github.com/qichengzx/mattermost-server@v4.5.1-0.20180604164826-2c75247c97d0+incompatible/api4/openGraph.go (about)

     1  // Copyright (c) 2017-present Mattermost, Inc. All Rights Reserved.
     2  // See License.txt for license information.
     3  
     4  package api4
     5  
     6  import (
     7  	"net/http"
     8  
     9  	"github.com/dyatlov/go-opengraph/opengraph"
    10  	"github.com/mattermost/mattermost-server/model"
    11  	"github.com/mattermost/mattermost-server/utils"
    12  )
    13  
    14  const OPEN_GRAPH_METADATA_CACHE_SIZE = 10000
    15  
    16  var openGraphDataCache = utils.NewLru(OPEN_GRAPH_METADATA_CACHE_SIZE)
    17  
    18  func (api *API) InitOpenGraph() {
    19  	api.BaseRoutes.OpenGraph.Handle("", api.ApiSessionRequired(getOpenGraphMetadata)).Methods("POST")
    20  
    21  	// Dump the image cache if the proxy settings have changed. (need switch URLs to the correct proxy)
    22  	api.App.AddConfigListener(func(before, after *model.Config) {
    23  		if (before.ServiceSettings.ImageProxyType != after.ServiceSettings.ImageProxyType) ||
    24  			(before.ServiceSettings.ImageProxyURL != after.ServiceSettings.ImageProxyType) {
    25  			openGraphDataCache.Purge()
    26  		}
    27  	})
    28  }
    29  
    30  func OpenGraphDataWithProxyAddedToImageURLs(ogdata *opengraph.OpenGraph, toProxyURL func(string) string) *opengraph.OpenGraph {
    31  	for _, image := range ogdata.Images {
    32  		var url string
    33  		if image.SecureURL != "" {
    34  			url = image.SecureURL
    35  		} else {
    36  			url = image.URL
    37  		}
    38  
    39  		image.URL = ""
    40  		image.SecureURL = toProxyURL(url)
    41  	}
    42  
    43  	return ogdata
    44  }
    45  
    46  func getOpenGraphMetadata(c *Context, w http.ResponseWriter, r *http.Request) {
    47  	if !*c.App.Config().ServiceSettings.EnableLinkPreviews {
    48  		c.Err = model.NewAppError("getOpenGraphMetadata", "api.post.link_preview_disabled.app_error", nil, "", http.StatusNotImplemented)
    49  		return
    50  	}
    51  
    52  	props := model.StringInterfaceFromJson(r.Body)
    53  
    54  	url := ""
    55  	ok := false
    56  	if url, ok = props["url"].(string); len(url) == 0 || !ok {
    57  		c.SetInvalidParam("url")
    58  		return
    59  	}
    60  
    61  	ogJSONGeneric, ok := openGraphDataCache.Get(url)
    62  	if ok {
    63  		w.Write(ogJSONGeneric.([]byte))
    64  		return
    65  	}
    66  
    67  	og := c.App.GetOpenGraphMetadata(url)
    68  
    69  	// If image proxy enabled modify open graph data to feed though proxy
    70  	if toProxyURL := c.App.ImageProxyAdder(); toProxyURL != nil {
    71  		og = OpenGraphDataWithProxyAddedToImageURLs(og, toProxyURL)
    72  	}
    73  
    74  	ogJSON, err := og.ToJSON()
    75  	openGraphDataCache.AddWithExpiresInSecs(props["url"], ogJSON, 3600) // Cache would expire after 1 hour
    76  	if err != nil {
    77  		w.Write([]byte(`{"url": ""}`))
    78  		return
    79  	}
    80  
    81  	w.Write(ogJSON)
    82  }