breaking out the salt storing functionality so i can reuse it

database/salt_store.cpp

@@ -0,0 +1,63 @@
+#include "salt_store.h"
+#include <cstdlib>
+#include <cstdio>
+#include <unistd.h>
+#include <stdint.h>
+#include <ctime>
+
+SaltStore::SaltStore(uint64_t key_lifetime, size_t salt_size, std::string secret) {
+	this->key_lifetime = key_lifetime;
+	this->salt_size = salt_size;
+	this->secret = secret;
+}
+
+std::string SaltStore::getSalt() {
+	expireKeys();
+	char bfr[salt_size];
+	FILE * rand_in = fopen("/dev/urandom", "r");
+	if(!rand_in) {
+		fprintf(stderr, "Could not open /dev/urandom!\n");
+		return "";
+	}
+	if(salt_size != fread(bfr, sizeof(char), salt_size, rand_in)) {
+		fclose(rand_in);
+		fprintf(stderr, "Could not read from /dev/urandom!\n");
+		return "";
+	}
+	fclose(rand_in);
+
+	// zero-terminated strings suck
+	for(unsigned int i=0;i<salt_size;++i)
+		if(bfr[i] == 0)
+			bfr[i] = 1;
+	bfr[salt_size-1] = 0;
+
+	std::string salt(bfr);
+
+	valid_keys.push_back(std::pair<uint64_t, SHA1Hash>((uint64_t)time(NULL), SHA1Hash(salt + secret)));
+	return salt;
+}
+
+bool SaltStore::consumeKey(std::string key) {
+	expireKeys();
+	SHA1Hash h;
+	h.fromHex(key);
+	std::list<std::pair<uint64_t, SHA1Hash> >::iterator p;
+	for(p = valid_keys.begin();p != valid_keys.end(); ++p) {
+		if(p->second == h) {
+			valid_keys.erase(p);
+			return true;
+		}
+	}
+	return false;
+}
+
+void SaltStore::expireKeys() {
+	std::list<std::pair<uint64_t, SHA1Hash> >::iterator p;
+	uint64_t cur_t = (uint64_t)time(NULL);
+	for(p = valid_keys.begin();p != valid_keys.end();++p) {
+		if((cur_t - p->first) > key_lifetime)
+			p = valid_keys.erase(p);
+	}
+}
+

database/salt_store.h

@@ -0,0 +1,25 @@
+#ifndef _SALT_STORE_H_
+#define _SALT_STORE_H_
+#include "sha1.h"
+#include <string>
+#include <list>
+
+class SaltStore {
+
+public:
+	SaltStore(uint64_t key_lifetime, size_t salt_size, std::string secret);
+	~SaltStore();
+	std::string getSalt();
+	bool consumeKey(std::string key);
+
+private:
+	void expireKeys();
+	std::list<std::pair<uint64_t, SHA1Hash> > valid_keys;
+	uint64_t key_lifetime;
+	size_t salt_size;
+	std::string secret;
+
+};
+
+#endif
+