rss/rss.go
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package rss import ( "bytes" "errors" "fmt" "io" "net" "net/http" "strings" "text/tabwriter" "time" ) // Parse RSS or Atom data. func Parse(data []byte) (*Feed, error) { if strings.Contains(string(data), "<rss") { if debug { fmt.Println("[i] Parsing as RSS 2.0") } return parseRSS2(data) } else if strings.Contains(string(data), "xmlns=\"http://purl.org/rss/1.0/\"") { if debug { fmt.Println("[i] Parsing as RSS 1.0") } return parseRSS1(data) } else { if debug { fmt.Println("[i] Parsing as Atom") } return parseAtom(data) } } // A FetchFunc is a function that fetches a feed for given URL. type FetchFunc func(url string) (resp *http.Response, err error) // DefaultFetchFunc uses http.DefaultClient to fetch a feed. var DefaultFetchFunc = func(url string) (resp *http.Response, err error) { client := http.DefaultClient client.Timeout = 20 * time.Second return client.Get(url) } // Fetch downloads and parses the RSS feed at the given URL func Fetch(url string) (*Feed, error) { return FetchByFunc(DefaultFetchFunc, url) } // FetchByClient uses a http.Client to fetch a URL. func FetchByClient(url string, client *http.Client) (*Feed, error) { fetchFunc := func(url string) (resp *http.Response, err error) { return client.Get(url) } return FetchByFunc(fetchFunc, url) } // FetchByFunc uses a func to fetch a URL. func FetchByFunc(fetchFunc FetchFunc, url string) (*Feed, error) { resp, err := fetchFunc(url) if err != nil { return nil, err } defer resp.Body.Close() body, err := io.ReadAll(resp.Body) if err != nil { return nil, err } out, err := Parse(body) if err != nil { return nil, err } if out.Link == "" { out.Link = url } out.UpdateURL = url out.FetchFunc = fetchFunc return out, nil } // Feed is the top-level structure. type Feed struct { Nickname string `json:"nickname"` // This is not set by the package, but could be helpful. Title string `json:"title"` Language string `json:"language"` Author string `json:"author"` Description string `json:"description"` Link string `json:"link"` // Link to the creator's website. UpdateURL string `json:"updateurl"` // URL of the feed itself. Image *Image `json:"image"` // Feed icon. Categories []string `json:"categories"` Items []*Item `json:"items"` ItemMap map[string]struct{} `json:"itemmap"` // Used in checking whether an item has been seen before. Refresh time.Time `json:"refresh"` // Earliest time this feed should next be checked. Unread uint32 `json:"unread"` // Number of unread items. Used by aggregators. FetchFunc FetchFunc `json:"-"` } type refreshError string var _ net.Error = refreshError("") func (r refreshError) Error() string { return string(r) } func (r refreshError) Timeout() bool { return false } func (r refreshError) Temporary() bool { return true } var errUpdateNotReady refreshError = "not ready to update: too soon to refresh" // DefaultRefreshInterval is the minimum // wait until the next refresh, provided // the feed does not provide its own // interval. // // Setting this too high will delay the // feed receiving new items, setting it // too low will put excessive load on // the feed hosts. // // The default value is 12 hours. var DefaultRefreshInterval = 12 * time.Hour // Update fetches any new items and updates f. func (f *Feed) Update() error { if f.FetchFunc == nil { f.FetchFunc = DefaultFetchFunc } return f.UpdateByFunc(f.FetchFunc) } // UpdateByFunc uses a func to update f. func (f *Feed) UpdateByFunc(fetchFunc FetchFunc) error { // Check that we don't update too often. if f.Refresh.After(time.Now()) { return errUpdateNotReady } if f.UpdateURL == "" { return errors.New("feed has no URL") } if f.ItemMap == nil { f.ItemMap = make(map[string]struct{}) for _, item := range f.Items { if _, ok := f.ItemMap[item.ID]; !ok { f.ItemMap[item.ID] = struct{}{} } } } update, err := FetchByFunc(fetchFunc, f.UpdateURL) if err != nil { return err } f.Refresh = update.Refresh f.Title = update.Title f.Description = update.Description for _, item := range update.Items { if _, ok := f.ItemMap[item.ID]; !ok { f.Items = append(f.Items, item) f.ItemMap[item.ID] = struct{}{} f.Unread++ } } return nil } func (f *Feed) Stale() bool { return f.Refresh.Before(time.Now()) } func (f *Feed) String() string { buf := new(bytes.Buffer) if debug { w := tabwriter.NewWriter(buf, 0, 8, 0, '\t', tabwriter.StripEscape) fmt.Fprintf(w, "Feed {\n") fmt.Fprintf(w, "\xff\t\xffNickname:\t%q\n", f.Nickname) fmt.Fprintf(w, "\xff\t\xffTitle:\t%q\n", f.Title) fmt.Fprintf(w, "\xff\t\xffDescription:\t%q\n", f.Description) fmt.Fprintf(w, "\xff\t\xffLink:\t%q\n", f.Link) fmt.Fprintf(w, "\xff\t\xffUpdateURL:\t%q\n", f.UpdateURL) fmt.Fprintf(w, "\xff\t\xffImage:\t%q (%s)\n", f.Image.Title, f.Image.URL) fmt.Fprintf(w, "\xff\t\xffRefresh:\t%s\n", f.Refresh.Format(DATE)) fmt.Fprintf(w, "\xff\t\xffUnread:\t%d\n", f.Unread) fmt.Fprintf(w, "\xff\t\xffItems:\t(%d) {\n", len(f.Items)) for _, item := range f.Items { fmt.Fprintf(w, "%s\n", item.Format(2)) } fmt.Fprintf(w, "\xff\t\xff}\n}\n") w.Flush() } else { w := buf fmt.Fprintf(w, "Feed %q\n", f.Title) fmt.Fprintf(w, "\t%q\n", f.Description) fmt.Fprintf(w, "\t%q\n", f.Link) fmt.Fprintf(w, "\t%s\n", f.Image) fmt.Fprintf(w, "\tRefresh at %s\n", f.Refresh.Format(DATE)) fmt.Fprintf(w, "\tUnread: %d\n", f.Unread) fmt.Fprintf(w, "\tItems:\n") for _, item := range f.Items { fmt.Fprintf(w, "\t%s\n", item.Format(2)) } } return buf.String() } // Item represents a single story. type Item struct { Title string `json:"title"` Summary string `json:"summary"` Categories []string `json:"category"` Link string `json:"link"` Date time.Time `json:"date"` Image *Image `json:"image"` DateValid bool ID string `json:"id"` Enclosures []*Enclosure `json:"enclosures"` Read bool `json:"read"` } func (i *Item) String() string { return i.Format(0) } // Format formats an item using tabs. func (i *Item) Format(indent int) string { buf := new(bytes.Buffer) single := strings.Repeat("\t", indent) double := single + "\t" if debug { w := tabwriter.NewWriter(buf, 0, 8, 0, '\t', tabwriter.StripEscape) fmt.Fprintf(w, "\xff%s\xffItem {\n", single) fmt.Fprintf(w, "\xff%s\xffTitle:\t%q\n", double, i.Title) fmt.Fprintf(w, "\xff%s\xffSummary:\t%q\n", double, i.Summary) fmt.Fprintf(w, "\xff%s\xffCategories:\t%q\n", double, i.Categories) fmt.Fprintf(w, "\xff%s\xffLink:\t%s\n", double, i.Link) fmt.Fprintf(w, "\xff%s\xffDate:\t%s\n", double, i.Date.Format(DATE)) fmt.Fprintf(w, "\xff%s\xffID:\t%s\n", double, i.ID) fmt.Fprintf(w, "\xff%s\xffRead:\t%v\n", double, i.Read) fmt.Fprintf(w, "\xff%s\xff}\n", single) w.Flush() } else { w := buf fmt.Fprintf(w, "%sItem %q\n", single, i.Title) fmt.Fprintf(w, "%s%q\n", double, i.Link) fmt.Fprintf(w, "%s%s\n", double, i.Date.Format(DATE)) fmt.Fprintf(w, "%s%q\n", double, i.ID) fmt.Fprintf(w, "%sRead: %v\n", double, i.Read) } return buf.String() } // Enclosure maps an enclosure. type Enclosure struct { URL string `json:"url"` Type string `json:"type"` Length uint `json:"length"` } // Get uses http.Get to fetch an enclosure. func (e *Enclosure) Get() (io.ReadCloser, error) { if e == nil || e.URL == "" { return nil, errors.New("No enclosure") } res, err := http.Get(e.URL) if err != nil { return nil, err } return res.Body, nil } // Image maps an image. type Image struct { Title string `json:"title"` Href string `json:"href"` URL string `json:"url"` Height uint32 `json:"height"` Width uint32 `json:"width"` } // Get uses http.Get to fetch an image. func (i *Image) Get() (io.ReadCloser, error) { if i == nil || i.URL == "" { return nil, errors.New("No image") } res, err := http.Get(i.URL) if err != nil { return nil, err } return res.Body, nil } func (i *Image) String() string { return fmt.Sprintf("Image %q", i.Title) }