add osmo_sockaddr_str_is_nonzero()

Often, an IP address of 0.0.0.0 is considered an unset value (for clients
requiring a server address; not for listening on "any").

osmo_sockaddr_str_is_set() does return false when the port is 0, but there is
no simple way to tell whether the IP address is actually set to a server
address.

Add osmo_sockaddr_str_is_nonzero() to return false if:
- the port is zero, or
- the IP address is zero (0.0.0.0 or ::0), or
- the IP address cannot be parsed.

A practical use example: osmo-msc so far accepts an RTP IP address of 0.0.0.0
as valid. I noticed when trying to trigger error handling from a ttcn3 test.
osmo-msc can use this function to reject invalid addresses from MGCP messages.

Related: I53ddb19a70fda3deb906464e1b89c12d9b4c7cbd (osmo-msc)
Change-Id: I73cbcab90cffcdc9a5f8d5281c57c1f87b2c3550

1 files changed, 3 insertions, 0 deletions

diff --git a/tests/sockaddr_str/sockaddr_str_test.c b/tests/sockaddr_str/sockaddr_str_test.c
index d2e7944d..4284387b 100644
--- a/tests/sockaddr_str/sockaddr_str_test.c
+++ b/tests/sockaddr_str/sockaddr_str_test.c
@@ -53,6 +53,8 @@ struct osmo_sockaddr_str oip_data[] = {
 	{ .af = AF_INET, .ip = "1.2.3.4", .port = 0 },
 	{ .af = AF_INET, .ip = "1.2.3:4:5", .port = 0 },
 	{ .af = AF_INET6, .ip = "::1:10.9.8.7", .port = 1 },
+	{ .af = AF_INET, .ip = "0.0.0.0", .port = 5 },
+	{ .af = AF_INET6, .ip = "::", .port = 5 },
 };
 
 const char *af_name(int af)
@@ -106,6 +108,7 @@ void sockaddr_str_test_conversions()
 		dump_oip(x);
 
 		printf("  osmo_sockaddr_str_is_set() = %s\n", osmo_sockaddr_str_is_set(x) ? "true" : "false");
+		printf("  osmo_sockaddr_str_is_nonzero() = %s\n", osmo_sockaddr_str_is_nonzero(x) ? "true" : "false");
 
 		{
 			struct in_addr a = {};