1 files changed, 312 insertions, 0 deletions

diff --git a/pkg/libgopher/libgopher.go b/pkg/libgopher/libgopher.go
new file mode 100644
index 0000000..86d58ff
--- /dev/null
+++ b/pkg/libgopher/libgopher.go
@@ -0,0 +1,312 @@
+package libgopher
+
+import (
+        "bufio"
+        "errors"
+        "io"
+        "log"
+        "net"
+        "net/url"
+        "strings"
+)
+
+// Item Types
+const (
+        FILE        = ItemType('0') // Item is a file
+        DIRECTORY   = ItemType('1') // Item is a directory
+        PHONEBOOK   = ItemType('2') // Item is a CSO phone-book server
+        ERROR       = ItemType('3') // Error
+        BINHEX      = ItemType('4') // Item is a BinHexed Macintosh file.
+        DOSARCHIVE  = ItemType('5') // Item is DOS binary archive of some sort. (*)
+        UUENCODED   = ItemType('6') // Item is a UNIX uuencoded file.
+        INDEXSEARCH = ItemType('7') // Item is an Index-Search server.
+        TELNET      = ItemType('8') // Item points to a text-based telnet session.
+        BINARY      = ItemType('9') // Item is a binary file! (*)
+
+        // (*) Client must read until the TCP connection is closed.
+
+        REDUNDANT = ItemType('+') // Item is a redundant server
+        TN3270    = ItemType('T') // Item points to a text-based tn3270 session.
+        GIF       = ItemType('g') // Item is a GIF format graphics file.
+        IMAGE     = ItemType('I') // Item is some kind of image file.
+
+        // non-standard
+        INFO  = ItemType('i') // Item is an informational message
+        HTML  = ItemType('h') // Item is a HTML document
+        AUDIO = ItemType('s') // Item is an Audio file
+        PNG   = ItemType('p') // Item is a PNG Image
+        DOC   = ItemType('d') // Item is a Document
+)
+
+const (
+        // END represents the terminator used in directory responses
+        END = byte('.')
+
+        // TAB is the delimiter used to separate item response parts
+        TAB = byte('\t')
+
+        // CRLF is the delimiter used per line of response item
+        CRLF = "\r\n"
+
+        // DEFAULT is the default item type
+        DEFAULT = BINARY
+)
+
+// ItemType represents the type of an item
+type ItemType byte
+
+// Return a human friendly represation of an ItemType
+func (it ItemType) String() string {
+        switch it {
+        case FILE:
+                return "TXT"
+        case DIRECTORY:
+                return "DIR"
+        case PHONEBOOK:
+                return "PHO"
+        case ERROR:
+                return "ERR"
+        case BINHEX:
+                return "HEX"
+        case DOSARCHIVE:
+                return "ARC"
+        case UUENCODED:
+                return "UUE"
+        case INDEXSEARCH:
+                return "QRY"
+        case TELNET:
+                return "TEL"
+        case BINARY:
+                return "BIN"
+        case REDUNDANT:
+                return "DUP"
+        case TN3270:
+                return "TN3"
+        case GIF:
+                return "GIF"
+        case IMAGE:
+                return "IMG"
+        case INFO:
+                return "NFO"
+        case HTML:
+                return "HTM"
+        case AUDIO:
+                return "SND"
+        case PNG:
+                return "PNG"
+        case DOC:
+                return "DOC"
+        default:
+                return "???"
+        }
+}
+
+// Item describes an entry in a directory listing.
+type Item struct {
+        Type        ItemType `json:"type"`
+        Description string   `json:"description"`
+        Selector    string   `json:"selector"`
+        Host        string   `json:"host"`
+        Port        string   `json:"port"`
+
+        // non-standard extensions (ignored by standard clients)
+        Extras []string `json:"extras"`
+}
+
+// ParseItem parses a line of text into an item
+func ParseItem(line string) (item *Item, err error) {
+        parts := strings.Split(strings.Trim(line, "\r\n"), "\t")
+
+        if len(parts[0]) < 1 {
+                return nil, errors.New("no item type: " + string(line))
+        }
+
+        item = &Item{
+                Type:        ItemType(parts[0][0]),
+                Description: string(parts[0][1:]),
+                Extras:      make([]string, 0),
+        }
+
+        // Selector
+        if len(parts) > 1 {
+                item.Selector = string(parts[1])
+        } else {
+                item.Selector = ""
+        }
+
+        // Host
+        if len(parts) > 2 {
+                item.Host = string(parts[2])
+        } else {
+                item.Host = "null.host"
+        }
+
+        // Port
+        if len(parts) > 3 {
+                item.Port = string(parts[3])
+        } else {
+                item.Port = "0"
+        }
+
+        // Extras
+        if len(parts) >= 4 {
+                for _, v := range parts[4:] {
+                        item.Extras = append(item.Extras, string(v))
+                }
+        }
+
+        return
+}
+
+func (i *Item) isDirectoryLike() bool {
+        switch i.Type {
+        case DIRECTORY:
+                return true
+        case INDEXSEARCH:
+                return true
+        default:
+                return false
+        }
+}
+
+// Directory representes a Gopher Menu of Items
+type Directory struct {
+        Items []*Item `json:"items"`
+}
+
+// Response represents a Gopher resource that
+// Items contains a non-empty array of Item(s)
+// for directory types, otherwise the Body
+// contains the fetched resource (file, image, etc).
+type Response struct {
+        Type ItemType
+        Dir  Directory
+        Body io.Reader
+}
+
+// Get fetches a Gopher resource by URI
+func Get(uri string) (*Response, error) {
+        u, err := url.Parse(uri)
+        if err != nil {
+                return nil, err
+        }
+
+        if u.Scheme != "gopher" {
+                return nil, errors.New("invalid scheme for uri")
+        }
+
+        host := u.Hostname()
+        port := u.Port()
+
+        if port == "" {
+                port = "70"
+        }
+
+        var (
+                Type     ItemType
+                Selector string
+        )
+
+        path := strings.TrimPrefix(u.Path, "/")
+        if len(path) > 2 {
+                Type = ItemType(path[0])
+                Selector = path[1:]
+                if u.RawQuery != "" {
+                        Selector += "\t" + u.RawQuery
+                }
+        } else if len(path) == 1 {
+                Type = ItemType(path[0])
+                Selector = ""
+        } else {
+                Type = ItemType(DIRECTORY)
+                Selector = ""
+        }
+
+        i := Item{Type: Type, Selector: Selector, Host: host, Port: port}
+        res := Response{Type: i.Type}
+
+        if i.isDirectoryLike() {
+                d, err := i.FetchDirectory()
+                if err != nil {
+                        return nil, err
+                }
+
+                res.Dir = d
+        } else {
+                reader, err := i.FetchFile()
+                if err != nil {
+                        return nil, err
+                }
+
+                res.Body = reader
+        }
+
+        return &res, nil
+}
+
+// FetchFile fetches data, not directory information.
+// Calling this on a DIRECTORY Item type
+// or unsupported type will return an error.
+func (i *Item) FetchFile() (io.Reader, error) {
+        if i.Type == DIRECTORY {
+                return nil, errors.New("cannot fetch a directory as a file")
+        }
+
+        conn, err := net.Dial("tcp", net.JoinHostPort(i.Host, i.Port))
+        if err != nil {
+                return nil, err
+        }
+
+        _, err = conn.Write([]byte(i.Selector + CRLF))
+        if err != nil {
+                conn.Close()
+                return nil, err
+        }
+
+        return conn, nil
+}
+
+// FetchDirectory fetches directory information, not data.
+// Calling this on an Item whose type is not DIRECTORY will return an error.
+func (i *Item) FetchDirectory() (Directory, error) {
+        if !i.isDirectoryLike() {
+                return Directory{}, errors.New("cannot fetch a file as a directory")
+        }
+
+        conn, err := net.Dial("tcp", net.JoinHostPort(i.Host, i.Port))
+        if err != nil {
+                return Directory{}, err
+        }
+
+        _, err = conn.Write([]byte(i.Selector + CRLF))
+        if err != nil {
+                return Directory{}, err
+        }
+
+        reader := bufio.NewReader(conn)
+        scanner := bufio.NewScanner(reader)
+        scanner.Split(bufio.ScanLines)
+
+        var items []*Item
+
+        for scanner.Scan() {
+                line := strings.Trim(scanner.Text(), "\r\n")
+
+                if len(line) == 0 {
+                        continue
+                }
+
+                if len(line) == 1 && line[0] == END {
+                        break
+                }
+
+                item, err := ParseItem(line)
+                if err != nil {
+                        log.Printf("Error parsing %q: %q", line, err)
+                        continue
+                }
+                items = append(items, item)
+        }
+
+        return Directory{items}, nil
+}