Add vendored deps

vendor/git.autistici.org/ai3/go-common/clientutil/backend.go

+package clientutil
+
+import (
+	"crypto/tls"
+	"fmt"
+	"net/http"
+	"net/url"
+	"sync"
+	"time"
+)
+
+// BackendConfig specifies the configuration to access a service.
+//
+// Services with multiple backends can be replicated or partitioned,
+// depending on a configuration switch, making it a deployment-time
+// decision. Clients are expected to compute their own sharding
+// function (either by database lookup or other methods), and expose a
+// 'shard' parameter on their APIs.
+type BackendConfig struct {
+	URL       string           `yaml:"url"`
+	Sharded   bool             `yaml:"sharded"`
+	TLSConfig *TLSClientConfig `yaml:"tls_config"`
+}
+
+// Backend is a runtime class that provides http Clients for use with
+// a specific service backend. If the service can't be partitioned,
+// pass an empty string to the Client method.
+type Backend interface {
+	// URL for the service for a specific shard.
+	URL(string) string
+
+	// Client that can be used to make a request to the service.
+	Client(string) *http.Client
+}
+
+// NewBackend returns a new Backend with the given config.
+func NewBackend(config *BackendConfig) (Backend, error) {
+	u, err := url.Parse(config.URL)
+	if err != nil {
+		return nil, err
+	}
+
+	var tlsConfig *tls.Config
+	if config.TLSConfig != nil {
+		tlsConfig, err = config.TLSConfig.TLSConfig()
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	if config.Sharded {
+		return &replicatedClient{
+			u: u,
+			c: newHTTPClient(u, tlsConfig),
+		}, nil
+	}
+	return &shardedClient{
+		baseURL:   u,
+		tlsConfig: tlsConfig,
+		urls:      make(map[string]*url.URL),
+		shards:    make(map[string]*http.Client),
+	}, nil
+}
+
+type replicatedClient struct {
+	c *http.Client
+	u *url.URL
+}
+
+func (r *replicatedClient) Client(_ string) *http.Client { return r.c }
+func (r *replicatedClient) URL(_ string) string          { return r.u.String() }
+
+type shardedClient struct {
+	baseURL   *url.URL
+	tlsConfig *tls.Config
+	mx        sync.Mutex
+	urls      map[string]*url.URL
+	shards    map[string]*http.Client
+}
+
+func (s *shardedClient) getShardURL(shard string) *url.URL {
+	if shard == "" {
+		return s.baseURL
+	}
+	u, ok := s.urls[shard]
+	if !ok {
+		var tmp = *s.baseURL
+		tmp.Host = fmt.Sprintf("%s.%s", shard, tmp.Host)
+		u = &tmp
+		s.urls[shard] = u
+	}
+	return u
+}
+
+func (s *shardedClient) URL(shard string) string {
+	s.mx.Lock()
+	defer s.mx.Unlock()
+	return s.getShardURL(shard).String()
+}
+
+func (s *shardedClient) Client(shard string) *http.Client {
+	s.mx.Lock()
+	defer s.mx.Unlock()
+
+	client, ok := s.shards[shard]
+	if !ok {
+		u := s.getShardURL(shard)
+		client = newHTTPClient(u, s.tlsConfig)
+		s.shards[shard] = client
+	}
+	return client
+}
+
+func newHTTPClient(u *url.URL, tlsConfig *tls.Config) *http.Client {
+	return &http.Client{
+		Transport: NewTransport([]string{u.Host}, tlsConfig, nil),
+		Timeout:   30 * time.Second,
+	}
+}

vendor/git.autistici.org/ai3/go-common/clientutil/json.go

+package clientutil
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"net/http"
+)
+
+// DoJSONHTTPRequest makes an HTTP POST request to the specified uri,
+// with a JSON-encoded request body. It will attempt to decode the
+// response body as JSON.
+func DoJSONHTTPRequest(ctx context.Context, client *http.Client, uri string, req, resp interface{}) error {
+	data, err := json.Marshal(req)
+	if err != nil {
+		return err
+	}
+
+	httpReq, err := http.NewRequest("POST", uri, bytes.NewReader(data))
+	if err != nil {
+		return err
+	}
+	httpReq.Header.Set("Content-Type", "application/json")
+	httpReq = httpReq.WithContext(ctx)
+
+	httpResp, err := RetryHTTPDo(client, httpReq, NewExponentialBackOff())
+	if err != nil {
+		return err
+	}
+	defer httpResp.Body.Close()
+
+	if httpResp.StatusCode != 200 {
+		return fmt.Errorf("HTTP status %d", httpResp.StatusCode)
+	}
+	if httpResp.Header.Get("Content-Type") != "application/json" {
+		return errors.New("not a JSON response")
+	}
+
+	if resp == nil {
+		return nil
+	}
+	return json.NewDecoder(httpResp.Body).Decode(resp)
+}

vendor/git.autistici.org/ai3/go-common/clientutil/retry.go

+package clientutil
+
+import (
+	"errors"
+	"net/http"
+	"time"
+
+	"github.com/cenkalti/backoff"
+)
+
+// NewExponentialBackOff creates a backoff.ExponentialBackOff object
+// with our own default values.
+func NewExponentialBackOff() *backoff.ExponentialBackOff {
+	b := backoff.NewExponentialBackOff()
+	b.InitialInterval = 100 * time.Millisecond
+	//b.Multiplier = 1.4142
+	return b
+}
+
+// A temporary (retriable) error is something that has a Temporary method.
+type tempError interface {
+	Temporary() bool
+}
+
+type tempErrorWrapper struct {
+	error
+}
+
+func (t tempErrorWrapper) Temporary() bool { return true }
+
+// TempError makes a temporary (retriable) error out of a normal error.
+func TempError(err error) error {
+	return tempErrorWrapper{err}
+}
+
+// Retry operation op until it succeeds according to the backoff
+// policy b.
+//
+// Note that this function reverses the error semantics of
+// backoff.Operation: all errors are permanent unless explicitly
+// marked as temporary (i.e. they have a Temporary() method that
+// returns true). This is to better align with the errors returned by
+// the net package.
+func Retry(op backoff.Operation, b backoff.BackOff) error {
+	innerOp := func() error {
+		err := op()
+		if err == nil {
+			return err
+		}
+		if tmpErr, ok := err.(tempError); ok && tmpErr.Temporary() {
+			return err
+		}
+		return backoff.Permanent(err)
+	}
+	return backoff.Retry(innerOp, b)
+}
+
+var errHTTPBackOff = TempError(errors.New("temporary http error"))
+
+func isStatusTemporary(code int) bool {
+	switch code {
+	case http.StatusTooManyRequests, http.StatusBadGateway, http.StatusServiceUnavailable, http.StatusGatewayTimeout:
+		return true
+	default:
+		return false
+	}
+}
+
+// RetryHTTPDo retries an HTTP request until it succeeds, according to
+// the backoff policy b. It will retry on temporary network errors and
+// upon receiving specific temporary HTTP errors. It will use the
+// context associated with the HTTP request object.
+func RetryHTTPDo(client *http.Client, req *http.Request, b backoff.BackOff) (*http.Response, error) {
+	var resp *http.Response
+	op := func() error {
+		// Clear up previous response if set.
+		if resp != nil {
+			resp.Body.Close()
+		}
+
+		var err error
+		resp, err = client.Do(req)
+		if err == nil && isStatusTemporary(resp.StatusCode) {
+			resp.Body.Close()
+			return errHTTPBackOff
+		}
+		return err
+	}
+
+	err := Retry(op, backoff.WithContext(b, req.Context()))
+	return resp, err
+}

vendor/git.autistici.org/ai3/go-common/clientutil/tls.go

+package clientutil
+
+import (
+	"crypto/tls"
+
+	common "git.autistici.org/ai3/go-common"
+)
+
+// TLSClientConfig defines the TLS parameters for a client connection
+// that should use a client X509 certificate for authentication.
+type TLSClientConfig struct {
+	Cert string `yaml:"cert"`
+	Key  string `yaml:"key"`
+	CA   string `yaml:"ca"`
+}
+
+// TLSConfig returns a tls.Config object with the current configuration.
+func (c *TLSClientConfig) TLSConfig() (*tls.Config, error) {
+	cert, err := tls.LoadX509KeyPair(c.Cert, c.Key)
+	if err != nil {
+		return nil, err
+	}
+	tlsConf := &tls.Config{
+		Certificates: []tls.Certificate{cert},
+	}
+
+	if c.CA != "" {
+		cas, err := common.LoadCA(c.CA)
+		if err != nil {
+			return nil, err
+		}
+		tlsConf.RootCAs = cas
+	}
+	tlsConf.BuildNameToCertificate()
+
+	return tlsConf, nil
+}

vendor/git.autistici.org/ai3/go-common/clientutil/transport.go

+package clientutil
+
+import (
+	"context"
+	"crypto/tls"
+	"errors"
+	"log"
+	"net"
+	"net/http"
+	"sync"
+	"time"
+)
+
+var errAllBackendsFailed = errors.New("all backends failed")
+
+type dnsResolver struct{}
+
+func (r *dnsResolver) ResolveIPs(hosts []string) []string {
+	var resolved []string
+	for _, hostport := range hosts {
+		host, port, err := net.SplitHostPort(hostport)
+		if err != nil {
+			log.Printf("error parsing %s: %v", hostport, err)
+			continue
+		}
+		hostIPs, err := net.LookupIP(host)
+		if err != nil {
+			log.Printf("error resolving %s: %v", host, err)
+			continue
+		}
+		for _, ip := range hostIPs {
+			resolved = append(resolved, net.JoinHostPort(ip.String(), port))
+		}
+	}
+	return resolved
+}
+
+var defaultResolver = &dnsResolver{}
+
+type resolver interface {
+	ResolveIPs([]string) []string
+}
+
+// Balancer for HTTP connections. It will round-robin across available
+// backends, trying to avoid ones that are erroring out, until one
+// succeeds or they all fail.
+//
+// This object should not be used for load balancing of individual
+// HTTP requests: once a new connection is established, requests will
+// be sent over it until it errors out. It's meant to provide a
+// *reliable* connection to a set of equivalent backends for HA
+// purposes.
+type balancer struct {
+	hosts    []string
+	resolver resolver
+	stop     chan bool
+
+	// List of currently valid (or untested) backends, and ones
+	// that errored out at least once.
+	mx    sync.Mutex
+	addrs []string
+	ok    map[string]bool
+}
+
+var backendUpdateInterval = 60 * time.Second
+
+// Periodically update the list of available backends.
+func (b *balancer) updateProc() {
+	tick := time.NewTicker(backendUpdateInterval)
+	for {
+		select {
+		case <-b.stop:
+			return
+		case <-tick.C:
+			resolved := b.resolver.ResolveIPs(b.hosts)
+			if len(resolved) > 0 {
+				b.mx.Lock()
+				b.addrs = resolved
+				b.mx.Unlock()
+			}
+		}
+	}
+}
+
+// Returns a list of all available backends, split into "good ones"
+// (no errors seen since last successful connection) and "bad ones".
+func (b *balancer) getBackends() ([]string, []string) {
+	b.mx.Lock()
+	defer b.mx.Unlock()
+
+	var good, bad []string
+	for _, addr := range b.addrs {
+		if ok := b.ok[addr]; ok {
+			good = append(good, addr)
+		} else {
+			bad = append(bad, addr)
+		}
+	}
+	return good, bad
+}
+
+func (b *balancer) notify(addr string, ok bool) {
+	b.mx.Lock()
+	b.ok[addr] = ok
+	b.mx.Unlock()
+}
+
+func netDialContext(ctx context.Context, network, addr string) (net.Conn, error) {
+	timeout := 30 * time.Second
+	// Go < 1.9 does not have net.DialContext, reimplement it in
+	// terms of net.DialTimeout.
+	if deadline, ok := ctx.Deadline(); ok {
+		timeout = time.Until(deadline)
+	}
+	return net.DialTimeout(network, addr, timeout)
+}
+
+func (b *balancer) dial(ctx context.Context, network, addr string) (net.Conn, error) {
+	// Start by attempting a connection on 'good' targets.
+	good, bad := b.getBackends()
+
+	for _, addr := range good {
+		// Go < 1.9 does not have DialContext, deal with it
+		conn, err := netDialContext(ctx, network, addr)
+		if err == nil {
+			return conn, nil
+		} else if err == context.Canceled {
+			// A timeout might be bad, set the error bit
+			// on the connection.
+			b.notify(addr, false)
+			return nil, err
+		}
+		b.notify(addr, false)
+	}
+
+	for _, addr := range bad {
+		conn, err := netDialContext(ctx, network, addr)
+		if err == nil {
+			b.notify(addr, true)
+			return conn, nil
+		} else if err == context.Canceled {
+			return nil, err
+		}
+	}
+
+	return nil, errAllBackendsFailed
+}
+
+// NewTransport returns a suitably configured http.RoundTripper that
+// talks to a specific backend service. It performs discovery of
+// available backends via DNS (using A or AAAA record lookups), tries
+// to route traffic away from faulty backends.
+//
+// It will periodically attempt to rediscover new backends.
+func NewTransport(backends []string, tlsConf *tls.Config, resolver resolver) http.RoundTripper {
+	if resolver == nil {
+		resolver = defaultResolver
+	}
+	addrs := resolver.ResolveIPs(backends)
+	b := &balancer{
+		hosts:    backends,
+		resolver: resolver,
+		addrs:    addrs,
+		ok:       make(map[string]bool),
+	}
+	go b.updateProc()
+
+	return &http.Transport{
+		DialContext:     b.dial,
+		TLSClientConfig: tlsConf,
+	}
+}

vendor/git.autistici.org/ai3/go-common/misc.go

+package common
+
+import (
+	"crypto/x509"
+	"io/ioutil"
+)
+
+// LoadCA loads a file containing CA certificates into a x509.CertPool.
+func LoadCA(path string) (*x509.CertPool, error) {
+	data, err := ioutil.ReadFile(path)
+	if err != nil {
+		return nil, err
+	}
+	cas := x509.NewCertPool()
+	cas.AppendCertsFromPEM(data)
+	return cas, nil
+}

vendor/git.autistici.org/ai3/go-common/serverutil/http.go

+package serverutil
+
+import (
+	"context"
+	"crypto/tls"
+	"io"
+	"log"
+	"net"
+	"net/http"
+	"net/http/pprof"
+	"os"
+	"os/signal"
+	"syscall"
+	"time"
+
+	"github.com/coreos/go-systemd/daemon"
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+)
+
+var gracefulShutdownTimeout = 3 * time.Second
+
+// ServerConfig stores common HTTP/HTTPS server configuration parameters.
+type ServerConfig struct {
+	TLS                 *TLSServerConfig `yaml:"tls"`
+	MaxInflightRequests int              `yaml:"max_inflight_requests"`
+	TrustedForwarders   []string         `yaml:"trusted_forwarders"`
+}
+
+func (config *ServerConfig) buildHTTPServer(h http.Handler) (*http.Server, error) {
+	var tlsConfig *tls.Config
+	var err error
+	if config != nil {
+		if config.TLS != nil {
+			tlsConfig, err = config.TLS.TLSConfig()
+			if err != nil {
+				return nil, err
+			}
+			h, err = config.TLS.TLSAuthWrapper(h)
+			if err != nil {
+				return nil, err
+			}
+		}
+
+		// If TrustedForwarders is defined, rewrite the request
+		// headers using X-Forwarded-Proto and X-Real-IP.
+		if len(config.TrustedForwarders) > 0 {
+			h, err = newProxyHeaders(h, config.TrustedForwarders)
+			if err != nil {
+				return nil, err
+			}
+		}
+
+		// If MaxInflightRequests is set, enable the load
+		// shedding wrapper.
+		if config.MaxInflightRequests > 0 {
+			h = newLoadSheddingWrapper(config.MaxInflightRequests, h)
+		}
+	}
+
+	// These are not meant to be external-facing servers, so we
+	// can be generous with the timeouts to keep the number of
+	// reconnections low.
+	return &http.Server{
+		Handler:      defaultHandler(h),
+		ReadTimeout:  30 * time.Second,
+		WriteTimeout: 30 * time.Second,
+		IdleTimeout:  600 * time.Second,
+		TLSConfig:    tlsConfig,
+	}, nil
+}
+
+// Serve HTTP(S) content on the specified address. If config.TLS is
+// not nil, enable HTTPS and TLS authentication.
+//
+// This function will return an error if there are problems creating
+// the listener, otherwise it will handle graceful termination on
+// SIGINT or SIGTERM and return nil.
+func Serve(h http.Handler, config *ServerConfig, addr string) error {
+	// Create the HTTP server.
+	srv, err := config.buildHTTPServer(h)
+	if err != nil {
+		return err
+	}
+
+	// Create the net.Listener first, so we can detect
+	// initialization-time errors safely.
+	l, err := net.Listen("tcp", addr)
+	if err != nil {
+		return err
+	}
+	if srv.TLSConfig != nil {
+		l = tls.NewListener(l, srv.TLSConfig)
+	}
+
+	// Install a signal handler for gentle process termination.
+	done := make(chan struct{})
+	sigCh := make(chan os.Signal, 1)
+	go func() {
+		<-sigCh
+		log.Printf("exiting")
+
+		// Gracefully terminate for 3 seconds max, then shut
+		// down remaining clients.
+		ctx, cancel := context.WithTimeout(context.Background(),<