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authorDavid Howells <dhowells@redhat.com>2018-10-04 14:27:55 +0100
committerDavid S. Miller <davem@davemloft.net>2018-10-04 09:40:52 -0700
commitbbb4c4323a4d9cb5ca04db904aa3050a7586839a (patch)
tree7737c6f82a31650e7d282f94a227cdea167599dc /include/linux/dns_resolver.h
parent0aa63eb9a904d50527cc5eadb061d16e607dd4c6 (diff)
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dns: Allow the dns resolver to retrieve a server set
Allow the DNS resolver to retrieve a set of servers and their associated addresses, ports, preference and weight ratings. In terms of communication with userspace, "srv=1" is added to the callout string (the '1' indicating the maximum data version supported by the kernel) to ask the userspace side for this. If the userspace side doesn't recognise it, it will ignore the option and return the usual text address list. If the userspace side does recognise it, it will return some binary data that begins with a zero byte that would cause the string parsers to give an error. The second byte contains the version of the data in the blob (this may be between 1 and the version specified in the callout data). The remainder of the payload is version-specific. In version 1, the payload looks like (note that this is packed): u8 Non-string marker (ie. 0) u8 Content (0 => Server list) u8 Version (ie. 1) u8 Source (eg. DNS_RECORD_FROM_DNS_SRV) u8 Status (eg. DNS_LOOKUP_GOOD) u8 Number of servers foreach-server { u16 Name length (LE) u16 Priority (as per SRV record) (LE) u16 Weight (as per SRV record) (LE) u16 Port (LE) u8 Source (eg. DNS_RECORD_FROM_NSS) u8 Status (eg. DNS_LOOKUP_GOT_NOT_FOUND) u8 Protocol (eg. DNS_SERVER_PROTOCOL_UDP) u8 Number of addresses char[] Name (not NUL-terminated) foreach-address { u8 Family (AF_INET{,6}) union { u8[4] ipv4_addr u8[16] ipv6_addr } } } This can then be used to fetch a whole cell's VL-server configuration for AFS, for example. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/linux/dns_resolver.h')
-rw-r--r--include/linux/dns_resolver.h4
1 files changed, 1 insertions, 3 deletions
diff --git a/include/linux/dns_resolver.h b/include/linux/dns_resolver.h
index 6ac3cad9aef1..34a744a1bafc 100644
--- a/include/linux/dns_resolver.h
+++ b/include/linux/dns_resolver.h
@@ -24,11 +24,9 @@
#ifndef _LINUX_DNS_RESOLVER_H
#define _LINUX_DNS_RESOLVER_H
-#ifdef __KERNEL__
+#include <uapi/linux/dns_resolver.h>
extern int dns_query(const char *type, const char *name, size_t namelen,
const char *options, char **_result, time64_t *_expiry);
-#endif /* KERNEL */
-
#endif /* _LINUX_DNS_RESOLVER_H */