Dependencies for the affinity router and the
affinity routing daemon.
Change-Id: Icda72c3594ef7f8f0bc0c33dc03087a4c25529ca
diff --git a/vendor/github.com/gregjones/httpcache/httpcache.go b/vendor/github.com/gregjones/httpcache/httpcache.go
new file mode 100644
index 0000000..f6a2ec4
--- /dev/null
+++ b/vendor/github.com/gregjones/httpcache/httpcache.go
@@ -0,0 +1,551 @@
+// Package httpcache provides a http.RoundTripper implementation that works as a
+// mostly RFC-compliant cache for http responses.
+//
+// It is only suitable for use as a 'private' cache (i.e. for a web-browser or an API-client
+// and not for a shared proxy).
+//
+package httpcache
+
+import (
+ "bufio"
+ "bytes"
+ "errors"
+ "io"
+ "io/ioutil"
+ "net/http"
+ "net/http/httputil"
+ "strings"
+ "sync"
+ "time"
+)
+
+const (
+ stale = iota
+ fresh
+ transparent
+ // XFromCache is the header added to responses that are returned from the cache
+ XFromCache = "X-From-Cache"
+)
+
+// A Cache interface is used by the Transport to store and retrieve responses.
+type Cache interface {
+ // Get returns the []byte representation of a cached response and a bool
+ // set to true if the value isn't empty
+ Get(key string) (responseBytes []byte, ok bool)
+ // Set stores the []byte representation of a response against a key
+ Set(key string, responseBytes []byte)
+ // Delete removes the value associated with the key
+ Delete(key string)
+}
+
+// cacheKey returns the cache key for req.
+func cacheKey(req *http.Request) string {
+ if req.Method == http.MethodGet {
+ return req.URL.String()
+ } else {
+ return req.Method + " " + req.URL.String()
+ }
+}
+
+// CachedResponse returns the cached http.Response for req if present, and nil
+// otherwise.
+func CachedResponse(c Cache, req *http.Request) (resp *http.Response, err error) {
+ cachedVal, ok := c.Get(cacheKey(req))
+ if !ok {
+ return
+ }
+
+ b := bytes.NewBuffer(cachedVal)
+ return http.ReadResponse(bufio.NewReader(b), req)
+}
+
+// MemoryCache is an implemtation of Cache that stores responses in an in-memory map.
+type MemoryCache struct {
+ mu sync.RWMutex
+ items map[string][]byte
+}
+
+// Get returns the []byte representation of the response and true if present, false if not
+func (c *MemoryCache) Get(key string) (resp []byte, ok bool) {
+ c.mu.RLock()
+ resp, ok = c.items[key]
+ c.mu.RUnlock()
+ return resp, ok
+}
+
+// Set saves response resp to the cache with key
+func (c *MemoryCache) Set(key string, resp []byte) {
+ c.mu.Lock()
+ c.items[key] = resp
+ c.mu.Unlock()
+}
+
+// Delete removes key from the cache
+func (c *MemoryCache) Delete(key string) {
+ c.mu.Lock()
+ delete(c.items, key)
+ c.mu.Unlock()
+}
+
+// NewMemoryCache returns a new Cache that will store items in an in-memory map
+func NewMemoryCache() *MemoryCache {
+ c := &MemoryCache{items: map[string][]byte{}}
+ return c
+}
+
+// Transport is an implementation of http.RoundTripper that will return values from a cache
+// where possible (avoiding a network request) and will additionally add validators (etag/if-modified-since)
+// to repeated requests allowing servers to return 304 / Not Modified
+type Transport struct {
+ // The RoundTripper interface actually used to make requests
+ // If nil, http.DefaultTransport is used
+ Transport http.RoundTripper
+ Cache Cache
+ // If true, responses returned from the cache will be given an extra header, X-From-Cache
+ MarkCachedResponses bool
+}
+
+// NewTransport returns a new Transport with the
+// provided Cache implementation and MarkCachedResponses set to true
+func NewTransport(c Cache) *Transport {
+ return &Transport{Cache: c, MarkCachedResponses: true}
+}
+
+// Client returns an *http.Client that caches responses.
+func (t *Transport) Client() *http.Client {
+ return &http.Client{Transport: t}
+}
+
+// varyMatches will return false unless all of the cached values for the headers listed in Vary
+// match the new request
+func varyMatches(cachedResp *http.Response, req *http.Request) bool {
+ for _, header := range headerAllCommaSepValues(cachedResp.Header, "vary") {
+ header = http.CanonicalHeaderKey(header)
+ if header != "" && req.Header.Get(header) != cachedResp.Header.Get("X-Varied-"+header) {
+ return false
+ }
+ }
+ return true
+}
+
+// RoundTrip takes a Request and returns a Response
+//
+// If there is a fresh Response already in cache, then it will be returned without connecting to
+// the server.
+//
+// If there is a stale Response, then any validators it contains will be set on the new request
+// to give the server a chance to respond with NotModified. If this happens, then the cached Response
+// will be returned.
+func (t *Transport) RoundTrip(req *http.Request) (resp *http.Response, err error) {
+ cacheKey := cacheKey(req)
+ cacheable := (req.Method == "GET" || req.Method == "HEAD") && req.Header.Get("range") == ""
+ var cachedResp *http.Response
+ if cacheable {
+ cachedResp, err = CachedResponse(t.Cache, req)
+ } else {
+ // Need to invalidate an existing value
+ t.Cache.Delete(cacheKey)
+ }
+
+ transport := t.Transport
+ if transport == nil {
+ transport = http.DefaultTransport
+ }
+
+ if cacheable && cachedResp != nil && err == nil {
+ if t.MarkCachedResponses {
+ cachedResp.Header.Set(XFromCache, "1")
+ }
+
+ if varyMatches(cachedResp, req) {
+ // Can only use cached value if the new request doesn't Vary significantly
+ freshness := getFreshness(cachedResp.Header, req.Header)
+ if freshness == fresh {
+ return cachedResp, nil
+ }
+
+ if freshness == stale {
+ var req2 *http.Request
+ // Add validators if caller hasn't already done so
+ etag := cachedResp.Header.Get("etag")
+ if etag != "" && req.Header.Get("etag") == "" {
+ req2 = cloneRequest(req)
+ req2.Header.Set("if-none-match", etag)
+ }
+ lastModified := cachedResp.Header.Get("last-modified")
+ if lastModified != "" && req.Header.Get("last-modified") == "" {
+ if req2 == nil {
+ req2 = cloneRequest(req)
+ }
+ req2.Header.Set("if-modified-since", lastModified)
+ }
+ if req2 != nil {
+ req = req2
+ }
+ }
+ }
+
+ resp, err = transport.RoundTrip(req)
+ if err == nil && req.Method == "GET" && resp.StatusCode == http.StatusNotModified {
+ // Replace the 304 response with the one from cache, but update with some new headers
+ endToEndHeaders := getEndToEndHeaders(resp.Header)
+ for _, header := range endToEndHeaders {
+ cachedResp.Header[header] = resp.Header[header]
+ }
+ resp = cachedResp
+ } else if (err != nil || (cachedResp != nil && resp.StatusCode >= 500)) &&
+ req.Method == "GET" && canStaleOnError(cachedResp.Header, req.Header) {
+ // In case of transport failure and stale-if-error activated, returns cached content
+ // when available
+ return cachedResp, nil
+ } else {
+ if err != nil || resp.StatusCode != http.StatusOK {
+ t.Cache.Delete(cacheKey)
+ }
+ if err != nil {
+ return nil, err
+ }
+ }
+ } else {
+ reqCacheControl := parseCacheControl(req.Header)
+ if _, ok := reqCacheControl["only-if-cached"]; ok {
+ resp = newGatewayTimeoutResponse(req)
+ } else {
+ resp, err = transport.RoundTrip(req)
+ if err != nil {
+ return nil, err
+ }
+ }
+ }
+
+ if cacheable && canStore(parseCacheControl(req.Header), parseCacheControl(resp.Header)) {
+ for _, varyKey := range headerAllCommaSepValues(resp.Header, "vary") {
+ varyKey = http.CanonicalHeaderKey(varyKey)
+ fakeHeader := "X-Varied-" + varyKey
+ reqValue := req.Header.Get(varyKey)
+ if reqValue != "" {
+ resp.Header.Set(fakeHeader, reqValue)
+ }
+ }
+ switch req.Method {
+ case "GET":
+ // Delay caching until EOF is reached.
+ resp.Body = &cachingReadCloser{
+ R: resp.Body,
+ OnEOF: func(r io.Reader) {
+ resp := *resp
+ resp.Body = ioutil.NopCloser(r)
+ respBytes, err := httputil.DumpResponse(&resp, true)
+ if err == nil {
+ t.Cache.Set(cacheKey, respBytes)
+ }
+ },
+ }
+ default:
+ respBytes, err := httputil.DumpResponse(resp, true)
+ if err == nil {
+ t.Cache.Set(cacheKey, respBytes)
+ }
+ }
+ } else {
+ t.Cache.Delete(cacheKey)
+ }
+ return resp, nil
+}
+
+// ErrNoDateHeader indicates that the HTTP headers contained no Date header.
+var ErrNoDateHeader = errors.New("no Date header")
+
+// Date parses and returns the value of the Date header.
+func Date(respHeaders http.Header) (date time.Time, err error) {
+ dateHeader := respHeaders.Get("date")
+ if dateHeader == "" {
+ err = ErrNoDateHeader
+ return
+ }
+
+ return time.Parse(time.RFC1123, dateHeader)
+}
+
+type realClock struct{}
+
+func (c *realClock) since(d time.Time) time.Duration {
+ return time.Since(d)
+}
+
+type timer interface {
+ since(d time.Time) time.Duration
+}
+
+var clock timer = &realClock{}
+
+// getFreshness will return one of fresh/stale/transparent based on the cache-control
+// values of the request and the response
+//
+// fresh indicates the response can be returned
+// stale indicates that the response needs validating before it is returned
+// transparent indicates the response should not be used to fulfil the request
+//
+// Because this is only a private cache, 'public' and 'private' in cache-control aren't
+// signficant. Similarly, smax-age isn't used.
+func getFreshness(respHeaders, reqHeaders http.Header) (freshness int) {
+ respCacheControl := parseCacheControl(respHeaders)
+ reqCacheControl := parseCacheControl(reqHeaders)
+ if _, ok := reqCacheControl["no-cache"]; ok {
+ return transparent
+ }
+ if _, ok := respCacheControl["no-cache"]; ok {
+ return stale
+ }
+ if _, ok := reqCacheControl["only-if-cached"]; ok {
+ return fresh
+ }
+
+ date, err := Date(respHeaders)
+ if err != nil {
+ return stale
+ }
+ currentAge := clock.since(date)
+
+ var lifetime time.Duration
+ var zeroDuration time.Duration
+
+ // If a response includes both an Expires header and a max-age directive,
+ // the max-age directive overrides the Expires header, even if the Expires header is more restrictive.
+ if maxAge, ok := respCacheControl["max-age"]; ok {
+ lifetime, err = time.ParseDuration(maxAge + "s")
+ if err != nil {
+ lifetime = zeroDuration
+ }
+ } else {
+ expiresHeader := respHeaders.Get("Expires")
+ if expiresHeader != "" {
+ expires, err := time.Parse(time.RFC1123, expiresHeader)
+ if err != nil {
+ lifetime = zeroDuration
+ } else {
+ lifetime = expires.Sub(date)
+ }
+ }
+ }
+
+ if maxAge, ok := reqCacheControl["max-age"]; ok {
+ // the client is willing to accept a response whose age is no greater than the specified time in seconds
+ lifetime, err = time.ParseDuration(maxAge + "s")
+ if err != nil {
+ lifetime = zeroDuration
+ }
+ }
+ if minfresh, ok := reqCacheControl["min-fresh"]; ok {
+ // the client wants a response that will still be fresh for at least the specified number of seconds.
+ minfreshDuration, err := time.ParseDuration(minfresh + "s")
+ if err == nil {
+ currentAge = time.Duration(currentAge + minfreshDuration)
+ }
+ }
+
+ if maxstale, ok := reqCacheControl["max-stale"]; ok {
+ // Indicates that the client is willing to accept a response that has exceeded its expiration time.
+ // If max-stale is assigned a value, then the client is willing to accept a response that has exceeded
+ // its expiration time by no more than the specified number of seconds.
+ // If no value is assigned to max-stale, then the client is willing to accept a stale response of any age.
+ //
+ // Responses served only because of a max-stale value are supposed to have a Warning header added to them,
+ // but that seems like a hassle, and is it actually useful? If so, then there needs to be a different
+ // return-value available here.
+ if maxstale == "" {
+ return fresh
+ }
+ maxstaleDuration, err := time.ParseDuration(maxstale + "s")
+ if err == nil {
+ currentAge = time.Duration(currentAge - maxstaleDuration)
+ }
+ }
+
+ if lifetime > currentAge {
+ return fresh
+ }
+
+ return stale
+}
+
+// Returns true if either the request or the response includes the stale-if-error
+// cache control extension: https://tools.ietf.org/html/rfc5861
+func canStaleOnError(respHeaders, reqHeaders http.Header) bool {
+ respCacheControl := parseCacheControl(respHeaders)
+ reqCacheControl := parseCacheControl(reqHeaders)
+
+ var err error
+ lifetime := time.Duration(-1)
+
+ if staleMaxAge, ok := respCacheControl["stale-if-error"]; ok {
+ if staleMaxAge != "" {
+ lifetime, err = time.ParseDuration(staleMaxAge + "s")
+ if err != nil {
+ return false
+ }
+ } else {
+ return true
+ }
+ }
+ if staleMaxAge, ok := reqCacheControl["stale-if-error"]; ok {
+ if staleMaxAge != "" {
+ lifetime, err = time.ParseDuration(staleMaxAge + "s")
+ if err != nil {
+ return false
+ }
+ } else {
+ return true
+ }
+ }
+
+ if lifetime >= 0 {
+ date, err := Date(respHeaders)
+ if err != nil {
+ return false
+ }
+ currentAge := clock.since(date)
+ if lifetime > currentAge {
+ return true
+ }
+ }
+
+ return false
+}
+
+func getEndToEndHeaders(respHeaders http.Header) []string {
+ // These headers are always hop-by-hop
+ hopByHopHeaders := map[string]struct{}{
+ "Connection": struct{}{},
+ "Keep-Alive": struct{}{},
+ "Proxy-Authenticate": struct{}{},
+ "Proxy-Authorization": struct{}{},
+ "Te": struct{}{},
+ "Trailers": struct{}{},
+ "Transfer-Encoding": struct{}{},
+ "Upgrade": struct{}{},
+ }
+
+ for _, extra := range strings.Split(respHeaders.Get("connection"), ",") {
+ // any header listed in connection, if present, is also considered hop-by-hop
+ if strings.Trim(extra, " ") != "" {
+ hopByHopHeaders[http.CanonicalHeaderKey(extra)] = struct{}{}
+ }
+ }
+ endToEndHeaders := []string{}
+ for respHeader, _ := range respHeaders {
+ if _, ok := hopByHopHeaders[respHeader]; !ok {
+ endToEndHeaders = append(endToEndHeaders, respHeader)
+ }
+ }
+ return endToEndHeaders
+}
+
+func canStore(reqCacheControl, respCacheControl cacheControl) (canStore bool) {
+ if _, ok := respCacheControl["no-store"]; ok {
+ return false
+ }
+ if _, ok := reqCacheControl["no-store"]; ok {
+ return false
+ }
+ return true
+}
+
+func newGatewayTimeoutResponse(req *http.Request) *http.Response {
+ var braw bytes.Buffer
+ braw.WriteString("HTTP/1.1 504 Gateway Timeout\r\n\r\n")
+ resp, err := http.ReadResponse(bufio.NewReader(&braw), req)
+ if err != nil {
+ panic(err)
+ }
+ return resp
+}
+
+// cloneRequest returns a clone of the provided *http.Request.
+// The clone is a shallow copy of the struct and its Header map.
+// (This function copyright goauth2 authors: https://code.google.com/p/goauth2)
+func cloneRequest(r *http.Request) *http.Request {
+ // shallow copy of the struct
+ r2 := new(http.Request)
+ *r2 = *r
+ // deep copy of the Header
+ r2.Header = make(http.Header)
+ for k, s := range r.Header {
+ r2.Header[k] = s
+ }
+ return r2
+}
+
+type cacheControl map[string]string
+
+func parseCacheControl(headers http.Header) cacheControl {
+ cc := cacheControl{}
+ ccHeader := headers.Get("Cache-Control")
+ for _, part := range strings.Split(ccHeader, ",") {
+ part = strings.Trim(part, " ")
+ if part == "" {
+ continue
+ }
+ if strings.ContainsRune(part, '=') {
+ keyval := strings.Split(part, "=")
+ cc[strings.Trim(keyval[0], " ")] = strings.Trim(keyval[1], ",")
+ } else {
+ cc[part] = ""
+ }
+ }
+ return cc
+}
+
+// headerAllCommaSepValues returns all comma-separated values (each
+// with whitespace trimmed) for header name in headers. According to
+// Section 4.2 of the HTTP/1.1 spec
+// (http://www.w3.org/Protocols/rfc2616/rfc2616-sec4.html#sec4.2),
+// values from multiple occurrences of a header should be concatenated, if
+// the header's value is a comma-separated list.
+func headerAllCommaSepValues(headers http.Header, name string) []string {
+ var vals []string
+ for _, val := range headers[http.CanonicalHeaderKey(name)] {
+ fields := strings.Split(val, ",")
+ for i, f := range fields {
+ fields[i] = strings.TrimSpace(f)
+ }
+ vals = append(vals, fields...)
+ }
+ return vals
+}
+
+// cachingReadCloser is a wrapper around ReadCloser R that calls OnEOF
+// handler with a full copy of the content read from R when EOF is
+// reached.
+type cachingReadCloser struct {
+ // Underlying ReadCloser.
+ R io.ReadCloser
+ // OnEOF is called with a copy of the content of R when EOF is reached.
+ OnEOF func(io.Reader)
+
+ buf bytes.Buffer // buf stores a copy of the content of R.
+}
+
+// Read reads the next len(p) bytes from R or until R is drained. The
+// return value n is the number of bytes read. If R has no data to
+// return, err is io.EOF and OnEOF is called with a full copy of what
+// has been read so far.
+func (r *cachingReadCloser) Read(p []byte) (n int, err error) {
+ n, err = r.R.Read(p)
+ r.buf.Write(p[:n])
+ if err == io.EOF {
+ r.OnEOF(bytes.NewReader(r.buf.Bytes()))
+ }
+ return n, err
+}
+
+func (r *cachingReadCloser) Close() error {
+ return r.R.Close()
+}
+
+// NewMemoryCacheTransport returns a new Transport using the in-memory cache implementation
+func NewMemoryCacheTransport() *Transport {
+ c := NewMemoryCache()
+ t := NewTransport(c)
+ return t
+}