Adds support to the server ID generation

The server ID is a sha-1 identifier generated from the mac address of the first
ethernet device plus the server name. The process is the same used by
ModSecurity 2.9

src/utils/sha1.h

@@ -0,0 +1,79 @@
+/*
+ * ModSecurity, http://www.modsecurity.org/
+ * Copyright (c) 2015 Trustwave Holdings, Inc. (http://www.trustwave.com/)
+ *
+ * You may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * If any of the files related to licensing are missing or if you have any
+ * other questions related to licensing please contact Trustwave Holdings, Inc.
+ * directly using the email address security@modsecurity.org.
+ *
+ */
+
+/** TODO: Reimplement this on the same terms and/or check if we use it. */
+/*
+    sha1.h - header of
+
+    ============
+    SHA-1 in C++
+    ============
+
+    100% Public Domain.
+
+    Original C Code
+        -- Steve Reid <steve@edmweb.com>
+    Small changes to fit into bglibs
+        -- Bruce Guenter <bruce@untroubled.org>
+    Translation to simpler C++ Code
+        -- Volker Grabsch <vog@notjusthosting.com>
+*/
+
+#ifndef SRC_UTILS_SHA1_H_
+#define SRC_UTILS_SHA1_H_
+
+#include <algorithm>
+#include <iostream>
+#include <string>
+
+namespace ModSecurity {
+namespace Utils {
+
+class SHA1 {
+ public:
+    SHA1();
+    void update(std::string *s);
+    void update(std::istream *is);
+    std::string final();
+
+ private:
+    /* just needs to be at least 32bit */
+    typedef unsigned long int uint32;
+    /* just needs to be at least 64bit */
+    typedef unsigned long long uint64;
+
+    /* number of 32bit integers per SHA1 digest */
+    static const unsigned int DIGEST_INTS = 5;
+    /* number of 32bit integers per SHA1 block */
+    static const unsigned int BLOCK_INTS = 16;
+    static const unsigned int BLOCK_BYTES = BLOCK_INTS * 4;
+
+    uint32 digest[DIGEST_INTS];
+    std::string buffer;
+    uint64 transforms;
+
+    void reset();
+    void transform(uint32 block[BLOCK_BYTES]);
+
+    static void buffer_to_block(const std::string &buffer,
+        uint32 block[BLOCK_BYTES]);
+
+    void read(std::istream *is, std::string *s, int max);
+};
+
+}  // namespace Utils
+}  // namespace ModSecurity
+
+#endif  // SRC_UTILS_SHA1_H_