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@ -23,10 +23,16 @@ |
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#include <ares.h> |
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#include "absl/strings/str_cat.h" |
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#include "absl/types/optional.h" |
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#include "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.h" |
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#include "src/core/ext/filters/client_channel/server_address.h" |
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#include "src/core/lib/gprpp/orphanable.h" |
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#include "src/core/lib/iomgr/iomgr.h" |
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#include "src/core/lib/iomgr/polling_entity.h" |
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#include "src/core/lib/iomgr/resolve_address.h" |
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#include "src/core/lib/iomgr/timer.h" |
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#include "src/core/lib/iomgr/work_serializer.h" |
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#define GRPC_DNS_ARES_DEFAULT_QUERY_TIMEOUT_MS 120000 |
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@ -42,61 +48,284 @@ extern grpc_core::TraceFlag grpc_trace_cares_resolver; |
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} \
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} while (0) |
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typedef struct grpc_ares_request grpc_ares_request; |
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/* Asynchronously resolve \a name. Use \a default_port if a port isn't
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designated in \a name, otherwise use the port in \a name. grpc_ares_init() |
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must be called at least once before this function. \a on_done may be |
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called directly in this function without being scheduled with \a exec_ctx, |
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so it must not try to acquire locks that are being held by the caller. */ |
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extern void (*grpc_resolve_address_ares)(const char* name, |
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const char* default_port, |
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grpc_pollset_set* interested_parties, |
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grpc_closure* on_done, |
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grpc_resolved_addresses** addresses); |
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/* Asynchronously resolve \a name. It will try to resolve grpclb SRV records in
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addition to the normal address records. For normal address records, it uses |
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\a default_port if a port isn't designated in \a name, otherwise it uses the |
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port in \a name. grpc_ares_init() must be called at least once before this |
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function. \a on_done may be called directly in this function without being |
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scheduled with \a exec_ctx, so it must not try to acquire locks that are |
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being held by the caller. The returned grpc_ares_request object is owned |
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by the caller and it is safe to free after on_done is called back. */ |
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extern grpc_ares_request* (*grpc_dns_lookup_ares_locked)( |
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const char* dns_server, const char* name, const char* default_port, |
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grpc_pollset_set* interested_parties, grpc_closure* on_done, |
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namespace grpc_core { |
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/// An AresRequest is a handle over a complete name resolution process
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/// (A queries, AAAA queries, etc.). An AresRequest is created with a call
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/// to LookupAresLocked, and the name resolution process begins when
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/// it's created. The name resolution process can be terminated abruptly
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/// by invoking \a Orphan. The \a interested_parties parameter must remain
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/// alive until either the \a Orphan is invoked, or \a on_done is called,
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/// whichever happens first.
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class AresRequest final : public InternallyRefCounted<AresRequest> { |
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public: |
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static OrphanablePtr<AresRequest> Create( |
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absl::string_view dns_server, absl::string_view name, |
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absl::string_view default_port, grpc_pollset_set* interested_parties, |
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std::function<void(grpc_error*)> on_done, |
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std::unique_ptr<grpc_core::ServerAddressList>* addrs, |
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std::unique_ptr<grpc_core::ServerAddressList>* balancer_addrs, |
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absl::optional<std::string>* service_config_json, int query_timeout_ms, |
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std::shared_ptr<grpc_core::WorkSerializer> work_serializer); |
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/// Callers should only create an AresRequest via \a LookupAresLocked, this
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/// ctor is made public only to help the factory method.
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AresRequest( |
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std::unique_ptr<grpc_core::ServerAddressList>* addresses_out, |
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std::unique_ptr<grpc_core::ServerAddressList>* balancer_addresses_out, |
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absl::optional<std::string>* service_config_json_out, |
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grpc_pollset_set* pollset_set, int query_timeout_ms, |
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std::function<void(grpc_error*)> on_done, |
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std::shared_ptr<grpc_core::WorkSerializer> work_serializer); |
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~AresRequest() final; |
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/// Unref and Cancel the pending request if it's still in flight. Must be
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/// called while holding the WorkSerializer that was used to call \a
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/// LookupAresLocked.
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void Orphan() override; |
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/// Initialize the gRPC ares wrapper. Must be called at least once before
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/// ResolveAddressAres().
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static grpc_error* Init(void); |
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/// Uninitialized the gRPC ares wrapper. If there was more than one previous
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/// call to AresInit(), this function uninitializes the gRPC ares
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/// wrapper only if it has been called the same number of times as
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/// AresInit().
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static void Shutdown(void); |
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private: |
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/// Tracks state needed to perform one A or AAAA lookup with the c-ares lib.
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/// Note that \a Create both constructs an AddressQuery object and arranges
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/// for it's deletion.
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class AddressQuery final { |
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public: |
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static void Create(AresRequest* request, const std::string& host, |
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uint16_t port, bool is_balancer, int address_family); |
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~AddressQuery(); |
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private: |
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AddressQuery(AresRequest* request, const std::string& host, uint16_t port, |
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bool is_balancer, int address_family); |
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static void OnHostByNameDoneLocked(void* arg, int status, int timeouts, |
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struct hostent* hostent); |
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// the request which spawned this query
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AresRequest* request_; |
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// host to resolve
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const std::string host_; |
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// port to use in resulting socket addresses, in network byte order
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const uint16_t port_; |
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// is it a grpclb address
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const bool is_balancer_; |
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// for logging and errors: the query type ("A" or "AAAA")
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const char* qtype_; |
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// the address family (AF_INET or AF_INET6)
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const int address_family_; |
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}; |
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/// Tracks state needed to perform one SRV lookup with the c-ares lib.
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/// Note that \a Create both constructs an AddressQuery object and arranges
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/// for it's deletion.
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class SRVQuery final { |
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public: |
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static void Create(AresRequest* request); |
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~SRVQuery(); |
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private: |
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explicit SRVQuery(AresRequest* request); |
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static void OnSRVQueryDoneLocked(void* arg, int status, int timeouts, |
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unsigned char* abuf, int alen); |
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// the request which spawned this query
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AresRequest* request_; |
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}; |
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/// Tracks state needed to perform one TXT lookup with the c-ares lib.
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/// Note that \a Create both constructs an AddressQuery object and arranges
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/// for it's deletion.
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class TXTQuery final { |
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public: |
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static void Create(AresRequest* request); |
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~TXTQuery(); |
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private: |
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explicit TXTQuery(AresRequest* request); |
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static void OnTXTDoneLocked(void* arg, int status, int timeouts, |
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unsigned char* buf, int len); |
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// the request which spawned this query
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AresRequest* request_; |
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}; |
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// An FdNode tracks an fd and its relevant state for polling it as
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// needed to carry out a c-ares resolution.
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class FdNode final { |
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public: |
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FdNode(RefCountedPtr<AresRequest> request, |
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std::unique_ptr<grpc_core::GrpcPolledFd> grpc_polled_fd); |
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~FdNode(); |
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void MaybeRegisterForOnReadableLocked(); |
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void MaybeRegisterForOnWritableLocked(); |
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void MaybeShutdownLocked(absl::string_view reason); |
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bool IsActiveLocked(); |
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bool shutdown() { return shutdown_; } |
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GrpcPolledFd* grpc_polled_fd() { return grpc_polled_fd_.get(); } |
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private: |
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void OnReadableLocked(grpc_error* error); |
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static void OnReadable(void* arg, grpc_error* error); |
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void OnWritableLocked(grpc_error* error); |
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static void OnWritable(void* arg, grpc_error* error); |
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RefCountedPtr<AresRequest> request_; |
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// a closure wrapping OnReadableLocked, which should be
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// invoked when the fd in this node becomes readable.
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grpc_closure read_closure_; |
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// a closure wrapping OnWritableLocked, which should be
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// invoked when the fd in this node becomes writable.
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grpc_closure write_closure_; |
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// wrapped fd that's polled by grpc's poller for the current platform
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std::unique_ptr<grpc_core::GrpcPolledFd> grpc_polled_fd_; |
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// if the readable closure has been registered
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bool readable_registered_ = false; |
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// if the writable closure has been registered
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bool writable_registered_ = false; |
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// if the fd has been shutdown yet from grpc iomgr perspective
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bool shutdown_ = false; |
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}; |
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void ShutdownIOLocked(absl::string_view reason); |
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grpc_millis CalculateNextAresBackupPollAlarm() const; |
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void OnTimeoutLocked(grpc_error* error); |
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static void OnTimeout(void* arg, grpc_error* error); |
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void OnAresBackupPollAlarmLocked(grpc_error* error); |
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static void OnAresBackupPollAlarm(void* arg, grpc_error* error); |
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void NotifyOnEventLocked(); |
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void ContinueAfterCheckLocalhostAndIPLiteralsLocked( |
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absl::string_view dns_server); |
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void DecrementPendingQueries(); |
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void MaybeCallOnDoneLocked(); |
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bool ResolveAsIPLiteralLocked(); |
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bool MaybeResolveLocalHostManuallyLocked(); |
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std::string srv_qname() const { |
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return absl::StrCat("_grpclb._tcp.", target_host_); |
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} |
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std::string txt_qname() const { |
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return absl::StrCat("_grpc_config.", target_host_); |
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} |
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// the host component of the service name to resolve
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std::string target_host_; |
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// the numeric port number to access the service on, stored in
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// network byte order
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uint16_t target_port_ = 0; |
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// the pointer to receive the resolved addresses
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std::unique_ptr<grpc_core::ServerAddressList>* addresses_out_; |
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// the pointer to receive the resolved balancer addresses
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std::unique_ptr<grpc_core::ServerAddressList>* balancer_addresses_out_; |
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// the pointer to receive the service config in JSON
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absl::optional<std::string>* service_config_json_out_; |
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// the ares_channel owned by this request
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ares_channel channel_ = nullptr; |
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// pollset set for driving the IO events of the channel
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grpc_pollset_set* pollset_set_; |
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// work_serializer to synchronize c-ares and I/O callbacks on
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std::shared_ptr<grpc_core::WorkSerializer> work_serializer_; |
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// Number of active DNS queries (one for A, another for AAAA, etc.).
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int pending_queries_ = 0; |
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// the fds that this request is currently using.
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std::map<ares_socket_t, std::unique_ptr<FdNode>> fds_; |
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// is this request being shut down
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bool shutting_down_ = false; |
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// Owned by the ev_driver. Creates new GrpcPolledFd's
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std::unique_ptr<grpc_core::GrpcPolledFdFactory> polled_fd_factory_; |
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// query timeout in milliseconds
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int query_timeout_ms_; |
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// alarm to cancel active queries
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grpc_timer query_timeout_; |
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// cancels queries on a timeout
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grpc_closure on_timeout_locked_; |
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// alarm to poll ares_process on in case fd events don't happen
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grpc_timer ares_backup_poll_alarm_; |
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// polls ares_process on a periodic timer
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grpc_closure on_ares_backup_poll_alarm_locked_; |
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// callback to schedule when the request completes, empty means that
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// we've already scheduled the callback
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std::function<void(grpc_error*)> on_done_; |
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// the errors explaining query failures, appended to in query callbacks
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grpc_error* error_ = GRPC_ERROR_NONE; |
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}; |
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/// Asynchronously resolve \a name. Use \a default_port if a port isn't
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/// designated in \a name, otherwise use the port in \a name.
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/// AresInit() must be called at least once before this function.
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extern void (*ResolveAddressAres)(const char* name, const char* default_port, |
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grpc_pollset_set* interested_parties, |
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grpc_closure* on_done, |
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grpc_resolved_addresses** addresses); |
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/// Asynchronously resolve \a name. It will try to resolve grpclb SRV records in
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/// addition to the normal address records if \a balancer_addresses is not
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/// nullptr. For normal address records, it uses \a default_port if a port isn't
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/// designated in \a name, otherwise it uses the port in \a name. AresInit()
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/// must be called at least once before this function. The returned
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/// AresRequest is safe to destroy after \a on_done is called back.
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///
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/// TODO(apolcyn): as a part of moving to new gRPC DNS API, remove the
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/// work_serializer parameter and synchronize internally instead.
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extern OrphanablePtr<AresRequest> (*LookupAresLocked)( |
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absl::string_view dns_server, absl::string_view name, |
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absl::string_view default_port, grpc_pollset_set* interested_parties, |
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std::function<void(grpc_error*)> on_done, |
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std::unique_ptr<grpc_core::ServerAddressList>* addresses, |
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std::unique_ptr<grpc_core::ServerAddressList>* balancer_addresses, |
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char** service_config_json, int query_timeout_ms, |
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absl::optional<std::string>* service_config_json, int query_timeout_ms, |
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std::shared_ptr<grpc_core::WorkSerializer> work_serializer); |
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/* Cancel the pending grpc_ares_request \a request */ |
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extern void (*grpc_cancel_ares_request_locked)(grpc_ares_request* request); |
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/* Initialize gRPC ares wrapper. Must be called at least once before
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grpc_resolve_address_ares(). */ |
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grpc_error* grpc_ares_init(void); |
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/// Indicates whether or not AAAA queries should be attempted.
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/// E.g., return false if ipv6 is known to not be available.
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bool AresQueryIPv6(); |
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/* Uninitialized gRPC ares wrapper. If there was more than one previous call to
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grpc_ares_init(), this function uninitializes the gRPC ares wrapper only if |
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it has been called the same number of times as grpc_ares_init(). */ |
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void grpc_ares_cleanup(void); |
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/// Sorts destinations in \a addresses according to RFC 6724.
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void AddressSortingSort(const AresRequest* request, |
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ServerAddressList* addresses, |
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const std::string& logging_prefix); |
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/** Schedules the desired callback for request completion
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* and destroys the grpc_ares_request */ |
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void grpc_ares_complete_request_locked(grpc_ares_request* request); |
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namespace internal { |
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/* Indicates whether or not AAAA queries should be attempted. */ |
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/* E.g., return false if ipv6 is known to not be available. */ |
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bool grpc_ares_query_ipv6(); |
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/// Exposed in this header for C-core tests only
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extern void (*AresTestOnlyInjectConfig)(ares_channel channel); |
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/* Sorts destinations in lb_addrs according to RFC 6724. */ |
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void grpc_cares_wrapper_address_sorting_sort( |
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const grpc_ares_request* request, grpc_core::ServerAddressList* addresses); |
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} // namespace internal
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/* Exposed in this header for C-core tests only */ |
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extern void (*grpc_ares_test_only_inject_config)(ares_channel channel); |
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} // namespace grpc_core
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#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_RESOLVER_DNS_C_ARES_GRPC_ARES_WRAPPER_H \ |
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*/ |
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apolcyn
4 years ago
committed by
GitHub