add cveid, tests

1 files changed, 112 insertions, 0 deletions

diff --git a/internal/feed/cveid.go b/internal/feed/cveid.go
new file mode 100644
index 0000000..8796029
--- /dev/null
+++ b/internal/feed/cveid.go
@@ -0,0 +1,112 @@
+package feed
+
+import (
+  "encoding/json"
+  "fmt"
+  "regexp"
+  "strconv"
+)
+
+// CVE ID
+type CveId uint32
+
+var cveIdRe = regexp.MustCompile("\\ACVE-(\\d{4})-(\\d{1,8})\\z")
+
+// parse year component of CVE ID
+func parseCveIdYear(s string) (uint16, error) {
+  // parse year, check for error
+  year, err := strconv.ParseUint(s, 10, 16)
+  if err != nil {
+    return 0, err
+  }
+
+  // check bounds
+  if year < 2000 || year > 2127 {
+    return 0, fmt.Errorf("year out of bounds: %s", s)
+  }
+
+  // return value
+  return uint16(year), nil
+}
+
+// parse number component of CVE ID
+func parseCveIdNum(s string) (uint32, error) {
+  // parse number, check for error
+  num, err := strconv.ParseUint(s, 10, 32)
+  if err != nil {
+    return 0, err
+  }
+
+  // check bounds
+  if num > 0x01ffffff {
+    return 0, fmt.Errorf("number out of bounds: %d", num)
+  }
+
+  // return value
+  return uint32(num), nil
+}
+
+// Encode CVE ID as uint32.  
+func encodeCveId(year uint16, num uint32) uint32 {
+  return uint32((uint32((year - 2000) & 0x7f) << 25) | (num & 0x01ffffff))
+}
+
+// Create CVE ID from string.
+func NewCveId(s string) (CveId, error) {
+  // match components, check for error
+  md := cveIdRe.FindStringSubmatch(s)
+  if len(md) != 3 {
+    return CveId(0), fmt.Errorf("invalid CVE ID: %s", s)
+  }
+
+  // parse year, check for error
+  year, err := parseCveIdYear(md[1])
+  if err != nil {
+    return CveId(0), err
+  }
+
+  // parse number, check for error
+  num, err := parseCveIdNum(md[2])
+  if err != nil {
+    return CveId(0), err
+  }
+
+  // encode and return result
+  return CveId(encodeCveId(year, num)), nil
+}
+
+// Unmarshal CVE ID from JSON.
+func (me *CveId) UnmarshalJSON(b []byte) error {
+  // decode string, check for error
+  var s string
+  if err := json.Unmarshal(b, &s); err != nil {
+    return err
+  }
+
+  // parse year, check for error
+  r, err := NewCveId(s)
+  if err != nil {
+    return err
+  }
+
+  // serialize ID
+  *me = r
+
+  // return success
+  return nil
+}
+
+// Get year component.
+func (me CveId) Year() uint16 {
+  return uint16((uint32(me) >> 25) & 0x7f) + 2000
+}
+
+// Get number component.
+func (me CveId) Number() uint32 {
+  return (uint32(me) & 0x01ffffff)
+}
+
+// Return string representation of CVE ID.
+func (me CveId) String() string {
+  return fmt.Sprintf("CVE-%04d-%04d", me.Year(), me.Number())
+}