client: reconnect with multiple addresses

Allow multiple hostnames/addresses separated by comma to be specified
with the -h option. Hostnames are resolved to up to 16 addresses. When
connecting to an address fails or no reply is received, try the next
address in the list.

Set the default value for the -h option to 127.0.0.1,::1.

diff --git a/Makefile.in b/Makefile.in
index 79be3c4c32d81ecdec3033c4f4e3571f9f541dfa..6ac0c9e6fcb91516c601d4b7e04d1d970e82d9a2 100644 (file)
--- a/Makefile.in
+++ b/Makefile.in
@@ -44,7 +44,7 @@ OBJS = array.o cmdparse.o conf.o local.o logging.o main.o memory.o \
 
 EXTRA_OBJS=@EXTRA_OBJECTS@
 
-CLI_OBJS = client.o cmdparse.o getdate.o memory.o nameserv.o \
+CLI_OBJS = array.o client.o cmdparse.o getdate.o memory.o nameserv.o \
            pktlength.o util.o $(HASH_OBJ)
 
 ALL_OBJS = $(OBJS) $(EXTRA_OBJS) $(CLI_OBJS)

diff --git a/chrony.texi.in b/chrony.texi.in
index e04d029ac9a2c92b89a04188c5a14ad15437e728..0b31bb666b277289d9d05e6d15724060b47971d4 100644 (file)
--- a/chrony.texi.in
+++ b/chrony.texi.in
@@ -3252,9 +3252,9 @@ Chronyc supports the following command line options.
 @item -v
 Displays the version number of chronyc on the terminal, and exists.
 @item -h <host>
-This option allows the user to specify which host running the
-@code{chronyd} program is to be contacted.  This allows for remote
-configuration, without having to ssh to the other host first.
+This option allows the user to specify which host (or comma-separated list of
+addresses) running the @code{chronyd} program is to be contacted.  This allows
+for remote configuration, without having to ssh to the other host first.
 
 The default is to contact @code{chronyd} running on the same host as
 that where chronyc is being run.

diff --git a/chronyc.1.in b/chronyc.1.in
index acd76ad642c45f61dc65c5f72cd10a09a1bf20e7..33d7ff8372d7bc22452a5a713319daee61fe76ea 100644 (file)
--- a/chronyc.1.in
+++ b/chronyc.1.in
@@ -24,7 +24,7 @@ A summary of the options supported by \fBchronyc\fR is included below.
 
 .TP
 \fB\-h\fR \fIhostname\fR
-specify hostname (default 127.0.0.1)
+specify hostname or comma-separated list of addresses (default 127.0.0.1,::1)
 .TP
 \fB\-p\fR \fIport-number\fR
 specify port-number

diff --git a/client.c b/client.c
index 01774c97066082dc577495a9c05aae532fc358b7..a201bc4b408a76c0874c496024e656142d50b6c6 100644 (file)
--- a/client.c
+++ b/client.c
@@ -30,6 +30,7 @@
 
 #include "sysincl.h"
 
+#include "array.h"
 #include "candm.h"
 #include "logging.h"
 #include "memory.h"
@@ -60,7 +61,9 @@ union sockaddr_all {
   struct sockaddr sa;
 };
 
-static int sock_fd;
+static ARR_Instance sockaddrs;
+
+static int sock_fd = -1;
 
 static int quit = 0;
 
@@ -128,66 +131,119 @@ read_line(void)
   
 }
 
+/* ================================================== */
+
+#define MAX_ADDRESSES 16
+
+static ARR_Instance
+get_sockaddrs(const char *hostnames, int port)
+{
+  ARR_Instance addrs;
+  char *hostname, *s1, *s2;
+  IPAddr ip_addrs[MAX_ADDRESSES];
+  union sockaddr_all *addr;
+  int i;
+
+  addrs = ARR_CreateInstance(sizeof (union sockaddr_all));
+  s1 = Strdup(hostnames);
+
+  /* Parse the comma-separated list of hostnames */
+  for (hostname = s1; hostname && *hostname; hostname = s2) {
+    s2 = strchr(hostname, ',');
+    if (s2)
+      *s2++ = '\0';
+
+    /* hostname starting with / is considered a path of Unix domain socket */
+    if (hostname[0] == '/') {
+      addr = (union sockaddr_all *)ARR_GetNewElement(addrs);
+      if (snprintf(addr->un.sun_path, sizeof (addr->un.sun_path), "%s", hostname) >=
+          sizeof (addr->un.sun_path))
+        LOG_FATAL(LOGF_Client, "Unix socket path too long");
+      addr->un.sun_family = AF_UNIX;
+    } else {
+      if (DNS_Name2IPAddress(hostname, ip_addrs, MAX_ADDRESSES) != DNS_Success) {
+        DEBUG_LOG(LOGF_Client, "Could not get IP address for %s", hostname);
+        break;
+      }
+
+      for (i = 0; i < MAX_ADDRESSES && ip_addrs[i].family != IPADDR_UNSPEC; i++) {
+        addr = (union sockaddr_all *)ARR_GetNewElement(addrs);
+        UTI_IPAndPortToSockaddr(&ip_addrs[i], port, (struct sockaddr *)addr);
+        DEBUG_LOG(LOGF_Client, "Resolved %s to %s", hostname, UTI_IPToString(&ip_addrs[i]));
+      }
+    }
+  }
+
+  Free(s1);
+  return addrs;
+}
+
 /* ================================================== */
 /* Initialise the socket used to talk to the daemon */
 
-static void
-open_io(const char *hostname, int port)
+static int
+prepare_socket(union sockaddr_all *addr)
 {
-  union sockaddr_all addr;
   socklen_t addr_len;
-  IPAddr ip;
   char *dir;
 
-  /* hostname starting with / is considered a path of Unix domain socket */
-  if (hostname[0] == '/') {
-    if (snprintf(addr.un.sun_path, sizeof (addr.un.sun_path), "%s", hostname) >=
-        sizeof (addr.un.sun_path))
-      LOG_FATAL(LOGF_Client, "Unix socket path too long");
-    addr.un.sun_family = AF_UNIX;
-    addr_len = sizeof (addr.un);
-  } else {
-    /* Note, this call could block for a while */
-    if (DNS_Name2IPAddress(hostname, &ip, 1) != DNS_Success) {
-      LOG_FATAL(LOGF_Client, "Could not get IP address for %s", hostname);
-    }
-
-    addr_len = UTI_IPAndPortToSockaddr(&ip, port, &addr.sa);
+  switch (addr->sa.sa_family) {
+    case AF_UNIX:
+      addr_len = sizeof (addr->un);
+      break;
+    case AF_INET:
+      addr_len = sizeof (addr->in4);
+      break;
+#ifdef FEAT_IPV6
+    case AF_INET6:
+      addr_len = sizeof (addr->in6);
+      break;
+#endif
+    default:
+      assert(0);
   }
 
-  sock_fd = socket(addr.sa.sa_family, SOCK_DGRAM, 0);
+  sock_fd = socket(addr->sa.sa_family, SOCK_DGRAM, 0);
 
   if (sock_fd < 0) {
-    LOG_FATAL(LOGF_Client, "Could not create socket : %s", strerror(errno));
+    DEBUG_LOG(LOGF_Client, "Could not create socket : %s", strerror(errno));
+    return 0;
   }
 
-  if (connect(sock_fd, &addr.sa, addr_len) < 0) {
-    LOG_FATAL(LOGF_Client, "Could not connect socket : %s", strerror(errno));
+  if (connect(sock_fd, &addr->sa, addr_len) < 0) {
+    DEBUG_LOG(LOGF_Client, "Could not connect socket : %s", strerror(errno));
+    return 0;
   }
 
-  if (addr.sa.sa_family == AF_UNIX) {
+  if (addr->sa.sa_family == AF_UNIX) {
+    struct sockaddr_un sun;
+
     /* Construct path of our socket.  Use the same directory as the server
        socket and include our process ID to allow multiple chronyc instances
        running at the same time. */
-    dir = UTI_PathToDir(hostname);
-    if (snprintf(addr.un.sun_path, sizeof (addr.un.sun_path),
-             "%s/chronyc.%d.sock", dir, getpid()) >= sizeof (addr.un.sun_path))
+    dir = UTI_PathToDir(addr->un.sun_path);
+    if (snprintf(sun.sun_path, sizeof (sun.sun_path),
+                 "%s/chronyc.%d.sock", dir, getpid()) >= sizeof (sun.sun_path))
       LOG_FATAL(LOGF_Client, "Unix socket path too long");
     Free(dir);
 
-    addr.un.sun_family = AF_UNIX;
-    unlink(addr.un.sun_path);
+    sun.sun_family = AF_UNIX;
+    unlink(sun.sun_path);
 
     /* Bind the socket to the path */
-    if (bind(sock_fd, &addr.sa, sizeof (addr.un)) < 0) {
-      LOG_FATAL(LOGF_Client, "Could not bind socket : %s", strerror(errno));
+    if (bind(sock_fd, (struct sockaddr *)&sun, sizeof (sun)) < 0) {
+      DEBUG_LOG(LOGF_Client, "Could not bind socket : %s", strerror(errno));
+      return 0;
     }
 
     /* Allow server without root privileges to send replies to our socket */
-    if (chmod(addr.un.sun_path, 0666) < 0) {
-      LOG_FATAL(LOGF_Client, "Could not change socket permissions : %s", strerror(errno));
+    if (chmod(sun.sun_path, 0666) < 0) {
+      DEBUG_LOG(LOGF_Client, "Could not change socket permissions : %s", strerror(errno));
+      return 0;
     }
   }
+
+  return 1;
 }
 
 /* ================================================== */
@@ -198,6 +254,9 @@ close_io(void)
   union sockaddr_all addr;
   socklen_t addr_len = sizeof (addr);
 
+  if (sock_fd < 0)
+    return;
+
   /* Remove our Unix domain socket */
   if (getsockname(sock_fd, &addr.sa, &addr_len) < 0)
     LOG_FATAL(LOGF_Client, "getsockname() failed : %s", strerror(errno));
@@ -206,6 +265,36 @@ close_io(void)
     unlink(addr.un.sun_path);
 
   close(sock_fd);
+  sock_fd = -1;
+}
+
+/* ================================================== */
+
+static int
+open_io(void)
+{
+  static unsigned int address_index = 0;
+  union sockaddr_all *addr;
+
+  /* If a socket is already opened, close it and try the next address */
+  if (sock_fd >= 0) {
+    close_io();
+    address_index++;
+  }
+
+  /* Find an address for which a socket can be opened and connected */
+  for (; address_index < ARR_GetSize(sockaddrs); address_index++) {
+    addr = (union sockaddr_all *)ARR_GetElement(sockaddrs, address_index);
+    DEBUG_LOG(LOGF_Client, "Opening connection to %s",
+              UTI_SockaddrToString(&addr->sa));
+
+    if (prepare_socket(addr))
+      return 1;
+
+    close_io();
+  }
+
+  return 0;
 }
 
 /* ================================================== */
@@ -1463,7 +1552,10 @@ request_reply(CMD_Request *request, CMD_Reply *reply, int requested_reply, int v
   int reply_auth_ok;
   int status;
 
-  if (!submit_request(request, reply, &reply_auth_ok)) {
+  while (!submit_request(request, reply, &reply_auth_ok)) {
+    /* Try connecting to other addresses before giving up */
+    if (open_io())
+      continue;
     printf("506 Cannot talk to daemon\n");
     return 0;
   }
@@ -2764,7 +2856,7 @@ main(int argc, char **argv)
 {
   char *line;
   const char *progname = argv[0];
-  const char *hostname = NULL;
+  const char *hostnames = NULL;
   const char *conf_file = DEFAULT_CONF_FILE;
   int ret = 1, multi = 0, auto_auth = 0, family = IPADDR_UNSPEC;
   int port = DEFAULT_CANDM_PORT;
@@ -2774,7 +2866,7 @@ main(int argc, char **argv)
     if (!strcmp(*argv, "-h")) {
       ++argv, --argc;
       if (*argv) {
-        hostname = *argv;
+        hostnames = *argv;
       }
     } else if (!strcmp(*argv, "-p")) {
       ++argv, --argc;
@@ -2827,8 +2919,8 @@ main(int argc, char **argv)
   
   DNS_SetAddressFamily(family);
 
-  if (!hostname) {
-    hostname = family == IPADDR_INET6 ? "::1" : "127.0.0.1";
+  if (!hostnames) {
+    hostnames = "127.0.0.1,::1";
 #ifdef FEAT_ASYNCDNS
     initial_timeout /= 10;
 #endif
@@ -2836,7 +2928,10 @@ main(int argc, char **argv)
 
   UTI_SetQuitSignalsHandler(signal_handler);
 
-  open_io(hostname, port);
+  sockaddrs = get_sockaddrs(hostnames, port);
+
+  if (!open_io())
+    LOG_FATAL(LOGF_Client, "Could not open connection to daemon");
 
   if (auto_auth) {
     ret = authenticate_from_config(conf_file);
@@ -2861,6 +2956,7 @@ main(int argc, char **argv)
   close_io();
 
   Free(password);
+  ARR_DestroyInstance(sockaddrs);
 
   return !ret;
 }