Allow connecting from clients with different user id

Makefile-docs.am

@@ -1,7 +1,6 @@
 XSLTPROC = xsltproc
 
 XSLTPROC_FLAGS = \
-	--nonet \
 	--stringparam man.output.quietly 1 \
 	--stringparam funcsynopsis.style ansi \
 	--stringparam man.th.extra1.suppress 1 \

README.md

@@ -4,3 +4,32 @@ xdg-dbus-proxy
 xdg-dbus-proxy is a filtering proxy for D-Bus connections. It was originally
 part of the flatpak project, but it has been broken out as a standalone module
 to facilitate using it in other contexts.
+
+Building
+--------
+
+You need to have autotools installed. On Debian, don't forget to install 
+`autoconf-archive` too.
+
+- Run `./autogen.sh`. It will generate configure script and Makefile
+- Run `./configure` (see `./configure --help` for additional options)
+- Run `make`
+- Run `make install`
+
+To build debug version you can add flags to make, for example: 
+
+	make -e CFLAGS="-g -O0 -fsanitize=address" LDFLAGS="-fsanitize=address"
+
+Usage example
+-------------
+
+Start proxy with:
+
+	xdg-dbus-proxy "$DBUS_SESSION_BUS_ADDRESS" /tmp/proxy.socket --log 
+
+Test it using: 
+
+	DBUS_SESSION_BUS_ADDRESS=unix:path=/tmp/proxy.socket dbus-send --session --dest=org.freedesktop.DBus --print-reply /org/freedesktop/DBus org.freedesktop.DBus.ListNames
+
+This will display a list of D-Bus names visible through the proxy. You can 
+also use programs like D-Feet to examine the bus.

dbus-proxy.c

@@ -29,6 +29,7 @@
 #include <sys/stat.h>
 #include <errno.h>
 #include <locale.h>
+#include <ctype.h>
 
 #include "flatpak-proxy.h"
 // Taken from glibc unistd.h
@@ -49,7 +50,7 @@ static void usage (int ecode, FILE *out) G_GNUC_NORETURN;
 static void
 usage (int ecode, FILE *out)
 {
-  fprintf (out, "usage: %s [OPTIONS...] [ADDRESS PATH [OPTIONS...] ...]\n\n", argv0);
+  fprintf (out, "usage: %s [OPTIONS...] [BUS_ADDRESS LISTEN_SOCKET_PATH [OPTIONS...] ...]\n\n", argv0);
 
   fprintf (out,
            "Options:\n"
@@ -66,6 +67,8 @@ usage (int ecode, FILE *out)
            "    --own=NAME                   Set 'own' policy for NAME\n"
            "    --call=NAME=RULE             Set RULE for calls on NAME\n"
            "    --broadcast=NAME=RULE        Set RULE for broadcasts from NAME\n"
+           "    --accept-uids=UID1,UID2,...  Accept connections made only by processes with these "
+           "user ids\n"
           );
   exit (ecode);
 }
@@ -225,6 +228,66 @@ parse_generic_args (GPtrArray *args, int *args_i)
     }
 }
 
+#define PIL_ERROR_LENGTH 200
+static char pil_error[PIL_ERROR_LENGTH] = "\0";
+
+/**
+ * Parses a comma-separated list of non-negative integers from 
+ * uids_string (e.g. "1,2,3") info uids array. If anything goes wrong, 
+ * writes an error message into parse_error, otherwise writes NULL to it.
+ */
+static void
+parse_int_list (const gchar *uids_string, GArray *uids, char **parse_error)
+{
+  *parse_error = NULL;
+  const gchar *ptr = uids_string;
+  gchar *endptr = NULL;
+
+  do {
+    gint64 number = g_ascii_strtoll(ptr, &endptr, 10);
+
+    if (endptr == ptr) {
+      snprintf(pil_error, PIL_ERROR_LENGTH, "expected a digit, but got character '%c' instead", ptr[0]);
+      *parse_error = pil_error;
+      return;
+    }
+
+    if (number < 0) {
+      snprintf(pil_error, PIL_ERROR_LENGTH, "numbers must be non-negative");
+      *parse_error = pil_error;
+      return;
+    }
+
+    if (number <= LONG_MIN || number >= LONG_MAX) {
+      snprintf(pil_error, PIL_ERROR_LENGTH, "number is too large");
+      *parse_error = pil_error;
+      return;
+    }
+
+    ptr = endptr;
+    gint inserted_number = (gint)number;
+    g_array_append_val(uids, inserted_number);
+
+    while (ptr[0] != '\0') {
+      char ch = ptr[0];
+      ptr++;
+
+      if (ch == ',') {
+        break;
+      }
+
+      if (isspace(ch)) {
+        continue;
+      }
+
+      snprintf(pil_error, PIL_ERROR_LENGTH, "expected space, end of line or comma, but got '%c'", ch);
+      *parse_error = pil_error;
+      return;
+    }
+
+  } while (ptr[0] != '\0');
+}
+
 static gboolean
 start_proxy (GPtrArray *args, int *args_i)
 {
@@ -320,6 +383,21 @@ start_proxy (GPtrArray *args, int *args_i)
 
           *args_i += 1;
         }
+      else if (g_str_has_prefix (arg, "--accept-uids="))
+        {
+          g_autofree char *uids_string = g_strdup (strchr (arg, '=') + 1);
+          g_autoptr(GArray) uids = g_array_new(FALSE, FALSE, sizeof(gint));
+          char *parse_error = NULL;
+          parse_int_list(uids_string, uids, &parse_error);
+          if (parse_error) {
+            g_printerr ("error while parsing list of integers in argument '%s': %s\n", 
+              arg, parse_error);
+            return FALSE;
+          }
+
+          flatpak_proxy_set_accepted_uids(proxy, uids);
+          *args_i += 1;
+        }
       else if (g_str_equal (arg, "--log"))
         {
           flatpak_proxy_set_log_messages (proxy, TRUE);