Added support for binding to local IP addresses in ogs_sctp_client and
ogs_sctp_server, and correct SGsAP configuration
Implemented the ability to bind to one or multiple local IP addresses using
`sctp_bindx()` in both the `ogs_sctp_client()` and `ogs_sctp_server()` APIs.
Users can now specify local addresses in the configuration files under the new
`local_addresses` field, reducing unnecessary complexity and signaling caused
by binding to `ANY_ADDR`.
This update addresses issue https://osmocom.org/issues/6509 by ensuring
correct operation in multi-interface and complex networking setups.
Additionally, corrected the `sgsap` configuration by changing it
from `server` to `client`, and added support for specifying `local_addresses`
for local binding as follows:
```
sgsap:
client:
- address: msc.open5gs.org # SCTP server address configured on the MSC/VL
local_address: 127.0.0.2 # SCTP local IP addresses to be bound in the M
```
Most of the time, an application wants to perform some amount of data buffering
in addition to just responding to events. When we want to write data,
for example, the usual pattern runs something like:
1. Decide that we want to write some data to a connection;
put that data in a buffer.
2. Wait for the connection to become writable
3. Write as much of the data as we can
4. Remember how much we wrote, and if we still have more data to write,
wait for the connection to become writable again.
Now, Open5GS implements the above method by default when transmitting data
in a stream type socket.
