7e0b47311d
Rather than passing functions to construct complex objects such as Dialer and QUICDialer, pass interface implementations. Ensure that a nil implementation does not cause harm. Make Saver implement the correct interface either directly or indirectly. We need to implement the correct interface indirectly for TCP conns (or connected UDP sockets) because we have two distinct use cases inside netx: observing just the connect event and observing just the I/O events. With this change, the construction of composed Dialers and QUICDialers is greatly simplified and more obvious. Part of https://github.com/ooni/probe/issues/2121
67 lines
2.2 KiB
Go
67 lines
2.2 KiB
Go
// Package dialer allows you to create a net.Dialer-compatible
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// DialContext-enabled dialer with error wrapping, optional logging,
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// optional network-events saving, and optional proxying.
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package dialer
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import (
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"net/url"
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"github.com/ooni/probe-cli/v3/internal/bytecounter"
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"github.com/ooni/probe-cli/v3/internal/engine/netx/tracex"
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"github.com/ooni/probe-cli/v3/internal/model"
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"github.com/ooni/probe-cli/v3/internal/netxlite"
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)
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// Config contains the settings for New.
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type Config struct {
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// ContextByteCounting optionally configures context-based
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// byte counting. By default we don't do that.
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//
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// Use WithExperimentByteCounter and WithSessionByteCounter
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// to assign byte counters to a context. The code will use
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// corresponding, private functions to access the configured
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// byte counters and will notify them about I/O events.
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//
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// Bug
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//
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// This implementation cannot properly account for the bytes that are sent by
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// persistent connections, because they stick to the counters set when the
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// connection was established. This typically means we miss the bytes sent and
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// received when submitting a measurement. Such bytes are specifically not
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// seen by the experiment specific byte counter.
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//
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// For this reason, this implementation may be heavily changed/removed.
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ContextByteCounting bool
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// DialSaver is the optional saver for dialing events. If not
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// set, we will not save any dialing event.
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DialSaver *tracex.Saver
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// Logger is the optional logger. If not set, there
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// will be no logging from the new dialer.
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Logger model.DebugLogger
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// ProxyURL is the optional proxy URL.
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ProxyURL *url.URL
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// ReadWriteSaver is like DialSaver but for I/O events.
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ReadWriteSaver *tracex.Saver
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}
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// New creates a new Dialer from the specified config and resolver.
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func New(config *Config, resolver model.Resolver) model.Dialer {
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var logger model.DebugLogger = model.DiscardLogger
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if config.Logger != nil {
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logger = config.Logger
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}
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d := netxlite.NewDialerWithResolver(
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logger, resolver, config.DialSaver.NewConnectObserver(),
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config.ReadWriteSaver.NewReadWriteObserver(),
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)
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d = &netxlite.MaybeProxyDialer{ProxyURL: config.ProxyURL, Dialer: d}
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if config.ContextByteCounting {
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d = &bytecounter.ContextAwareDialer{Dialer: d}
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}
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return d
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}
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