From 7b41936ce87ec9a212ad96b980c9545655a59a9d Mon Sep 17 00:00:00 2001
From: brain <brain@e03df62e-2008-0410-955e-edbf42e46eb7>
Date: Wed, 12 Jul 2006 15:35:59 +0000
Subject: Document class Resolver

git-svn-id: http://svn.inspircd.org/repository/trunk/inspircd@4369 e03df62e-2008-0410-955e-edbf42e46eb7
---
 include/dns.h | 88 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 87 insertions(+), 1 deletion(-)

(limited to 'include/dns.h')

diff --git a/include/dns.h b/include/dns.h
index 6da7d4778..c6c1d9a23 100644
--- a/include/dns.h
+++ b/include/dns.h
@@ -29,6 +29,9 @@ struct dns_ip4list
 	dns_ip4list *next;
 };
 
+/**
+ * Error types that class Resolver can emit to its error method.
+ */
 enum ResolverError
 {
 	RESOLVER_NOERROR	=	0,
@@ -40,6 +43,10 @@ enum ResolverError
 
 /** The DNS class allows fast nonblocking resolution of hostnames
  * and ip addresses. It is based heavily upon firedns by Ian Gulliver.
+ * Modules SHOULD avoid using this class to resolve hostnames and IP
+ * addresses, as it is a low-level wrapper around the UDP socket routines
+ * and is probably not abstracted enough for real use. Please see the
+ * Resolver class if you wish to resolve hostnames.
  */
 class DNS : public Extensible
 {
@@ -109,34 +116,113 @@ public:
 	void SetNS(const std::string &dnsserver);
 };
 
+/**
+ * The Resolver class is a high-level abstraction for resolving DNS entries.
+ * It can do forward and reverse IPv4 lookups, and when IPv6 is supported, will
+ * also be able to do those, transparent of protocols. Module developers must
+ * extend this class via inheritence, and then insert a pointer to their derived
+ * class into the core using Server::AddResolver(). Once you have done this,
+ * the class will be able to receive callbacks. There are two callbacks which
+ * can occur by calling virtual methods, one is a success situation, and the other
+ * an error situation.
+ */
 class Resolver : public Extensible
 {
  private:
+	/**
+	 * The lowlevel DNS object used by Resolver
+	 */
 	DNS Query;
+	/**
+	 * The input data, either a host or an IP address
+	 */
 	std::string input;
+	/**
+	 * True if a forward lookup is being performed, false if otherwise
+	 */
 	bool fwd;
+	/**
+	 * The DNS erver being used for lookups. If this is an empty string,
+	 * the value of ServerConfig::DNSServer is used instead.
+	 */
 	std::string server;
+	/**
+	 * The file descriptor used for the DNS lookup
+	 */
 	int fd;
+	/**
+	 * The output data, e.g. a hostname or an IP.
+	 */
 	std::string result;
  public:
+	/**
+	 * Initiate DNS lookup. Your class should not attempt to delete or free these
+	 * objects, as the core will do this for you. They must always be created upon
+	 * the heap using new, as you cannot be sure at what time they will be deleted.
+	 * Allocating them on the stack or attempting to delete them yourself could cause
+	 * the object to go 'out of scope' and cause a segfault in the core if the result
+	 * arrives at a later time.
+	 * @param source The IP or hostname to resolve
+	 * @param forward Set to true to perform a forward lookup (hostname to ip) or false
+	 * to perform a reverse lookup (ip to hostname). Lookups on A records and PTR
+	 * records are supported. CNAME and MX are not supported by this resolver.
+	 * @param dnsserver This optional parameter specifies an alterate nameserver to use.
+	 * If it is not specified, or is an empty string, the value of ServerConfig::DNSServer
+	 * is used instead.
+	 * @throw This class may throw an instance of ModuleException, in the event there are
+	 * no more file descriptors, or a similar hard error occurs such as the network being
+	 * down.
+	 */
 	Resolver(const std::string &source, bool forward, const std::string &dnsserver);
+	/**
+	 * The default destructor does nothing.
+	 */
 	virtual ~Resolver();
+	/**
+	 * When your lookup completes, this method will be called.
+	 * @param result The resulting DNS lookup, either an IP address or a hostname.
+	 */
 	virtual void OnLookupComplete(const std::string &result);
+	/**
+	 * If an error occurs (such as NXDOMAIN, no domain name found) then this method
+	 * will be called.
+	 * @param e A ResolverError enum containing the error type which has occured.
+	 */
 	virtual void OnError(ResolverError e);
-
+	/**
+	 * This method is called by the core when the object's file descriptor is ready
+	 * for reading, and will then dispatch a call to either OnLookupComplete or
+	 * OnError. You should never call this method yourself.
+	 */
 	bool ProcessResult();
+	/**
+	 * Returns the file descriptor of this class. This is primarily used by the core
+	 * to determine where in various tables to place a pointer to your class, but it
+	 * is safe to call and use this method.
+	 */
 	int GetFd();
 };
 
+/**
+ * Clear the pointer table used for Resolver classes
+ */
 void init_dns();
+/**
+ * Deal with a Resolver class which has become writeable
+ */
 void dns_deal_with_classes(int fd);
+/**
+ * Add a resolver class to our active table
+ */
 bool dns_add_class(Resolver* r);
 
+#ifdef THREADED_DNS
 /** This is the handler function for multi-threaded DNS.
  * It cannot be a class member as pthread will not let us
  * create a thread whos handler function is a member of
  * a class (ugh).
  */
 void* dns_task(void* arg);
+#endif
 
 #endif
-- 
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