[OpenWrt-Devel] [PATCH] fw3: robustify flow table detection.

[Rui Salvaterra]

The flowtable detection fails if the respective target module is built-in,
since it's looking for the module itself. Create a generic helper and
instead check for existence of the FLOWTABLE target in
/proc/net/ip_tables_targets.

Signed-off-by: Rui Salvaterra <rsalvate...@gmail.com>
---
 defaults.c | 24 ++++++------------------
 utils.c    | 26 ++++++++++++++++++++++++++
 utils.h    |  2 ++
 3 files changed, 34 insertions(+), 18 deletions(-)

diff --git a/defaults.c b/defaults.c
index f03765c..51ed142 100644
--- a/defaults.c
+++ b/defaults.c
@@ -85,26 +85,14 @@ check_policy(struct uci_element *e, enum fw3_flag *pol, 
const char *name)
 }
 
 static void
-check_kmod(struct uci_element *e, bool *module, const char *name)
+check_target(struct uci_element *e, bool *available, const char *target)
 {
-       FILE *f;
-       char buf[128];
-
-       if (!*module)
-               return;
-
-       snprintf(buf, sizeof(buf), "/sys/module/%s/refcnt", name);
-
-       f = fopen(buf, "r");
-
-       if (f)
+       const bool b = fw3_has_target(target);
+       if (!b)
        {
-               fclose(f);
-               return;
+               warn_elem(e, "requires unavailable target extension %s, 
disabling", target);
        }
-
-       warn_elem(e, "requires not available kernel module %s, disabling", 
name);
-       *module = false;
+       *available = b;
 }
 
 static void
@@ -171,7 +159,7 @@ fw3_load_defaults(struct fw3_state *state, struct 
uci_package *p)
 
                check_any_reject_code(e, &defs->any_reject_code);
 
-               check_kmod(e, &defs->flow_offloading, "xt_FLOWOFFLOAD");
+               check_target(e, &defs->flow_offloading, "FLOWOFFLOAD");
        }
 }
 
diff --git a/utils.c b/utils.c
index 441dbd2..df100a7 100644
--- a/utils.c
+++ b/utils.c
@@ -344,6 +344,32 @@ fw3_has_table(bool ipv6, const char *table)
        return seen;
 }
 
+bool
+fw3_has_target(const char *target)
+{
+       FILE *f;
+
+       char line[12];
+       bool seen = false;
+
+       const char *path = "/proc/net/ip_tables_targets";
+
+       if (!(f = fopen(path, "r")))
+               return false;
+
+       while (fgets(line, sizeof(line), f))
+       {
+               if (!strncmp(line, target, strlen(target)))
+               {
+                       seen = true;
+                       break;
+               }
+       }
+
+       fclose(f);
+
+       return seen;
+}
 
 bool
 fw3_lock_path(int *fd, const char *path)
diff --git a/utils.h b/utils.h
index c8cf69a..093d2c6 100644
--- a/utils.h
+++ b/utils.h
@@ -105,6 +105,8 @@ void fw3_pr(const char *fmt, ...)
 
 bool fw3_has_table(bool ipv6, const char *table);
 
+bool fw3_has_target(const char *target);
+
 bool fw3_lock(void);
 void fw3_unlock(void);
 bool fw3_lock_path(int *fw3_lock_fd, const char *path);
-- 
2.25.0


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