libcli/dns: Add resolv.conf parsing

Right now this only looks at the nameserver setting. It is initally made for
asynchronous AD DC lookup routines, where we don't need the "search", "domain"
and other settings. When we convert general "net", "smbclient" and others to
use this, we might either add "domain" handling to this code or look at
something like c-ares which already does it.

Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>

diff --git a/libcli/dns/resolvconf.c b/libcli/dns/resolvconf.c
new file mode 100644 (file)
index 0000000..90d4e6a
--- /dev/null
+++ b/libcli/dns/resolvconf.c
@@ -0,0 +1,123 @@
+/*
+ *  Unix SMB/CIFS implementation.
+ *  Internal DNS query structures
+ *  Copyright (C) Volker Lendecke 2018
+ *
+ *  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 "replace.h"
+#include <stdio.h>
+#include <errno.h>
+#include "libcli/dns/resolvconf.h"
+#include "lib/util/memory.h"
+
+int parse_resolvconf_fp(
+       FILE *fp,
+       TALLOC_CTX *mem_ctx,
+       char ***pnameservers,
+       size_t *pnum_nameservers)
+{
+       char *line = NULL;
+       char **nameservers = NULL;
+       size_t num_nameservers = 0;
+       int ret = 0;
+
+       while (true) {
+               char *saveptr, *option, *ns;
+               char **tmp;
+               ssize_t n;
+               size_t len;
+
+               n = getline(&line, &len, fp);
+               if (n < 0) {
+                       if (!feof(fp)) {
+                               /* real error */
+                               ret = errno;
+                       }
+                       break;
+               }
+               if ((n > 0) && (line[n-1] == '\n')) {
+                       line[n-1] = '\0';
+               }
+
+               if ((line[0] == '#') || (line[0] == ';')) {
+                       continue;
+               }
+
+               option = strtok_r(line, " \t", &saveptr);
+               if (option == NULL) {
+                       continue;
+               }
+
+               if (strcmp(option, "nameserver") != 0) {
+                       continue;
+               }
+
+               ns = strtok_r(NULL, " \t", &saveptr);
+               if (ns == NULL) {
+                       continue;
+               }
+
+               tmp = talloc_realloc(
+                       mem_ctx,
+                       nameservers,
+                       char *,
+                       num_nameservers+1);
+               if (tmp == NULL) {
+                       ret = ENOMEM;
+                       break;
+               }
+               nameservers = tmp;
+
+               nameservers[num_nameservers] = talloc_strdup(nameservers, ns);
+               if (nameservers[num_nameservers] == NULL) {
+                       ret = ENOMEM;
+                       break;
+               }
+               num_nameservers += 1;
+       }
+
+       SAFE_FREE(line);
+
+       if (ret == 0) {
+               *pnameservers = nameservers;
+               *pnum_nameservers = num_nameservers;
+       } else {
+               TALLOC_FREE(nameservers);
+       }
+
+       return ret;
+}
+
+int parse_resolvconf(
+       const char *resolvconf,
+       TALLOC_CTX *mem_ctx,
+       char ***pnameservers,
+       size_t *pnum_nameservers)
+{
+       FILE *fp;
+       int ret;
+
+       fp = fopen(resolvconf ? resolvconf : "/etc/resolv.conf", "r");
+       if (fp == NULL) {
+               return errno;
+       }
+
+       ret = parse_resolvconf_fp(fp, mem_ctx, pnameservers, pnum_nameservers);
+
+       fclose(fp);
+
+       return ret;
+}

diff --git a/libcli/dns/resolvconf.h b/libcli/dns/resolvconf.h
new file mode 100644 (file)
index 0000000..3ea258c
--- /dev/null
+++ b/libcli/dns/resolvconf.h
@@ -0,0 +1,37 @@
+/*
+ *  Unix SMB/CIFS implementation.
+ *  Internal DNS query structures
+ *  Copyright (C) Volker Lendecke 2018
+ *
+ *  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 __LIBCLI_DNS_RESOLVCONF_H__
+#define __LIBCLI_DNS_RESOLVCONF_H__
+
+#include <talloc.h>
+#include <stdio.h>
+
+int parse_resolvconf_fp(
+       FILE *fp,
+       TALLOC_CTX *mem_ctx,
+       char ***pnameservers,
+       size_t *pnum_nameservers);
+int parse_resolvconf(
+       const char *resolvconf,
+       TALLOC_CTX *mem_ctx,
+       char ***pnameservers,
+       size_t *pnum_nameservers);
+
+#endif

diff --git a/libcli/dns/resolvconftest.c b/libcli/dns/resolvconftest.c
new file mode 100644 (file)
index 0000000..6395264
--- /dev/null
+++ b/libcli/dns/resolvconftest.c
@@ -0,0 +1,82 @@
+/*
+ *  Unix SMB/CIFS implementation.
+ *  Internal DNS query structures
+ *  Copyright (C) Volker Lendecke 2018
+ *
+ *  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 <stdio.h>
+#include <string.h>
+#include <talloc.h>
+#include <errno.h>
+#include "libcli/dns/resolvconf.h"
+#include "lib/util/memory.h"
+
+static int resolvconftest1(void)
+{
+       const char *content =
+               "#foo\nbar\nnameserver 1.2.3.4\nnameserver 2.3.4.5";
+       char *file;
+       FILE *fp;
+       int ret;
+       char **nameservers;
+       size_t num_nameservers;
+
+       file = strdup(content);
+       if (file == NULL) {
+               perror("strdup failed");
+               return ENOMEM;
+       }
+       fp = fmemopen(file, strlen(file), "r");
+       if (fp == NULL) {
+               perror("fmemopen failed");
+               return errno;
+       }
+
+       ret = parse_resolvconf_fp(fp, NULL, &nameservers, &num_nameservers);
+       if (ret != 0) {
+               fprintf(stderr, "parse_resolvconf_fp failed: %s\n",
+                       strerror(ret));
+               return ret;
+       }
+
+       if (num_nameservers != 2) {
+               fprintf(stderr, "expected 2 nameservers, got %zu\n",
+                       num_nameservers);
+               return EIO;
+       }
+       if ((strcmp(nameservers[0], "1.2.3.4") != 0) ||
+           (strcmp(nameservers[1], "2.3.4.5") != 0)) {
+               fprintf(stderr, "got wrong nameservers\n");
+               return EIO;
+       }
+
+       TALLOC_FREE(nameservers);
+       fclose(fp);
+       SAFE_FREE(file);
+
+       return 0;
+}
+
+int main(void) {
+       int ret;
+
+       ret = resolvconftest1();
+       if (ret != 0) {
+               return 1;
+       }
+
+       return 0;
+}

diff --git a/libcli/dns/wscript_build b/libcli/dns/wscript_build
index 2dcd8c17d9d1f8518edb0435685c3dcba7b8f6e1..0d7c746dd80863427f8f38ca1c7c95db5b713751 100644 (file)
--- a/libcli/dns/wscript_build
+++ b/libcli/dns/wscript_build
@@ -1,5 +1,10 @@
 #!/usr/bin/env python
 
 bld.SAMBA_SUBSYSTEM('clidns',
-        source='dns.c',
+        source='dns.c resolvconf.c',
         public_deps='LIBTSOCKET tevent-util NDR_DNS')
+
+bld.SAMBA_BINARY('resolvconftest',
+                  source='resolvconftest.c',
+                  deps='clidns',
+                  install=False)

diff --git a/source3/script/tests/test_resolvconf.sh b/source3/script/tests/test_resolvconf.sh
new file mode 100755 (executable)
index 0000000..ffe4da9
--- /dev/null
+++ b/source3/script/tests/test_resolvconf.sh
@@ -0,0 +1,20 @@
+#!/bin/sh
+
+incdir=`dirname $0`/../../../testprogs/blackbox
+. $incdir/subunit.sh
+
+if [ ! -x $BINDIR/resolvconftest ] ; then
+    # Some machines don't have /bin/true, simulate it
+    cat >$BINDIR/resolvconftest <<EOF
+#!/bin/sh
+exit 0
+EOF
+    chmod +x $BINDIR/resolvconftest
+fi
+
+failed=0
+
+testit "resolvconf" $VALGRIND $BINDIR/resolvconftest ||
+       failed=`expr $failed + 1`
+
+testok $0 $failed

diff --git a/source3/selftest/tests.py b/source3/selftest/tests.py
index c0fde3ad3f0db21b71142a4590f7376bab2a586c..46f078759e16f6a71e072ce5b8ece96c06febd98 100755 (executable)
--- a/source3/selftest/tests.py
+++ b/source3/selftest/tests.py
@@ -406,6 +406,10 @@ if with_pthreadpool:
                                 "script/tests/test_libwbclient_threads.sh"),
                    "$DOMAIN", "$DC_USERNAME"])
 
+plantestsuite(
+    "samba3.resolvconf", "none",
+    [os.path.join(samba3srcdir, "script/tests/test_resolvconf.sh")])
+
 plantestsuite("samba3.async_req", "nt4_dc",
               [os.path.join(samba3srcdir, "script/tests/test_async_req.sh")])