client: Add helper functions for formatting and executing queries.

These are basically taken over from the SysDB webui code which will be based
on this new code in the future.

diff --git a/client/query.go b/client/query.go
new file mode 100644 (file)
index 0000000..d1224f4
--- /dev/null
+++ b/client/query.go
@@ -0,0 +1,136 @@
+//
+// Copyright (C) 2014-2015 Sebastian 'tokkee' Harl <sh@tokkee.org>
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions
+// are met:
+// 1. Redistributions of source code must retain the above copyright
+//    notice, this list of conditions and the following disclaimer.
+// 2. Redistributions in binary form must reproduce the above copyright
+//    notice, this list of conditions and the following disclaimer in the
+//    documentation and/or other materials provided with the distribution.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+// TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+// PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR
+// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
+// OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+// WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
+// OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+// ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+package client
+
+import (
+       "errors"
+       "fmt"
+       "regexp"
+       "time"
+
+       "github.com/sysdb/go/proto"
+       "github.com/sysdb/go/sysdb"
+)
+
+// An Identifier is a string that may not be quoted or escaped in a query.
+type Identifier string
+
+// The default format for date-time values.
+var dtFormat = "2006-01-02 15:04:05"
+
+func stringify(values ...interface{}) ([]interface{}, error) {
+       str := make([]interface{}, len(values))
+       for i, v := range values {
+               switch val := v.(type) {
+               case uint8, uint16, uint32, uint64, int8, int16, int32, int64, int:
+                       str[i] = fmt.Sprintf("%d", val)
+               case float32, float64:
+                       str[i] = fmt.Sprintf("%e", val)
+               case Identifier:
+                       str[i] = string(val)
+               case string:
+                       str[i] = proto.EscapeString(val)
+               case time.Time:
+                       str[i] = val.Format(dtFormat)
+               default:
+                       return nil, fmt.Errorf("cannot embed value %v of type %T in query", v, v)
+               }
+       }
+       return str, nil
+}
+
+// The fmt package does not expose these errors except through the formatted
+// string. Let's just assume that this pattern never occurs in a real query
+// string (or else, users will have to work around this by not using
+// QueryString()).
+var badArgRE = regexp.MustCompile(`%!.?\(.+`)
+
+// QueryString formats a query string. The query q may include printf string
+// verbs (%s) for each argument. The arguments may be of type Identifier,
+// string, or time.Time and will be formatted to make them suitable for use in
+// a query.
+//
+// This function tries to prevent injection attacks but it's not fool-proof.
+// It will go away once the SysDB network protocol supports arguments to
+// queries.
+func QueryString(q string, args ...interface{}) (string, error) {
+       args, err := stringify(args...)
+       if err != nil {
+               return "", err
+       }
+
+       str := fmt.Sprintf(q, args...)
+
+       // Try to identify format string errors.
+       if e := badArgRE.Find([]byte(str)); e != nil {
+               return "", errors.New(string(e))
+       }
+
+       return str, nil
+}
+
+// Query executes a query on the server. It returns a sysdb object on success.
+func (c *Client) Query(q string) (interface{}, error) {
+       res, err := c.Call(&proto.Message{
+               Type: proto.ConnectionQuery,
+               Raw:  []byte(q),
+       })
+       if err != nil {
+               return nil, err
+       }
+       if res.Type != proto.ConnectionData {
+               return nil, fmt.Errorf("unexpected result type %d", res.Type)
+       }
+
+       t, err := res.DataType()
+       if err != nil {
+               return nil, fmt.Errorf("failed to unmarshal response: %v", err)
+       }
+
+       var obj interface{}
+       switch t {
+       case proto.HostList:
+               var hosts []sysdb.Host
+               err = proto.Unmarshal(res, &hosts)
+               obj = hosts
+       case proto.Host:
+               var host sysdb.Host
+               err = proto.Unmarshal(res, &host)
+               obj = &host
+       case proto.Timeseries:
+               var ts sysdb.Timeseries
+               err = proto.Unmarshal(res, &ts)
+               obj = &ts
+       default:
+               return nil, fmt.Errorf("unsupported data type %d", t)
+       }
+       if err != nil {
+               return nil, fmt.Errorf("failed to unmarshal response: %v", err)
+       }
+       return obj, nil
+}
+
+// vim: set tw=78 sw=4 sw=4 noexpandtab :

diff --git a/client/query_test.go b/client/query_test.go
new file mode 100644 (file)
index 0000000..c62fed7
--- /dev/null
+++ b/client/query_test.go
@@ -0,0 +1,66 @@
+//
+// Copyright (C) 2015 Sebastian 'tokkee' Harl <sh@tokkee.org>
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions
+// are met:
+// 1. Redistributions of source code must retain the above copyright
+//    notice, this list of conditions and the following disclaimer.
+// 2. Redistributions in binary form must reproduce the above copyright
+//    notice, this list of conditions and the following disclaimer in the
+//    documentation and/or other materials provided with the distribution.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+// TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+// PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR
+// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
+// OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+// WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
+// OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+// ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+package client
+
+import (
+       "testing"
+       "time"
+)
+
+func TestQueryString(t *testing.T) {
+       ts, _ := time.Parse("2006-01-02 15:04:05", "2006-01-02 15:04:05")
+       for _, test := range []struct {
+               q       string
+               args    []interface{}
+               want    string
+               wantErr bool
+       }{
+               {"some %s; foo %s", []interface{}{"thing", "bar"}, "some 'thing'; foo 'bar'", false},
+               {"s=%s", []interface{}{"'a"}, "s='''a'", false},
+               {"t=%s", []interface{}{ts}, "t=2006-01-02 15:04:05", false},
+               {"i=%s; f=%s", []interface{}{1234, 47.11}, "i=1234; f=4.711000e+01", false},
+               {"t=%d", []interface{}{ts}, "", true},
+               {"some %s; foo %s", []interface{}{"a", "b", "c"}, "", true},
+               {"some %s; foo %s", []interface{}{"a"}, "", true},
+               {"s=%s", []interface{}{`multi
+line
+text`}, "s='multi\nline\ntext'", false},
+               {"s=%d", []interface{}{`multi
+line
+error`}, "", true},
+       } {
+               s, err := QueryString(test.q, test.args...)
+               if s != test.want || (err != nil) != test.wantErr {
+                       e := "<nil>"
+                       if test.wantErr {
+                               e = "<err>"
+                       }
+                       t.Errorf("QueryString(%q, %v) = %q, %v; want %q, %s", test.q, test.args, s, err, test.want, e)
+               }
+       }
+}
+
+// vim: set tw=78 sw=4 sw=4 noexpandtab :