Add an asynchronous hostname resolver and make tcp client use it

diff --git a/Makefile b/Makefile
index 129683b6b04f74a72c8f4421caeb01defaf2c9d6..f3e1abe2dc83b1dffc388585b999b0f5cf2888cd 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,8 @@
 -include ../config.mak
 
 SRCS = main.c dispatch.c channels.c transports.c teletext.c psi.c \
-       subscriptions.c tsmux.c tsdemux.c pes.c buffer.c tcp.c plugin.c
+       subscriptions.c tsmux.c tsdemux.c pes.c buffer.c tcp.c plugin.c \
+       resolver.c
 
 SRCS += http.c htmlui.c
 

diff --git a/resolver.c b/resolver.c
new file mode 100644 (file)
index 0000000..81d1148
--- /dev/null
+++ b/resolver.c
@@ -0,0 +1,321 @@
+/*
+ *  Async resolver
+ *  Copyright (C) 2007 Andreas Öman
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <pthread.h>
+
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <netdb.h>
+
+#include <libhts/htsmsg.h>
+#include <libhts/htsmsg_binary.h>
+
+#include <libhts/htsq.h>
+
+#include "resolver.h"
+#include "dispatch.h"
+
+static int res_seq_tally;
+
+static int to_thread_fd[2];
+static int from_thread_fd[2];
+
+LIST_HEAD(res_list, res);
+
+static struct res_list pending_resolve;
+
+static void *resolver_loop(void *aux);
+
+typedef struct res {
+  void (*cb)(void *opaque, struct sockaddr *so, const char *error);
+  void *opaque;
+  int seqno;
+  LIST_ENTRY(res) link;
+} res_t;
+
+static char response_buf[256];
+static int  response_buf_ptr;
+
+/**
+ * Process response from resolver thread and invoke callback
+ */
+static void 
+resolver_socket_callback(int events, void *opaque, int fd)
+{
+  htsmsg_t *m;
+  int r, msglen;
+  uint32_t seq;
+  const char *err;
+  res_t *res;
+  struct sockaddr_in si;
+  const void *ipv4;
+  size_t ipv4len;
+
+  if(response_buf_ptr < 4) {
+    msglen = 4;
+  } else {
+    msglen = (response_buf[0] << 24 | response_buf[1] << 16 |
+      response_buf[2] << 8 | response_buf[3]) + 4;
+    if(msglen > 250) {
+      fprintf(stderr, "Internal resolver error, max msglen exceeded\n");
+      exit(1);
+    }
+  }
+
+  r = read(from_thread_fd[0], response_buf + response_buf_ptr, 
+          msglen - response_buf_ptr);
+  if(r < 1) {
+    fprintf(stderr, "Internal resolver error, reading failed (%d)\n", r);
+    perror("read");
+    exit(1);
+  }
+
+  response_buf_ptr += r;
+
+  if(msglen > 4 && response_buf_ptr == msglen) {
+    m = htsmsg_binary_deserialize(response_buf + 4, msglen - 4, NULL);
+
+    htsmsg_get_u32(m, "seq", &seq);
+
+    LIST_FOREACH(res, &pending_resolve, link) 
+      if(res->seqno == seq)
+       break;
+    
+    if(res != NULL) {
+
+      err = htsmsg_get_str(m, "error");
+      if(err) {
+       res->cb(res->opaque, NULL, err);
+      } else if(htsmsg_get_bin(m, "ipv4", &ipv4, &ipv4len) == 0) {
+       memset(&si, 0, sizeof(si));
+       si.sin_family = AF_INET;
+       memcpy(&si.sin_addr, ipv4, 4);
+       res->cb(res->opaque, (struct sockaddr *)&si, NULL);
+      }
+
+      LIST_REMOVE(res, link);
+      free(res);
+    }
+    response_buf_ptr = 0;
+  }
+}
+
+
+
+
+/**
+ * Setup async resolver
+ */
+static void
+async_resolver_init(void)
+{
+  static int inited;
+  pthread_t ptid;
+  int fd;
+
+  if(inited)
+    return;
+
+  inited = 1;
+
+  if(pipe(to_thread_fd) == -1) {
+    perror("Async resolver, cannot create pipe");
+    exit(1);
+  }
+
+  if(pipe(from_thread_fd) == -1) {
+    perror("Async resolver, cannot create pipe");
+    exit(1);
+  }
+
+  pthread_create(&ptid, NULL, resolver_loop, NULL);
+
+  fd = from_thread_fd[0];
+  fcntl(fd, F_SETFL, fcntl(fd, F_GETFL) | O_NONBLOCK);
+  dispatch_addfd(fd, resolver_socket_callback, NULL, DISPATCH_READ);
+}
+
+
+
+/**
+ * Resolver thread
+ */
+
+static void *
+resolver_loop(void *aux)
+{
+  htsmsg_t *m;
+  void *buf;
+  int r, res, herr;
+  unsigned int l, len;
+  struct hostent hostbuf, *hp;
+  size_t hstbuflen;
+  char *tmphstbuf;
+  const char *hostname;
+  const char *errtxt;
+
+  hstbuflen = 1024;
+  tmphstbuf = malloc(hstbuflen);
+
+  while(1) {
+  
+    r = read(to_thread_fd[0], &l, 4);
+    if(r != 4) {
+      fprintf(stderr, "resolver: read error: header, r = %d\n", r);
+      perror("read");
+      break;
+    }
+
+    l = ntohl(l);
+    buf = malloc(l);
+
+    if(read(to_thread_fd[0], buf, l) != l) {
+      free(buf);
+      fprintf(stderr, "resolver: read error: payload, r = %d\n", r);
+      perror("read");
+      break;
+    }
+
+    m = htsmsg_binary_deserialize(buf, l, buf);
+    free(buf);
+    if(m == NULL) {
+      fprintf(stderr, "resolver: cannot deserialize\n");
+      continue;
+    }
+    hostname = htsmsg_get_str(m, "hostname");
+    if(hostname == NULL) {
+      fprintf(stderr, "resolver: missing hostname\n");
+      break;
+    }
+    while((res = gethostbyname_r(hostname, &hostbuf, tmphstbuf, hstbuflen,
+                                &hp, &herr)) == ERANGE) {
+      hstbuflen *= 2;
+      tmphstbuf = realloc (tmphstbuf, hstbuflen);
+    }
+
+    if(res != 0) {
+      htsmsg_add_str(m, "error", "internal error");
+    } else if(herr != 0) {
+      switch(herr) {
+      case HOST_NOT_FOUND:
+       errtxt = "The specified host is unknown";
+       break;
+      case NO_ADDRESS:
+       errtxt = "The requested name is valid but does not have an IP address";
+       break;
+
+      case NO_RECOVERY:
+       errtxt = "A non-recoverable name server error occurred";
+       break;
+
+      case TRY_AGAIN:
+       errtxt = "A temporary error occurred on an authoritative name server";
+       break;
+
+      default:
+       errtxt = "Unknown error";
+       break;
+      }
+      htsmsg_add_str(m, "error", errtxt);
+    } else if(hp == NULL) {
+      htsmsg_add_str(m, "error", "internal error");
+    } else {
+      switch(hp->h_addrtype) {
+
+      case AF_INET:
+       htsmsg_add_bin(m, "ipv4", hp->h_addr, 4);
+       break;
+
+      default:
+       htsmsg_add_str(m, "error", "Unsupported address family");
+       break;
+      }
+    }
+
+    if(htsmsg_binary_serialize(m, &buf, &len, -1) < 0) {
+      fprintf(stderr, "Resolver: serialization error\n");
+      break;
+    }
+
+    write(from_thread_fd[1], buf, len);
+free(buf);
+  }
+  fprintf(stderr, "Internal resolver error\n");
+  exit(1);
+}
+
+
+/**
+ * Public function for resolving a hostname with a callback and opaque
+ */
+void *
+async_resolve(const char *hostname,
+             void (*cb)(void *opaque, struct sockaddr *so, const char *error),
+             void *opaque)
+{
+  htsmsg_t *m;
+  void *buf;
+  unsigned int len;
+  int r;
+  res_t *res;
+
+  async_resolver_init();
+
+  res_seq_tally++;
+
+  m = htsmsg_create();
+  htsmsg_add_str(m, "hostname", hostname);
+  htsmsg_add_u32(m, "seq", res_seq_tally);
+
+  if(htsmsg_binary_serialize(m, &buf, &len, -1) < 0) {
+    htsmsg_destroy(m);
+    return NULL;
+  }
+
+  r = write(to_thread_fd[1], buf, len);
+
+  free(buf);
+  htsmsg_destroy(m);
+
+  if(r < 0)
+    return NULL;
+
+  res = calloc(1, sizeof(res_t));
+  res->cb = cb;
+  res->opaque = opaque;
+  res->seqno = res_seq_tally;
+
+  LIST_INSERT_HEAD(&pending_resolve, res, link);
+  return res;
+}
+
+/**
+ * Cancel a pending resolve
+ */
+void
+async_resolve_cancel(void *ar)
+{
+  res_t *res = ar;
+
+  LIST_REMOVE(res, link);
+  free(res);
+}

diff --git a/resolver.h b/resolver.h
new file mode 100644 (file)
index 0000000..3c9e681
--- /dev/null
+++ b/resolver.h
@@ -0,0 +1,29 @@
+/*
+ *  Async resolver
+ *  Copyright (C) 2007 Andreas Öman
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef RESOLVER_H
+#define RESOLVER_H
+
+void *async_resolve(const char *hostname,
+                   void (*cb)(void *opaque, struct sockaddr *so,
+                              const char *error),
+                   void *opaque);
+
+void async_resolve_cancel(void *ar);
+
+#endif /* RESOLVER_H */

diff --git a/tcp.c b/tcp.c
index f5e750fb42e5aab405d459e10a682a43429dced8..df02755f0aefb74fc8d7dd0a0cc826cfb8be6df7 100644 (file)
--- a/tcp.c
+++ b/tcp.c
@@ -31,6 +31,7 @@
 
 #include "dispatch.h"
 #include "tcp.h"
+#include "resolver.h"
 
 static void tcp_client_reconnect_timeout(void *aux, int64_t now);
 
@@ -391,7 +392,9 @@ tcp_start_session(tcp_session_t *ses)
   snprintf(ses->tcp_peer_txt, sizeof(ses->tcp_peer_txt), "%s:%d",
           inet_ntoa(si->sin_addr), ntohs(si->sin_port));
 
-  syslog(LOG_INFO, "%s: %s: connected", ses->tcp_name, ses->tcp_peer_txt);
+  syslog(LOG_INFO, "%s: %s%sConnected to %s", ses->tcp_name,
+        ses->tcp_hostname ?: "", ses->tcp_hostname ? ": " : "",
+        ses->tcp_peer_txt);
 
 
   ses->tcp_dispatch_handle = dispatch_addfd(ses->tcp_fd, tcp_socket_callback,
@@ -421,8 +424,8 @@ tcp_client_connect_fail(tcp_session_t *c, int error)
   struct sockaddr_in *si = (struct sockaddr_in *)&c->tcp_peer_addr;
 
   
-  syslog(LOG_ERR, "%s: Unable to connect to %s:%d -- %s",
-        c->tcp_name, inet_ntoa(si->sin_addr),
+  syslog(LOG_ERR, "%s: Unable to connect to \"%s\" (%s) : %d -- %s",
+        c->tcp_name, c->tcp_hostname, inet_ntoa(si->sin_addr),
         ntohs(si->sin_port), strerror(error));
 
   /* Try to reconnect in 10 seconds */
@@ -471,11 +474,28 @@ tcp_client_connect_timeout(void *aux, int64_t now)
  *
  */
 static void
-tcp_session_try_connect(tcp_session_t *c)
+tcp_session_peer_resolved(void *aux, struct sockaddr *so, const char *error)
 {
+  tcp_session_t *c = aux;
+  struct sockaddr_in *si;
+  
+  if(error != NULL) {
+    syslog(LOG_ERR, "%s: Unable to resolve \"%s\" -- %s",
+          c->tcp_name, c->tcp_hostname, error);
+    /* Try again in 30 seconds */
+    dtimer_arm(&c->tcp_timer, tcp_client_reconnect_timeout, c, 30);
+    return;
+  }
+
+
   c->tcp_fd = socket(AF_INET, SOCK_STREAM, 0);
   fcntl(c->tcp_fd, F_SETFL, fcntl(c->tcp_fd, F_GETFL) | O_NONBLOCK);
 
+
+  si = (struct sockaddr_in *)&c->tcp_peer_addr;
+  memcpy(si, so, sizeof(struct sockaddr_in));
+  si->sin_port = htons(c->tcp_port);
+
   if(connect(c->tcp_fd, (struct sockaddr *)&c->tcp_peer_addr,
             sizeof(struct sockaddr_in)) == 0) {
     tcp_client_connected(c);
@@ -496,6 +516,15 @@ tcp_session_try_connect(tcp_session_t *c)
   tcp_client_connect_fail(c, errno);
 }
 
+/**
+ * Start by resolving hostname
+ */
+static void
+tcp_session_try_connect(tcp_session_t *c)
+{
+  async_resolve(c->tcp_hostname, tcp_session_peer_resolved, c);
+}
+
 
 /**
  * We come here after a failed connection attempt or if we disconnected
@@ -512,24 +541,17 @@ tcp_client_reconnect_timeout(void *aux, int64_t now)
  * Create a TCP based client
  */
 void *
-tcp_create_client(struct in_addr ip, int port, size_t session_size,
+tcp_create_client(const char *hostname, int port, size_t session_size,
                  const char *name, tcp_callback_t *cb)
 {
-  struct sockaddr_in *si;
   tcp_session_t *c = calloc(1, session_size);
 
   c->tcp_callback = cb;
   c->tcp_name = strdup(name);
-  
-  si = (struct sockaddr_in *)&c->tcp_peer_addr;
-  
-  memset(si, 0, sizeof(struct sockaddr_in));
-  si->sin_family = AF_INET;
-  si->sin_port = htons(port);
-  si->sin_addr = ip;
+  c->tcp_port = port;
+  c->tcp_hostname = strdup(hostname);
 
   tcp_session_try_connect(c);
-
   return c;
 }
 

diff --git a/tcp.h b/tcp.h
index bf58a989ea1879e1ff0435005c6374debaa45efc..5300fc1bdbe5d2e19ec5aedc66efca6e84bbb311 100644 (file)
--- a/tcp.h
+++ b/tcp.h
@@ -65,7 +65,8 @@ typedef struct tcp_session {
 
   dtimer_t tcp_timer;
   char *tcp_name;
-
+  int tcp_port;
+  char *tcp_hostname;
   
   /* Output queueing */
 
@@ -104,7 +105,7 @@ void tcp_qprintf(tcp_queue_t *tq, const char *fmt, ...);
 
 void tcp_output_queue(tcp_session_t *ses, tcp_queue_t *dst, tcp_queue_t *src);
 
-void *tcp_create_client(struct in_addr ip, int port, size_t session_size,
+void *tcp_create_client(const char *hostname, int port, size_t session_size,
                        const char *name, tcp_callback_t *cb);
 
 #endif /* TCP_H_ */