37 lines
1.4 KiB
Go
37 lines
1.4 KiB
Go
package main
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import (
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"crypto/sha256"
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"crypto/subtle"
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"net/http"
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)
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// This middleware handles authentication & authorization for the app.
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// It uses BasicAuth because I doubt there is a need for something sophisticated in a small hobby project
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// Originally taken from https://www.alexedwards.net/blog/basic-authentication-in-go (13.03.2024)
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// TODO: why did I have to convert Handler from HandlerFunc?
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func basicAuth(next http.Handler) http.Handler {
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return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
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username, password, ok := r.BasicAuth()
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if ok {
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// Calculate SHA-256 hashes for equal length in ConstantTimeCompare
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usernameHash := sha256.Sum256([]byte(username))
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passwordHash := sha256.Sum256([]byte(password))
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expectedUsernameHash := sha256.Sum256([]byte(Cfg.Username))
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expectedPasswordHash := sha256.Sum256([]byte(Cfg.Password))
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usernameMatch := subtle.ConstantTimeCompare(usernameHash[:], expectedUsernameHash[:]) == 1
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passwordMatch := subtle.ConstantTimeCompare(passwordHash[:], expectedPasswordHash[:]) == 1
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if usernameMatch && passwordMatch {
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next.ServeHTTP(w, r)
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return
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}
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// TODO: Note failed login attempt?
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}
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// Unauthorized, inform client that we have auth and return 401
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w.Header().Set("WWW-Authenticate", `Basic realm="restricted", charset="UTF-8"`)
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http.Error(w, "Unauthorized", http.StatusUnauthorized)
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})
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}
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