Provide a way to extract a serialised integer

src/libckpool.c

@@ -1255,6 +1255,18 @@ int ser_number(uchar *s, int32_t val)
 	return len;
 }
 
+int get_sernumber(uchar *s)
+{
+	int32_t val = 0;
+	int len;
+
+	len = s[0];
+	if (unlikely(len < 1 || len > 4))
+		return 0;
+	memcpy(&val, &s[1], len);
+	return le32toh(val);
+}
+
 /* For testing a le encoded 256 byte hash against a target */
 bool fulltest(const uchar *hash, const uchar *target)
 {

src/libckpool.h

@@ -344,6 +344,7 @@ void b58tobin(char *b58bin, const char *b58);
 
 void address_to_pubkeytxn(char *pkh, const char *addr);
 int ser_number(uchar *s, int32_t val);
+int get_sernumber(uchar *s);
 bool fulltest(const uchar *hash, const uchar *target);
 
 void copy_tv(tv_t *dest, const tv_t *src);