Add listen mode

src/client.c

@@ -25,6 +25,8 @@ struct client *client_create( struct server *serve, int socket )
 
 	c->stop_signal = self_pipe_create();
 
+	c->entrusted = 0;
+
 	return c;
 }
 
@@ -241,12 +243,18 @@ void client_write_init( struct client * client, uint64_t size )
 	);
 }
 
+
+
 /* Check to see if the client's request needs a reply constructing.
  * Returns 1 if we do, 0 otherwise.
  * request_err is set to 0 if the client sent a bad request, in which
- * case we send an error reply.
+ * case we drop the connection.
+ * FIXME: after an ENTRUST, there's no way to distinguish between a
+ * DISCONNECT and any bad request.
  */
-int client_request_needs_reply( struct client * client, struct nbd_request request, int *request_err )
+int client_request_needs_reply( struct client * client, 
+		struct nbd_request request,
+		int *should_disconnect )
 {
 	debug("request type %d", request.type);
 	
@@ -257,8 +265,12 @@ int client_request_needs_reply( struct client * client, struct nbd_request reque
 	switch (request.type)
 	{
 	case REQUEST_READ:
+		FATAL_IF( client->entrusted,
+				"Received a read request after an entrust message.");
 		break;
 	case REQUEST_WRITE:
+		FATAL_IF( client->entrusted,
+				"Received a write request after an entrust message.");
 		/* check it's not out of range */
 		if ( request.from+request.len > client->serve->size) {
 			debug("request read %ld+%d out of range", 
@@ -266,14 +278,19 @@ int client_request_needs_reply( struct client * client, struct nbd_request reque
 			  request.len
 			);
 			client_write_reply( client, &request, 1 );
-			*request_err = 0;
+			*should_disconnect = 0;
 			return 0;
 		}
 		break;
 		
+	case REQUEST_ENTRUST:
+		/* Yes, we need to reply to an entrust, but we take no
+		 * further action */
+		debug("request entrust");
+		break;
 	case REQUEST_DISCONNECT:
 		debug("request disconnect");
-		*request_err  = 1;
+		*should_disconnect = 1;
 		return 0;
 		
 	default:
@@ -283,6 +300,19 @@ int client_request_needs_reply( struct client * client, struct nbd_request reque
 }
 
 
+void client_reply_to_entrust( struct client * client, struct nbd_request request )
+{
+	/* An entrust needs a response, but has no data. */
+	debug( "request entrust" );
+
+	client_write_reply( client, &request, 0 );
+	/* We set this after trying to send the reply, so we know the
+	 * reply got away safely.
+	 */
+	client->entrusted = 1;
+}
+
+
 void client_reply_to_read( struct client* client, struct nbd_request request )
 {
 	off64_t offset;
@@ -345,15 +375,17 @@ void client_reply( struct client* client, struct nbd_request request )
 	case REQUEST_READ:
 		client_reply_to_read( client, request );
 		break;
-
 	case REQUEST_WRITE:
 		client_reply_to_write( client, request );
 		break;
+	case REQUEST_ENTRUST:
+		client_reply_to_entrust( client, request );
+		break;
 	}
 }
 
 
-/* Returns 0 if a request was successfully served. */
+/* Returns 0 if we should continue trying to serve requests */
 int client_serve_request(struct client* client)
 {
 	struct nbd_request    request;
@@ -416,6 +448,10 @@ void* client_serve(void* client_uncast)
 		;
 	client->stopped = 1;
 		
+	if ( client->entrusted ){
+		server_control_arrived( client->serve );
+	}
+
 	FATAL_IF_NEGATIVE(
 		close(client->socket),
 		"Couldn't close socket %d", 

src/client.h

@@ -19,6 +19,9 @@ struct client {
 	struct self_pipe * stop_signal;
 	
 	struct server* serve; /* FIXME: remove above duplication */
+
+	/* Have we seen a REQUEST_ENTRUST message? */
+	int     entrusted;
 };
 
 

src/flexnbd.c

@@ -21,6 +21,7 @@
 
 
 #include "serve.h"
+#include "listen.h"
 #include "util.h"
 
 #include <stdio.h>
@@ -115,7 +116,7 @@ void params_readwrite(
 	}
 }
 
-void do_serve(struct server* params);
+int do_serve(struct server* params);
 void do_read(struct mode_readwrite_params* params);
 void do_write(struct mode_readwrite_params* params);
 void do_remote_command(char* command, char* mode, int argc, char** argv);
@@ -153,6 +154,50 @@ void read_serve_param( int c, char **ip_addr, char **ip_port, char **file, char
 }
 
 
+void read_listen_param( int c, 
+		char **ip_addr, 
+		char **rebind_ip_addr, 
+		char **ip_port, 
+		char **rebind_ip_port, 
+		char **file, 
+		char **sock, 
+		int *default_deny )
+{
+	switch(c){
+		case 'h':
+			fprintf(stdout, listen_help_text );
+			exit(0);
+			break;
+		case 'l':
+			*ip_addr = optarg;
+			break;
+		case 'L':
+			*rebind_ip_addr = optarg;
+			break;
+		case 'p':
+			*ip_port = optarg;
+			break;
+		case 'P':
+			*rebind_ip_port = optarg;
+			break;
+		case 'f':
+			*file = optarg;
+			break;
+		case 's':
+			*sock = optarg;
+			break;
+		case 'd':
+			*default_deny = 1;
+			break;
+		case 'v':
+			log_level = 0;
+			break;
+		default:
+			exit_err( listen_help_text );
+			break;
+	}
+}
+
 void read_readwrite_param( int c, char **ip_addr, char **ip_port, char **bind_addr, char **from, char **size)
 {
 	switch(c){
@@ -269,13 +314,60 @@ int mode_serve( int argc, char *argv[] )
 	}
 	if ( err ) { exit_err( serve_help_text ); }
 
-	serve = server_create( ip_addr, ip_port, file, sock, default_deny, argc - optind, argv + optind, MAX_NBD_CLIENTS );
-	do_serve( serve );
+	serve = server_create( ip_addr, ip_port, file, sock, default_deny, argc - optind, argv + optind, MAX_NBD_CLIENTS, 1 );
+	if ( 0 == do_serve( serve ) ) {
+		info( "Control transfered.");
+	}
 	server_destroy( serve );
 
 	return 0;
 }
 
+
+int mode_listen( int argc, char *argv[] )
+{
+	int c;
+	char *ip_addr = NULL;
+	char *rebind_ip_addr = NULL;
+	char *ip_port = NULL;
+	char *rebind_ip_port = NULL;
+	char *file    = NULL;
+	char *sock    = NULL;
+	int default_deny = 0; // not on by default
+	int err = 0;
+
+	struct listen * listen;
+
+	while (1) {
+		c = getopt_long(argc, argv, listen_short_options, listen_options, NULL);
+		if ( c == -1 ) { break; }
+
+		read_listen_param( c, &ip_addr, &rebind_ip_addr, &ip_port, &rebind_ip_port, 
+				&file, &sock, &default_deny );
+	}
+
+	if ( NULL == ip_addr || NULL == ip_port ) {
+		err = 1;
+		fprintf( stderr, "both --addr and --port are required.\n" );
+	}
+	if ( NULL == file ) {
+		err = 1;
+		fprintf( stderr, "--file is required\n" );
+	}
+	if ( err ) { exit_err( listen_help_text ); }
+
+	listen = listen_create( ip_addr, rebind_ip_addr, 
+			ip_port, rebind_ip_port, 
+			file, sock, default_deny, 
+			argc - optind, argv + optind, MAX_NBD_CLIENTS );
+	do_listen( listen );
+	listen_destroy( listen );
+
+	return 0;
+
+}
+
+
 int mode_read( int argc, char *argv[] )
 {
 	int c;
@@ -439,6 +531,8 @@ int mode_help( int argc, char *argv[] )
 		cmd = argv[0];
 		if (IS_CMD( CMD_SERVE, cmd ) ) {
 			help_text = serve_help_text;
+		} else if ( IS_CMD( CMD_LISTEN, cmd ) ) {
+			help_text = listen_help_text;
 		} else if ( IS_CMD( CMD_READ, cmd ) ) {
 			help_text = read_help_text;
 		} else if ( IS_CMD( CMD_WRITE, cmd ) ) {
@@ -462,6 +556,9 @@ void mode(char* mode, int argc, char **argv)
 	if ( IS_CMD( CMD_SERVE, mode ) ) {
 		mode_serve( argc, argv );
 	}
+	else if ( IS_CMD( CMD_LISTEN, mode ) ) {
+		mode_listen( argc, argv );
+	}
 	else if ( IS_CMD( CMD_READ, mode ) ) {
 		mode_read( argc, argv );
 	}

src/listen.c

@@ -0,0 +1,87 @@
+#include "listen.h"
+#include "serve.h"
+#include "util.h"
+
+#include <stdlib.h>
+
+struct listen * listen_create( 
+		char* s_ip_address, 
+		char* s_rebind_ip_address, 
+		char* s_port, 
+		char* s_rebind_port, 
+		char* s_file,
+		char *s_ctrl_sock, 
+		int default_deny,
+		int acl_entries, 
+		char** s_acl_entries,
+		int max_nbd_clients )
+{
+	struct listen * listen;
+
+	listen = (struct listen *)xmalloc( sizeof( listen ) );
+	listen->init_serve = server_create( s_ip_address, 
+			s_port, 
+			s_file,
+			s_ctrl_sock, 
+			default_deny, 
+			acl_entries, 
+			s_acl_entries, 
+			1, 0);
+	listen->main_serve = server_create( 
+			s_rebind_ip_address ? s_rebind_ip_address : s_ip_address, 
+			s_rebind_port ? s_rebind_port : s_port, 
+			s_file,
+			s_ctrl_sock, 
+			default_deny, 
+			acl_entries, 
+			s_acl_entries, 
+			max_nbd_clients, 1);
+	return listen;
+}
+
+
+void listen_destroy( struct listen * listen )
+{
+	NULLCHECK( listen );
+	free( listen );
+}
+
+
+void listen_switch( struct listen * listen )
+{
+	NULLCHECK( listen );
+
+	/* TODO: Copy acl from init_serve to main_serve */
+	/* TODO: rename underlying file from foo.INCOMPLETE to foo */
+}
+
+
+void listen_cleanup( void * unused __attribute__((unused)) )
+{
+}
+
+void do_listen( struct listen * listen )
+{
+	NULLCHECK( listen );
+
+	int have_control = 0;
+
+	have_control = do_serve( listen->init_serve );
+
+	if( have_control ) {
+		info( "Taking control.");
+		listen_switch( listen );
+		server_destroy( listen->init_serve );
+		info( "Switched to the main server, serving." );
+		do_serve( listen->main_serve );
+	}
+	else {
+		warn("Failed to take control, giving up.");
+		server_destroy( listen->init_serve );
+	}
+	server_destroy( listen->main_serve );
+
+	info("Listen done.");
+	listen_cleanup( listen );
+}
+

src/listen.h

@@ -0,0 +1,26 @@
+#ifndef LISTEN_H
+#define LISTEN_H
+
+#include "serve.h"
+
+struct listen {
+	struct server * init_serve;
+	struct server * main_serve;
+};
+
+struct listen * listen_create( 
+		char* s_ip_address, 
+		char* s_rebind_ip_address, 
+		char* s_port, 
+		char* s_rebind_port, 
+		char* s_file,
+		char *s_ctrl_sock, 
+		int default_deny,
+		int acl_entries, 
+		char** s_acl_entries,
+		int max_nbd_clients );
+void listen_destroy( struct listen* );
+
+void do_listen( struct listen * );
+
+#endif

src/options.h

@@ -5,8 +5,10 @@
 
 #define OPT_HELP "help"
 #define OPT_ADDR "addr"
+#define OPT_REBIND_ADDR "rebind-addr"
 #define OPT_BIND "bind"
 #define OPT_PORT "port"
+#define OPT_REBIND_PORT "rebind-port"
 #define OPT_FILE "file"
 #define OPT_SOCK "sock"
 #define OPT_FROM "from"
@@ -14,6 +16,7 @@
 #define OPT_DENY "default-deny"
 
 #define CMD_SERVE  "serve"
+#define CMD_LISTEN "listen"
 #define CMD_READ   "read"
 #define CMD_WRITE  "write"
 #define CMD_ACL    "acl"
@@ -32,7 +35,9 @@
 #define GETOPT_DENY GETOPT_FLAG( OPT_DENY, 'd' )
 
 #define GETOPT_ADDR GETOPT_ARG( OPT_ADDR, 'l' )
+#define GETOPT_REBIND_ADDR GETOPT_ARG( OPT_REBIND_ADDR, 'L')
 #define GETOPT_PORT GETOPT_ARG( OPT_PORT, 'p' )
+#define GETOPT_REBIND_PORT GETOPT_ARG( OPT_REBIND_PORT, 'P')
 #define GETOPT_FILE GETOPT_ARG( OPT_FILE, 'f' )
 #define GETOPT_SOCK GETOPT_ARG( OPT_SOCK, 's' )
 #define GETOPT_FROM GETOPT_ARG( OPT_FROM, 'F' )
@@ -81,6 +86,36 @@ static char serve_help_text[] =
 	SOCK_LINE
 	VERBOSE_LINE;
 
+
+static struct option listen_options[] = {
+	GETOPT_HELP,
+	GETOPT_ADDR,
+	GETOPT_REBIND_ADDR,
+	GETOPT_PORT,
+	GETOPT_REBIND_ADDR,
+	GETOPT_FILE,
+	GETOPT_SOCK,
+	GETOPT_DENY,
+	GETOPT_VERBOSE,
+	{0}
+};
+static char listen_short_options[] = "hl:L:p:P:f:s:d" SOPT_VERBOSE;
+static char listen_help_text[] =
+	"Usage: flexnbd " CMD_LISTEN " <options> [<acl_address>*]\n\n"
+	"Listen for an incoming migration on ADDR:PORT, "
+	"then switch to REBIND_ADDR:REBIND_PORT on completion "
+	"to serve FILE.\n\n"
+	HELP_LINE
+	"\t--" OPT_ADDR ",-l <ADDR>\tThe address to listen on.\n"
+	"\t--" OPT_REBIND_ADDR ",-L <REBIND_ADDR>\tThe address to switch to, if given.\n"
+	"\t--" OPT_PORT ",-p <PORT>\tThe port to listen on.\n"
+	"\t--" OPT_REBIND_PORT ",-P <REBIND_PORT>\tThe port to switch to, if given..\n"
+	"\t--" OPT_FILE ",-f <FILE>\tThe file to serve.\n"
+	"\t--" OPT_DENY ",-d\tDeny connections by default unless in ACL.\n"
+	SOCK_LINE
+	VERBOSE_LINE;
+
+
 static struct option read_options[] = {
 	GETOPT_HELP,
 	GETOPT_ADDR,

src/parse.c

@@ -11,6 +11,9 @@ int atoi(const char *nptr);
 /* FIXME: should change this to return negative on error like everything else */
 int parse_ip_to_sockaddr(struct sockaddr* out, char* src)
 {
+	NULLCHECK( out );
+	NULLCHECK( src );
+
 	char temp[64];
 	struct sockaddr_in *v4  = (struct sockaddr_in *) out;
 	struct sockaddr_in6 *v6 = (struct sockaddr_in6 *) out;

src/serve.c

@@ -44,10 +44,12 @@ struct server * server_create (
 	int default_deny,
 	int acl_entries,
 	char** s_acl_entries,
-	int max_nbd_clients)
+	int max_nbd_clients,
+	int has_control)
 {
 	struct server * out;
 	out = xmalloc( sizeof( struct server ) );
+	out->has_control = has_control;
 	out->max_nbd_clients = max_nbd_clients;
 	out->nbd_client = xmalloc( max_nbd_clients * sizeof( struct client_tbl_entry ) );
 
@@ -56,6 +58,7 @@ struct server * server_create (
 	FATAL_IF_NULL(s_ip_address, "No IP address supplied");
 	FATAL_IF_NULL(s_port, "No port number supplied");
 	FATAL_IF_NULL(s_file, "No filename supplied");
+	NULLCHECK( s_ip_address );
 	FATAL_IF_ZERO(
 		parse_ip_to_sockaddr(&out->bind_to.generic, s_ip_address),
 		"Couldn't parse server address '%s' (use 0 if "
@@ -271,7 +274,7 @@ int cleanup_client_thread( struct client_tbl_entry * entry )
 
 void cleanup_client_threads( struct client_tbl_entry * entries, size_t entries_len )
 {
-	int i;
+	size_t i;
 	for( i = 0; i < entries_len; i++ ) {
 		cleanup_client_thread( &entries[i] );
 	}
@@ -575,19 +578,13 @@ int server_accept( struct server * params )
 	}
 
 	if ( FD_ISSET( params->server_fd, &fds ) ){
-		
 		client_fd = accept( params->server_fd, &client_address.generic, &socklen );
-		
 		debug("Accepted nbd client socket");
-		
 		accept_nbd_client(params, client_fd, &client_address);
-
-	} else if( FD_ISSET( params->control_fd, &fds ) ) {
-		
+	} 
+	else if( FD_ISSET( params->control_fd, &fds ) ) {
 		client_fd = accept( params->control_fd, &client_address.generic, &socklen );
-		
 		debug("Accepted control client socket"); 
-		
 		accept_control_connection(params, client_fd, &client_address);
 	}
 
@@ -639,6 +636,17 @@ void serve_wait_for_close( struct server * serve )
 	}
 }
 
+/* We've just had an ENTRUST/DISCONNECT pair, so we need to shut down
+ * and signal our listener that we can safely take over.
+ */
+void server_control_arrived( struct server *serve )
+{
+	NULLCHECK( serve );
+
+	serve->has_control = 1;
+	serve_signal_close( serve );
+}
+
 
 /** Closes sockets, frees memory and waits for all client threads to finish */
 void serve_cleanup(struct server* params, 
@@ -676,15 +684,20 @@ void serve_cleanup(struct server* params,
 }
 
 /** Full lifecycle of the server */
-void do_serve(struct server* params)
+int do_serve(struct server* params)
 {
 	NULLCHECK( params );
+
+	int has_control;
 	
 	error_set_handler((cleanup_handler*) serve_cleanup, params);
 	serve_open_server_socket(params);
 	serve_open_control_socket(params);
 	serve_init_allocation_map(params);
 	serve_accept_loop(params);
+	has_control = params->has_control;
 	serve_cleanup(params, 0);
+
+	return has_control;
 }
 

src/serve.h

@@ -82,6 +82,13 @@ struct server {
 	
 	int                  max_nbd_clients;
 	struct client_tbl_entry *nbd_client;
+
+
+	/* Marker for whether or not this server has control over the
+	 * data in the file, or if we're waiting to receive it from an
+	 * inbound migration which hasn't yet finished.
+	 */
+	int has_control;
 };
 
 struct server * server_create( 
@@ -92,7 +99,8 @@ struct server * server_create(
 		int default_deny,
 		int acl_entries, 
 		char** s_acl_entries,
-		int max_nbd_clients );
+		int max_nbd_clients,
+		int has_control );
 void server_destroy( struct server * );
 int server_is_closed(struct server* serve);
 void server_dirty(struct server *serve, off64_t from, int len);
@@ -101,7 +109,9 @@ void server_unlock_io( struct server* serve );
 void serve_signal_close( struct server *serve );
 void serve_wait_for_close( struct server * serve );
 void server_replace_acl( struct server *serve, struct acl * acl);
+void server_control_arrived( struct server *serve );
 
+int do_serve( struct server * );
 
 struct mode_readwrite_params {
 	union mysockaddr     connect_to;