Changeset b4049f9 in code

Timestamp:

Mar 4, 2014, 10:34:57 AM (11 years ago)

Author:

Mike Belopuhov <mike@…>

Branches:

master

Children:

5815eef

Parents:

fa271b8

Message:

Rewrite DNS resolver to do things truly asynchronously

Files:

• dns.c (modified) (9 diffs)
• icbd.c (modified) (4 diffs)
• icbd.h (modified) (1 diff)

dns.c

@@ -1 +1 @@
 /*
+ * Copyright (c) 2013 Mike Belopuhov
  * Copyright (c) 2009 Michael Shalayeff
  * All rights reserved.
@@ -23 +24 @@
 #include <errno.h>
 #include <stdlib.h>
+#include <string.h>
 #include <unistd.h>
 #include <syslog.h>
@@ -35 +37 @@
 
 void dns_dispatch(int, short, void *);
+void dns_done(int, short, void *);
 int dns_pipe;
 
+
+struct icbd_dnsquery {
+        uint64_t                        sid;
+        union {
+                struct sockaddr_storage req;
+                char                    rep[MAXHOSTNAMELEN];
+        } u;
+};
+
 int
-icbd_dns_init(void)
+dns_init(void)
 {
-        struct event    ev;
-        int             pipe[2];
-        struct passwd   *pw;
+        static struct event ev;
+        struct passwd *pw;
+        int pipes[2];
 
-        if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, pipe) == -1) {
+        if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, pipes) == -1) {
                 syslog(LOG_ERR, "socketpair: %m");
                 exit(EX_OSERR);
@@ -57 +69 @@
 
         default:
-                close(pipe[1]);
-                dns_pipe = pipe[0];
+                close(pipes[1]);
+                dns_pipe = pipes[0];
+
+                /* event for the reply */
+                event_set(&ev, dns_pipe, EV_READ | EV_PERSIST,
+                    dns_done, NULL);
+                if (event_add(&ev, NULL) < 0) {
+                        syslog(LOG_ERR, "event_add: %m");
+                        exit (EX_UNAVAILABLE);
+                }
                 return (0);
         }
 
         setproctitle("dns resolver");
-        close(pipe[0]);
+        close(pipes[0]);
 
         if ((pw = getpwnam(ICBD_USER)) == NULL) {
@@ -86 +106 @@
         event_init();
 
-        event_set(&ev, pipe[1], EV_READ | EV_PERSIST, dns_dispatch, NULL);
+        /* event for the request */
+        event_set(&ev, pipes[1], EV_READ | EV_PERSIST, dns_dispatch, NULL);
         if (event_add(&ev, NULL) < 0) {
                 syslog(LOG_ERR, "event_add: %m");
@@ -96 +117 @@
 
 void
-dns_dispatch(int fd, short event, void *arg)
+dns_dispatch(int fd, short event, void *arg __attribute__((unused)))
 {
         char host[NI_MAXHOST];
-        struct sockaddr_storage ss;
-        struct sockaddr *sa = (struct sockaddr *)&ss;
-        int gerr, ss_len = sizeof ss;
+        struct sockaddr *sa;
+        struct icbd_dnsquery q;
+        int gerr;
 
         arg = NULL;
@@ -107 +128 @@
                 return;
 
-        if (read(fd, &ss, ss_len) != ss_len) {
+        if (read(fd, &q, sizeof q) != sizeof q) {
                 syslog(LOG_ERR, "dns read: %m");
                 exit(1);
         }
 
+        sa = (struct sockaddr *)&q.u.req;
         if ((gerr = getnameinfo(sa, sa->sa_len,
             host, sizeof host, NULL, 0, NI_NOFQDN))) {
                 syslog(LOG_ERR, "getnameinfo: %s", gai_strerror(gerr));
-                write(fd, host, sizeof host);
                 return;
         }
@@ -122 +143 @@
                 syslog(LOG_DEBUG, "dns_dispatch: resolved %s", host);
 
-        if (write(fd, host, sizeof host) != sizeof host)
+        memcpy(&q.u.rep, host, sizeof host);
+        if (write(fd, &q, sizeof q) != sizeof q)
                 syslog(LOG_ERR, "dns write: %m");
+}
+
+void
+dns_done(int fd, short event, void *arg __attribute__((unused)))
+{
+        struct icb_session *is;
+        struct icbd_dnsquery q;
+
+        if (event != EV_READ)
+                return;
+
+        if (read(fd, &q, sizeof q) != sizeof q) {
+                syslog(LOG_ERR, "read: %m");
+                return;
+        }
+
+        if ((is = icbd_session_lookup(q.sid)) == NULL) {
+                syslog(LOG_ERR, "failed to find session %llu", q.sid);
+                return;
+        }
+
+        memcpy(is->host, q.u.rep, MAXHOSTNAMELEN);
+        is->host[sizeof is->host - 1] = '\0';
+
+        if (verbose)
+                syslog(LOG_DEBUG, "icbd_dns: resolved %s", is->host);
 }
 
@@ -129 +177 @@
 dns_rresolv(struct icb_session *is, struct sockaddr_storage *ss)
 {
-        /* one-shot event for the reply */
-        event_set(&is->ev, dns_pipe, EV_READ, icbd_dns, is);
-        if (event_add(&is->ev, NULL) < 0) {
-                syslog(LOG_ERR, "event_add: %m");
-                exit (EX_UNAVAILABLE);
-        }
-
-        inet_ntop(ss->ss_family, ss->ss_family == AF_INET ?
-            (void *)&((struct sockaddr_in *)ss)->sin_addr :
-            (void *)&((struct sockaddr_in6 *)ss)->sin6_addr,
-            is->host, sizeof is->host);
+        struct icbd_dnsquery q;
 
         if (verbose)
                 syslog(LOG_DEBUG, "resolving: %s", is->host);
 
-        if (write(dns_pipe, ss, sizeof *ss) != sizeof *ss) {
+        memset(&q, 0, sizeof q);
+        q.sid = is->id;
+        memcpy(&q.u.req, ss, sizeof *ss);
+        if (write(dns_pipe, &q, sizeof q) != sizeof q) {
                 syslog(LOG_ERR, "write: %m");
                 exit (EX_OSERR);

icbd.c

@@ -213 +213 @@
 
         /* start a dns resolver thread */
-        icbd_dns_init();
+        dns_init();
 
         if (!foreground)
@@ -225 +225 @@
 
         return (EX_UNAVAILABLE);
-}
-
-void
-icbd_dns(int fd, short event, void *arg)
-{
-        struct icb_session *is = arg;
-
-        if (event != EV_READ)
-                return;
-
-        if (read(fd, is->host, sizeof is->host) < 0)
-                syslog(LOG_ERR, "read: %m");
-
-        is->host[sizeof is->host - 1] = '\0';
-
-        if (verbose)
-                syslog(LOG_DEBUG, "icbd_dns: resolved %s", is->host);
 }
 
@@ -547 +530 @@
 {
         struct sockaddr_storage ss;
+        struct sockaddr_in *sin = (struct sockaddr_in *)&ss;
+        struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)&ss;
         socklen_t ss_len = sizeof ss;
 
@@ -557 +542 @@
         switch (ss.ss_family) {
         case AF_INET:
-                is->port = ntohs(((struct sockaddr_in *)&ss)->sin_port);
+                is->port = ntohs(sin->sin_port);
                 break;
 
         case AF_INET6:
-                is->port = ntohs(((struct sockaddr_in6 *)&ss)->sin6_port);
+                is->port = ntohs(sin6->sin6_port);
                 break;
         }
 
+        inet_ntop(ss.ss_family, ss.ss_family == AF_INET ?
+            (void *)&sin->sin_addr : (void *)&sin6->sin6_addr,
+            is->host, sizeof is->host);
+
         dns_rresolv(is, &ss);
 }

icbd.h

@@ -29 +29 @@
 /* dns.c */
 struct sockaddr_storage;
-int     icbd_dns_init(void);
-void    icbd_dns(int, short, void *);
+int     dns_init(void);
 int     dns_rresolv(struct icb_session *, struct sockaddr_storage *);