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, 1 insertions, 0 deletions

diff --git a/include/osmocom/core/sockaddr_str.h b/include/osmocom/core/sockaddr_str.h
index d16dc86f..d47b2a4e 100644
--- a/include/osmocom/core/sockaddr_str.h
+++ b/include/osmocom/core/sockaddr_str.h
@@ -65,6 +65,7 @@ struct osmo_sockaddr_str {
 #define OSMO_SOCKADDR_STR_FMT_ARGS(R) ((R)? (R)->ip : "NULL"), ((R)? (R)->port : 0)
 
 bool osmo_sockaddr_str_is_set(const struct osmo_sockaddr_str *sockaddr_str);
+bool osmo_sockaddr_str_is_nonzero(const struct osmo_sockaddr_str *sockaddr_str);
 
 int osmo_sockaddr_str_from_str(struct osmo_sockaddr_str *sockaddr_str, const char *ip, uint16_t port);