techknowlogick
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// Copyright (c) 2014 - Gustavo Niemeyer <gustavo@niemeyer.net>
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//
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// All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are met:
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//
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// 1. Redistributions of source code must retain the above copyright notice, this
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// list of conditions and the following disclaimer.
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// 2. Redistributions in binary form must reproduce the above copyright notice,
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// this list of conditions and the following disclaimer in the documentation
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// and/or other materials provided with the distribution.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
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// ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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// ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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// Pacakage scram implements a SCRAM-{SHA-1,etc} client per RFC5802.
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//
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// http://tools.ietf.org/html/rfc5802
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//
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package scram |
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import ( |
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"bytes" |
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"crypto/hmac" |
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"crypto/rand" |
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"encoding/base64" |
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"fmt" |
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"hash" |
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"strconv" |
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"strings" |
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) |
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// Client implements a SCRAM-* client (SCRAM-SHA-1, SCRAM-SHA-256, etc).
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//
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// A Client may be used within a SASL conversation with logic resembling:
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//
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// var in []byte
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// var client = scram.NewClient(sha1.New, user, pass)
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// for client.Step(in) {
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// out := client.Out()
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// // send out to server
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// in := serverOut
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// }
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// if client.Err() != nil {
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// // auth failed
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// }
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//
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type Client struct { |
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newHash func() hash.Hash |
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user string |
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pass string |
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step int |
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out bytes.Buffer |
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err error |
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clientNonce []byte |
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serverNonce []byte |
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saltedPass []byte |
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authMsg bytes.Buffer |
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} |
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// NewClient returns a new SCRAM-* client with the provided hash algorithm.
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//
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// For SCRAM-SHA-256, for example, use:
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//
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// client := scram.NewClient(sha256.New, user, pass)
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//
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func NewClient(newHash func() hash.Hash, user, pass string) *Client { |
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c := &Client{ |
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newHash: newHash, |
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user: user, |
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pass: pass, |
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} |
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c.out.Grow(256) |
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c.authMsg.Grow(256) |
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return c |
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} |
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// Out returns the data to be sent to the server in the current step.
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func (c *Client) Out() []byte { |
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if c.out.Len() == 0 { |
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return nil |
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} |
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return c.out.Bytes() |
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} |
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// Err returns the error that ocurred, or nil if there were no errors.
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func (c *Client) Err() error { |
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return c.err |
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} |
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// SetNonce sets the client nonce to the provided value.
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// If not set, the nonce is generated automatically out of crypto/rand on the first step.
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func (c *Client) SetNonce(nonce []byte) { |
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c.clientNonce = nonce |
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} |
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var escaper = strings.NewReplacer("=", "=3D", ",", "=2C") |
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// Step processes the incoming data from the server and makes the
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// next round of data for the server available via Client.Out.
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// Step returns false if there are no errors and more data is
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// still expected.
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func (c *Client) Step(in []byte) bool { |
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c.out.Reset() |
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if c.step > 2 || c.err != nil { |
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return false |
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} |
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c.step++ |
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switch c.step { |
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case 1: |
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c.err = c.step1(in) |
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case 2: |
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c.err = c.step2(in) |
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case 3: |
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c.err = c.step3(in) |
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} |
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return c.step > 2 || c.err != nil |
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} |
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func (c *Client) step1(in []byte) error { |
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if len(c.clientNonce) == 0 { |
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const nonceLen = 16 |
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buf := make([]byte, nonceLen+b64.EncodedLen(nonceLen)) |
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if _, err := rand.Read(buf[:nonceLen]); err != nil { |
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return fmt.Errorf("cannot read random SCRAM-SHA-256 nonce from operating system: %v", err) |
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} |
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c.clientNonce = buf[nonceLen:] |
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b64.Encode(c.clientNonce, buf[:nonceLen]) |
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} |
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c.authMsg.WriteString("n=") |
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escaper.WriteString(&c.authMsg, c.user) |
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c.authMsg.WriteString(",r=") |
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c.authMsg.Write(c.clientNonce) |
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c.out.WriteString("n,,") |
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c.out.Write(c.authMsg.Bytes()) |
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return nil |
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} |
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var b64 = base64.StdEncoding |
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func (c *Client) step2(in []byte) error { |
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c.authMsg.WriteByte(',') |
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c.authMsg.Write(in) |
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fields := bytes.Split(in, []byte(",")) |
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if len(fields) != 3 { |
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return fmt.Errorf("expected 3 fields in first SCRAM-SHA-256 server message, got %d: %q", len(fields), in) |
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} |
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if !bytes.HasPrefix(fields[0], []byte("r=")) || len(fields[0]) < 2 { |
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return fmt.Errorf("server sent an invalid SCRAM-SHA-256 nonce: %q", fields[0]) |
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} |
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if !bytes.HasPrefix(fields[1], []byte("s=")) || len(fields[1]) < 6 { |
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return fmt.Errorf("server sent an invalid SCRAM-SHA-256 salt: %q", fields[1]) |
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} |
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if !bytes.HasPrefix(fields[2], []byte("i=")) || len(fields[2]) < 6 { |
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return fmt.Errorf("server sent an invalid SCRAM-SHA-256 iteration count: %q", fields[2]) |
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} |
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c.serverNonce = fields[0][2:] |
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if !bytes.HasPrefix(c.serverNonce, c.clientNonce) { |
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return fmt.Errorf("server SCRAM-SHA-256 nonce is not prefixed by client nonce: got %q, want %q+\"...\"", c.serverNonce, c.clientNonce) |
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} |
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salt := make([]byte, b64.DecodedLen(len(fields[1][2:]))) |
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n, err := b64.Decode(salt, fields[1][2:]) |
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if err != nil { |
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return fmt.Errorf("cannot decode SCRAM-SHA-256 salt sent by server: %q", fields[1]) |
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} |
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salt = salt[:n] |
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iterCount, err := strconv.Atoi(string(fields[2][2:])) |
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if err != nil { |
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return fmt.Errorf("server sent an invalid SCRAM-SHA-256 iteration count: %q", fields[2]) |
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} |
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c.saltPassword(salt, iterCount) |
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c.authMsg.WriteString(",c=biws,r=") |
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c.authMsg.Write(c.serverNonce) |
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c.out.WriteString("c=biws,r=") |
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c.out.Write(c.serverNonce) |
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c.out.WriteString(",p=") |
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c.out.Write(c.clientProof()) |
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return nil |
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} |
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func (c *Client) step3(in []byte) error { |
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var isv, ise bool |
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var fields = bytes.Split(in, []byte(",")) |
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if len(fields) == 1 { |
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isv = bytes.HasPrefix(fields[0], []byte("v=")) |
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ise = bytes.HasPrefix(fields[0], []byte("e=")) |
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} |
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if ise { |
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return fmt.Errorf("SCRAM-SHA-256 authentication error: %s", fields[0][2:]) |
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} else if !isv { |
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return fmt.Errorf("unsupported SCRAM-SHA-256 final message from server: %q", in) |
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} |
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if !bytes.Equal(c.serverSignature(), fields[0][2:]) { |
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return fmt.Errorf("cannot authenticate SCRAM-SHA-256 server signature: %q", fields[0][2:]) |
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} |
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return nil |
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} |
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func (c *Client) saltPassword(salt []byte, iterCount int) { |
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mac := hmac.New(c.newHash, []byte(c.pass)) |
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mac.Write(salt) |
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mac.Write([]byte{0, 0, 0, 1}) |
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ui := mac.Sum(nil) |
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hi := make([]byte, len(ui)) |
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copy(hi, ui) |
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for i := 1; i < iterCount; i++ { |
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mac.Reset() |
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mac.Write(ui) |
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mac.Sum(ui[:0]) |
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for j, b := range ui { |
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hi[j] ^= b |
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} |
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} |
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c.saltedPass = hi |
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} |
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func (c *Client) clientProof() []byte { |
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mac := hmac.New(c.newHash, c.saltedPass) |
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mac.Write([]byte("Client Key")) |
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clientKey := mac.Sum(nil) |
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hash := c.newHash() |
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hash.Write(clientKey) |
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storedKey := hash.Sum(nil) |
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mac = hmac.New(c.newHash, storedKey) |
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mac.Write(c.authMsg.Bytes()) |
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clientProof := mac.Sum(nil) |
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for i, b := range clientKey { |
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clientProof[i] ^= b |
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} |
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clientProof64 := make([]byte, b64.EncodedLen(len(clientProof))) |
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b64.Encode(clientProof64, clientProof) |
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return clientProof64 |
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} |
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func (c *Client) serverSignature() []byte { |
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mac := hmac.New(c.newHash, c.saltedPass) |
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mac.Write([]byte("Server Key")) |
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serverKey := mac.Sum(nil) |
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mac = hmac.New(c.newHash, serverKey) |
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mac.Write(c.authMsg.Bytes()) |
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serverSignature := mac.Sum(nil) |
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encoded := make([]byte, b64.EncodedLen(len(serverSignature))) |
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b64.Encode(encoded, serverSignature) |
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return encoded |
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} |
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@ -1,14 +0,0 @@ |
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// +build go1.7
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package pq |
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import "crypto/tls" |
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// Accept renegotiation requests initiated by the backend.
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//
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// Renegotiation was deprecated then removed from PostgreSQL 9.5, but
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// the default configuration of older versions has it enabled. Redshift
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// also initiates renegotiations and cannot be reconfigured.
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func sslRenegotiation(conf *tls.Config) { |
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conf.Renegotiation = tls.RenegotiateFreelyAsClient |
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} |
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@ -1,8 +0,0 @@ |
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// +build !go1.7
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package pq |
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import "crypto/tls" |
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// Renegotiation is not supported by crypto/tls until Go 1.7.
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func sslRenegotiation(*tls.Config) {} |
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