From 7e4d74b9150b58dc2eea0a0fd1bfb2e4b65465fb Mon Sep 17 00:00:00 2001
From: Rasmus Dahlberg <rasmus@rgdd.se>
Date: Fri, 17 Mar 2023 10:09:38 +0100
Subject: Add utils

---
 internal/utils/utils.go | 56 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 56 insertions(+)
 create mode 100644 internal/utils/utils.go

diff --git a/internal/utils/utils.go b/internal/utils/utils.go
new file mode 100644
index 0000000..7f5b1bc
--- /dev/null
+++ b/internal/utils/utils.go
@@ -0,0 +1,56 @@
+package utils
+
+import (
+	"crypto/sha256"
+	"fmt"
+	"os"
+
+	"git.cs.kau.se/rasmoste/ct-sans/internal/merkle"
+	"gitlab.torproject.org/rgdd/ct/pkg/metadata"
+)
+
+// Logs select logs that count towards CT-compliance checks.  Logs that don't
+// have a description are skipped after printing a warning.
+func Logs(md metadata.Metadata) (logs []metadata.Log) {
+	for _, operators := range md.Operators {
+		for _, log := range operators.Logs {
+			if log.Description == nil {
+				fmt.Fprintf(os.Stderr, "WARNING: skipping log without description")
+				continue
+			}
+			if log.State == nil {
+				continue // skip logs with unknown states
+			}
+			if log.State.Name == metadata.LogStatePending {
+				continue // pending logs do not count towards CT-compliance
+			}
+			if log.State.Name == metadata.LogStateRetired {
+				continue // retired logs are not necessarily reachable
+			}
+			if log.State.Name == metadata.LogStateRejected {
+				continue // rejected logs do not count towards CT-compliance
+			}
+
+			logs = append(logs, log)
+		}
+	}
+	return
+}
+
+// Proof formats hashes so that they can be passed to the merkle package
+func Proof(hashes [][]byte) (p [][sha256.Size]byte) {
+	for _, hash := range hashes {
+		var h [sha256.Size]byte
+		copy(h[:], hash)
+		p = append(p, h)
+	}
+	return
+}
+
+// LeafHashes formats a list of data as leaf hashes
+func LeafHashes(data [][]byte) (lh [][sha256.Size]byte) {
+	for _, d := range data {
+		lh = append(lh, merkle.HashLeafNode(d))
+	}
+	return
+}
-- 
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