Tilman Baumann
2017-07-19 09:20:53 UTC
Hi folks,
I'm trying to teach a vpn software (openfortivpn) how to properly set up
DNS in a systemd-resolve environment.
I'm trying to set up a equivalent to this in C.
busctl call org.freedesktop.resolve1 /org/freedesktop/resolve1
org.freedesktop.resolve1.Manager SetLinkDNS 'ia(iay)' 16 2 2 4 10 10 10
10 2 4 10 10 10 11
[https://gist.github.com/tbaumann/d484efb2e27613654a52dbe11cfe53b8]
I came up with this quick proof of concept code based on the example
code in the sd-bus docu.
Of course it segfaults. No surprise, I have done nothing to hint at the
length of the inner byte array. (ay)
I was unable to find any example code that would give me a hint on how
to pass such more complex data structures into sd_bus_call_method()
int SetLinkDNSv4(sd_bus *bus, int if_index, struct in_addr ns1, struct
in_addr ns2) {
sd_bus_error error = SD_BUS_ERROR_NULL;
sd_bus_message *m = NULL;
int r;
struct dns_address {
int sin_family;
struct in_addr ip_addr;
};
struct dns_address addresses[2];
addresses[0].sin_family = AF_INET;
addresses[0].ip_addr = ns1;
addresses[1].sin_family = AF_INET;
addresses[1].ip_addr = ns2;
r = sd_bus_call_method(bus,
"org.freedesktop.resolve1", /*
service to contact */
"/org/freedesktop/resolve1", /* object
path */
"org.freedesktop.resolve1.Manager", /*
interface name */
"SetLinkDNS", /* method
name */
&error, /* object
to return error in */
&m, /* return
message on success */
"ia(iay)", /* input
signature */
if_index,
2, /* Array
size */
addresses);
}
[Full code:
https://gist.github.com/tbaumann/0f466c984c858767c966458d53483697]
My guess is that I can have it easier if I somehow use
sd_bus_message_append() to assemble the message. But I don't see a clear
path either.
Also, the length of the array can be one or two. So that bit is variable
too.
Thanks for any hints
Tilman Baumann
I'm trying to teach a vpn software (openfortivpn) how to properly set up
DNS in a systemd-resolve environment.
I'm trying to set up a equivalent to this in C.
busctl call org.freedesktop.resolve1 /org/freedesktop/resolve1
org.freedesktop.resolve1.Manager SetLinkDNS 'ia(iay)' 16 2 2 4 10 10 10
10 2 4 10 10 10 11
[https://gist.github.com/tbaumann/d484efb2e27613654a52dbe11cfe53b8]
I came up with this quick proof of concept code based on the example
code in the sd-bus docu.
Of course it segfaults. No surprise, I have done nothing to hint at the
length of the inner byte array. (ay)
I was unable to find any example code that would give me a hint on how
to pass such more complex data structures into sd_bus_call_method()
int SetLinkDNSv4(sd_bus *bus, int if_index, struct in_addr ns1, struct
in_addr ns2) {
sd_bus_error error = SD_BUS_ERROR_NULL;
sd_bus_message *m = NULL;
int r;
struct dns_address {
int sin_family;
struct in_addr ip_addr;
};
struct dns_address addresses[2];
addresses[0].sin_family = AF_INET;
addresses[0].ip_addr = ns1;
addresses[1].sin_family = AF_INET;
addresses[1].ip_addr = ns2;
r = sd_bus_call_method(bus,
"org.freedesktop.resolve1", /*
service to contact */
"/org/freedesktop/resolve1", /* object
path */
"org.freedesktop.resolve1.Manager", /*
interface name */
"SetLinkDNS", /* method
name */
&error, /* object
to return error in */
&m, /* return
message on success */
"ia(iay)", /* input
signature */
if_index,
2, /* Array
size */
addresses);
}
[Full code:
https://gist.github.com/tbaumann/0f466c984c858767c966458d53483697]
My guess is that I can have it easier if I somehow use
sd_bus_message_append() to assemble the message. But I don't see a clear
path either.
Also, the length of the array can be one or two. So that bit is variable
too.
Thanks for any hints
Tilman Baumann