[Guile-commits] 05/07: Allow null bytes in UNIX sockets.

[Ludovic Courtès]

civodul pushed a commit to branch main
in repository guile.

commit 01b686b701dc06f6623f0cc75acd4583c0296333
Author: Liliana Marie Prikler <liliana.prikler@gmail.com>
AuthorDate: Thu Feb 10 21:42:31 2022 +0100

    Allow null bytes in UNIX sockets.
    
    The current socket address constructors all assume, that there are no
    null bytes in the socket path.  This assumption does not hold in Linux,
    which uses an initial null byte to demarcate abstract sockets and
    ignores all further null bytes [1].
    
    [1] https://www.man7.org/linux/man-pages/man7/unix.7.html
    
    * libguile/sockets.c (scm_fill_sockaddr)[HAVE_UNIX_DOMAIN_SOCKETS]:
    Use scm_to_locale_stringn to construct c_address.
    Use memcpy instead of strcpy and calculate size directly instead of
    using SUN_LEN.
    (_scm_from_sockaddr): Copy the entire path up to the limits imposed by
    addr_size.
    * test-suite/tests/00-socket.test: ("make-socket-address"): Add case for
    abstract unix sockets.
    ("AF_UNIX/SOCK_STREAM"): Add abstract socket versions of bind, listen,
    connect and accept.
    
    Signed-off-by: Ludovic Courtès <ludo@gnu.org>
---
 libguile/socket.c               | 20 +++++++----
 test-suite/tests/00-socket.test | 79 ++++++++++++++++++++++++++++++++++++++---
 2 files changed, 89 insertions(+), 10 deletions(-)

diff --git a/libguile/socket.c b/libguile/socket.c
index b137a7932..4818d62bd 100644
--- a/libguile/socket.c
+++ b/libguile/socket.c
@@ -813,10 +813,11 @@ scm_fill_sockaddr (int fam, SCM address, SCM *args, int 
which_arg,
        struct sockaddr_un *soka;
        int addr_size;
        char *c_address;
+       size_t c_address_size;
 
        scm_dynwind_begin (0);
 
-       c_address = scm_to_locale_string (address);
+       c_address = scm_to_locale_stringn (address, &c_address_size);
        scm_dynwind_free (c_address);
 
        /* the static buffer size in sockaddr_un seems to be arbitrary
@@ -826,12 +827,14 @@ scm_fill_sockaddr (int fam, SCM address, SCM *args, int 
which_arg,
           connect/bind etc., to fail.  sun_path is always the last
           member of the structure.  */
        addr_size = sizeof (struct sockaddr_un)
-         + MAX (0, strlen (c_address) + 1 - (sizeof soka->sun_path));
+         + MAX (0, c_address_size + 1 - (sizeof soka->sun_path));
        soka = (struct sockaddr_un *) scm_malloc (addr_size);
-       memset (soka, 0, addr_size);  /* for sun_len: see sin_len above. */
+       memset (soka, 0, addr_size);
        soka->sun_family = AF_UNIX;
-       strcpy (soka->sun_path, c_address);
-       *size = SUN_LEN (soka);
+        /* we accept 0-bytes here (used for abstract sockets in Linux);
+           therefore do not use strlen() or SUN_LEN!  */
+       memcpy (soka->sun_path, c_address, c_address_size);
+       *size = offsetof (struct sockaddr_un, sun_path) + c_address_size;
 
        scm_dynwind_end ();
        return (struct sockaddr *) soka;
@@ -1045,7 +1048,12 @@ _scm_from_sockaddr (const scm_t_max_sockaddr *address, 
unsigned addr_size,
        if (addr_size <= offsetof (struct sockaddr_un, sun_path))
          SCM_SIMPLE_VECTOR_SET(result, 1, SCM_BOOL_F);
        else
-         SCM_SIMPLE_VECTOR_SET(result, 1, scm_from_locale_string 
(nad->sun_path));
+          {
+            size_t path_size = addr_size - offsetof (struct sockaddr_un, 
sun_path);
+            SCM_SIMPLE_VECTOR_SET (result, 1,
+                                   scm_from_locale_stringn (nad->sun_path,
+                                                            path_size));
+          }
       }
       break;
 #endif
diff --git a/test-suite/tests/00-socket.test b/test-suite/tests/00-socket.test
index 027bd8519..b3692f61a 100644
--- a/test-suite/tests/00-socket.test
+++ b/test-suite/tests/00-socket.test
@@ -128,10 +128,15 @@
               (= (sockaddr:flowinfo sa*) 1)))))
 
   (if (defined? 'AF_UNIX)
-      (pass-if "AF_UNIX"
-       (let ((sa (make-socket-address AF_UNIX "/tmp/unix-socket")))
-         (and (= (sockaddr:fam sa) AF_UNIX)
-              (string=? (sockaddr:path sa) "/tmp/unix-socket"))))))
+      (begin
+        (pass-if "AF_UNIX"
+         (let ((sa (make-socket-address AF_UNIX "/tmp/unix-socket")))
+           (and (= (sockaddr:fam sa) AF_UNIX)
+                (string=? (sockaddr:path sa) "/tmp/unix-socket"))))
+        (pass-if "AF_UNIX abstract"
+          (let ((sa (make-socket-address AF_UNIX "\x00/tmp/abstract-socket")))
+           (and (= (sockaddr:fam sa) AF_UNIX)
+                (string=? (sockaddr:path sa) "\x00/tmp/abstract-socket")))))))
 
 ;;;
 ;;; setsockopt
@@ -319,6 +324,72 @@
 
        #t)
 
+      ;; testing `bind', `listen' and `connect' on abstract stream-oriented 
sockets
+
+      (let ((server-socket (socket AF_UNIX SOCK_STREAM 0))
+           (server-bound? #f)
+           (server-listening? #f)
+           (server-pid #f)
+           (path (temp-file-path)))
+
+        (false-if-exception (delete-file path))
+        (set! path (string-append "\x00" path))
+
+       (pass-if "bind abstract"
+         (catch 'system-error
+           (lambda ()
+             (bind server-socket AF_UNIX path)
+             (set! server-bound? #t)
+              #t)
+           (lambda args
+             (let ((errno (system-error-errno args)))
+               (if (= errno EADDRINUSE)
+                    (throw 'unresolved)
+                   (apply throw args))))))
+
+       (pass-if "listen abstract"
+         (if (not server-bound?)
+             (throw 'unresolved)
+             (begin
+               (listen server-socket 123)
+               (set! server-listening? #t)
+               #t)))
+
+       (force-output (current-output-port))
+       (force-output (current-error-port))
+       (when server-listening?
+          (let ((pid (primitive-fork-if-available)))
+           ;; Spawn a server process.
+           (case pid
+             ((-1)  ;; fork not available
+               #f)
+             ((0)   ;; the kid:  serve one connection and exit
+              (let serve ((conn
+                           (false-if-exception (accept server-socket)))
+                          (count 0))
+                (if (not conn)
+                    (exit 1)
+                    (exit 0))))
+             (else  ;; the parent
+              (set! server-pid pid)
+              #t))))
+
+       (pass-if "connect abstract"
+         (if (not server-pid)
+             (throw 'unresolved)
+             (let ((s (socket AF_UNIX SOCK_STREAM 0)))
+                (display "connect abstract\n")
+               (connect s AF_UNIX path)
+               #t)))
+
+       (pass-if "accept abstract"
+         (if (not server-pid)
+             (throw 'unresolved)
+              (begin
+               (let ((status (cdr (waitpid server-pid))))
+                 (eqv? 0 (status:exit-val status))))))
+
+       #t)
 
       ;; Testing `send', `recv!' & co. on stream-oriented sockets (with
       ;; a bit of duplication with the above.)