Fix incorrect difficulty regexp.

diff --git a/src/bin/server.ts b/src/bin/server.ts
index 0d9a2f03e558af1fcd518346e4e234a7255700d2..58b97e7f768a799935012753be8d3818dceded12 100755 (executable)
--- a/src/bin/server.ts
+++ b/src/bin/server.ts
@@ -109,7 +109,7 @@ async function respond (res: http.ServerResponse, data: Buffer[]): Promise<void>
                if (!/^[0-9A-Fa-f]{64}$/.test(hash ?? '')) {
                        throw new Error('Invalid hash. Must be a 64-character hex string.')
                }
-               if (difficulty && !/^[1-9A-Fa-f][0-9A-Fa-f]{0,15}$/.test(difficulty)) {
+               if (difficulty && !/^[1-9A-Fa-f]{1}[0-9A-Fa-f]{0,15}$/.test(difficulty)) {
                        throw new Error('Invalid difficulty. Must be a hexadecimal string between 1-FFFFFFFFFFFFFFFF.')
                }
                if (action === 'work_validate' && !/^[0-9A-Fa-f]{16}$/.test(work ?? '')) {