Added asynchronous DNS resolver. See #47

5 files changed, 139 insertions, 21 deletions

diff --git a/daemon/Makefile.am b/daemon/Makefile.am
index 63f5169..28dceaf 100644
--- a/daemon/Makefile.am
+++ b/daemon/Makefile.am
@@ -8,6 +8,7 @@ rrdbotd_SOURCES = rrdbotd.c rrdbotd.h config.c \
                 ../common/compat.h ../common/compat.c \
                 ../common/hash.h ../common/hash.c \
                 ../common/config-parser.h ../common/config-parser.c \
+                ../common/async-resolver.h ../common/async-resolver.c \
                 ../mib/mib-parser.h ../mib/mib-parser.c
 rrdbotd_CFLAGS = -I${top_srcdir}/common/ -I${top_srcdir}/bsnmp/ -I${top_srcdir} \
                  -DCONF_PREFIX=\"$(sysconfdir)\" -DDATA_PREFIX=\"$(datadir)\"
diff --git a/daemon/config.c b/daemon/config.c
index 0f68c79..3e7c534 100644
--- a/daemon/config.c
+++ b/daemon/config.c
@@ -196,6 +196,7 @@ parse_item(const char* field, char* uri, config_ctx *ctx)
 {
     rb_item *ritem;
     rb_host *rhost;
+    int r;
 
     const char *msg;
     char* copy;
@@ -235,17 +236,29 @@ parse_item(const char* field, char* uri, config_ctx *ctx)
         rhost->version = 1;
         rhost->name = host;
         rhost->community = user ? user : "public";
+        rhost->is_resolved = 1;
+        rhost->resolve_interval = 0;
+        rhost->last_resolved = 0;
 
-        /* TODO: Eventually resolving should be in a separate thread,
-           and done regularly */
-        if(sock_any_pton(host, &(rhost->address),
-                         SANY_OPT_DEFPORT(161) | SANY_OPT_DEFLOCAL) == -1)
+        /* Try and resolve the DNS name */
+        r = sock_any_pton(host, &(rhost->address),
+                         SANY_OPT_DEFPORT(161) | SANY_OPT_DEFLOCAL | SANY_OPT_NORESOLV);
+
+        if(r == -1)
         {
-            rb_message(LOG_WARNING, "couldn't resolve host address (ignoring): %s", host);
+            rb_message(LOG_WARNING, "couldn't parse host address (ignoring): %s", host);
             free(rhost);
             return NULL;
         }
 
+        /*
+         * If we got back SANY_AF_DNS, then it needs resolving. The actual
+         * interval and stuff are worked out in rb_config_parse() once all
+         * the hosts, polls etc... have been parsed.
+         */
+        if(r == SANY_AF_DNS)
+            rhost->is_resolved = 0;
+
         /* And add it to the list */
         rhost->next = g_state.hosts;
         g_state.hosts = rhost;
@@ -346,6 +359,7 @@ void
 rb_config_parse()
 {
     config_ctx ctx;
+    rb_poller* poll;
 
     /* Setup the hash tables properly */
     g_state.poll_by_key = hsh_create();
@@ -358,6 +372,35 @@ rb_config_parse()
 
     if(!g_state.polls)
         errx(1, "no config files found in config directory: %s", g_state.confdir);
+
+    /* Organize the async resolve intervals */
+    for(poll = g_state.polls; poll; poll = poll->next)
+    {
+        rb_item *item;
+        mstime resint;
+
+        /* When less than three minutes, resolve once per minute */
+        if(poll->interval <= 180000)
+            resint = 60000;
+
+        /* When between 3 and 10 minutes resolve once per cycle */
+        else if(poll->interval <= 600000)
+            resint = poll->interval;
+
+        /* Otherwise resolve thrice per cycle */
+        else
+            resint = poll->interval / 3;
+
+        for(item = poll->items; item; item = item->next)
+        {
+            /* The lowest interval (since hosts can be shared by pollers) wins */
+            if(!item->host->is_resolved && item->host->resolve_interval < resint)
+            {
+                rb_host* host = (rb_host*)item->host;
+                host->resolve_interval = resint;
+            }
+        }
+    }
 }
 
 /* -----------------------------------------------------------------------------
diff --git a/daemon/rrdbotd.c b/daemon/rrdbotd.c
index a2976a5..9e81350 100644
--- a/daemon/rrdbotd.c
+++ b/daemon/rrdbotd.c
@@ -50,6 +50,7 @@
 
 #include "rrdbotd.h"
 #include "server-mainloop.h"
+#include "async-resolver.h"
 
 /* The default command line options */
 #define DEFAULT_CONFIG      CONF_PREFIX "/rrdbot"
@@ -134,14 +135,14 @@ rb_vmessage(int level, int err, const char* msg, va_list ap)
     buf[MAX_MSGLEN - 1] = 0;
 
     /* Either to syslog or stderr */
-    if (daemonized)
-        vsyslog (level, buf, ap);
+    if(daemonized)
+        vsyslog(level, buf, ap);
     else
-        vwarnx (buf, ap);
+        vwarnx(buf, ap);
 }
 
 void
-rb_messagex (int level, const char* msg, ...)
+rb_messagex(int level, const char* msg, ...)
 {
     va_list ap;
     va_start(ap, msg);
@@ -150,7 +151,7 @@ rb_messagex (int level, const char* msg, ...)
 }
 
 void
-rb_message (int level, const char* msg, ...)
+rb_message(int level, const char* msg, ...)
 {
     va_list ap;
     va_start(ap, msg);
@@ -301,6 +302,10 @@ main(int argc, char* argv[])
     /* The mainloop server */
     server_init();
 
+    /* Setup the Async DNS resolver */
+    if(async_resolver_init() < 0)
+        err(1, "couldn't initialize resolver");
+
     /* Parse config and setup SNMP system */
     rb_config_parse();
 
@@ -345,6 +350,7 @@ main(int argc, char* argv[])
     /* Cleanups */
     rb_snmp_engine_uninit();
     rb_config_free();
+    async_resolver_uninit();
     server_uninit();
 
     return 0;
diff --git a/daemon/rrdbotd.h b/daemon/rrdbotd.h
index 061beb2..35b3912 100644
--- a/daemon/rrdbotd.h
+++ b/daemon/rrdbotd.h
@@ -100,8 +100,10 @@ typedef struct _rb_host
 
     /* Host resolving and book keeping */
     struct sockaddr_any address;
-    mstime interval;
+    mstime resolve_interval;
+    mstime last_resolve_try;
     mstime last_resolved;
+    int is_resolved;
 
     /* Next in list of hosts */
     struct _rb_host* next;
@@ -155,6 +157,9 @@ extern rb_state g_state;
  * UTILITIES (rrdbotd.c)
  */
 
+typedef void (*resolve_callback)(void *context, int unused, const char *name,
+                                 const unsigned char *addr, size_t addrlen);
+
 void rb_messagex(int level, const char* msg, ...);
 void rb_message(int level, const char* msg, ...);
 void rb_vmessage(int level, int err, const char* msg, va_list ap);
diff --git a/daemon/snmp-engine.c b/daemon/snmp-engine.c
index 479bc85..c2afbe9 100644
--- a/daemon/snmp-engine.c
+++ b/daemon/snmp-engine.c
@@ -37,16 +37,20 @@
  */
 
 #include "usuals.h"
+#include <sys/types.h>
+#include <sys/socket.h>
 #include <errno.h>
 #include <unistd.h>
 #include <syslog.h>
 #include <err.h>
+#include <arpa/inet.h>
 
 #include <bsnmp/asn1.h>
 #include <bsnmp/snmp.h>
 
 #include "rrdbotd.h"
 #include "server-mainloop.h"
+#include "async-resolver.h"
 
 /* The socket to use */
 static int snmp_socket = -1;
@@ -61,7 +65,6 @@ static unsigned char snmp_buffer[0x1000];
  * REQUESTS
  */
 
-/* rb_request waaaaayyyyy too big */
 typedef struct _rb_request
 {
     /* The SNMP request identifier */
@@ -229,6 +232,23 @@ send_req(rb_request* req, mstime when)
     struct asn_buf b;
     ssize_t ret;
 
+    /* Update our bookkeeping */
+    req->sent++;
+    if(req->sent <= g_state.retries)
+        req->next_retry = when + req->interval;
+    else
+        req->next_retry = 0;
+    req->last_sent = when;
+
+    /* No sending if no address */
+    if(!req->host->is_resolved)
+    {
+        if(req->sent <= 1)
+            rb_messagex(LOG_DEBUG, "skipping snmp request: host not resolved: %s",
+                        req->host->name);
+        return;
+    }
+
     b.asn_ptr = snmp_buffer;
     b.asn_len = sizeof(snmp_buffer);
 
@@ -243,14 +263,6 @@ send_req(rb_request* req, mstime when)
         else
             rb_messagex(LOG_DEBUG, "sent request #%d to: %s", req->id, req->host->name);
     }
-
-    /* And update our bookkeeping */
-    req->sent++;
-    if(req->sent <= g_state.retries)
-        req->next_retry = when + req->interval;
-    else
-        req->next_retry = 0;
-    req->last_sent = when;
 }
 
 static void
@@ -272,7 +284,6 @@ timeout_req(rb_request* req, mstime when)
         if(it->req == req)
         {
             rb_messagex(LOG_DEBUG, "value for field '%s' timed out", it->rrdfield);
-
             it->vtype = VALUE_UNSET;
             it->req = NULL;
         }
@@ -601,6 +612,54 @@ prep_timer(mstime when, void* arg)
     return 0;
 }
 
+static void
+resolve_cb(int ecode, struct addrinfo* ai, void* arg)
+{
+    rb_host* host = (rb_host*)arg;
+
+    if(ecode)
+    {
+        rb_messagex(LOG_WARNING, "couldn't resolve hostname: %s: %s", host->name,
+                    gai_strerror(ecode));
+        return;
+    }
+
+    /* A successful resolve */
+    memcpy(&SANY_ADDR(host->address), ai->ai_addr, ai->ai_addrlen);
+    SANY_LEN(host->address) = ai->ai_addrlen;
+    host->last_resolved = server_get_time();
+    host->is_resolved = 1;
+
+    rb_messagex(LOG_DEBUG, "resolved host: %s", host->name);
+}
+
+static int
+resolve_timer(mstime when, void* arg)
+{
+    rb_host* host;
+
+    /* Go through hosts and see which ones need resolving */
+    for(host = g_state.hosts; host; host = host->next)
+    {
+        /* No need to resolve? */
+        if(!host->resolve_interval)
+            continue;
+
+        if(when - host->resolve_interval > host->last_resolve_try)
+        {
+            /* Automatically strips port number */
+            rb_messagex(LOG_DEBUG, "resolving host: %s", host->name);
+            async_resolver_queue(host->name, "161", resolve_cb, host);
+            host->last_resolve_try = when;
+        }
+
+        /* When the last 3 resolves have failed, set to unresolved */
+        if(when - (host->resolve_interval * 3) > host->last_resolved)
+            host->is_resolved = 0;
+    }
+
+    return 1;
+}
 
 void
 rb_snmp_engine_init()
@@ -636,6 +695,10 @@ rb_snmp_engine_init()
     /* We fire off the resend timer every 1/5 second */
     if(server_timer(200, resend_timer, NULL) == -1)
         err(1, "couldn't setup timer");
+
+    /* resolve timer goes once per second */
+    if(server_timer(1000, resolve_timer, NULL) == -1)
+        err(1, "couldn't setup timer");
 }
 
 void