github.com/slspeek/camlistore_namedsearch@v0.0.0-20140519202248-ed6f70f7721a/pkg/httputil/auth.go (about)

     1  /*
     2  Copyright 2013 The Camlistore Authors
     3  
     4  Licensed under the Apache License, Version 2.0 (the "License");
     5  you may not use this file except in compliance with the License.
     6  You may obtain a copy of the License at
     7  
     8       http://www.apache.org/licenses/LICENSE-2.0
     9  
    10  Unless required by applicable law or agreed to in writing, software
    11  distributed under the License is distributed on an "AS IS" BASIS,
    12  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  See the License for the specific language governing permissions and
    14  limitations under the License.
    15  */
    16  
    17  package httputil
    18  
    19  import (
    20  	"encoding/base64"
    21  	"fmt"
    22  	"log"
    23  	"net/http"
    24  	"os"
    25  	"regexp"
    26  	"runtime"
    27  	"strings"
    28  
    29  	"camlistore.org/pkg/netutil"
    30  )
    31  
    32  var kBasicAuthPattern = regexp.MustCompile(`^Basic ([a-zA-Z0-9\+/=]+)`)
    33  
    34  // IsLocalhost reports whether the requesting connection is from this machine
    35  // and has the same owner as this process.
    36  func IsLocalhost(req *http.Request) bool {
    37  	uid := os.Getuid()
    38  	from, err := netutil.HostPortToIP(req.RemoteAddr, nil)
    39  	if err != nil {
    40  		return false
    41  	}
    42  	to, err := netutil.HostPortToIP(req.Host, from)
    43  	if err != nil {
    44  		return false
    45  	}
    46  
    47  	// If our OS doesn't support uid.
    48  	// TODO(bradfitz): netutil on OS X uses "lsof" to figure out
    49  	// ownership of tcp connections, but when fuse is mounted and a
    50  	// request is outstanding (for instance, a fuse request that's
    51  	// making a request to camlistored and landing in this code
    52  	// path), lsof then blocks forever waiting on a lock held by the
    53  	// VFS, leading to a deadlock.  Instead, on darwin, just trust
    54  	// any localhost connection here, which is kinda lame, but
    55  	// whatever.  Macs aren't very multi-user anyway.
    56  	if uid == -1 || runtime.GOOS == "darwin" {
    57  		return from.IP.IsLoopback() && to.IP.IsLoopback()
    58  	}
    59  	if uid == 0 {
    60  		log.Printf("camlistored running as root. Don't do that.")
    61  		return false
    62  	}
    63  	if uid > 0 {
    64  		connUid, err := netutil.AddrPairUserid(from, to)
    65  		if err == nil {
    66  			if uid == connUid {
    67  				return true
    68  			}
    69  			log.Printf("auth: local connection uid %d doesn't match server uid %d", connUid, uid)
    70  		}
    71  	}
    72  	return false
    73  }
    74  
    75  // BasicAuth parses the Authorization header on req
    76  // If absent or invalid, an error is returned.
    77  func BasicAuth(req *http.Request) (username, password string, err error) {
    78  	auth := req.Header.Get("Authorization")
    79  	if auth == "" {
    80  		err = fmt.Errorf("Missing \"Authorization\" in header")
    81  		return
    82  	}
    83  	matches := kBasicAuthPattern.FindStringSubmatch(auth)
    84  	if len(matches) != 2 {
    85  		err = fmt.Errorf("Bogus Authorization header")
    86  		return
    87  	}
    88  	encoded := matches[1]
    89  	enc := base64.StdEncoding
    90  	decBuf := make([]byte, enc.DecodedLen(len(encoded)))
    91  	n, err := enc.Decode(decBuf, []byte(encoded))
    92  	if err != nil {
    93  		return
    94  	}
    95  	pieces := strings.SplitN(string(decBuf[0:n]), ":", 2)
    96  	if len(pieces) != 2 {
    97  		err = fmt.Errorf("didn't get two pieces")
    98  		return
    99  	}
   100  	return pieces[0], pieces[1], nil
   101  }