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path: root/src/resolve/resolved-dns-transaction.c
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2015-08-03sd-event: make sure sd_event_now() cannot failLennart Poettering
Previously, if the event loop never ran before sd_event_now() would fail. With this change it will instead fall back to invoking now(). This way, the function cannot fail anymore, except for programming error when invoking it with wrong parameters. This takes into account the fact that many callers did not handle the error condition correctly, and if the callers did, then they kept simply invoking now() as fall back on their own. Hence let's shorten the code using this call, and make things more robust, and let's just fall back to now() internally. Whether now() is used or the cache timestamp may still be detected via the return value of sd_event_now(). If > 0 is returned, then the fall back to now() was used, if == 0 is returned, then the cached value was returned. This patch also simplifies many of the invocations of sd_event_now(): the manual fall back to now() can be removed. Also, in cases where the call is invoked withing void functions we can now protect the invocation via assert_se(), acknowledging the fact that the call cannot fail anymore except for programming errors with the parameters. This change is inspired by #841.
2015-08-03resolved: transaction - exponentially increase retry timeoutsTom Gundersen
Rather than fixing this to 5s for unicast DNS and 1s for LLMNR, start at a tenth of those values and increase exponentially until the old values are reached. For LLMNR the recommended timeout for IEEE802 networks (which basically means all of the ones we care about) is 100ms, so that should be uncontroversial. For unicast DNS I have found no recommended value. However, it seems vastly more likely that hitting a 500ms timeout is casued by a packet loss, rather than the RTT genuinely being greater than 500ms, so taking this as a startnig value seems reasonable to me. In the common case this greatly reduces the latency due to normal packet loss. Moreover, once we get support for probing for features, this means that we can send more packets before degrading the feature level whilst still allowing us to settle on the correct feature level in a reasonable timeframe. The timeouts are tracked per server (or per scope for the multicast protocols), and once a server (or scope) receives a successfull package the timeout is reset. We also track the largest RTT for the given server/scope, and always start our timouts at twice the largest observed RTT.
2015-07-28resolved: compare dns question arrays properlyLennart Poettering
Let's optimize things a bit and properly compare DNS question arrays, instead of checking if they are mutual supersets. This also makes ANY query handling more accurate.
2015-07-27resolved: transaction - don't explicitly verify packet sourceTom Gundersen
This is handled by the kernel now that the socket is connect()ed.
2015-07-27resolved: transaction - don't unref server when creating TCP socketTom Gundersen
This was a bug.
2015-07-27resolved: transaction - introduce dns_transaction_emit()Tom Gundersen
This function emits the UDP packet via the scope, but first it will determine the current server (and connect to it) and store the server in the transaction. This should not change the behavior, but simplifies the code.
2015-07-27resolved: transaction - move a couple of functionsTom Gundersen
No functional change, but makes follow-up patch clearer.
2015-07-27resolved: transaction - move DNS UDP socket creation to the scopeTom Gundersen
With access to the server when creating the socket, we can connect() to the server and hence simplify message sending and receiving in follow-up patches.
2015-07-27resolved: transaction - close socket when changing serverTom Gundersen
Close the socket when changing the server in a transaction, in order for it to be reopened with the right server when we send the next packet. This fixes a regression where we could get stuck with a failing server.
2015-07-27resolved: transaction - don't request PKTINFO for unicast DNSTom Gundersen
This was only ever used by LLMNR, so don't request this for unicast DNS packets.
2015-07-27resloved: transaction - unify IPv4 and IPv6 socketsTom Gundersen
A transaction can only have one socket at a time, so no need to distinguish these.
2015-07-23resolve: transaction - stop processing packet when found to be invalidTom Gundersen
We were stopping the transaction, but we need to stop processing the packet alltogether.
2015-07-14resolved: use one UDP socket per transactionTom Gundersen
We used to have one global socket, use one per transaction instead. This has the side-effect of giving us a random UDP port per transaction, and hence increasing the entropy and making cache poisoining significantly harder to achieve. We still reuse the same port number for packets belonging to the same transaction (resent packets).
2015-07-14resolved: implement RFC5452Tom Gundersen
This improves the resilience against cache poisoning by being stricter about only accepting responses that match precisely the requst they are in reply to. It should be noted that we still only use one port (which is picked at random), rather than one port for each transaction. Port randomization would improve things further, but is not required by the RFC.
2015-07-14resolved: pin the server used in a transactionTom Gundersen
We want to discover information about the server and use that in when crafting packets to be resent.
2015-07-13resolved: separate LLMNR specific header bitsDaniel Mack
The C and T bits in the DNS packet header definitions are specific to LLMNR. In regular DNS, they are called AA and RD instead. Reflect that by calling the macros accordingly, and alias LLMNR specific macros. While at it, define RA, AD and CD getters as well.
2015-07-13resolved: use a #define for LLMNR portDaniel Mack
De-duplicate some magic numbers.
2015-04-11shared: add random-util.[ch]Ronny Chevalier
2015-03-27fix gcc warnings about uninitialized variablesHarald Hoyer
like: src/shared/install.c: In function ‘unit_file_lookup_state’: src/shared/install.c:1861:16: warning: ‘r’ may be used uninitialized in this function [-Wmaybe-uninitialized] return r < 0 ? r : state; ^ src/shared/install.c:1796:13: note: ‘r’ was declared here int r; ^
2014-09-15hashmap: introduce hash_ops to make struct Hashmap smallerMichal Schmidt
It is redundant to store 'hash' and 'compare' function pointers in struct Hashmap separately. The functions always comprise a pair. Store a single pointer to struct hash_ops instead. systemd keeps hundreds of hashmaps, so this saves a little bit of memory.
2014-08-11resolved: actually, the peer with the lower IP address wins conflictsLennart Poettering
2014-08-11resolved: make sure we don't mark the wrong zone RRs conflictingLennart Poettering
2014-08-11resolved: be a bit more communicative about conflictsLennart Poettering
2014-08-11resolved: implement full LLMNR conflict detection logicLennart Poettering
2014-08-05resolved: don't abort if a transaction is aborted because its scope is removedLennart Poettering
2014-08-05resolved: add 100ms initial jitter to all LLMNR requestsLennart Poettering
2014-08-05resolved: when sending fails, don't try connecting to the next DNS server if ↵Lennart Poettering
we actually use LLMNR as protocol
2014-08-05resolved: bypass local cache when we issue a transaction for verification ↵Lennart Poettering
purposes
2014-08-01resolved: flush cache each time we change to a different DNS serverLennart Poettering
2014-08-01resolved: use CLOCK_BOOTTIME instead of CLOCK_MONOTONIC when aging caches ↵Lennart Poettering
and timeing out transactions That way the cache doens't get confused when the system is suspended.
2014-07-31resolved: implement LLMNR uniqueness verificationLennart Poettering