nidus-sync/auth/auth.go

package auth

import (
	"context"
	"errors"
	"fmt"
	"net/http"
	"strconv"
	"strings"

	"github.com/Gleipnir-Technology/nidus-sync/platform"
	"github.com/rs/zerolog/log"
	"golang.org/x/crypto/bcrypt"
)

type NoCredentialsError struct{}

func (e NoCredentialsError) Error() string { return "No credentials were present in the request" }

type InvalidCredentials struct{}

func (e InvalidCredentials) Error() string { return "No username with that password exists" }

type InvalidUsername struct{}

func (e InvalidUsername) Error() string { return "That username doesn't exist" }

type AuthenticatedHandler func(http.ResponseWriter, *http.Request, platform.User)
type EnsureAuth struct {
	handler AuthenticatedHandler
}

func AddUserSession(r *http.Request, user *platform.User) {
	id := strconv.Itoa(int(user.ID))
	sessionManager.Put(r.Context(), "user_id", id)
	sessionManager.Put(r.Context(), "username", user.Username)
}

func GetAuthenticatedUser(r *http.Request) (*platform.User, error) {
	ctx := r.Context()
	user_id_str := sessionManager.GetString(ctx, "user_id")
	if user_id_str != "" {
		user_id, err := strconv.Atoi(user_id_str)
		if err != nil {
			return nil, fmt.Errorf("Failed to convert user_id to int: %w", err)
		}
		username := sessionManager.GetString(ctx, "username")
		if user_id > 0 && username != "" {
			return platform.UserByID(ctx, user_id)
		}
	}
	// If we can't get the user from the session try to get from auth headers
	username, password, ok := r.BasicAuth()
	if !ok {
		return nil, &NoCredentialsError{}
	}
	user, err := validateUser(ctx, username, password)
	if err != nil {
		return nil, err
	}
	AddUserSession(r, user)
	return user, nil
}

func NewEnsureAuth(handlerToWrap AuthenticatedHandler) *EnsureAuth {
	return &EnsureAuth{handlerToWrap}
}

func (ea *EnsureAuth) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	// If this is an API request respond with a more machine-readable error state
	accept := r.Header.Values("Accept")
	offers := []string{"application/json", "text/html"}

	content_type := NegotiateContent(accept, offers)
	user, err := GetAuthenticatedUser(r)
	if err != nil || user == nil {
		var msg []byte
		// Separate return codes for different authentication failures
		if _, ok := err.(*NoCredentialsError); ok {
			log.Info().Msg("No credentials present and no session")
			w.Header().Set("WWW-Authenticate-Error", "no-credentials")
			msg = []byte("Please provide credentials.\n")
		} else if _, ok := err.(*platform.NoUserError); ok {
			w.Header().Set("WWW-Authenticate-Error", "invalid-credentials")
			msg = []byte("Invalid credentials provided.\n")
		} else if _, ok := err.(*InvalidCredentials); ok {
			w.Header().Set("WWW-Authenticate-Error", "invalid-credentials")
			msg = []byte("Invalid credentials provided.\n")
		}

		if content_type == "text/html" {
			http.Redirect(w, r, "/signin?next="+r.URL.Path, http.StatusSeeOther)
			return
		}
		w.Header().Set("WWW-Authenticate", `Basic realm="Nidus Sync"`)
		w.WriteHeader(401)
		w.Write(msg)
		return
	}
	ea.handler(w, r, *user)
}
func SigninUser(r *http.Request, username string, password string) (*platform.User, error) {
	user, err := validateUser(r.Context(), username, password)
	if err != nil {
		return nil, err
	}
	if user == nil {
		return nil, errors.New("No matching user")
	}
	AddUserSession(r, user)
	return user, nil
}

func SignoutUser(r *http.Request, user platform.User) {
	sessionManager.Put(r.Context(), "user_id", "")
	sessionManager.Put(r.Context(), "username", "")
	log.Info().Str("username", user.Username).Int32("user_id", int32(user.ID)).Msg("Ended user session")
}

func SignupUser(ctx context.Context, username string, name string, password string) (*platform.User, error) {
	password_hash, err := HashPassword(password)
	if err != nil {
		return nil, fmt.Errorf("Cannot signup user, failed to create hashed password: %w", err)
	}
	u, err := platform.CreateUser(ctx, username, name, password_hash)
	if err != nil {
		return nil, fmt.Errorf("create user: %s", err)
	}
	return u, nil
}

func HashPassword(password string) (string, error) {
	bytes, err := bcrypt.GenerateFromPassword([]byte(password), 14)
	return string(bytes), err
}

func redact(s string) string {
	if len(s) <= 4 {
		return s
	}

	first_two := s[:2]
	last_two := s[len(s)-2:]
	middle_length := len(s) - 4

	return first_two + strings.Repeat("*", middle_length) + last_two
}

func validatePassword(password, hash string) bool {
	err := bcrypt.CompareHashAndPassword([]byte(hash), []byte(password))
	return err == nil
}

func validateUser(ctx context.Context, username string, password string) (*platform.User, error) {
	passwordHash, err := HashPassword(password)
	if err != nil {
		return nil, fmt.Errorf("Failed to hash password: %w", err)
	}
	user, err := platform.UserByUsername(ctx, username)
	if err != nil {
		return nil, fmt.Errorf("Failed to query for user: %w", err)
	}
	if user == nil {
		log.Info().Str("username", username).Str("password", redact(password)).Msg("Invalid username")
		return nil, InvalidUsername{}
	}
	if !validatePassword(password, user.PasswordHash) {
		log.Info().Str("username", username).Str("password", redact(password)).Str("hash", passwordHash).Msg("Invalid password for user")
		return nil, InvalidCredentials{}
	}
	return user, nil
}