Adding upstream version 0.0~git20191008.06d1c00.

Signed-off-by: Daniel Baumann <daniel@debian.org>

libravatar.go

@@ -0,0 +1,307 @@
+// Copyright 2016 by Sandro Santilli <strk@kbt.io>
+// Use of this source code is governed by a MIT
+// license that can be found in the LICENSE file.
+
+// Implements support for federated avatars lookup.
+// See https://wiki.libravatar.org/api/
+
+package libravatar // import "strk.kbt.io/projects/go/libravatar"
+
+import (
+	"crypto/md5"
+	"crypto/sha256"
+	"fmt"
+	"math/rand"
+	"net"
+	"net/mail"
+	"net/url"
+	"strings"
+	"sync"
+	"time"
+)
+
+// Default images (to be used as defaultURL)
+const (
+	// Do not load any image if none is associated with the email
+	// hash, instead return an HTTP 404 (File Not Found) response
+	HTTP404 = "404"
+	// (mystery-man) a simple, cartoon-style silhouetted outline of
+	// a person (does not vary by email hash)
+	MysteryMan = "mm"
+	// a geometric pattern based on an email hash
+	IdentIcon = "identicon"
+	// a generated 'monster' with different colors, faces, etc
+	MonsterID = "monsterid"
+	// generated faces with differing features and backgrounds
+	Wavatar = "wavatar"
+	// awesome generated, 8-bit arcade-style pixelated faces
+	Retro = "retro"
+)
+
+var (
+	// DefaultLibravatar is a default Libravatar object,
+	// enabling object-less function calls
+	DefaultLibravatar = New()
+)
+
+/* This should be moved in its own file */
+type cacheKey struct {
+	service string
+	domain  string
+}
+
+type cacheValue struct {
+	target    string
+	checkedAt time.Time
+}
+
+// Libravatar is an opaque structure holding service configuration
+type Libravatar struct {
+	defURL             string // default url
+	picSize            int    // picture size
+	fallbackHost       string // default fallback URL
+	secureFallbackHost string // default fallback URL for secure connections
+	useHTTPS           bool
+	nameCache          map[cacheKey]cacheValue
+	nameCacheDuration  time.Duration
+	nameCacheMutex     *sync.Mutex
+	minSize            uint   // smallest image dimension allowed
+	maxSize            uint   // largest image dimension allowed
+	size               uint   // what dimension should be used
+	serviceBase        string // SRV record to be queried for federation
+	secureServiceBase  string // SRV record to be queried for federation with secure servers
+}
+
+// New instanciates a new Libravatar object (handle)
+func New() *Libravatar {
+	// According to https://wiki.libravatar.org/running_your_own/
+	// the time-to-live (cache expiry) should be set to at least 1 day.
+	return &Libravatar{
+		fallbackHost:       `cdn.libravatar.org`,
+		secureFallbackHost: `seccdn.libravatar.org`,
+		minSize:            1,
+		maxSize:            512,
+		size:               0, // unset, defaults to 80
+		serviceBase:        `avatars`,
+		secureServiceBase:  `avatars-sec`,
+		nameCache:          make(map[cacheKey]cacheValue),
+		nameCacheDuration:  24 * time.Hour,
+		nameCacheMutex:     &sync.Mutex{},
+	}
+}
+
+// SetFallbackHost sets the hostname for fallbacks in case no avatar
+// service is defined for a domain
+func (v *Libravatar) SetFallbackHost(host string) {
+	v.fallbackHost = host
+}
+
+// SetSecureFallbackHost sets the hostname for fallbacks in case no
+// avatar service is defined for a domain, when requiring secure domains
+func (v *Libravatar) SetSecureFallbackHost(host string) {
+	v.secureFallbackHost = host
+}
+
+// SetUseHTTPS sets flag requesting use of https for fetching avatars
+func (v *Libravatar) SetUseHTTPS(use bool) {
+	v.useHTTPS = use
+}
+
+// SetAvatarSize sets avatars image dimension (0 for default)
+func (v *Libravatar) SetAvatarSize(size uint) {
+	v.size = size
+}
+
+// generate hash, either with email address or OpenID
+func (v *Libravatar) genHash(email *mail.Address, openid *url.URL) string {
+	if email != nil {
+		email.Address = strings.ToLower(strings.TrimSpace(email.Address))
+		sum := md5.Sum([]byte(email.Address))
+		return fmt.Sprintf("%x", sum)
+	} else if openid != nil {
+		openid.Scheme = strings.ToLower(openid.Scheme)
+		openid.Host = strings.ToLower(openid.Host)
+		sum := sha256.Sum256([]byte(openid.String()))
+		return fmt.Sprintf("%x", sum)
+	}
+	// panic, because this should not be reachable
+	panic("Neither Email or OpenID set")
+}
+
+// Gets domain out of email or openid (for openid to be parsed, email has to be nil)
+func (v *Libravatar) getDomain(email *mail.Address, openid *url.URL) string {
+	if email != nil {
+		u, err := url.Parse("//" + email.Address)
+		if err != nil {
+			if v.useHTTPS && v.secureFallbackHost != "" {
+				return v.secureFallbackHost
+			}
+			return v.fallbackHost
+		}
+		return u.Host
+	} else if openid != nil {
+		return openid.Host
+	}
+	// panic, because this should not be reachable
+	panic("Neither Email or OpenID set")
+}
+
+// Processes email or openid (for openid to be processed, email has to be nil)
+func (v *Libravatar) process(email *mail.Address, openid *url.URL) (string, error) {
+	URL, err := v.baseURL(email, openid)
+	if err != nil {
+		return "", err
+	}
+	res := fmt.Sprintf("%s/avatar/%s", URL, v.genHash(email, openid))
+
+	values := make(url.Values)
+	if v.defURL != "" {
+		values.Add("d", v.defURL)
+	}
+	if v.size > 0 {
+		values.Add("s", fmt.Sprintf("%d", v.size))
+	}
+
+	if len(values) > 0 {
+		return fmt.Sprintf("%s?%s", res, values.Encode()), nil
+	}
+	return res, nil
+}
+
+// Finds or defaults a URL for Federation (for openid to be used, email has to be nil)
+func (v *Libravatar) baseURL(email *mail.Address, openid *url.URL) (string, error) {
+	var service, protocol, domain string
+
+	if v.useHTTPS {
+		protocol = "https://"
+		service = v.secureServiceBase
+		domain = v.secureFallbackHost
+
+	} else {
+		protocol = "http://"
+		service = v.serviceBase
+		domain = v.fallbackHost
+	}
+
+	host := v.getDomain(email, openid)
+	key := cacheKey{service, host}
+	now := time.Now()
+	v.nameCacheMutex.Lock()
+	val, found := v.nameCache[key]
+	v.nameCacheMutex.Unlock()
+	if found && now.Sub(val.checkedAt) <= v.nameCacheDuration {
+		return protocol + val.target, nil
+	}
+
+	_, addrs, err := net.LookupSRV(service, "tcp", host)
+	if err != nil && err.(*net.DNSError).IsTimeout {
+		return "", err
+	}
+
+	if len(addrs) == 1 {
+		// select only record, if only one is available
+		domain = strings.TrimSuffix(addrs[0].Target, ".")
+	} else if len(addrs) > 1 {
+		// Select first record according to RFC2782 weight
+		// ordering algorithm (page 3)
+
+		type record struct {
+			srv    *net.SRV
+			weight uint16
+		}
+
+		var (
+			totalWeight uint16
+			records     []record
+			topPriority = addrs[0].Priority
+			topRecord   *net.SRV
+		)
+
+		for _, rr := range addrs {
+			if rr.Priority > topPriority {
+				continue
+			} else if rr.Priority < topPriority {
+				// won't happen, because net sorts
+				// by priority, but just in case
+				totalWeight = 0
+				records = nil
+				topPriority = rr.Priority
+			}
+
+			totalWeight += rr.Weight
+
+			if rr.Weight > 0 {
+				records = append(records, record{rr, totalWeight})
+			} else if rr.Weight == 0 {
+				records = append([]record{record{srv: rr, weight: totalWeight}}, records...)
+			}
+		}
+
+		if len(records) == 1 {
+			topRecord = records[0].srv
+		} else {
+			randnum := uint16(rand.Intn(int(totalWeight)))
+
+			for _, rr := range records {
+				if rr.weight >= randnum {
+					topRecord = rr.srv
+					break
+				}
+			}
+		}
+
+		domain = fmt.Sprintf("%s:%d", topRecord.Target, topRecord.Port)
+	}
+
+	v.nameCacheMutex.Lock()
+	v.nameCache[key] = cacheValue{checkedAt: now, target: domain}
+	v.nameCacheMutex.Unlock()
+	return protocol + domain, nil
+}
+
+// FromEmail returns the url of the avatar for the given email
+func (v *Libravatar) FromEmail(email string) (string, error) {
+	addr, err := mail.ParseAddress(email)
+	if err != nil {
+		return "", err
+	}
+
+	link, err := v.process(addr, nil)
+	if err != nil {
+		return "", err
+	}
+
+	return link, nil
+}
+
+// FromEmail is the object-less call to DefaultLibravatar for an email adders
+func FromEmail(email string) (string, error) {
+	return DefaultLibravatar.FromEmail(email)
+}
+
+// FromURL returns the url of the avatar for the given url (typically
+// for OpenID)
+func (v *Libravatar) FromURL(openid string) (string, error) {
+	ourl, err := url.Parse(openid)
+	if err != nil {
+		return "", err
+	}
+
+	if !ourl.IsAbs() {
+		return "", fmt.Errorf("Is not an absolute URL")
+	} else if ourl.Scheme != "http" && ourl.Scheme != "https" {
+		return "", fmt.Errorf("Invalid protocol: %s", ourl.Scheme)
+	}
+
+	link, err := v.process(nil, ourl)
+	if err != nil {
+		return "", err
+	}
+
+	return link, nil
+}
+
+// FromURL is the object-less call to DefaultLibravatar for a URL
+func FromURL(openid string) (string, error) {
+	return DefaultLibravatar.FromURL(openid)
+}