[PATCH] gbproxy: Add gbprox_clear_patch_filter() (Coverity)

[Jacob Erlbeck]

Add a separate function to clear the IMSI filter to be used instead of
gbprox_set_patch_filter(cfg, NULL, ...). Albeit it fixes a Coverity
issue (Unchecked return value), it is a false positive, since the
return value is always 0 in these cases. Nevertheless it is more
obvious what happens when an explicit clear function is called. Using
NULL as filter argument of gbprox_set_patch_filter still clears the
filter.

Fixes: Coverity CID 1231255
Sponsored-by: On-Waves ehf
---
openbsc/include/openbsc/gb_proxy.h | 1 +
openbsc/src/gprs/gb_proxy.c | 13 +++++++++----
openbsc/src/gprs/gb_proxy_vty.c | 4 ++--
openbsc/tests/gbproxy/gbproxy_test.c | 6 ++++++
4 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/openbsc/include/openbsc/gb_proxy.h b/openbsc/include/openbsc/gb_proxy.h
index 039a9a1..d6dde10 100644
--- a/openbsc/include/openbsc/gb_proxy.h
+++ b/openbsc/include/openbsc/gb_proxy.h
@@ -115,6 +115,7 @@ void gbprox_reset(struct gbproxy_config *cfg);

int gbprox_set_patch_filter(struct gbproxy_config *cfg, const char *filter,
const char **err_msg);
+void gbprox_clear_patch_filter(struct gbproxy_config *cfg);

void gbprox_delete_tlli(struct gbproxy_peer *peer,
struct gbproxy_tlli_info *tlli_info);
diff --git a/openbsc/src/gprs/gb_proxy.c b/openbsc/src/gprs/gb_proxy.c
index a8ce3cc..64fb55b 100644
--- a/openbsc/src/gprs/gb_proxy.c
+++ b/openbsc/src/gprs/gb_proxy.c
@@ -481,16 +481,21 @@ static void gbprox_delete_tllis(struct gbproxy_peer *peer)
OSMO_ASSERT(llist_empty(&state->enabled_tllis));
}

+void gbprox_clear_patch_filter(struct gbproxy_config *cfg)
+{
+ if (cfg->check_imsi) {
+ regfree(&cfg->imsi_re_comp);
+ cfg->check_imsi = 0;
+ }
+}
+
int gbprox_set_patch_filter(struct gbproxy_config *cfg, const char *filter,
const char **err_msg)
{
static char err_buf[300];
int rc;

- if (cfg->check_imsi) {
- regfree(&cfg->imsi_re_comp);
- cfg->check_imsi = 0;
- }
+ gbprox_clear_patch_filter(cfg);

if (!filter)
return 0;
diff --git a/openbsc/src/gprs/gb_proxy_vty.c b/openbsc/src/gprs/gb_proxy_vty.c
index ec73ae6..9574a45 100644
--- a/openbsc/src/gprs/gb_proxy_vty.c
+++ b/openbsc/src/gprs/gb_proxy_vty.c
@@ -193,7 +193,7 @@ static int set_core_apn(struct vty *vty, const char *apn, const char *filter)
talloc_free(g_cfg->core_apn);
g_cfg->core_apn = NULL;
g_cfg->core_apn_size = 0;
- gbprox_set_patch_filter(g_cfg, NULL, NULL);
+ gbprox_clear_patch_filter(g_cfg);
return CMD_SUCCESS;
}

@@ -206,7 +206,7 @@ static int set_core_apn(struct vty *vty, const char *apn, const char *filter)
}

if (!filter) {
- gbprox_set_patch_filter(g_cfg, NULL, NULL);
+ gbprox_clear_patch_filter(g_cfg);
} else if (gbprox_set_patch_filter(g_cfg, filter, &err_msg) != 0) {
vty_out(vty, "Match expression invalid: %s%s",
err_msg, VTY_NEWLINE);
diff --git a/openbsc/tests/gbproxy/gbproxy_test.c b/openbsc/tests/gbproxy/gbproxy_test.c
index 964c6da..5363749 100644
--- a/openbsc/tests/gbproxy/gbproxy_test.c
+++ b/openbsc/tests/gbproxy/gbproxy_test.c
@@ -1571,6 +1571,12 @@ static void test_gbproxy_imsi_matching(void)
OSMO_ASSERT(gbprox_set_patch_filter(&cfg, NULL, &err_msg) == 0);
OSMO_ASSERT(cfg.check_imsi == 0);

+ OSMO_ASSERT(gbprox_set_patch_filter(&cfg, filter_re2, &err_msg) == 0);
+ OSMO_ASSERT(cfg.check_imsi == 1);
+
+ gbprox_clear_patch_filter(&cfg);
+ OSMO_ASSERT(cfg.check_imsi == 0);
+
peer = gbproxy_peer_alloc(&cfg, 20);

OSMO_ASSERT(gbprox_set_patch_filter(&cfg, filter_re2, &err_msg) == 0);