Make threaded dns stable by placing some mutexes around some stl stuff (this really...

[user/henk/code/inspircd.git] / src / dns.cpp

diff --git a/src/dns.cpp b/src/dns.cpp
index 89386664cf99cbd5bb328ac2f638a3d5b3f0bcc3..a6e41307170d513938cba0f29795373935c5a97c 100644 (file)
--- a/src/dns.cpp
+++ b/src/dns.cpp
@@ -49,12 +49,18 @@ using namespace std;
 #include "dns.h"
 #include "inspircd.h"
 #include "helperfuncs.h"
+#include "inspircd_config.h"
 #include "socketengine.h"
 #include "configreader.h"
 
+#ifdef THREADED_DNS
+pthread_mutex_t connmap_lock = PTHREAD_MUTEX_INITIALIZER;
+#endif
+
 extern InspIRCd* ServerInstance;
 extern ServerConfig* Config;
 extern time_t TIME;
+extern userrec* fd_ref_table[MAX_DESCRIPTORS];
 
 enum QueryType { DNS_QRY_A = 1, DNS_QRY_PTR = 12 };
 enum QueryFlags1 { FLAGS1_MASK_RD = 0x01, FLAGS1_MASK_TC = 0x02, FLAGS1_MASK_AA = 0x04, FLAGS1_MASK_OPCODE = 0x78, FLAGS1_MASK_QR = 0x80 };
@@ -71,7 +77,6 @@ Resolver* dns_classes[MAX_DESCRIPTORS];
 struct in_addr servers4[8];
 int i4;
 int initdone = 0;
-int wantclose = 0;
 int lastcreate = -1;
 
 class s_connection
@@ -169,11 +174,6 @@ void dns_close(int fd)
                ServerInstance->SE->DelFd(fd);
 #endif
        log(DEBUG,"DNS: dns_close on fd %d",fd);
-       if (fd == lastcreate)
-       {
-               wantclose = 1;
-               return;
-       }
        shutdown(fd,2);
        close(fd);
        return;
@@ -292,16 +292,15 @@ s_connection *dns_add_query(s_header *h)
                return NULL;
        }
        /* create new connection object, add to linked list */
+#ifdef THREADED_DNS
+       pthread_mutex_lock(&connmap_lock);
+#endif
        if (connections.find(s->fd) == connections.end())
                connections[s->fd] = s;
+#ifdef THREADED_DNS
+       pthread_mutex_unlock(&connmap_lock);
+#endif
 
-       if (wantclose == 1)
-       {
-               shutdown(lastcreate,2);
-               close(lastcreate);
-               wantclose = 0;
-       }
-       lastcreate = s->fd;
        return s;
 }
 
@@ -464,6 +463,14 @@ char* DNS::dns_getresult_s(const int cfd, char *res) { /* retrieve result of DNS
                *res = 0;
 
        /* FireDNS used a linked list for this. How ugly (and slow). */
+
+#ifdef THREADED_DNS
+       /* XXX: STL really does NOT like being poked and prodded in more than
+        * one orifice by threaded apps. Make sure we remain nice to it, and
+        * lock a mutex around any access to the std::map.
+        */
+       pthread_mutex_lock(&connmap_lock);
+#endif
        connlist_iter n_iter = connections.find(cfd);
        if (n_iter == connections.end())
        {
@@ -477,6 +484,9 @@ char* DNS::dns_getresult_s(const int cfd, char *res) { /* retrieve result of DNS
                /* We don't delete c here, because its done later when needed */
                connections.erase(n_iter);
        }
+#ifdef THREADED_DNS
+       pthread_mutex_unlock(&connmap_lock);
+#endif
 
        l = recv(c->fd,buffer,sizeof(s_header),0);
        dns_close(c->fd);
@@ -595,6 +605,7 @@ char* DNS::dns_getresult_s(const int cfd, char *res) { /* retrieve result of DNS
                        {
                                if (h.payload[i] > 63)
                                {
+                                       log(DEBUG,"DNS: h.payload[i] > 63");
                                        memcpy(&p,&h.payload[i],2);
                                        i = ntohs(p) - 0xC000 - 12;
                                }
@@ -799,6 +810,7 @@ std::string DNS::GetResult()
                if (ServerInstance && ServerInstance->stats)
                        ServerInstance->stats->statsDnsGood++;
                dns_close(this->myfd);
+               this->myfd = -1;
                return result;
        }
        else
@@ -808,6 +820,7 @@ std::string DNS::GetResult()
                if (this->myfd != -1)
                {
                        dns_close(this->myfd);
+                       this->myfd = -1;
                }
                return "";
        }
@@ -821,6 +834,7 @@ std::string DNS::GetResultIP()
        if (this->myfd != -1)
        {
                dns_close(this->myfd);
+               this->myfd = -1;
        }
        if (result)
        {
@@ -845,42 +859,64 @@ std::string DNS::GetResultIP()
 
 
 #ifdef THREADED_DNS
+
+/* This function is a thread function which can be thought of as a lightweight process
+ * to all you non-threaded people. In actuality its so much more, and pretty damn cool.
+ * With threaded dns enabled, each user which connects gets a thread attached to their
+ * user record when their DNS lookup starts. This function starts in parallel, and
+ * commences a blocking dns lookup. Because its a seperate thread, this occurs without
+ * actually blocking the main application. Once the dns lookup is completed, the thread
+ * checks if the user is still around by checking their fd against the reference table,
+ * and if they are, writes the hostname into the struct and terminates, after setting
+ * userrec::dns_done to true. Because this is multi-threaded it can make proper use of
+ * SMP setups (like the one i have here *grin*).
+ * This is in comparison to the non-threaded dns, which must monitor the thread sockets
+ * in a nonblocking fashion, consuming more resources to do so.
+ */
 void* dns_task(void* arg)
 {
        userrec* u = (userrec*)arg;
+       int thisfd = u->fd;
+
        log(DEBUG,"DNS thread for user %s",u->nick);
        DNS dns1;
        DNS dns2;
        std::string host;
        std::string ip;
-       if (dns1.ReverseLookup((char*)inet_ntoa(u->ip4)))
+       if (dns1.ReverseLookup(inet_ntoa(u->ip4),false))
        {
                while (!dns1.HasResult())
-               {
                        usleep(100);
-               }
                host = dns1.GetResult();
                if (host != "")
                {
-                       if (dns2.ForwardLookup(host), false)
+                       if (dns2.ForwardLookup(host, false))
                        {
                                while (!dns2.HasResult())
-                               {
                                        usleep(100);
-                               }
                                ip = dns2.GetResultIP();
-                               if (ip == std::string((char*)inet_ntoa(u->ip4)))
+                               if (ip == std::string(inet_ntoa(u->ip4)))
                                {
-                                       if (host.length() < 160)
+                                       if (host.length() < 65)
                                        {
-                                               strcpy(u->host,host.c_str());
-                                               strcpy(u->dhost,host.c_str());
+                                               if ((fd_ref_table[thisfd] == u) && (fd_ref_table[thisfd]))
+                                               {
+                                                       if (!u->dns_done)
+                                                       {
+                                                               strcpy(u->host,host.c_str());
+                                                               if ((fd_ref_table[thisfd] == u) && (fd_ref_table[thisfd]))
+                                                               {
+                                                                       strcpy(u->dhost,host.c_str());
+                                                               }
+                                                       }
+                                               }
                                        }
                                }
                        }
                }
        }
-       u->dns_done = true;
+       if ((fd_ref_table[thisfd] == u) && (fd_ref_table[thisfd]))
+               u->dns_done = true;
        return NULL;
 }
 #endif
@@ -900,12 +936,15 @@ Resolver::Resolver(const std::string &source, bool forward, const std::string &d
        else
        {
                Query.ReverseLookup(input.c_str(), false);
-               this->Fd = Query.GetFD();
+               this->fd = Query.GetFD();
        }
        if (fd < 0)
        {
                log(DEBUG,"Resolver::Resolver: RESOLVER_NSDOWN");
                this->OnError(RESOLVER_NSDOWN);
+               ModuleException e("Resolver: Nameserver is down");
+               throw e;
+               /* We shouldnt get here really */
                return;
        }
 
@@ -918,6 +957,10 @@ Resolver::Resolver(const std::string &source, bool forward, const std::string &d
        {
                log(DEBUG,"Resolver::Resolver: RESOLVER_NOTREADY");
                this->OnError(RESOLVER_NOTREADY);
+               ModuleException e("Resolver: Core not initialized yet");
+               throw e;
+               /* We shouldnt get here really */
+               return;
        }
 }