Fd passing support

diff --git a/frontend.ml b/frontend.ml
index 56d1d9f..9d444c3 100644 (file)
--- a/frontend.ml
+++ b/frontend.ml
@@ -4,6 +4,7 @@ open Printf
 open Unix
 open Globals
 open Directfifowatcher
+open Unixsocketwatcher
 
 (** frontendhandler class: Methods to create and unlink pipes and directories 
   @param root_dir vsys directory inside a slice
@@ -25,7 +26,7 @@ object(this)
     let realperm = perm land (lnot 0o111) in
       match rp with Relpath(rel) ->
         let fqp = String.concat "/" [root_dir;rel] in
-          if (is_fd_passer rel) then
+          if (this#is_fd_passer rel) then
             let res = Unixsocketwatcher.mkentry fqp abspath realperm slice_name in
               begin
                 match res with

diff --git a/unixsocketwatcher.ml b/unixsocketwatcher.ml
new file mode 100644 (file)
index 0000000..6ef359a
--- /dev/null
+++ b/unixsocketwatcher.ml
@@ -0,0 +1,157 @@
+(** unixsocketwathcer.ml: Routines to handle unix sockets for fd passing *)
+(* Semantics for the client C, script S and Vsys, V
+ * - V creates a UNIX socket and listens on it, adding a watch
+ * - C connects to the socket
+ * - V accepts the connection, forks, execve()s S and gets out of the way
+ * - S sends an fd to C and closes the connection
+ * - If one of S or C dies, then the other gets a SIGPIPE, Vsys gets a sigchld,
+ * either way, Vsys should survive the transaction.
+ *)
+
+open Unix
+open Globals
+open Dirwatcher
+open Printf
+
+let close_if_open fd = (try (ignore(close fd);) with _ -> ())
+
+type in_pathname = string
+type directory = string
+type base_pathname = string
+type slice_name = string
+
+let unix_socket_table: (in_pathname,(directory*base_pathname*slice_name*Unix.file_descr) option) Hashtbl.t = 
+  Hashtbl.create 1024
+
+let pidmap: (int,in_pathname * Unix.file_descr) Hashtbl.t = Hashtbl.create 1024
+
+let move_gate fname =
+  let tmpfname=String.concat "." [fname;"tmp"] in 
+    Unix.rename fname tmpfname;
+    tmpfname
+
+let move_ungate fname restore =
+  Unix.rename restore fname
+
+let list_check lst elt _ =
+  let rec list_check_rec lst = 
+    match lst with
+      | [] -> false
+      | car::cdr -> 
+          if (car==elt) then
+               true
+          else
+            list_check_rec cdr
+  in
+    list_check_rec lst
+
+let openentry_int fifoin =
+  let fdin =
+    try openfile fifoin [O_RDONLY;O_NONBLOCK] 0o777 with 
+        e->logprint "Error opening and connecting FIFO: %s,%o\n" fifoin 0o777;raise e
+  in
+    fdin
+
+(** Open entry safely, by first masking out the file to be opened *)
+let openentry_safe root_dir fqp_in backend_spec =
+  let restore = move_gate fqp_in in
+  let fd_in = openentry_int restore in
+    move_ungate fqp_in restore;
+    let (fqp,slice_name) = backend_spec in
+      Hashtbl.replace direct_fifo_table fqp_in (Some(root_dir,fqp,slice_name,fd_in))
+
+let openentry root_dir fqp backend_spec =
+  let control_file = String.concat "." [fqp;"control"] in
+    openentry_safe root_dir fqp_in backend_spec
+
+let reopenentry fifoin =
+  let entry = try Hashtbl.find direct_fifo_table fifoin with _ -> None in
+    match entry with
+      | Some(dir, fqp,slice_name,fd) -> close_if_open fd;openentry_safe dir fifoin (fqp,slice_name)
+      | None -> ()
+
+(* vsys is activated when a client opens an in file *)
+let connect_file fqp_in =
+  (* Do we care about this file? *)
+  let entry_info = try
+    Hashtbl.find direct_fifo_table fqp_in with _ -> None in
+    match entry_info with
+      | Some(_,execpath,slice_name,fifo_fdin) ->
+          begin
+            let len = String.length fqp_in in
+            let fqp = String.sub fqp_in 0 (len-3) in
+            let fqp_out = String.concat "." [fqp;"out"] in
+            let fifo_fdout =
+              try openfile fqp_out [O_WRONLY;O_NONBLOCK] 0o777 with
+                  _-> (* The client is opening the descriptor too fast *)
+                    sleep 1;try openfile fqp_out [O_WRONLY;O_NONBLOCK] 0o777 with
+                        _->
+                        logprint "%s Output pipe not open, using stdout in place of %s\n" slice_name fqp_out;stdout
+            in
+              ignore(sigprocmask SIG_BLOCK [Sys.sigchld]);
+              (
+                clear_nonblock fifo_fdin;
+                let pid=try Some(create_process execpath [|execpath;slice_name|] fifo_fdin fifo_fdout fifo_fdout) with e -> None in
+                  match pid with 
+                    | Some(pid) ->
+                        if (fifo_fdout <> stdout) then close_if_open fifo_fdout;
+                        Hashtbl.add pidmap pid (fqp_in,fifo_fdout)
+                    | None ->logprint "Error executing service: %s\n" execpath;reopenentry fqp_in
+              );
+              ignore(sigprocmask SIG_UNBLOCK [Sys.sigchld]);
+          end
+      | None -> ()
+
+
+(** Make a pair of fifo entries *)
+let mkentry fqp abspath perm uname = 
+  logprint "Making control entry %s->%s\n" fqp abspath;
+  let control_filename=sprintf "%s.control" fqp in
+    try
+      let listening_socket = socket PF_UNIX SOCK_STREAM 0 in
+        (try Unix.unlink control_filename with _ -> ());
+        let socket_address = ADDR_UNIX(control_filename) in
+          bind listening_socket socket_address;
+          ( (* Make the user the owner of the pipes in a non-chroot environment *)
+            if (!Globals.nochroot) then
+              let pwentry = Unix.getpwnam uname in
+                Unix.chown control_filename pwentry.pw_uid pwentry.pw_gid
+          );
+          Success
+    with 
+        e->logprint "Error creating FIFO: %s->%s. May be something wrong at the frontend.\n" fqp fifoout;Failed)
+
+
+(** Close fifos that just got removed *)
+let closeentry fqp =
+  let control_filename = String.concat "." [fqp;"control"] in
+  let entry = try Hashtbl.find direct_fifo_table fqp_in with Not_found -> None in
+    match entry with
+      | None -> ()
+      | Some(_,_,_,fd) -> 
+          close_if_open fd;
+          Hashtbl.remove direct_fifo_table fqp_in
+
+let sigchld_handle s =
+  let pid,_=Unix.waitpid [Unix.WNOHANG] 0 in
+    try
+      let fqp_in,fd_out = Hashtbl.find pidmap pid in
+        begin
+          reopenentry fqp_in
+        end
+    with _ -> ()
+
+let rec add_dir_watch fqp =
+  Dirwatcher.add_watch fqp [S_Open] direct_fifo_handler
+and
+    direct_fifo_handler wd dirname evlist fname =
+  let is_event = list_check evlist in
+    if (is_event Open Attrib) then 
+      let fqp_in = String.concat "/" [dirname;fname] in
+        connect_file fqp_in
+
+let del_dir_watch fqp =
+  ()
+
+let initialize () =
+  Sys.set_signal Sys.sigchld (Sys.Signal_handle sigchld_handle)