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tap-vsockd: if the client closes, be prepared to reconnect

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In `connect` mode the client looping calling `connect` and `close` on a timer.
This could result in the server accepting the connection and the client accidentally
closing it immediately. This patch makes `tap-vsockd` keep trying to (re-)establish
the connection. Note that daemonization is delayed until after the first successful
negotiation, so attempts to send a packet afterwards should succeed.

Signed-off-by: David Scott <dave.scott@docker.com>
This commit is contained in:
David Scott 2016-05-21 14:42:21 +01:00
parent 67bc700af3
commit b72e8de310
1 changed files with 47 additions and 33 deletions
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80
alpine/packages/tap-vsockd/tap-vsockd.c
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@ -77,8 +77,8 @@ void set_macaddr(const char *dev, uint8_t *mac) {
close(fd); close(fd);
} }
/* Negotiate a vmnet connection, returns 0 on success and 1 on error. */
void negotiate(int fd, struct vif_info *vif) int negotiate(int fd, struct vif_info *vif)
{ {
/* Negotiate with com.docker.slirp */ /* Negotiate with com.docker.slirp */
struct init_message *me = create_init_message(); struct init_message *me = create_init_message();
@ -105,9 +105,10 @@ void negotiate(int fd, struct vif_info *vif)
if (read_vif_info(fd, vif) == -1) { if (read_vif_info(fd, vif) == -1) {
goto err; goto err;
} }
return; return 0;
err: err:
fatal("Failed to negotiate with com.docker.slirp"); syslog(LOG_CRIT, "Failed to negotiate vmnet connection");
return 1;
} }
@ -175,28 +176,16 @@ static void* tap_to_vmnet(void *arg)
return NULL; return NULL;
} }
/* Handle a connection. Handshake with the com.docker.slirp process and start /* Handle a connection by exchanging ethernet frames forever.
* exchanging ethernet frames between the socket and the tap device.
*/ */
static void handle(int fd, char *tap, int tapfd) static void handle(struct connection *connection)
{ {
struct connection connection;
pthread_t v2t, t2v; pthread_t v2t, t2v;
connection.fd = fd; if (pthread_create(&v2t, NULL, vmnet_to_tap, connection) != 0){
negotiate(fd, &connection.vif);
syslog(LOG_INFO, "VMNET VIF has MAC %02x:%02x:%02x:%02x:%02x:%02x",
connection.vif.mac[0], connection.vif.mac[1], connection.vif.mac[2],
connection.vif.mac[3], connection.vif.mac[4], connection.vif.mac[5]
);
set_macaddr(tap, &connection.vif.mac[0]);
connection.tapfd = tapfd;
if (pthread_create(&v2t, NULL, vmnet_to_tap, &connection) != 0){
fatal("Failed to create the vmnet_to_tap thread"); fatal("Failed to create the vmnet_to_tap thread");
} }
if (pthread_create(&t2v, NULL, tap_to_vmnet, &connection) != 0){ if (pthread_create(&t2v, NULL, tap_to_vmnet, connection) != 0){
fatal("Failed to create the tap_to_vmnet thread"); fatal("Failed to create the tap_to_vmnet thread");
} }
if (pthread_join(v2t, NULL) != 0){ if (pthread_join(v2t, NULL) != 0){
@ -400,19 +389,44 @@ int main(int argc, char **argv)
} }
openlog(argv[0], log_flags, LOG_DAEMON); openlog(argv[0], log_flags, LOG_DAEMON);
int sock = -1;
if (listen_flag) {
syslog(LOG_INFO, "starting in listening mode with serviceid=%s and tap=%s", serviceid, tap);
int lsocket = create_listening_socket(sid);
sock = accept_socket(lsocket);
} else {
syslog(LOG_INFO, "starting in connect mode with serviceid=%s and tap=%s", serviceid, tap);
sock = connect_socket(sid);
}
/* Bring up the tap device before we daemonize */
int tapfd = alloc_tap(tap); int tapfd = alloc_tap(tap);
if (daemon_flag) daemonize(pidfile);
handle(sock, tap, tapfd); struct connection connection;
exit(0); connection.tapfd = tapfd;
int sock = -1;
for (;;) {
if (sock != -1) {
close(sock);
sock = -1;
}
if (listen_flag) {
syslog(LOG_INFO, "starting in listening mode with serviceid=%s and tap=%s", serviceid, tap);
int lsocket = create_listening_socket(sid);
sock = accept_socket(lsocket);
close(lsocket);
} else {
syslog(LOG_INFO, "starting in connect mode with serviceid=%s and tap=%s", serviceid, tap);
sock = connect_socket(sid);
}
connection.fd = sock;
if (negotiate(sock, &connection.vif) != 0) {
sleep(1);
continue;
}
syslog(LOG_INFO, "VMNET VIF has MAC %02x:%02x:%02x:%02x:%02x:%02x",
connection.vif.mac[0], connection.vif.mac[1], connection.vif.mac[2],
connection.vif.mac[3], connection.vif.mac[4], connection.vif.mac[5]
);
set_macaddr(tap, &connection.vif.mac[0]);
/* Daemonize after we've made our first reliable connection */
if (daemon_flag) {
daemon_flag = 0;
daemonize(pidfile);
}
handle(&connection);
}
} }