flexnbd-proxy: Add UNIX socket support for the listen address

README.proxy.txt

@@ -27,13 +27,12 @@ returning the response to the client.
 USAGE
 -----
 
-  $ flexnbd-proxy --addr <ADDR> --port <PORT>
+  $ flexnbd-proxy --addr <ADDR> [ --port <PORT> ]
     --conn-addr <ADDR> --conn-port <PORT> [--bind <ADDR>] [option]*
 
 Proxy requests from an NBD client to an NBD server, resiliently. Only one
-client can be connected (to the address specified by --addr and --port) at a
+client can be connected at a time, and ACLs cannot be applied to the client, as they 
-time, and ACLs cannot be applied to the client, as they can be to clients
+can be to clients connecting directly to a flexnbd in serve mode.
-connecting directly to a flexnbd in serve mode.
 
 On starting up, the proxy will attempt to connect to the server specified by
 --conn-addr and --conn-port (from the address specified by --bind, if given). If
@@ -62,10 +61,11 @@ Options
 ~~~~~~~
 
 *--addr, -l ADDR*:
-    The address to listen on. Required.
+    The address to listen on. If this begins with a '/', it is assumed to be
-
+    a UNIX domain socket to create. Otherwise, it should be an IPv4 or IPv6
+    address.
 *--port, -p PORT*:
-    The port to listen on. Required.
+    The port to listen on, if --addr is not a UNIX socket. 
 
 *--conn-addr, -C ADDR*:
     The address of the NBD server to connect to. Required.
@@ -161,17 +161,16 @@ Current issues include:
 * Only old-style NBD negotiation is supported
 * Only one request may be in-flight at a time
 * All I/O is blocking, and signals terminate the process immediately
-* No UNIX socket support
+* UNIX socket support is limited to the listen address
 * FLUSH and TRIM commands, and the FUA flag, are not supported
 * DISCONNECT requests do not get passed through to the NBD server
 * No active timeout-retry of requests - we trust the kernel's idea of failure
 
 AUTHOR
 ------
-
 Written by Alex Young <alex@bytemark.co.uk>.
 Original concept and core code by Matthew Bloch <matthew@bytemark.co.uk>.
-Some additions by Nick Thomas <nick@bytemark.co.uk>
+Proxy mode written by Nick Thomas <nick@bytemark.co.uk>
 
 COPYING
 -------

src/parse.c

@@ -8,6 +8,7 @@ int atoi(const char *nptr);
                               ((x) >= 'A' && (x) <= 'F' ) || \
                                (x) == ':' || (x) == '.'      \
                             )
+
 /* FIXME: should change this to return negative on error like everything else */
 int parse_ip_to_sockaddr(struct sockaddr* out, char* src)
 {
@@ -47,6 +48,22 @@ int parse_ip_to_sockaddr(struct sockaddr* out, char* src)
 	return 0;
 }
 
+
+int parse_to_sockaddr(struct sockaddr* out, char* address)
+{
+	struct sockaddr_un* un = (struct sockaddr_un*) out;
+
+	NULLCHECK( address );
+
+	if ( address[0] == '/' ) {
+		un->sun_family = AF_UNIX;
+		strncpy( un->sun_path, address, 108 ); /* FIXME: linux only */
+		return 1;
+	}
+
+	return parse_ip_to_sockaddr( out, address );
+}
+
 int parse_acl(struct ip_and_mask (**out)[], int max, char **entries)
 {
 	struct ip_and_mask* list;

src/parse.h

@@ -2,6 +2,8 @@
 #define PARSE_H
 
 #include <sys/socket.h>
+#include <sys/un.h>
+
 #include <arpa/inet.h>
 #include <unistd.h>
 
@@ -10,6 +12,7 @@ union mysockaddr {
 	struct sockaddr     generic;
         struct sockaddr_in  v4;
         struct sockaddr_in6 v6;
+        struct sockaddr_un  un;
 };
 
 struct ip_and_mask {
@@ -18,6 +21,7 @@ struct ip_and_mask {
 };
 
 int parse_ip_to_sockaddr(struct sockaddr* out, char* src);
+int parse_to_sockaddr(struct sockaddr* out, char* src);
 int parse_acl(struct ip_and_mask (**out)[], int max, char **entries);
 void parse_port( char *s_port, struct sockaddr_in *out );
 

src/proxy-main.c

@@ -19,10 +19,11 @@ static struct option proxy_options[] = {
 static char proxy_short_options[] = "hl:p:C:P:b:" SOPT_QUIET SOPT_VERBOSE;
 static char proxy_help_text[] =
 	"Usage: flexnbd-proxy <options>\n\n"
-	"Resiliently proxy an NBD connection between client and server\n\n"
+	"Resiliently proxy an NBD connection between client and server\n"
+	"We can listen on TCP or UNIX socket, but only connect to TCP servers.\n\n"
 	HELP_LINE
 	"\t--" OPT_ADDR ",-l <ADDR>\tThe address we will bind to as a proxy.\n"
-	"\t--" OPT_PORT ",-p <PORT>\tThe port we will bind to as a proxy.\n"
+	"\t--" OPT_PORT ",-p <PORT>\tThe port we will bind to as a proxy, if required.\n"
 	"\t--" OPT_CONNECT_ADDR ",-C <ADDR>\tAddress of the proxied server.\n"
 	"\t--" OPT_CONNECT_PORT ",-P <PORT>\tPort of the proxied server.\n"
 	"\t--" OPT_BIND ",-b <ADDR>\tThe address we connect from, as a proxy.\n"
@@ -114,8 +115,8 @@ int main( int argc, char *argv[] )
 		);
 	}
 
-	if ( NULL == downstream_addr || NULL == downstream_port ){
+	if ( NULL == downstream_addr  ){
-		fprintf( stderr, "both --addr and --port are required.\n" );
+		fprintf( stderr, "--addr is required.\n" );
 		exit_err( proxy_help_text );
 	} else if ( NULL == upstream_addr || NULL == upstream_port ){
 		fprintf( stderr, "both --conn-addr and --conn-port are required.\n" );
@@ -136,10 +137,17 @@ int main( int argc, char *argv[] )
 	sigaction(SIGINT,  &exit_action, NULL);
 	signal(SIGPIPE, SIG_IGN); /* calls to splice() unhelpfully throw this */
 
-	info(
+	if ( NULL != downstream_port ) {
-		"Proxying between %s %s (downstream) and %s %s (upstream)",
+		info(
-		downstream_addr, downstream_port, upstream_addr, upstream_port
+			"Proxying between %s %s (downstream) and %s %s (upstream)",
-	);
+			downstream_addr, downstream_port, upstream_addr, upstream_port
+		);
+	} else {
+		info(
+			"Proxying between %s (downstream) and %s %s (upstream)",
+			downstream_addr, upstream_addr, upstream_port
+		);
+	}
 
 	success = do_proxy( proxy );
 	proxy_destroy( proxy );

src/proxy.c

@@ -24,15 +24,15 @@ struct proxier* proxy_create(
 	NULLCHECK( s_downstream_address );
 
 	FATAL_UNLESS(
-		parse_ip_to_sockaddr( &out->listen_on.generic, s_downstream_address ),
+		parse_to_sockaddr( &out->listen_on.generic, s_downstream_address ),
-		"Couldn't parse downstream address '%s' (use 0 if "
+		"Couldn't parse downstream address %s"
-		"you want to bind all IPs)",
-		s_downstream_address
 	);
 
-	FATAL_IF_NULL( s_downstream_port, "Downstream port not specified" );
+	if ( out->listen_on.family != AF_UNIX ) {
-	NULLCHECK( s_downstream_port );
+		FATAL_IF_NULL( s_downstream_port, "Downstream port not specified" );
-	parse_port( s_downstream_port, &out->listen_on.v4 );
+		NULLCHECK( s_downstream_port );
+		parse_port( s_downstream_port, &out->listen_on.v4 );
+	}
 
 	FATAL_IF_NULL(s_upstream_address, "Upstream address not specified");
 	NULLCHECK( s_upstream_address );
@@ -143,10 +143,12 @@ void proxy_open_listen_socket(struct proxier* params)
 		SHOW_ERRNO( "Couldn't set SO_REUSEADDR" )
 	);
 
-	FATAL_IF_NEGATIVE(
+	if( AF_UNIX != params->listen_on.family ) {
-		sock_set_tcp_nodelay(params->listen_fd, 1),
+		FATAL_IF_NEGATIVE(
-		SHOW_ERRNO( "Couldn't set TCP_NODELAY" )
+			sock_set_tcp_nodelay(params->listen_fd, 1),
-	);
+			SHOW_ERRNO( "Couldn't set TCP_NODELAY" )
+		);
+	}
 
 	FATAL_UNLESS_ZERO(
 		sock_try_bind( params->listen_fd, &params->listen_on.generic ),
@@ -379,8 +381,10 @@ int proxy_accept( struct proxier* params )
 	if ( FD_ISSET( params->listen_fd, &fds ) ) {
 		client_fd = accept( params->listen_fd, &client_address.generic, &socklen );
 
-		if ( sock_set_tcp_nodelay(client_fd, 1) == -1 ) {
+		if ( client_address.family != AF_UNIX ) {
-			warn( SHOW_ERRNO( "Failed to set TCP_NODELAY" ) );
+			if ( sock_set_tcp_nodelay(client_fd, 1) == -1 ) {
+				warn( SHOW_ERRNO( "Failed to set TCP_NODELAY" ) );
+			}
 		}
 
 		info( "Accepted nbd client socket fd %d", client_fd );
@@ -440,6 +444,12 @@ void proxy_cleanup( struct proxier* proxy )
 		proxy->upstream_fd = -1;
 	}
 
+	if ( AF_UNIX == proxy->listen_on.family ) {
+		if ( -1 == unlink( proxy->listen_on.un.sun_path ) ) {
+			warn( SHOW_ERRNO( "Failed to unlink %s", proxy->listen_on.un.sun_path ) );
+		}
+	}
+
 	debug( "Cleanup done" );
 }
 

src/sockutil.c

@@ -4,12 +4,14 @@
 #include <sys/types.h>
 #include <arpa/inet.h>
 #include <netinet/tcp.h>
+#include <sys/un.h>
 
 #include "sockutil.h"
 #include "util.h"
 
 size_t sockaddr_size( const struct sockaddr* sa )
 {
+	struct sockaddr_un* un = (struct sockaddr_un*) sa;
 	size_t ret = 0;
 
 	switch( sa->sa_family ) {
@@ -19,6 +21,9 @@ size_t sockaddr_size( const struct sockaddr* sa )
 		case AF_INET6:
 			ret = sizeof( struct sockaddr_in6 );
 			break;
+		case AF_UNIX:
+			ret = sizeof( un->sun_family ) + SUN_LEN( un );
+			break;
 	}
 
 	return ret;
@@ -31,6 +36,7 @@ const char* sockaddr_address_string( const struct sockaddr* sa, char* dest, size
 
 	struct sockaddr_in*  in  = ( struct sockaddr_in*  ) sa;
 	struct sockaddr_in6* in6 = ( struct sockaddr_in6* ) sa;
+	struct sockaddr_un*  un  = ( struct sockaddr_un*  ) sa;
 
 	unsigned short real_port = ntohs( in->sin_port ); // common to in and in6
 	size_t size;
@@ -42,13 +48,15 @@ const char* sockaddr_address_string( const struct sockaddr* sa, char* dest, size
 		ret = inet_ntop( AF_INET, &in->sin_addr, dest, len );
 	} else if ( sa->sa_family == AF_INET6 ) {
 		ret = inet_ntop( AF_INET6, &in6->sin6_addr, dest, len );
+	} else if ( sa->sa_family == AF_UNIX ) {
+		ret = strncpy( dest, un->sun_path, SUN_LEN( un ) );
 	}
 
 	if ( ret == NULL ) {
 		strncpy( dest, "???", len );
 	}
 
-	if ( NULL != ret && real_port > 0 ) {
+	if ( NULL != ret && real_port > 0 && sa->sa_family != AF_UNIX ) {
 		size = strlen( dest );
 		snprintf( dest + size, len - size, " port %d", real_port );
 	}