On 09/19/2012 11:31 AM, Amos Kong wrote:
> On 14/09/12 02:58, Orit Wasserman wrote:
>> 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
>
>
> Hi Orit,
>
> We almost get to the destination :)
>
>> 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/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;
>
> This member is not used.
I will remove it.
>
>> +} ConnectState;
>
> # make (gcc-4.4.6-4.el6.x86_64)
> CC qemu-sockets.o
> qemu-sockets.c:229: error: redefinition of typedef ‘ConnectState’
> qemu_socket.h:46: note: previous declaration of ‘ConnectState’ was here
> make: *** [qemu-sockets.o] Error 1
>
>
> struct ConnectState {
> int fd;
> struct addrinfo *addr_list;
> struct addrinfo *current_addr;
> ConnectHandler *callback;
> void *opaque;
> };
>
>
>> +
>> 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);
>
> # man getsockopt
> RETURN VALUE
> On success, zero is returned. On error, -1 is returned, and errno is
> set appropriately.
>
> .. original code:
> ..
> .. do {
> .. ret = getsockopt(s->fd, SOL_SOCKET, SO_ERROR, (void *) &val,
> &valsize);
> .. } while (ret == -1 && (socket_error()) == EINTR);
> ..
> .. if (ret < 0) { // ret equals to -1, and socket_error() != EINTR
>
> If ret < 0, just set the error state, but the callback function is not set to
> NULL.
> Then tcp_wait_for_connect() will be called again, and retry to checking
> current
> socket by getsockopt().
>
> But in this patch, we will abandon current socket, and connect next address
> on the list.
> We should reserve that block, and move qemu_set_fd_handler2(...NULL..) below
> it.
I'm sorry I don't get you point, it makes no difference where is
qemu_set_fd_handlers(...NULL...).
rc < 0 happens in two cases:
1. val != 0 - connect error
2. getsockopt failed for reason different than EINTR .
In both cases we can only move to the next addr in the list,
inet_connect_addr will call qemu_set_fd_handlers with the new socket fd.
>
> .. migrate_fd_error(s);
> .. return;
> .. }
> ..
> .. qemu_set_fd_handler2(s->fd, NULL, NULL, NULL, NULL);
>
>> + /* update rc to contain error details */
>> + if (!rc && val) {
>> + rc = -val;
>
> another issue: val >= 0 all the time?
yes, I can had a check anyway.
>
>> + }
>> +
>> + /* 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;
>> +}
>
>
>
