From b3dc36421f133ea6983574891720e974cf7974dd Mon Sep 17 00:00:00 2001
From: Paul Duncan <pabs@pablotron.org>
Date: Mon, 31 Jan 2022 11:09:58 -0500
Subject: initial commit

---
 internal/feed/meta.go | 104 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 104 insertions(+)
 create mode 100644 internal/feed/meta.go

(limited to 'internal/feed/meta.go')

diff --git a/internal/feed/meta.go b/internal/feed/meta.go
new file mode 100644
index 0000000..da2849d
--- /dev/null
+++ b/internal/feed/meta.go
@@ -0,0 +1,104 @@
+package feed
+
+import (
+  "bufio"
+  "encoding/hex"
+  "fmt"
+  "io"
+  "strconv"
+  "strings"
+  "time"
+)
+
+// NVD metadata.
+type Meta struct {
+  LastModifiedDate  time.Time // last modified time
+  Size              uint64    // uncompressed size, in bytes
+  ZipSize           uint64    // zip file size, in bytes
+  GzSize            uint64    // gz file size, in bytes
+  Sha256            [32]byte  // sha256 hash of uncompressed data
+}
+
+func parseMetaSize(name, val string) (uint64, error) {
+  // parse value, check for error
+  v, err := strconv.ParseUint(val, 10, 64)
+  if err == nil {
+    // return size
+    return v, nil
+  } else {
+    // return error
+    return 0, fmt.Errorf("invalid %s: \"%s\"", name, val)
+  }
+}
+
+// Unmarshal new Metadata from reader.
+func NewMeta(r io.Reader) (*Meta, error) {
+  // declare result
+  var m Meta
+
+  // create scanner
+  scanner := bufio.NewScanner(r)
+
+  // read lines
+  for scanner.Scan() {
+    // split into key/value pair, check for error
+    pair := strings.SplitN(scanner.Text(), ":", 2)
+    if len(pair) != 2 {
+      return nil, fmt.Errorf("bad meta line: \"%s\"", scanner.Text())
+    }
+
+    switch pair[0] {
+    case "lastModifiedDate":
+      // parse time, check for error
+      if err := m.LastModifiedDate.UnmarshalText([]byte(pair[1])); err != nil {
+        return nil, err
+      }
+    case "size":
+      if v, err := parseMetaSize("size", pair[1]); err == nil {
+        m.Size = v
+      } else {
+        return nil, err
+      }
+    case "zipSize":
+      if v, err := parseMetaSize("zipSize", pair[1]); err == nil {
+        m.ZipSize = v
+      } else {
+        return nil, err
+      }
+    case "gzSize":
+      if v, err := parseMetaSize("gzSize", pair[1]); err == nil {
+        m.GzSize = v
+      } else {
+        return nil, err
+      }
+    case "sha256":
+      // check hash length
+      if len(pair[1]) != 64 {
+        return nil, fmt.Errorf("invalid sha256 hash length: \"%d\"", len(pair[1]))
+      }
+
+      // decode hex, check for error
+      buf, err := hex.DecodeString(pair[1])
+      if err != nil {
+        return nil, fmt.Errorf("invalid sha256 hash: %v", err)
+      }
+
+      // save to buffer, check for error
+      len := copy(m.Sha256[:], buf[0:32])
+      if len != 32 {
+        return nil, fmt.Errorf("invalid sha256 hash length: %d", len)
+      }
+    default:
+      // return error
+      return nil, fmt.Errorf("unknown key: \"%s\"", pair[0])
+    }
+  }
+
+  // check for scanner error
+  if err := scanner.Err(); err != nil {
+    return nil, err
+  }
+
+  // return success
+  return &m, nil
+}
-- 
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