github.com/meulengracht/snapd@v0.0.0-20210719210640-8bde69bcc84e/cmd/snap/cmd_known.go (about)

     1  // -*- Mode: Go; indent-tabs-mode: t -*-
     2  
     3  /*
     4   * Copyright (C) 2016 Canonical Ltd
     5   *
     6   * This program is free software: you can redistribute it and/or modify
     7   * it under the terms of the GNU General Public License version 3 as
     8   * published by the Free Software Foundation.
     9   *
    10   * This program is distributed in the hope that it will be useful,
    11   * but WITHOUT ANY WARRANTY; without even the implied warranty of
    12   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    13   * GNU General Public License for more details.
    14   *
    15   * You should have received a copy of the GNU General Public License
    16   * along with this program.  If not, see <http://www.gnu.org/licenses/>.
    17   *
    18   */
    19  
    20  package main
    21  
    22  import (
    23  	"fmt"
    24  	"strings"
    25  
    26  	"github.com/jessevdk/go-flags"
    27  	"golang.org/x/xerrors"
    28  
    29  	"github.com/snapcore/snapd/asserts"
    30  	"github.com/snapcore/snapd/client"
    31  	"github.com/snapcore/snapd/i18n"
    32  	"github.com/snapcore/snapd/overlord/auth"
    33  	"github.com/snapcore/snapd/store"
    34  )
    35  
    36  type cmdKnown struct {
    37  	clientMixin
    38  	KnownOptions struct {
    39  		// XXX: how to get a list of assert types for completion?
    40  		AssertTypeName assertTypeName `required:"true"`
    41  		HeaderFilters  []string       `required:"0"`
    42  	} `positional-args:"true" required:"true"`
    43  
    44  	Remote bool `long:"remote"`
    45  	Direct bool `long:"direct"`
    46  }
    47  
    48  var shortKnownHelp = i18n.G("Show known assertions of the provided type")
    49  var longKnownHelp = i18n.G(`
    50  The known command shows known assertions of the provided type.
    51  If header=value pairs are provided after the assertion type, the assertions
    52  shown must also have the specified headers matching the provided values.
    53  `)
    54  
    55  func init() {
    56  	addCommand("known", shortKnownHelp, longKnownHelp, func() flags.Commander {
    57  		return &cmdKnown{}
    58  	}, map[string]string{
    59  		// TRANSLATORS: This should not start with a lowercase letter.
    60  		"remote": i18n.G("Query the store for the assertion, via snapd if possible"),
    61  		// TRANSLATORS: This should not start with a lowercase letter.
    62  		"direct": i18n.G("Query the store for the assertion, without attempting to go via snapd"),
    63  	}, []argDesc{
    64  		{
    65  			// TRANSLATORS: This needs to begin with < and end with >
    66  			name: i18n.G("<assertion type>"),
    67  			// TRANSLATORS: This should not start with a lowercase letter.
    68  			desc: i18n.G("Assertion type name"),
    69  		}, {
    70  			// TRANSLATORS: This needs to begin with < and end with >
    71  			name: i18n.G("<header filter>"),
    72  			// TRANSLATORS: This should not start with a lowercase letter.
    73  			desc: i18n.G("Constrain listing to those matching header=value"),
    74  		},
    75  	})
    76  }
    77  
    78  var storeNew = store.New
    79  
    80  func downloadAssertion(typeName string, headers map[string]string) ([]asserts.Assertion, error) {
    81  	var user *auth.UserState
    82  
    83  	// FIXME: set auth context
    84  	var storeCtx store.DeviceAndAuthContext
    85  
    86  	at := asserts.Type(typeName)
    87  	if at == nil {
    88  		return nil, fmt.Errorf("cannot find assertion type %q", typeName)
    89  	}
    90  	primaryKeys, err := asserts.PrimaryKeyFromHeaders(at, headers)
    91  	if err != nil {
    92  		return nil, fmt.Errorf("cannot query remote assertion: %v", err)
    93  	}
    94  
    95  	sto := storeNew(nil, storeCtx)
    96  	as, err := sto.Assertion(at, primaryKeys, user)
    97  	if err != nil {
    98  		return nil, err
    99  	}
   100  
   101  	return []asserts.Assertion{as}, nil
   102  }
   103  
   104  func (x *cmdKnown) Execute(args []string) error {
   105  	if len(args) > 0 {
   106  		return ErrExtraArgs
   107  	}
   108  
   109  	// TODO: share this kind of parsing once it's clearer how often is used in snap
   110  	headers := map[string]string{}
   111  	for _, headerFilter := range x.KnownOptions.HeaderFilters {
   112  		parts := strings.SplitN(headerFilter, "=", 2)
   113  		if len(parts) != 2 {
   114  			return fmt.Errorf(i18n.G("invalid header filter: %q (want key=value)"), headerFilter)
   115  		}
   116  		headers[parts[0]] = parts[1]
   117  	}
   118  
   119  	var assertions []asserts.Assertion
   120  	var err error
   121  	switch {
   122  	case x.Remote && !x.Direct:
   123  		// --remote will query snapd
   124  		assertions, err = x.client.Known(string(x.KnownOptions.AssertTypeName), headers, &client.KnownOptions{Remote: true})
   125  		// if snapd is unavailable automatically fallback
   126  		var connErr client.ConnectionError
   127  		if xerrors.As(err, &connErr) {
   128  			assertions, err = downloadAssertion(string(x.KnownOptions.AssertTypeName), headers)
   129  		}
   130  	case x.Direct:
   131  		// --direct implies remote
   132  		assertions, err = downloadAssertion(string(x.KnownOptions.AssertTypeName), headers)
   133  	default:
   134  		// default is to look only local
   135  		assertions, err = x.client.Known(string(x.KnownOptions.AssertTypeName), headers, nil)
   136  	}
   137  	if err != nil {
   138  		return err
   139  	}
   140  
   141  	enc := asserts.NewEncoder(Stdout)
   142  	for _, a := range assertions {
   143  		enc.Encode(a)
   144  	}
   145  
   146  	return nil
   147  }