bvandeusen
c3614c6333
golangci-lint flagged three errcheck: - stream_token.go: fmt.Fprintf(mac, ...) - hash.Hash never errors per documented contract, but errcheck wants explicit discard. Discard via _, _ assignment with a WHY comment. - config_test.go: os.Unsetenv calls in tests - discard the error via _ assignment. Test cleanup paths. Reviewers flagged the Fprintf one during Task 1 quality review but golangci-lint runs in a separate CI step that wasn't exercised on the per-task pushes (cancelled by subsequent push concurrency).
40 lines
1.4 KiB
Go
40 lines
1.4 KiB
Go
package api
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import (
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"crypto/hmac"
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"crypto/sha256"
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"encoding/hex"
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"fmt"
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"time"
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)
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// SignStreamToken returns the HMAC-SHA256 hex of "<trackID>|<exp>" keyed
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// by secret. The token is constant-time-comparable via VerifyStreamToken
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// so it's safe to expose the verification function in handlers.
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//
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// trackID is the canonical track UUID. exp is the Unix time after which
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// the token is invalid; the handler checks exp before serving.
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//
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// The secret comes from MINSTREL_STREAM_SECRET (or its auto-generated +
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// persisted fallback in app_preferences). The loader lands in slice 2
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// (POST /api/cast/stream-token); this file is the primitive both the
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// loader and the stream handler share.
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func SignStreamToken(secret []byte, trackID string, exp int64) string {
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mac := hmac.New(sha256.New, secret)
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// hash.Hash.Write is documented as never returning an error.
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_, _ = fmt.Fprintf(mac, "%s|%d", trackID, exp)
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return hex.EncodeToString(mac.Sum(nil))
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}
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// VerifyStreamToken returns true iff token is a valid HMAC for
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// (trackID, exp) AND exp has not yet passed. Wall-clock comparison —
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// callers must trust the server's clock. Uses hmac.Equal for
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// constant-time compare so a timing oracle can't bias token guessing.
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func VerifyStreamToken(secret []byte, trackID string, exp int64, token string) bool {
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if time.Now().Unix() > exp {
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return false
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}
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expected := SignStreamToken(secret, trackID, exp)
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return hmac.Equal([]byte(expected), []byte(token))
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}
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