Orit Wasserman <owass...@redhat.com> writes:
> getaddrinfo can give us a list of addresses, but we only try to
> connect to the first one. If that fails we never proceed to
> the next one. This is common on desktop setups that often have ipv6
> configured but not actually working.
>
> To fix this make inet_connect_nonblocking retry connection with a different
> address.
> callers on inet_nonblocking_connect register a callback function that will
> be called when connect opertion completes, in case of failure the fd will have
> a negative value
>
> Signed-off-by: Orit Wasserman <owass...@redhat.com>
> Signed-off-by: Michael S. Tsirkin <m...@redhat.com>
> ---
> migration-tcp.c | 29 +++++-----------
> qemu-char.c | 2 +-
> qemu-sockets.c | 95 +++++++++++++++++++++++++++++++++++++++++++++++-------
> qemu_socket.h | 13 ++++++--
> 4 files changed, 102 insertions(+), 37 deletions(-)
>
> diff --git a/migration-tcp.c b/migration-tcp.c
> index 7f6ad98..cadea36 100644
> --- a/migration-tcp.c
> +++ b/migration-tcp.c
> @@ -53,29 +53,18 @@ static int tcp_close(MigrationState *s)
> return r;
> }
>
> -static void tcp_wait_for_connect(void *opaque)
> +static void tcp_wait_for_connect(int fd, void *opaque)
> {
> MigrationState *s = opaque;
> - int val, ret;
> - socklen_t valsize = sizeof(val);
>
> - DPRINTF("connect completed\n");
> - do {
> - ret = getsockopt(s->fd, SOL_SOCKET, SO_ERROR, (void *) &val,
> &valsize);
> - } while (ret == -1 && (socket_error()) == EINTR);
> -
> - if (ret < 0) {
> + if (fd < 0) {
> + DPRINTF("migrate connect error\n");
> + s->fd = -1;
> migrate_fd_error(s);
> - return;
> - }
> -
> - qemu_set_fd_handler2(s->fd, NULL, NULL, NULL, NULL);
> -
> - if (val == 0)
> + } else {
> + DPRINTF("migrate connect success\n");
> + s->fd = fd;
> migrate_fd_connect(s);
> - else {
> - DPRINTF("error connecting %d\n", val);
> - migrate_fd_error(s);
> }
> }
>
> @@ -88,7 +77,8 @@ int tcp_start_outgoing_migration(MigrationState *s, const
> char *host_port,
> s->write = socket_write;
> s->close = tcp_close;
>
> - s->fd = inet_nonblocking_connect(host_port, &in_progress, errp);
> + s->fd = inet_nonblocking_connect(host_port, tcp_wait_for_connect, s,
> + &in_progress, errp);
> if (error_is_set(errp)) {
> migrate_fd_error(s);
> return -1;
> @@ -96,7 +86,6 @@ int tcp_start_outgoing_migration(MigrationState *s, const
> char *host_port,
>
> if (in_progress) {
> DPRINTF("connect in progress\n");
> - qemu_set_fd_handler2(s->fd, NULL, NULL, tcp_wait_for_connect, s);
> } else {
> migrate_fd_connect(s);
> }
> diff --git a/qemu-char.c b/qemu-char.c
> index c442952..11cd5ef 100644
> --- a/qemu-char.c
> +++ b/qemu-char.c
> @@ -2459,7 +2459,7 @@ static CharDriverState *qemu_chr_open_socket(QemuOpts
> *opts)
> if (is_listen) {
> fd = inet_listen_opts(opts, 0, NULL);
> } else {
> - fd = inet_connect_opts(opts, true, NULL, NULL);
> + fd = inet_connect_opts(opts, true, NULL, NULL, NULL);
> }
> }
> if (fd < 0) {
> diff --git a/qemu-sockets.c b/qemu-sockets.c
> index 212075d..d321c58 100644
> --- a/qemu-sockets.c
> +++ b/qemu-sockets.c
> @@ -24,6 +24,7 @@
>
> #include "qemu_socket.h"
> #include "qemu-common.h" /* for qemu_isdigit */
> +#include "main-loop.h"
>
> #ifndef AI_ADDRCONFIG
> # define AI_ADDRCONFIG 0
> @@ -217,11 +218,69 @@ listen:
> ((rc) == -EINPROGRESS)
> #endif
>
> +/* Struct to store connect state for non blocking connect */
> +typedef struct ConnectState {
> + int fd;
> + struct addrinfo *addr_list;
> + struct addrinfo *current_addr;
> + ConnectHandler *callback;
> + void *opaque;
> + Error *errp;
> +} ConnectState;
> +
> static int inet_connect_addr(struct addrinfo *addr, bool block,
> - bool *in_progress)
> + bool *in_progress, ConnectState *connect_state);
> +
> +static void wait_for_connect(void *opaque)
> +{
> + ConnectState *s = opaque;
> + int val = 0, rc = 0;
> + socklen_t valsize = sizeof(val);
> + bool in_progress = false;
> +
> + qemu_set_fd_handler2(s->fd, NULL, NULL, NULL, NULL);
> +
> + do {
> + rc = getsockopt(s->fd, SOL_SOCKET, SO_ERROR, (void *) &val,
> &valsize);
> + } while (rc == -1 && socket_error() == EINTR);
> +
> + /* update rc to contain error details */
> + if (!rc && val) {
> + rc = -val;
Would rc = -1 suffice? I'd find that clearer.
> + }
> +
> + /* connect error */
> + if (rc < 0) {
> + closesocket(s->fd);
> + s->fd = rc;
> + }
> +
> + /* try to connect to the next address on the list */
> + while (s->current_addr->ai_next != NULL && s->fd < 0) {
> + s->current_addr = s->current_addr->ai_next;
> + s->fd = inet_connect_addr(s->current_addr, false, &in_progress, s);
> + /* connect in progress */
> + if (in_progress) {
> + return;
> + }
> + }
> +
> + freeaddrinfo(s->addr_list);
> + if (s->callback) {
> + s->callback(s->fd, s->opaque);
> + }
> + g_free(s);
> + return;
> +}
> +
> +static int inet_connect_addr(struct addrinfo *addr, bool block,
> + bool *in_progress, ConnectState *connect_state)
connect_state is needed only for non-blocking connect, isn't it? Could
we drop block and simply use connect_state == NULL instead?
> {
> int sock, rc;
>
> + if (in_progress) {
> + *in_progress = false;
> + }
> sock = qemu_socket(addr->ai_family, addr->ai_socktype,
> addr->ai_protocol);
> if (sock < 0) {
> fprintf(stderr, "%s: socket(%s): %s\n", __func__,
> @@ -241,6 +300,9 @@ static int inet_connect_addr(struct addrinfo *addr, bool
> block,
> } while (rc == -EINTR);
>
> if (!block && QEMU_SOCKET_RC_INPROGRESS(rc)) {
> + connect_state->fd = sock;
> + qemu_set_fd_handler2(sock, NULL, NULL, wait_for_connect,
> + connect_state);
> if (in_progress) {
> *in_progress = true;
> }
> @@ -259,6 +321,7 @@ static struct addrinfo *inet_parse_connect_opts(QemuOpts
> *opts, Error **errp)
> const char *port;
>
> memset(&ai, 0, sizeof(ai));
> +
> ai.ai_flags = AI_CANONNAME | AI_ADDRCONFIG;
> ai.ai_family = PF_UNSPEC;
> ai.ai_socktype = SOCK_STREAM;
> @@ -291,7 +354,7 @@ static struct addrinfo *inet_parse_connect_opts(QemuOpts
> *opts, Error **errp)
> }
>
> int inet_connect_opts(QemuOpts *opts, bool block, bool *in_progress,
> - Error **errp)
> + Error **errp, ConnectState *connect_state)
Same as for inet_connect_addr(): could we drop block and simply use
connect_state == NULL instead?
> {
> struct addrinfo *res, *e;
> int sock = -1;
> @@ -301,19 +364,22 @@ int inet_connect_opts(QemuOpts *opts, bool block, bool
> *in_progress,
> return -1;
> }
>
> - if (in_progress) {
> - *in_progress = false;
> - }
> -
> for (e = res; e != NULL; e = e->ai_next) {
> - sock = inet_connect_addr(e, block, in_progress);
> - if (sock >= 0) {
> + if (!block) {
> + connect_state->addr_list = res;
> + connect_state->current_addr = e;
> + }
> + sock = inet_connect_addr(e, block, in_progress, connect_state);
> + if (in_progress && *in_progress) {
> + return sock;
> + } else if (sock >= 0) {
> break;
> }
> }
> if (sock < 0) {
> error_set(errp, QERR_SOCKET_CONNECT_FAILED);
> }
Testing in_progress is fishy: whether the caller passes in_progress or
not shouldn't affect what this function does, only how it reports what
it did.
inet_connect_addr() either
1. completes connect (returns valid fd, sets *in_progress to false), or
2. starts connect (returns valid fd, sets *in_progress to true), or
3. fails (returns -1 and sets *in_progress to false).
In case 3, we want to try the next address. If there is none, fail.
In cases 1 and 2, we want to break the loop and return sock.
What about:
for (e = res; sock < 0 && e != NULL; e = e->ai_next) {
if (!block) {
connect_state->addr_list = res;
connect_state->current_addr = e;
}
sock = inet_connect_addr(e, block, in_progress, connect_state);
}
if (sock < 0) {
error_set(errp, QERR_SOCKET_CONNECT_FAILED);
}
freeaddrinfo(res);
return sock;
> + g_free(connect_state);
connect_state isn't allocated in this function, are you sure you want to
free it here? If yes, are you sure you want to free it only sometimes?
> freeaddrinfo(res);
> return sock;
> }
> @@ -518,7 +584,7 @@ int inet_connect(const char *str, Error **errp)
>
> opts = qemu_opts_create(&dummy_opts, NULL, 0, NULL);
> if (inet_parse(opts, str) == 0) {
> - sock = inet_connect_opts(opts, true, NULL, errp);
> + sock = inet_connect_opts(opts, true, NULL, errp, NULL);
> } else {
> error_set(errp, QERR_SOCKET_CREATE_FAILED);
> }
> @@ -526,16 +592,19 @@ int inet_connect(const char *str, Error **errp)
> return sock;
> }
>
> -
> -int inet_nonblocking_connect(const char *str, bool *in_progress,
> - Error **errp)
> +int inet_nonblocking_connect(const char *str, ConnectHandler *callback,
> + void *opaque, bool *in_progress, Error **errp)
> {
> QemuOpts *opts;
> int sock = -1;
> + ConnectState *connect_state;
>
> opts = qemu_opts_create(&dummy_opts, NULL, 0, NULL);
> if (inet_parse(opts, str) == 0) {
> - sock = inet_connect_opts(opts, false, in_progress, errp);
> + connect_state = g_malloc0(sizeof(*connect_state));
> + connect_state->callback = callback;
> + connect_state->opaque = opaque;
> + sock = inet_connect_opts(opts, false, in_progress, errp,
> connect_state);
May leak connect_state, because inet_connect_opts() doesn't always free
it.
> } else {
> error_set(errp, QERR_SOCKET_CREATE_FAILED);
> }
> diff --git a/qemu_socket.h b/qemu_socket.h
> index 80696aa..715dc9d 100644
> --- a/qemu_socket.h
> +++ b/qemu_socket.h
> @@ -38,15 +38,22 @@ void socket_set_block(int fd);
> void socket_set_nonblock(int fd);
> int send_all(int fd, const void *buf, int len1);
>
> +/* callback function for nonblocking connect
> + * vaild fd on success, negative error code on failure
> + */
> +typedef void ConnectHandler(int fd, void *opaque);
> +/* structure for nonblocking connect state */
> +typedef struct ConnectState ConnectState;
> +
> /* New, ipv6-ready socket helper functions, see qemu-sockets.c */
> int inet_listen_opts(QemuOpts *opts, int port_offset, Error **errp);
> int inet_listen(const char *str, char *ostr, int olen,
> int socktype, int port_offset, Error **errp);
> int inet_connect_opts(QemuOpts *opts, bool block, bool *in_progress,
> - Error **errp);
> + Error **errp, ConnectState *s);
> int inet_connect(const char *str, Error **errp);
> -int inet_nonblocking_connect(const char *str, bool *in_progress,
> - Error **errp);
> +int inet_nonblocking_connect(const char *str, ConnectHandler *callback,
> + void *opaque, bool *in_progress, Error **errp);
> int inet_dgram_opts(QemuOpts *opts);
> const char *inet_strfamily(int family);
