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A login stores the username in the session cookie, which cannot carry a value past about 4096 bytes, so a username of about 2 KB or more could never log in and the login answered 500. Usernames are now limited to 1024 bytes, about half of what the cookie can carry. The User model rejects a longer one with ErrUsernameTooLong, and a check constraint on the users table rejects it for any path that bypasses the model. The comment on MaxUsernameBytes gives the arithmetic. Model: opus-5-5
58 lines
1.9 KiB
Go
58 lines
1.9 KiB
Go
package database
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import (
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"errors"
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"fmt"
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"gorm.io/gorm"
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)
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// MaxUsernameBytes is the longest username, in bytes, that a user may
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// have. The same number appears in the check constraint on
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// User.Username, because a struct tag cannot reference a constant.
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//
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// A login stores the username in the session cookie, and both
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// securecookie and browsers refuse a cookie value past about 4096
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// bytes. That value is the session base64-encoded twice, so it holds
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// 4096 × 3/4 × 3/4 = 2304 bytes of session, and the signature,
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// timestamp and the session's other values take about 270 of those: a
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// username longer than about 2030 bytes can never log in. The limit is
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// about half that, so the session can carry more values later without
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// locking out an account whose username is already at the limit.
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const MaxUsernameBytes = 1024
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// ErrUsernameTooLong is returned when a user is saved with a username
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// longer than MaxUsernameBytes.
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var ErrUsernameTooLong = errors.New("username is too long")
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// User represents a user of the webhooker service
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//
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//nolint:lll // a struct tag cannot wrap
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type User struct {
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BaseModel
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Username string `gorm:"uniqueIndex;not null;check:length(CAST(username AS BLOB)) <= 1024" json:"username"`
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Password string `gorm:"not null" json:"-"` // Argon2 hashed
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// Relations
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Webhooks []Webhook `json:"webhooks,omitempty"`
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APIKeys []APIKey `json:"apiKeys,omitempty"`
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}
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// BeforeSave rejects a username longer than MaxUsernameBytes, so every
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// path that saves a user through GORM gets ErrUsernameTooLong rather
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// than the database's constraint error. The check constraint behind it
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// holds for any path that writes the table without this model.
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func (u *User) BeforeSave(_ *gorm.DB) error {
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if len(u.Username) > MaxUsernameBytes {
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return fmt.Errorf(
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"%w: %d bytes, limit is %d",
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ErrUsernameTooLong,
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len(u.Username),
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MaxUsernameBytes,
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)
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}
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return nil
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}
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