SERVER-60342 Clean up OID string handling

2 files changed, 35 insertions, 20 deletions

diff --git a/src/mongo/bson/oid.cpp b/src/mongo/bson/oid.cpp
index 37fed3b5831..78850acbba1 100644
--- a/src/mongo/bson/oid.cpp
+++ b/src/mongo/bson/oid.cpp
@@ -51,6 +51,11 @@ const std::size_t kTimestampOffset = 0;
 const std::size_t kInstanceUniqueOffset = kTimestampOffset + OID::kTimestampSize;
 const std::size_t kIncrementOffset = kInstanceUniqueOffset + OID::kInstanceUniqueSize;
 OID::InstanceUnique _instanceUnique;
+
+bool isHexit(char c) {
+    return ((c >= '0') && (c <= '9')) || ((c >= 'a') && (c <= 'f')) || ((c >= 'A') && (c <= 'F'));
+}
+
 }  // namespace
 
 MONGO_INITIALIZER_GENERAL(OIDGeneration, (), ("default"))
@@ -147,12 +152,29 @@ void OID::initFromTermNumber(int64_t term) {
     _view().write<BigEndian<int64_t>>(term, kInstanceUniqueOffset);
 }
 
-void OID::init(const std::string& s) {
-    verify(s.size() == 24);
-    std::string blob = hexblob::decode(StringData(s).substr(0, 2 * kOIDSize));
+void OID::init(StringData s) {
+    verify(s.size() == (2 * kOIDSize));
+    std::string blob = hexblob::decode(s.substr(0, 2 * kOIDSize));
     std::copy(blob.begin(), blob.end(), _data);
 }
 
+StatusWith<OID> OID::parse(StringData input) {
+    if (input.size() != (2 * kOIDSize)) {
+        return {ErrorCodes::BadValue,
+                str::stream() << "Invalid string length for parsing to OID, expected "
+                              << (2 * kOIDSize) << " but found " << input.size()};
+    }
+
+    for (char c : input) {
+        if (!isHexit(c)) {
+            return {ErrorCodes::BadValue,
+                    str::stream() << "Invalid character found in hex string: " << c};
+        }
+    }
+
+    return OID(input);
+}
+
 void OID::init(Date_t date, bool max) {
     setTimestamp(uint32_t(date.toMillisSinceEpoch() / 1000));
     uint64_t rest = max ? std::numeric_limits<uint64_t>::max() : 0u;
diff --git a/src/mongo/bson/oid.h b/src/mongo/bson/oid.h
index 7a5818945f6..afe716e5b17 100644
--- a/src/mongo/bson/oid.h
+++ b/src/mongo/bson/oid.h
@@ -85,8 +85,8 @@ public:
 
     enum { kOIDSize = 12, kTimestampSize = 4, kInstanceUniqueSize = 5, kIncrementSize = 3 };
 
-    /** init from a 24 char hex std::string */
-    explicit OID(const std::string& s) {
+    /** init from a 24 char hex string */
+    explicit OID(StringData s) {
         init(s);
     }
 
@@ -141,31 +141,24 @@ public:
     }
 
     /**
+     * This method creates and initializes an OID from a string,
+     * returning a bad Status on failure.
+     */
+    static StatusWith<OID> parse(StringData input);
+
+    /**
      * This method creates and initializes an OID from a string, throwing a BadValue exception if
      * the string is not a valid OID.
      */
     static OID createFromString(StringData input) {
-        uassert(ErrorCodes::BadValue,
-                str::stream() << "Invalid string length for parsing to OID, expected 24 but found "
-                              << input.size(),
-                input.size() == 24);
-        for (auto digit : input) {
-            uassert(ErrorCodes::BadValue,
-                    str::stream() << "Invalid character found in hex string: " << digit,
-                    ('0' <= digit && digit <= '9') || ('a' <= digit && digit <= 'f') ||
-                        ('A' <= digit && digit <= 'F'));
-        }
-
-        OID result;
-        result.init(input.toString());
-        return result;
+        return uassertStatusOK(parse(input));
     }
 
     /** sets the contents to a new oid / randomized value */
     void init();
 
     /** init from a 24 char hex std::string */
-    void init(const std::string& s);
+    void init(StringData s);
 
     /** Set to the min/max OID that could be generated at given timestamp. */
     void init(Date_t date, bool max = false);