Initial commit

vendor/gopkg.in/masci/flickr.v3/client.go

@@ -0,0 +1,161 @@
+package flickr
+
+import (
+	"bytes"
+	"crypto/hmac"
+	"crypto/md5"
+	"crypto/sha1"
+	"encoding/base64"
+	"fmt"
+	"math/rand"
+	"net/http"
+	"net/url"
+	"sort"
+	"strings"
+	"time"
+)
+
+// Generate a random string of 8 chars, needed for OAuth signature
+func generateNonce() string {
+	rand.Seed(time.Now().UTC().UnixNano())
+	// For convenience, use a set of chars we don't need to url-escape
+	var letters = []rune("123456789abcdefghijkmnopqrstuvwxyzABCDEFGHJKLMNPQRSTUVWXYZ")
+	b := make([]rune, 8)
+	for i := range b {
+		b[i] = letters[rand.Intn(len(letters))]
+	}
+	return string(b)
+}
+
+// An utility type to wrap all resources and data needed to complete requests
+// to the Flickr API
+type FlickrClient struct {
+	// Flickr application api key
+	ApiKey string
+	// Flickr application api secret
+	ApiSecret string
+	// A generic HTTP client to perform GET and POST requests
+	HTTPClient *http.Client
+	// The base url for API endpoints
+	EndpointUrl string
+	// A string containing POST or GET, needed for OAuth signing
+	HTTPVerb string
+	// A set of url params to query the API
+	Args url.Values
+	// User access token
+	OAuthToken string
+	// User secret token
+	OAuthTokenSecret string
+	// User flickr ID
+	Id string
+}
+
+// Create a Flickr client, apiKey and apiSecret are mandatory
+func NewFlickrClient(apiKey string, apiSecret string) *FlickrClient {
+	return &FlickrClient{
+		ApiKey:     apiKey,
+		ApiSecret:  apiSecret,
+		HTTPClient: &http.Client{},
+		HTTPVerb:   "GET",
+		Args:       url.Values{},
+	}
+}
+
+// Sign the next request performed by the FlickrClient
+func (c *FlickrClient) Sign(tokenSecret string) {
+	// the "oauth_signature" param must not be included in the signing process
+	c.Args.Del("oauth_signature")
+	c.Args.Set("oauth_signature", c.getSignature(tokenSecret))
+}
+
+// Set the mandatory params for an OAuth request
+func (c *FlickrClient) SetOAuthDefaults() {
+	c.Args.Add("oauth_version", "1.0")
+	c.Args.Add("oauth_signature_method", "HMAC-SHA1")
+	c.Args.Add("oauth_nonce", generateNonce())
+	c.Args.Add("oauth_timestamp", fmt.Sprintf("%d", time.Now().Unix()))
+}
+
+// Sign the request with a default set of OAuth parameters, needed to authorize
+// users for certain writing/destructive operations.
+func (c *FlickrClient) OAuthSign() {
+	c.SetOAuthDefaults()
+	c.Args.Set("oauth_token", c.OAuthToken)
+	c.Args.Set("oauth_consumer_key", c.ApiKey)
+	c.Args.Set("api_key", c.ApiKey)
+
+	c.Sign(c.OAuthTokenSecret)
+}
+
+// Specific signing process for API calls: not the same as OAuth sign, used
+// for requests that don't need user authorizations.
+func (c *FlickrClient) ApiSign() {
+	c.Args.Set("api_key", c.ApiKey)
+	// the "api_sig" param must not be included in the signing process
+	c.Args.Del("api_sig")
+	c.Args.Set("api_sig", c.getApiSignature(c.ApiSecret))
+}
+
+// Evaluate the complete URL to make requests (base url + params)
+func (c *FlickrClient) GetUrl() string {
+	return fmt.Sprintf("%s?%s", c.EndpointUrl, c.Args.Encode())
+}
+
+// Remove all query params
+func (c *FlickrClient) ClearArgs() {
+	c.Args = url.Values{}
+}
+
+// Reset Args and set the default endpoint
+func (c *FlickrClient) Init() {
+	c.ClearArgs()
+	c.EndpointUrl = API_ENDPOINT
+}
+
+// Get the base string to compose the signature
+func (c *FlickrClient) getSigningBaseString() string {
+	request_url := url.QueryEscape(c.EndpointUrl)
+	flickr_encoded := strings.Replace(c.Args.Encode(), "+", "%20", -1)
+	query := url.QueryEscape(flickr_encoded)
+
+	ret := fmt.Sprintf("%s&%s&%s", c.HTTPVerb, request_url, query)
+	return ret
+}
+
+// Compute the signature of a signed request
+func (c *FlickrClient) getSignature(token_secret string) string {
+	key := fmt.Sprintf("%s&%s", url.QueryEscape(c.ApiSecret), url.QueryEscape(token_secret))
+	base_string := c.getSigningBaseString()
+
+	mac := hmac.New(sha1.New, []byte(key))
+	mac.Write([]byte(base_string))
+
+	ret := base64.StdEncoding.EncodeToString(mac.Sum(nil))
+
+	return ret
+}
+
+// Sign API requests. This method differs from the signing process needed for
+// OAuth authenticated requests.
+func (c *FlickrClient) getApiSignature(token_secret string) string {
+	var buf bytes.Buffer
+	buf.WriteString(token_secret)
+
+	keys := make([]string, 0, len(c.Args))
+	for k := range c.Args {
+		keys = append(keys, k)
+	}
+	// args needs to be in alphabetical order
+	sort.Strings(keys)
+
+	for _, k := range keys {
+		arg := c.Args[k][0]
+		buf.WriteString(k)
+		buf.WriteString(arg)
+	}
+
+	base := buf.String()
+
+	data := []byte(base)
+	return fmt.Sprintf("%x", md5.Sum(data))
+}