On 09/20/2012 04:14 PM, Markus Armbruster wrote:
> 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.
I guess so, I want the errno for more detailed error message
but those will come in another patch set and I can handle it than.
I agree that using -1 will make the code much cleaner.
>
>> + }
>> +
>> + /* 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?
it is a good idea !
>
>> {
>> 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?
>
inet_nonblocking connect allocate connect_state.
In case connect succeeded/failed immediately than we need to free it (i.e
in_progress is true),
that the case here.
I will move it to inet_nonblocking_connect when I remove in_progress flag.
We still need to free in two places in the code ,the second is in
tcp_wait_for_connect.
>> 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.
it is freed by tcp_wait_for_connect after it calls the user callback function
Orit
>
>> } 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);
