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storage.go
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storage.go
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package main
import (
"bytes"
"crypto/md5"
"crypto/sha256"
"database/sql"
"fmt"
"html/template"
"math"
"math/rand"
"net/http"
"regexp"
"strings"
"time"
"github.com/labstack/echo"
)
func init() {
rand.Seed(time.Now().UnixNano())
}
const (
idLength = 5
fraudThreshold = 7
)
var (
rexpNoteID = regexp.MustCompile("[a-z0-9]+")
rexpLink = regexp.MustCompile("(ht|f)tps?://[^\\s]+")
)
type Note struct {
ID, Title, Text, Password, DeprecatedPassword, Encoded string
Published, Edited time.Time
Views int
Content, Ads template.HTML
}
func (n *Note) Fraud() bool {
res := rexpLink.FindAllString(n.Text, -1)
if len(res) < 3 {
return false
}
stripped := rexpLink.ReplaceAllString(n.Text, "")
l1 := len(n.Text)
l2 := len(stripped)
return n.Views > 150 &&
int(math.Ceil(100*float64(l1-l2)/float64(l1))) > fraudThreshold
}
func save(c echo.Context, db *sql.DB, n *Note) (*Note, error) {
if n.Password != "" {
clean := n.Password
n.Password = fmt.Sprintf("%x", sha256.Sum256([]byte(n.Password)))
h := md5.New()
h.Write([]byte(clean))
n.DeprecatedPassword = fmt.Sprintf("%x", h.Sum(nil))
}
if n.ID == "" {
return insert(c, db, n)
}
if !rexpNoteID.Match([]byte(n.ID)) {
return nil, errorBadRequest
}
return update(c, db, n)
}
func update(c echo.Context, db *sql.DB, n *Note) (*Note, error) {
c.Logger().Debugf("updating note %s", n.ID)
if n.Password == "" {
return nil, errorBadRequest
}
tx, err := db.Begin()
if err != nil {
return nil, err
}
s := "update notes set (text, edited, password) = (?, ?, ?) where id = ? and (password = ? or password = ?)"
if n.Text == "" {
s = "delete from notes where id = ? and (password = ? or password = ?)"
}
stmt, _ := tx.Prepare(s)
defer stmt.Close()
var res sql.Result
if n.Text == "" {
res, err = stmt.Exec(n.ID, n.Password, n.DeprecatedPassword)
} else {
res, err = stmt.Exec(n.Text, time.Now(), n.Password, n.ID, n.Password, n.DeprecatedPassword)
}
if err != nil {
tx.Rollback()
return nil, err
}
rows, err := res.RowsAffected()
if rows != 1 {
tx.Rollback()
return nil, errorUnathorised
}
c.Logger().Debugf("updating note %s (deletion: %t); committing transaction", n.ID, n.Text == "")
return n, tx.Commit()
}
func insert(c echo.Context, db *sql.DB, n *Note) (*Note, error) {
c.Logger().Debug("inserting new note")
tx, err := db.Begin()
if err != nil {
return nil, err
}
stmt, _ := tx.Prepare("insert into notes(id, text, password) values(?, ?, ?)")
defer stmt.Close()
id := randId()
_, err = stmt.Exec(id, n.Text, n.Password)
if err != nil {
tx.Rollback()
if strings.HasPrefix(err.Error(), "UNIQUE constraint failed") {
c.Logger().Infof("collision on id %s", id)
return save(c, db, n)
}
return nil, err
}
n.ID = id
c.Logger().Debugf("inserting new note %s; commiting transaction", n.ID)
return n, tx.Commit()
}
func randId() string {
buf := bytes.NewBuffer([]byte{})
for i := 0; i < idLength; i++ {
b := '0'
z := rand.Intn(36)
if z > 9 {
b = 'a'
z -= 10
}
buf.WriteRune(rune(z) + b)
}
return buf.String()
}
func load(c echo.Context, db *sql.DB) (*Note, int) {
q := c.Param("id")
if !rexpNoteID.Match([]byte(q)) {
code := http.StatusNotFound
return nil, code
}
c.Logger().Debugf("loading note %s", q)
stmt, _ := db.Prepare("select * from notes where id = ?")
defer stmt.Close()
row := stmt.QueryRow(q)
var id, text, password string
var published time.Time
var editedVal interface{}
var views int
if err := row.Scan(&id, &text, &published, &editedVal, &password, &views); err != nil {
code := http.StatusNotFound
return nil, code
}
n := &Note{
ID: id,
Text: text,
Views: views,
Published: published,
}
if editedVal != nil {
n.Edited = editedVal.(time.Time)
}
n.prepare()
return n, http.StatusOK
}