fast reload notification status to string */
 static const char*
 fr_notification_to_string(enum fast_reload_notification status)
@@ -6969,286 +6880,6 @@ done_error:
 }
 #endif /* !THREADS_DISABLED */
 
-/** create a socketpair for bidirectional communication, false on failure */
-static int
-create_socketpair(int* pair, struct ub_randstate* rand)
-{
-#ifndef USE_WINSOCK
-	if(socketpair(AF_UNIX, SOCK_STREAM, 0, pair) == -1) {
-		log_err("socketpair: %s", strerror(errno));
-		return 0;
-	}
-	(void)rand;
-#else
-	struct sockaddr_in addr, baddr, accaddr, connaddr;
-	socklen_t baddrlen, accaddrlen, connaddrlen;
-	uint8_t localhost[] = {127, 0, 0, 1};
-	uint8_t nonce[16], recvnonce[16];
-	size_t i;
-	int lst, pollin_event, bcount, loopcount;
-	int connect_poll_timeout = 200; /* msec to wait for connection */
-	ssize_t ret;
-	pair[0] = -1;
-	pair[1] = -1;
-	for(i=0; i<sizeof(nonce); i++) {
-		nonce[i] = ub_random_max(rand, 256);
-	}
-	lst = socket(AF_INET, SOCK_STREAM, 0);
-	if(lst == -1) {
-		log_err("create_socketpair: socket: %s", sock_strerror(errno));
-		return 0;
-	}
-	memset(&addr, 0, sizeof(addr));
-	addr.sin_family = AF_INET;
-	addr.sin_port = 0;
-	memcpy(&addr.sin_addr, localhost, 4);
-	if(bind(lst, (struct sockaddr*)&addr, (socklen_t)sizeof(addr))
-		== -1) {
-		log_err("create socketpair: bind: %s", sock_strerror(errno));
-		sock_close(lst);
-		return 0;
-	}
-	if(listen(lst, 12) == -1) {
-		log_err("create socketpair: listen: %s", sock_strerror(errno));
-		sock_close(lst);
-		return 0;
-	}
-
-	pair[1] = socket(AF_INET, SOCK_STREAM, 0);
-	if(pair[1] == -1) {
-		log_err("create socketpair: socket: %s", sock_strerror(errno));
-		sock_close(lst);
-		return 0;
-	}
-	baddrlen = (socklen_t)sizeof(baddr);
-	if(getsockname(lst, (struct sockaddr*)&baddr, &baddrlen) == -1) {
-		log_err("create socketpair: getsockname: %s",
-			sock_strerror(errno));
-		sock_close(lst);
-		sock_close(pair[1]);
-		pair[1] = -1;
-		return 0;
-	}
-	if(baddrlen > (socklen_t)sizeof(baddr)) {
-		log_err("create socketpair: getsockname returned addr too big");
-		sock_close(lst);
-		sock_close(pair[1]);
-		pair[1] = -1;
-		return 0;
-	}
-	/* the socket is blocking */
-	if(connect(pair[1], (struct sockaddr*)&baddr, baddrlen) == -1) {
-		log_err("create socketpair: connect: %s",
-			sock_strerror(errno));
-		sock_close(lst);
-		sock_close(pair[1]);
-		pair[1] = -1;
-		return 0;
-	}
-	if(!sock_poll_timeout(lst, connect_poll_timeout, 1, 0, &pollin_event)) {
-		log_err("create socketpair: poll for accept failed: %s",
-			sock_strerror(errno));
-		sock_close(lst);
-		sock_close(pair[1]);
-		pair[1] = -1;
-		return 0;
-	}
-	if(!pollin_event) {
-		log_err("create socketpair: poll timeout for accept");
-		sock_close(lst);
-		sock_close(pair[1]);
-		pair[1] = -1;
-		return 0;
-	}
-	accaddrlen = (socklen_t)sizeof(accaddr);
-	pair[0] = accept(lst, (struct sockaddr*)&accaddr, &accaddrlen);
-	if(pair[0] == -1) {
-		log_err("create socketpair: accept: %s", sock_strerror(errno));
-		sock_close(lst);
-		sock_close(pair[1]);
-		pair[1] = -1;
-		return 0;
-	}
-	if(accaddrlen > (socklen_t)sizeof(accaddr)) {
-		log_err("create socketpair: accept returned addr too big");
-		sock_close(lst);
-		sock_close(pair[0]);
-		sock_close(pair[1]);
-		pair[0] = -1;
-		pair[1] = -1;
-		return 0;
-	}
-	if(accaddr.sin_family != AF_INET ||
-	   memcmp(localhost, &accaddr.sin_addr, 4) != 0) {
-		log_err("create socketpair: accept from wrong address");
-		sock_close(lst);
-		sock_close(pair[0]);
-		sock_close(pair[1]);
-		pair[0] = -1;
-		pair[1] = -1;
-		return 0;
-	}
-	connaddrlen = (socklen_t)sizeof(connaddr);
-	if(getsockname(pair[1], (struct sockaddr*)&connaddr, &connaddrlen)
-		== -1) {
-		log_err("create socketpair: getsockname connectedaddr: %s",
-			sock_strerror(errno));
-		sock_close(lst);
-		sock_close(pair[0]);
-		sock_close(pair[1]);
-		pair[0] = -1;
-		pair[1] = -1;
-		return 0;
-	}
-	if(connaddrlen > (socklen_t)sizeof(connaddr)) {
-		log_err("create socketpair: getsockname connectedaddr returned addr too big");
-		sock_close(lst);
-		sock_close(pair[0]);
-		sock_close(pair[1]);
-		pair[0] = -1;
-		pair[1] = -1;
-		return 0;
-	}
-	if(connaddr.sin_family != AF_INET ||
-	   memcmp(localhost, &connaddr.sin_addr, 4) != 0) {
-		log_err("create socketpair: getsockname connectedaddr returned wrong address");
-		sock_close(lst);
-		sock_close(pair[0]);
-		sock_close(pair[1]);
-		pair[0] = -1;
-		pair[1] = -1;
-		return 0;
-	}
-	if(accaddr.sin_port != connaddr.sin_port) {
-		log_err("create socketpair: accept from wrong port");
-		sock_close(lst);
-		sock_close(pair[0]);
-		sock_close(pair[1]);
-		pair[0] = -1;
-		pair[1] = -1;
-		return 0;
-	}
-	sock_close(lst);
-
-	loopcount = 0;
-	bcount = 0;
-	while(1) {
-		if(++loopcount > IPC_LOOP_MAX) {
-			log_err("create socketpair: send failed due to loop");
-			sock_close(pair[0]);
-			sock_close(pair[1]);
-			pair[0] = -1;
-			pair[1] = -1;
-			return 0;
-		}
-		ret = send(pair[1], (void*)(nonce+bcount),
-			sizeof(nonce)-bcount, 0);
-		if(ret == -1) {
-			if(
-#ifndef USE_WINSOCK
-				errno == EINTR || errno == EAGAIN
-#  ifdef EWOULDBLOCK
-				|| errno == EWOULDBLOCK
-#  endif
-#else
-				WSAGetLastError() == WSAEINTR ||
-				WSAGetLastError() == WSAEINPROGRESS ||
-				WSAGetLastError() == WSAEWOULDBLOCK
-#endif
-				)
-				continue; /* Try again. */
-			log_err("create socketpair: send: %s", sock_strerror(errno));
-			sock_close(pair[0]);
-			sock_close(pair[1]);
-			pair[0] = -1;
-			pair[1] = -1;
-			return 0;
-		} else if(ret+(ssize_t)bcount != sizeof(nonce)) {
-			bcount += ret;
-			if((size_t)bcount < sizeof(nonce))
-				continue;
-		}
-		break;
-	}
-
-	if(!sock_poll_timeout(pair[0], connect_poll_timeout, 1, 0, &pollin_event)) {
-		log_err("create socketpair: poll failed: %s",
-			sock_strerror(errno));
-		sock_close(pair[0]);
-		sock_close(pair[1]);
-		pair[0] = -1;
-		pair[1] = -1;
-		return 0;
-	}
-	if(!pollin_event) {
-		log_err("create socketpair: poll timeout for recv");
-		sock_close(pair[0]);
-		sock_close(pair[1]);
-		pair[0] = -1;
-		pair[1] = -1;
-		return 0;
-	}
-
-	loopcount = 0;
-	bcount = 0;
-	while(1) {
-		if(++loopcount > IPC_LOOP_MAX) {
-			log_err("create socketpair: recv failed due to loop");
-			sock_close(pair[0]);
-			sock_close(pair[1]);
-			pair[0] = -1;
-			pair[1] = -1;
-			return 0;
-		}
-		ret = recv(pair[0], (void*)(recvnonce+bcount),
-			sizeof(nonce)-bcount, 0);
-		if(ret == -1) {
-			if(
-#ifndef USE_WINSOCK
-				errno == EINTR || errno == EAGAIN
-#  ifdef EWOULDBLOCK
-				|| errno == EWOULDBLOCK
-#  endif
-#else
-				WSAGetLastError() == WSAEINTR ||
-				WSAGetLastError() == WSAEINPROGRESS ||
-				WSAGetLastError() == WSAEWOULDBLOCK
-#endif
-				)
-				continue; /* Try again. */
-			log_err("create socketpair: recv: %s", sock_strerror(errno));
-			sock_close(pair[0]);
-			sock_close(pair[1]);
-			pair[0] = -1;
-			pair[1] = -1;
-			return 0;
-		} else if(ret == 0) {
-			log_err("create socketpair: stream closed");
-			sock_close(pair[0]);
-			sock_close(pair[1]);
-			pair[0] = -1;
-			pair[1] = -1;
-			return 0;
-		} else if(ret+(ssize_t)bcount != sizeof(nonce)) {
-			bcount += ret;
-			if((size_t)bcount < sizeof(nonce))
-				continue;
-		}
-		break;
-	}
-
-	if(memcmp(nonce, recvnonce, sizeof(nonce)) != 0) {
-		log_err("create socketpair: recv wrong nonce");
-		sock_close(pair[0]);
-		sock_close(pair[1]);
-		pair[0] = -1;
-		pair[1] = -1;
-		return 0;
-	}
-#endif
-	return 1;
-}
-
 /** fast reload thread. setup the thread info */
 static int
 fast_reload_thread_setup(struct worker* worker, int fr_verb, int fr_nopause,
diff --git a/util/net_help.c b/util/net_help.c
index 2bf4f47ed..f61bbed46 100644
--- a/util/net_help.c
+++ b/util/net_help.c
@@ -58,6 +58,9 @@
 #include "sldns/wire2str.h"
 #include "sldns/str2wire.h"
 #include <fcntl.h>
+#ifdef HAVE_POLL_H
+#include <poll.h>
+#endif
 #ifdef HAVE_OPENSSL_SSL_H
 #include <openssl/ssl.h>
 #include <openssl/evp.h>
@@ -92,6 +95,9 @@ int RRSET_ROUNDROBIN = 1;
 /** log tag queries with name instead of 'info' for filtering */
 int LOG_TAG_QUERYREPLY = 0;
 
+/** What number of loop iterations is too much for sock poll retries */
+#define SOCK_POLL_LOOP_MAX 200
+
 #ifdef HAVE_SSL
 static struct tls_session_ticket_key {
 	unsigned char *key_name;
@@ -2083,3 +2089,357 @@ hex_pton(const char* src, uint8_t* target, size_t targsize)
 	}
 	return t-target;
 }
+
+int
+sock_poll_timeout(int fd, int timeout, int pollin, int pollout, int* event)
+{
+	int loopcount = 0;
+	/* Loop if the system call returns an errno to do so, like EINTR. */
+	log_assert(pollin || pollout);
+	while(1) {
+		struct pollfd p, *fds;
+		int nfds, ret;
+		if(++loopcount > SOCK_POLL_LOOP_MAX) {
+			log_err("sock_poll_timeout: loop");
+			if(event)
+				*event = 0;
+			return 0;
+		}
+		if(fd == -1) {
+			fds = NULL;
+			nfds = 0;
+		} else {
+			fds = &p;
+			nfds = 1;
+			memset(&p, 0, sizeof(p));
+			p.fd = fd;
+#ifndef USE_WINSOCK
+			p.events = POLLERR
+				| POLLHUP
+				;
+#endif
+			if(pollin)
+				p.events |= POLLIN;
+			if(pollout)
+				p.events |= POLLOUT;
+		}
+#ifndef USE_WINSOCK
+		ret = poll(fds, nfds, timeout);
+#else
+		if(fds == NULL) {
+			Sleep(timeout);
+			ret = 0;
+		} else {
+			ret = WSAPoll(fds, nfds, timeout);
+		}
+#endif
+		if(ret == -1) {
+#ifndef USE_WINSOCK
+			if(
+				errno == EINTR || errno == EAGAIN
+#  ifdef EWOULDBLOCK
+				|| errno == EWOULDBLOCK
+#  endif
+			) continue; /* Try again. */
+#endif
+			/* For WSAPoll we only get errors here:
+			 * o WSAENETDOWN
+			 * o WSAEFAULT
+			 * o WSAEINVAL
+			 * o WSAENOBUFS
+			 */
+			log_err("poll: %s", sock_strerror(errno));
+			if(event)
+				*event = 0;
+			return 0;
+		} else if(ret == 0) {
+			/* Timeout */
+			if(event)
+				*event = 0;
+			return 1;
+		}
+		break;
+	}
+	if(event)
+		*event = 1;
+	return 1;
+}
+
+int
+create_socketpair(int* pair, struct ub_randstate* rand)
+{
+#ifndef USE_WINSOCK
+	if(socketpair(AF_UNIX, SOCK_STREAM, 0, pair) == -1) {
+		log_err("socketpair: %s", strerror(errno));
+		return 0;
+	}
+	(void)rand;
+#else
+	struct sockaddr_in addr, baddr, accaddr, connaddr;
+	socklen_t baddrlen, accaddrlen, connaddrlen;
+	uint8_t localhost[] = {127, 0, 0, 1};
+	uint8_t nonce[16], recvnonce[16];
+	size_t i;
+	int lst, pollin_event, bcount, loopcount;
+	int connect_poll_timeout = 200; /* msec to wait for connection */
+	ssize_t ret;
+	pair[0] = -1;
+	pair[1] = -1;
+	for(i=0; i<sizeof(nonce); i++) {
+		nonce[i] = ub_random_max(rand, 256);
+	}
+	lst = socket(AF_INET, SOCK_STREAM, 0);
+	if(lst == -1) {
+		log_err("create_socketpair: socket: %s", sock_strerror(errno));
+		return 0;
+	}
+	memset(&addr, 0, sizeof(addr));
+	addr.sin_family = AF_INET;
+	addr.sin_port = 0;
+	memcpy(&addr.sin_addr, localhost, 4);
+	if(bind(lst, (struct sockaddr*)&addr, (socklen_t)sizeof(addr))
+		== -1) {
+		log_err("create socketpair: bind: %s", sock_strerror(errno));
+		sock_close(lst);
+		return 0;
+	}
+	if(listen(lst, 12) == -1) {
+		log_err("create socketpair: listen: %s", sock_strerror(errno));
+		sock_close(lst);
+		return 0;
+	}
+
+	pair[1] = socket(AF_INET, SOCK_STREAM, 0);
+	if(pair[1] == -1) {
+		log_err("create socketpair: socket: %s", sock_strerror(errno));
+		sock_close(lst);
+		return 0;
+	}
+	baddrlen = (socklen_t)sizeof(baddr);
+	if(getsockname(lst, (struct sockaddr*)&baddr, &baddrlen) == -1) {
+		log_err("create socketpair: getsockname: %s",
+			sock_strerror(errno));
+		sock_close(lst);
+		sock_close(pair[1]);
+		pair[1] = -1;
+		return 0;
+	}
+	if(baddrlen > (socklen_t)sizeof(baddr)) {
+		log_err("create socketpair: getsockname returned addr too big");
+		sock_close(lst);
+		sock_close(pair[1]);
+		pair[1] = -1;
+		return 0;
+	}
+	/* the socket is blocking */
+	if(connect(pair[1], (struct sockaddr*)&baddr, baddrlen) == -1) {
+		log_err("create socketpair: connect: %s",
+			sock_strerror(errno));
+		sock_close(lst);
+		sock_close(pair[1]);
+		pair[1] = -1;
+		return 0;
+	}
+	if(!sock_poll_timeout(lst, connect_poll_timeout, 1, 0, &pollin_event)) {
+		log_err("create socketpair: poll for accept failed: %s",
+			sock_strerror(errno));
+		sock_close(lst);
+		sock_close(pair[1]);
+		pair[1] = -1;
+		return 0;
+	}
+	if(!pollin_event) {
+		log_err("create socketpair: poll timeout for accept");
+		sock_close(lst);
+		sock_close(pair[1]);
+		pair[1] = -1;
+		return 0;
+	}
+	accaddrlen = (socklen_t)sizeof(accaddr);
+	pair[0] = accept(lst, (struct sockaddr*)&accaddr, &accaddrlen);
+	if(pair[0] == -1) {
+		log_err("create socketpair: accept: %s", sock_strerror(errno));
+		sock_close(lst);
+		sock_close(pair[1]);
+		pair[1] = -1;
+		return 0;
+	}
+	if(accaddrlen > (socklen_t)sizeof(accaddr)) {
+		log_err("create socketpair: accept returned addr too big");
+		sock_close(lst);
+		sock_close(pair[0]);
+		sock_close(pair[1]);
+		pair[0] = -1;
+		pair[1] = -1;
+		return 0;
+	}
+	if(accaddr.sin_family != AF_INET ||
+	   memcmp(localhost, &accaddr.sin_addr, 4) != 0) {
+		log_err("create socketpair: accept from wrong address");
+		sock_close(lst);
+		sock_close(pair[0]);
+		sock_close(pair[1]);
+		pair[0] = -1;
+		pair[1] = -1;
+		return 0;
+	}
+	connaddrlen = (socklen_t)sizeof(connaddr);
+	if(getsockname(pair[1], (struct sockaddr*)&connaddr, &connaddrlen)
+		== -1) {
+		log_err("create socketpair: getsockname connectedaddr: %s",
+			sock_strerror(errno));
+		sock_close(lst);
+		sock_close(pair[0]);
+		sock_close(pair[1]);
+		pair[0] = -1;
+		pair[1] = -1;
+		return 0;
+	}
+	if(connaddrlen > (socklen_t)sizeof(connaddr)) {
+		log_err("create socketpair: getsockname connectedaddr returned addr too big");
+		sock_close(lst);
+		sock_close(pair[0]);
+		sock_close(pair[1]);
+		pair[0] = -1;
+		pair[1] = -1;
+		return 0;
+	}
+	if(connaddr.sin_family != AF_INET ||
+	   memcmp(localhost, &connaddr.sin_addr, 4) != 0) {
+		log_err("create socketpair: getsockname connectedaddr returned wrong address");
+		sock_close(lst);
+		sock_close(pair[0]);
+		sock_close(pair[1]);
+		pair[0] = -1;
+		pair[1] = -1;
+		return 0;
+	}
+	if(accaddr.sin_port != connaddr.sin_port) {
+		log_err("create socketpair: accept from wrong port");
+		sock_close(lst);
+		sock_close(pair[0]);
+		sock_close(pair[1]);
+		pair[0] = -1;
+		pair[1] = -1;
+		return 0;
+	}
+	sock_close(lst);
+
+	loopcount = 0;
+	bcount = 0;
+	while(1) {
+		if(++loopcount > SOCK_POLL_LOOP_MAX) {
+			log_err("create socketpair: send failed due to loop");
+			sock_close(pair[0]);
+			sock_close(pair[1]);
+			pair[0] = -1;
+			pair[1] = -1;
+			return 0;
+		}
+		ret = send(pair[1], (void*)(nonce+bcount),
+			sizeof(nonce)-bcount, 0);
+		if(ret == -1) {
+			if(
+#ifndef USE_WINSOCK
+				errno == EINTR || errno == EAGAIN
+#  ifdef EWOULDBLOCK
+				|| errno == EWOULDBLOCK
+#  endif
+#else
+				WSAGetLastError() == WSAEINTR ||
+				WSAGetLastError() == WSAEINPROGRESS ||
+				WSAGetLastError() == WSAEWOULDBLOCK
+#endif
+				)
+				continue; /* Try again. */
+			log_err("create socketpair: send: %s", sock_strerror(errno));
+			sock_close(pair[0]);
+			sock_close(pair[1]);
+			pair[0] = -1;
+			pair[1] = -1;
+			return 0;
+		} else if(ret+(ssize_t)bcount != sizeof(nonce)) {
+			bcount += ret;
+			if((size_t)bcount < sizeof(nonce))
+				continue;
+		}
+		break;
+	}
+
+	if(!sock_poll_timeout(pair[0], connect_poll_timeout, 1, 0, &pollin_event)) {
+		log_err("create socketpair: poll failed: %s",
+			sock_strerror(errno));
+		sock_close(pair[0]);
+		sock_close(pair[1]);
+		pair[0] = -1;
+		pair[1] = -1;
+		return 0;
+	}
+	if(!pollin_event) {
+		log_err("create socketpair: poll timeout for recv");
+		sock_close(pair[0]);
+		sock_close(pair[1]);
+		pair[0] = -1;
+		pair[1] = -1;
+		return 0;
+	}
+
+	loopcount = 0;
+	bcount = 0;
+	while(1) {
+		if(++loopcount > SOCK_POLL_LOOP_MAX) {
+			log_err("create socketpair: recv failed due to loop");
+			sock_close(pair[0]);
+			sock_close(pair[1]);
+			pair[0] = -1;
+			pair[1] = -1;
+			return 0;
+		}
+		ret = recv(pair[0], (void*)(recvnonce+bcount),
+			sizeof(nonce)-bcount, 0);
+		if(ret == -1) {
+			if(
+#ifndef USE_WINSOCK
+				errno == EINTR || errno == EAGAIN
+#  ifdef EWOULDBLOCK
+				|| errno == EWOULDBLOCK
+#  endif
+#else
+				WSAGetLastError() == WSAEINTR ||
+				WSAGetLastError() == WSAEINPROGRESS ||
+				WSAGetLastError() == WSAEWOULDBLOCK
+#endif
+				)
+				continue; /* Try again. */
+			log_err("create socketpair: recv: %s", sock_strerror(errno));
+			sock_close(pair[0]);
+			sock_close(pair[1]);
+			pair[0] = -1;
+			pair[1] = -1;
+			return 0;
+		} else if(ret == 0) {
+			log_err("create socketpair: stream closed");
+			sock_close(pair[0]);
+			sock_close(pair[1]);
+			pair[0] = -1;
+			pair[1] = -1;
+			return 0;
+		} else if(ret+(ssize_t)bcount != sizeof(nonce)) {
+			bcount += ret;
+			if((size_t)bcount < sizeof(nonce))
+				continue;
+		}
+		break;
+	}
+
+	if(memcmp(nonce, recvnonce, sizeof(nonce)) != 0) {
+		log_err("create socketpair: recv wrong nonce");
+		sock_close(pair[0]);
+		sock_close(pair[1]);
+		pair[0] = -1;
+		pair[1] = -1;
+		return 0;
+	}
+#endif
+	return 1;
+}
diff --git a/util/net_help.h b/util/net_help.h
index e9f6f3516..6bc23a08f 100644
--- a/util/net_help.h
+++ b/util/net_help.h
@@ -604,4 +604,20 @@ ssize_t hex_ntop(uint8_t const *src, size_t srclength, char *target,
 /** Convert hexadecimal data to binary. */
 ssize_t hex_pton(const char* src, uint8_t* target, size_t targsize);
 
+/**
+ * This routine polls a socket for readiness.
+ * @param fd: file descriptor, -1 uses no fd for a timer only.
+ * @param timeout: time in msec to wait. 0 means nonblocking test,
+ * 	-1 waits blocking for events.
+ * @param pollin: check for input event.
+ * @param pollout: check for output event.
+ * @param event: output variable, set to true if the event happens.
+ * 	It is false if there was an error or timeout.
+ * @return false is system call failure, also logged.
+ */
+int sock_poll_timeout(int fd, int timeout, int pollin, int pollout, int* event);
+
+/** create a socketpair for bidirectional communication, false on failure */
+int create_socketpair(int* pair, struct ub_randstate* rand);
+
 #endif /* NET_HELP_H */