From 2a71835d415113dbfd78c2bdd5ce585f1ba9baee Mon Sep 17 00:00:00 2001
From: Joshua Colp <jcolp@digium.com>
Date: Mon, 5 Jun 2006 15:44:37 +0000
Subject: Convert chan_iax2 to use dnsmgr in order to deal with hostnames that
 can change their resolved IP (aka dynamic dns setups) (issue #6305 reported
 and fixed by ivanfm)

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@32304 65c4cc65-6c06-0410-ace0-fbb531ad65f3
---
 dnsmgr.c | 68 +++++++++++++++++++++++++++++++++++++++++++++++++++-------------
 1 file changed, 55 insertions(+), 13 deletions(-)

(limited to 'dnsmgr.c')

diff --git a/dnsmgr.c b/dnsmgr.c
index 8e7f76453..9eba4951c 100644
--- a/dnsmgr.c
+++ b/dnsmgr.c
@@ -53,9 +53,11 @@ static int refresh_sched = -1;
 static pthread_t refresh_thread = AST_PTHREADT_NULL;
 
 struct ast_dnsmgr_entry {
-	struct in_addr *result;
+	struct in_addr *result; 	/* where we will store the resulting address */
+	struct in_addr last; 		/* the last result, used to check if address has changed */
+	int changed;
 	AST_LIST_ENTRY(ast_dnsmgr_entry) list;
-	char name[1];
+	char name[1];			/* just 1 here, but we use calloc to allocate the correct size */
 };
 
 static AST_LIST_HEAD_STATIC(entry_list, ast_dnsmgr_entry);
@@ -104,6 +106,8 @@ void ast_dnsmgr_release(struct ast_dnsmgr_entry *entry)
 	AST_LIST_LOCK(&entry_list);
 	AST_LIST_REMOVE(&entry_list, entry, list);
 	AST_LIST_UNLOCK(&entry_list);
+	if (option_verbose > 4)
+		ast_verbose(VERBOSE_PREFIX_4 "removing dns manager for '%s'\n", entry->name);
 	free(entry);
 }
 
@@ -116,7 +120,7 @@ int ast_dnsmgr_lookup(const char *name, struct in_addr *result, struct ast_dnsmg
 		return 0;
 
 	if (option_verbose > 3)
-		ast_verbose(VERBOSE_PREFIX_3 "doing lookup for '%s'\n", name);
+		ast_verbose(VERBOSE_PREFIX_3 "doing dnsmgr_lookup for '%s'\n", name);
 
 	/* if it's actually an IP address and not a name,
 	   there's no need for a managed lookup */
@@ -134,12 +138,58 @@ int ast_dnsmgr_lookup(const char *name, struct in_addr *result, struct ast_dnsmg
 		return 0;
 	} else {
 		if (option_verbose > 2)
-			ast_verbose(VERBOSE_PREFIX_2 "adding manager for '%s'\n", name);
+			ast_verbose(VERBOSE_PREFIX_2 "adding dns manager for '%s'\n", name);
 		*dnsmgr = ast_dnsmgr_get(name, result);
 		return !*dnsmgr;
 	}
 }
 
+/*
+ * Refresh a dnsmgr entry
+ *
+ * XXX maybe we must lock the entry to make safer
+ */
+int ast_dnsmgr_refresh(struct ast_dnsmgr_entry *entry, int verbose)
+{
+	struct ast_hostent ahp;
+	struct hostent *hp;
+        char iabuf[INET_ADDRSTRLEN];
+        char iabuf2[INET_ADDRSTRLEN];
+        struct in_addr tmp;
+        
+	if (verbose && (option_verbose > 2))
+		ast_verbose(VERBOSE_PREFIX_2 "refreshing '%s'\n", entry->name);
+
+	if ((hp = ast_gethostbyname(entry->name, &ahp))) {
+		/* check to see if it has changed, do callback if requested (where de callback is defined ????) */
+		memcpy(&tmp, hp->h_addr, sizeof(tmp));
+		if (tmp.s_addr != entry->last.s_addr) {
+			ast_log(LOG_NOTICE, "host '%s' changed from %s to %s\n", 
+				entry->name,
+				ast_inet_ntoa(iabuf, sizeof(iabuf), entry->last),
+				ast_inet_ntoa(iabuf2, sizeof(iabuf2), tmp));
+
+			memcpy(entry->result, hp->h_addr, sizeof(entry->result));
+			memcpy(&entry->last, hp->h_addr, sizeof(entry->last));
+			entry->changed = 1;
+			return 1;
+		} 
+		
+	}
+	return 0;
+}
+
+/*
+ * Check if dnsmgr entry has changed from since last call to this function
+ */
+int ast_dnsmgr_changed(struct ast_dnsmgr_entry *entry) 
+{
+	int ret = entry->changed;
+	entry->changed = 0;
+	
+	return ret;
+}
+
 static void *do_refresh(void *data)
 {
 	for (;;) {
@@ -155,8 +205,6 @@ static int refresh_list(void *data)
 {
 	struct refresh_info *info = data;
 	struct ast_dnsmgr_entry *entry;
-	struct ast_hostent ahp;
-	struct hostent *hp;
 
 	/* if a refresh or reload is already in progress, exit now */
 	if (ast_mutex_trylock(&refresh_lock)) {
@@ -172,13 +220,7 @@ static int refresh_list(void *data)
 		if (info->regex_present && regexec(&info->filter, entry->name, 0, NULL, 0))
 		    continue;
 
-		if (info->verbose && (option_verbose > 2))
-			ast_verbose(VERBOSE_PREFIX_2 "refreshing '%s'\n", entry->name);
-
-		if ((hp = ast_gethostbyname(entry->name, &ahp))) {
-			/* check to see if it has changed, do callback if requested */
-			memcpy(entry->result, hp->h_addr, sizeof(entry->result));
-		}
+		ast_dnsmgr_refresh(entry, info->verbose);
 	}
 	AST_LIST_UNLOCK(info->entries);
 
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