From 606600a176c981addcfedb0698f13fd0f2f4446e Mon Sep 17 00:00:00 2001 From: Sebastian Ottlik Date: Wed, 2 Oct 2013 12:23:12 +0200 Subject: [PATCH 1/5] util: add socket_set_fast_reuse function which will replace setting SO_REUSEADDR If a socket is closed it remains in TIME_WAIT state for some time. On operating systems using BSD sockets the endpoint of the socket may not be reused while in this state unless SO_REUSEADDR was set on the socket. On windows on the other hand the default behaviour is to allow reuse (i.e. identical to SO_REUSEADDR on other operating systems) and setting SO_REUSEADDR on a socket allows it to be bound to a endpoint even if the endpoint is already used by another socket independently of the other sockets state. This can even result in undefined behaviour. Many sockets used by QEMU should not block the use of their endpoint after being closed while they are still in TIME_WAIT state. Currently QEMU sets SO_REUSEADDR for such sockets, which can lead to problems on Windows. This patch introduces the function socket_set_fast_reuse that should be used instead of setting SO_REUSEADDR when fast socket reuse is desired and behaves correctly on all operating systems. As a failure of this function can only be caused by bad QEMU internal errors, an assertion handles these situations. The return value is still passed on, to minimize changes in client code and prevent unused variable warnings if NDEBUG is defined. Signed-off-by: Sebastian Ottlik Reviewed-by: Eric Blake Signed-off-by: Stefan Weil --- include/qemu/sockets.h | 1 + util/oslib-posix.c | 12 ++++++++++++ util/oslib-win32.c | 10 ++++++++++ 3 files changed, 23 insertions(+) diff --git a/include/qemu/sockets.h b/include/qemu/sockets.h index c5174d76a7..45588d7d58 100644 --- a/include/qemu/sockets.h +++ b/include/qemu/sockets.h @@ -39,6 +39,7 @@ int socket_set_cork(int fd, int v); int socket_set_nodelay(int fd); void qemu_set_block(int fd); void qemu_set_nonblock(int fd); +int socket_set_fast_reuse(int fd); int send_all(int fd, const void *buf, int len1); int recv_all(int fd, void *buf, int len1, bool single_read); diff --git a/util/oslib-posix.c b/util/oslib-posix.c index 253bc3df2e..e00a44c86f 100644 --- a/util/oslib-posix.c +++ b/util/oslib-posix.c @@ -157,6 +157,18 @@ void qemu_set_nonblock(int fd) fcntl(fd, F_SETFL, f | O_NONBLOCK); } +int socket_set_fast_reuse(int fd) +{ + int val = 1, ret; + + ret = setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, + (const char *)&val, sizeof(val)); + + assert(ret == 0); + + return ret; +} + void qemu_set_cloexec(int fd) { int f; diff --git a/util/oslib-win32.c b/util/oslib-win32.c index 983b7a2375..776ccfaaf0 100644 --- a/util/oslib-win32.c +++ b/util/oslib-win32.c @@ -124,6 +124,16 @@ void qemu_set_nonblock(int fd) qemu_fd_register(fd); } +int socket_set_fast_reuse(int fd) +{ + /* Enabling the reuse of an endpoint that was used by a socket still in + * TIME_WAIT state is usually performed by setting SO_REUSEADDR. On Windows + * fast reuse is the default and SO_REUSEADDR does strange things. So we + * don't have to do anything here. More info can be found at: + * http://msdn.microsoft.com/en-us/library/windows/desktop/ms740621.aspx */ + return 0; +} + int inet_aton(const char *cp, struct in_addr *ia) { uint32_t addr = inet_addr(cp); From 6669ca13c39a8515cc634695698d3dea5f39be1c Mon Sep 17 00:00:00 2001 From: Sebastian Ottlik Date: Wed, 2 Oct 2013 12:23:13 +0200 Subject: [PATCH 2/5] gdbstub: call socket_set_fast_reuse instead of setting SO_REUSEADDR SO_REUSEADDR should be avoided on Windows but is desired on other operating systems. So instead of setting it we call socket_set_fast_reuse that will result in the appropriate behaviour on all operating systems. Signed-off-by: Sebastian Ottlik Reviewed-by: Eric Blake Signed-off-by: Stefan Weil --- gdbstub.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/gdbstub.c b/gdbstub.c index 2b7f22b2d2..0e5a3f5bf9 100644 --- a/gdbstub.c +++ b/gdbstub.c @@ -1553,7 +1553,7 @@ static void gdb_accept(void) static int gdbserver_open(int port) { struct sockaddr_in sockaddr; - int fd, val, ret; + int fd, ret; fd = socket(PF_INET, SOCK_STREAM, 0); if (fd < 0) { @@ -1564,9 +1564,7 @@ static int gdbserver_open(int port) fcntl(fd, F_SETFD, FD_CLOEXEC); #endif - /* allow fast reuse */ - val = 1; - qemu_setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &val, sizeof(val)); + socket_set_fast_reuse(fd); sockaddr.sin_family = AF_INET; sockaddr.sin_port = htons(port); From bcbe92fb080420551125994f3b15c139019da694 Mon Sep 17 00:00:00 2001 From: Sebastian Ottlik Date: Wed, 2 Oct 2013 12:23:14 +0200 Subject: [PATCH 3/5] net: call socket_set_fast_reuse instead of setting SO_REUSEADDR SO_REUSEADDR should be avoided on Windows but is desired on other operating systems. So instead of setting it we call socket_set_fast_reuse that will result in the appropriate behaviour on all operating systems. An exception to this rule are multicast sockets where it is sensible to have multiple sockets listen on the same ip and port and we should set SO_REUSEADDR on windows. Signed-off-by: Sebastian Ottlik Reviewed-by: Eric Blake Signed-off-by: Stefan Weil --- net/socket.c | 19 ++++++++++--------- 1 file changed, 10 insertions(+), 9 deletions(-) diff --git a/net/socket.c b/net/socket.c index e61309d8d5..fb21e20a54 100644 --- a/net/socket.c +++ b/net/socket.c @@ -262,6 +262,11 @@ static int net_socket_mcast_create(struct sockaddr_in *mcastaddr, struct in_addr return -1; } + /* Allow multiple sockets to bind the same multicast ip and port by setting + * SO_REUSEADDR. This is the only situation where SO_REUSEADDR should be set + * on windows. Use socket_set_fast_reuse otherwise as it sets SO_REUSEADDR + * only on posix systems. + */ val = 1; ret = qemu_setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &val, sizeof(val)); if (ret < 0) { @@ -510,7 +515,7 @@ static int net_socket_listen_init(NetClientState *peer, NetClientState *nc; NetSocketState *s; struct sockaddr_in saddr; - int fd, val, ret; + int fd, ret; if (parse_host_port(&saddr, host_str) < 0) return -1; @@ -522,9 +527,7 @@ static int net_socket_listen_init(NetClientState *peer, } qemu_set_nonblock(fd); - /* allow fast reuse */ - val = 1; - qemu_setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &val, sizeof(val)); + socket_set_fast_reuse(fd); ret = bind(fd, (struct sockaddr *)&saddr, sizeof(saddr)); if (ret < 0) { @@ -645,7 +648,7 @@ static int net_socket_udp_init(NetClientState *peer, const char *lhost) { NetSocketState *s; - int fd, val, ret; + int fd, ret; struct sockaddr_in laddr, raddr; if (parse_host_port(&laddr, lhost) < 0) { @@ -661,11 +664,9 @@ static int net_socket_udp_init(NetClientState *peer, perror("socket(PF_INET, SOCK_DGRAM)"); return -1; } - val = 1; - ret = qemu_setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, - &val, sizeof(val)); + + ret = socket_set_fast_reuse(fd); if (ret < 0) { - perror("setsockopt(SOL_SOCKET, SO_REUSEADDR)"); closesocket(fd); return -1; } From aad1239a7e15f42c0b8a802433582c48417a4541 Mon Sep 17 00:00:00 2001 From: Sebastian Ottlik Date: Wed, 2 Oct 2013 12:23:15 +0200 Subject: [PATCH 4/5] slirp: call socket_set_fast_reuse instead of setting SO_REUSEADDR SO_REUSEADDR should be avoided on Windows but is desired on other operating systems. So instead of setting it we call socket_set_fast_reuse that will result in the appropriate behaviour on all operating systems. Signed-off-by: Sebastian Ottlik Reviewed-by: Eric Blake Signed-off-by: Stefan Weil --- slirp/misc.c | 3 +-- slirp/socket.c | 4 +--- slirp/tcp_subr.c | 6 ++---- slirp/udp.c | 4 ++-- 4 files changed, 6 insertions(+), 11 deletions(-) diff --git a/slirp/misc.c b/slirp/misc.c index c0d489950a..6c1636f7b6 100644 --- a/slirp/misc.c +++ b/slirp/misc.c @@ -212,8 +212,7 @@ fork_exec(struct socket *so, const char *ex, int do_pty) so->s = accept(s, (struct sockaddr *)&addr, &addrlen); } while (so->s < 0 && errno == EINTR); closesocket(s); - opt = 1; - qemu_setsockopt(so->s, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(int)); + socket_set_fast_reuse(so->s); opt = 1; qemu_setsockopt(so->s, SOL_SOCKET, SO_OOBINLINE, &opt, sizeof(int)); qemu_set_nonblock(so->s); diff --git a/slirp/socket.c b/slirp/socket.c index 25d60e7a89..37ac5cf2fb 100644 --- a/slirp/socket.c +++ b/slirp/socket.c @@ -627,9 +627,7 @@ tcp_listen(Slirp *slirp, uint32_t haddr, u_int hport, uint32_t laddr, addr.sin_port = hport; if (((s = qemu_socket(AF_INET,SOCK_STREAM,0)) < 0) || -#ifndef _WIN32 - (qemu_setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(int)) < 0) || -#endif + (socket_set_fast_reuse(s) < 0) || (bind(s,(struct sockaddr *)&addr, sizeof(addr)) < 0) || (listen(s,1) < 0)) { int tmperrno = errno; /* Don't clobber the real reason we failed */ diff --git a/slirp/tcp_subr.c b/slirp/tcp_subr.c index 043f28fcae..7571c5a282 100644 --- a/slirp/tcp_subr.c +++ b/slirp/tcp_subr.c @@ -337,8 +337,7 @@ int tcp_fconnect(struct socket *so) struct sockaddr_in addr; qemu_set_nonblock(s); - opt = 1; - qemu_setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt)); + socket_set_fast_reuse(s); opt = 1; qemu_setsockopt(s, SOL_SOCKET, SO_OOBINLINE, &opt, sizeof(opt)); @@ -426,8 +425,7 @@ void tcp_connect(struct socket *inso) return; } qemu_set_nonblock(s); - opt = 1; - qemu_setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(int)); + socket_set_fast_reuse(s); opt = 1; qemu_setsockopt(s, SOL_SOCKET, SO_OOBINLINE, &opt, sizeof(int)); socket_set_nodelay(s); diff --git a/slirp/udp.c b/slirp/udp.c index b105f871f3..8cc6cb66da 100644 --- a/slirp/udp.c +++ b/slirp/udp.c @@ -354,7 +354,7 @@ udp_listen(Slirp *slirp, uint32_t haddr, u_int hport, uint32_t laddr, { struct sockaddr_in addr; struct socket *so; - socklen_t addrlen = sizeof(struct sockaddr_in), opt = 1; + socklen_t addrlen = sizeof(struct sockaddr_in); so = socreate(slirp); if (!so) { @@ -372,7 +372,7 @@ udp_listen(Slirp *slirp, uint32_t haddr, u_int hport, uint32_t laddr, udp_detach(so); return NULL; } - qemu_setsockopt(so->s, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(int)); + socket_set_fast_reuse(so->s); getsockname(so->s,(struct sockaddr *)&addr,&addrlen); so->so_fport = addr.sin_port; From 04fd1c789677fe121cb9546c652d088c994477fb Mon Sep 17 00:00:00 2001 From: Sebastian Ottlik Date: Wed, 2 Oct 2013 12:23:16 +0200 Subject: [PATCH 5/5] util: call socket_set_fast_reuse instead of setting SO_REUSEADDR SO_REUSEADDR should be avoided on Windows but is desired on other operating systems. So instead of setting it we call socket_set_fast_reuse that will result in the appropriate behaviour on all operating systems. Signed-off-by: Sebastian Ottlik Reviewed-by: Eric Blake Signed-off-by: Stefan Weil --- util/qemu-sockets.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/util/qemu-sockets.c b/util/qemu-sockets.c index 095716ecdb..6b97dc11f9 100644 --- a/util/qemu-sockets.c +++ b/util/qemu-sockets.c @@ -155,7 +155,7 @@ int inet_listen_opts(QemuOpts *opts, int port_offset, Error **errp) continue; } - qemu_setsockopt(slisten, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)); + socket_set_fast_reuse(slisten); #ifdef IPV6_V6ONLY if (e->ai_family == PF_INET6) { /* listen on both ipv4 and ipv6 */ @@ -274,7 +274,7 @@ static int inet_connect_addr(struct addrinfo *addr, bool *in_progress, error_set_errno(errp, errno, QERR_SOCKET_CREATE_FAILED); return -1; } - qemu_setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)); + socket_set_fast_reuse(sock); if (connect_state != NULL) { qemu_set_nonblock(sock); } @@ -455,7 +455,7 @@ int inet_dgram_opts(QemuOpts *opts, Error **errp) error_set_errno(errp, errno, QERR_SOCKET_CREATE_FAILED); goto err; } - qemu_setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)); + socket_set_fast_reuse(sock); /* bind socket */ if (bind(sock, local->ai_addr, local->ai_addrlen) < 0) {