Extra quotation mark for unix sockets in coap_print_addr

[anyc]

Hello,

in the coap_print_addr() function, the path to a unix domain socket is enclosed in quotations marks:

libcoap/src/coap_debug.c

Line 258 in a1a16f3

snprintf((char *)buf, len, "'%s'", addr->addr.cun.sun_path);

Is there a specific reason why this is done?

In my code, I want to check over which endpoint a session has been started and I do a string comparison of the paths which becomes unnecessarily complicated with the quotation marks in my opinion. It is not a huge problem to work around this but if there is no need for the quotation marks I would open a PR to remove them. Or do you have concerns that this might break existing applications?

Thank you!

[mrdeep1]

I think when I first put this in place, I wanted to differentiate between an IP address of 1.2.3.4 and a filename of 1.2.3.4 (albeit an unlikely overlap).

Certainly when parsing a CoAP URI, this was implemented as starting with coap://%2F (i.e. implicit leading / for the file name following discussion (coap+unix:// was considered at one point)). So a filename of 1.2.3.4 is very unlikely to be used, but there is nothing stopping this being done programmatically rather than using the examples coap-client or coap-server.

coap_resolve_address_info() now checks for leading %2F or / in the host name before treating it as a Unix Domain name, so 1.2.3.4 is not ambiguous.

So, from that perspective, there is no need for the 's around around the file name.

I think it unlikely that things will get broken if the change is made. However, if coap_session_get_addr_local(session)->addr.sa.sa_family == AF_UNIX, you just need to access coap_session_get_addr_local(session)->addr.cun.sun_path to do your comparisons.

[anyc]

Thanks!