path: root/swarm/services/swap/swap.go

// Copyright 2016 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library 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 Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

package swap

import (
    "context"
    "crypto/ecdsa"
    "fmt"
    "math/big"
    "os"
    "path/filepath"
    "sync"
    "time"

    "github.com/ethereum/go-ethereum/accounts/abi/bind"
    "github.com/ethereum/go-ethereum/common"
    "github.com/ethereum/go-ethereum/contracts/chequebook"
    "github.com/ethereum/go-ethereum/contracts/chequebook/contract"
    "github.com/ethereum/go-ethereum/core/types"
    "github.com/ethereum/go-ethereum/crypto"
    "github.com/ethereum/go-ethereum/log"
    "github.com/ethereum/go-ethereum/swarm/services/swap/swap"
)

// SwAP       Swarm Accounting Protocol with
// SWAP^2     Strategies of Withholding Automatic Payments
// SWAP^3     Accreditation: payment via credit SWAP
// using chequebook pkg for delayed payments
// default parameters

var (
    autoCashInterval     = 300 * time.Second           // default interval for autocash
    autoCashThreshold    = big.NewInt(50000000000000)  // threshold that triggers autocash (wei)
    autoDepositInterval  = 300 * time.Second           // default interval for autocash
    autoDepositThreshold = big.NewInt(50000000000000)  // threshold that triggers autodeposit (wei)
    autoDepositBuffer    = big.NewInt(100000000000000) // buffer that is surplus for fork protection etc (wei)
    buyAt                = big.NewInt(20000000000)     // maximum chunk price host is willing to pay (wei)
    sellAt               = big.NewInt(20000000000)     // minimum chunk price host requires (wei)
    payAt                = 100                         // threshold that triggers payment {request} (units)
    dropAt               = 10000                       // threshold that triggers disconnect (units)
)

const (
    chequebookDeployRetries = 5
    chequebookDeployDelay   = 1 * time.Second // delay between retries
)

type SwapParams struct {
    *swap.Params
    *PayProfile
}

type SwapProfile struct {
    *swap.Profile
    *PayProfile
}

type PayProfile struct {
    PublicKey   string         // check against signature of promise
    Contract    common.Address // address of chequebook contract
    Beneficiary common.Address // recipient address for swarm sales revenue
    privateKey  *ecdsa.PrivateKey
    publicKey   *ecdsa.PublicKey
    owner       common.Address
    chbook      *chequebook.Chequebook
    lock        sync.RWMutex
}

func DefaultSwapParams(contract common.Address, prvkey *ecdsa.PrivateKey) *SwapParams {
    pubkey := &prvkey.PublicKey
    return &SwapParams{
        PayProfile: &PayProfile{
            PublicKey:   common.ToHex(crypto.FromECDSAPub(pubkey)),
            Contract:    contract,
            Beneficiary: crypto.PubkeyToAddress(*pubkey),
            privateKey:  prvkey,
            publicKey:   pubkey,
            owner:       crypto.PubkeyToAddress(*pubkey),
        },
        Params: &swap.Params{
            Profile: &swap.Profile{
                BuyAt:  buyAt,
                SellAt: sellAt,
                PayAt:  uint(payAt),
                DropAt: uint(dropAt),
            },
            Strategy: &swap.Strategy{
                AutoCashInterval:     autoCashInterval,
                AutoCashThreshold:    autoCashThreshold,
                AutoDepositInterval:  autoDepositInterval,
                AutoDepositThreshold: autoDepositThreshold,
                AutoDepositBuffer:    autoDepositBuffer,
            },
        },
    }
}

// swap constructor, parameters
// * global chequebook, assume deployed service and
// * the balance is at buffer.
// swap.Add(n) called in netstore
// n > 0 called when sending chunks = receiving retrieve requests
//                 OR sending cheques.
// n < 0  called when receiving chunks = receiving delivery responses
//                 OR receiving cheques.

func NewSwap(local *SwapParams, remote *SwapProfile, backend chequebook.Backend, proto swap.Protocol) (self *swap.Swap, err error) {
    var (
        ctx = context.TODO()
        ok  bool
        in  *chequebook.Inbox
        out *chequebook.Outbox
    )

    // check if remote chequebook is valid
    // insolvent chequebooks suicide so will signal as invalid
    // TODO: monitoring a chequebooks events
    ok, err = chequebook.ValidateCode(ctx, backend, remote.Contract)
    if !ok {
        log.Info(fmt.Sprintf("invalid contract %v for peer %v: %v)", remote.Contract.Hex()[:8], proto, err))
    } else {
        // remote contract valid, create inbox
        in, err = chequebook.NewInbox(local.privateKey, remote.Contract, local.Beneficiary, crypto.ToECDSAPub(common.FromHex(remote.PublicKey)), backend)
        if err != nil {
            log.Warn(fmt.Sprintf("unable to set up inbox for chequebook contract %v for peer %v: %v)", remote.Contract.Hex()[:8], proto, err))
        }
    }

    // check if local chequebook contract is valid
    ok, err = chequebook.ValidateCode(ctx, backend, local.Contract)
    if !ok {
        log.Warn(fmt.Sprintf("unable to set up outbox for peer %v:  chequebook contract (owner: %v): %v)", proto, local.owner.Hex(), err))
    } else {
        out = chequebook.NewOutbox(local.Chequebook(), remote.Beneficiary)
    }

    pm := swap.Payment{
        In:    in,
        Out:   out,
        Buys:  out != nil,
        Sells: in != nil,
    }
    self, err = swap.New(local.Params, pm, proto)
    if err != nil {
        return
    }
    // remote profile given (first) in handshake
    self.SetRemote(remote.Profile)
    var buy, sell string
    if self.Buys {
        buy = "purchase from peer enabled at " + remote.SellAt.String() + " wei/chunk"
    } else {
        buy = "purchase from peer disabled"
    }
    if self.Sells {
        sell = "selling to peer enabled at " + local.SellAt.String() + " wei/chunk"
    } else {
        sell = "selling to peer disabled"
    }
    log.Warn(fmt.Sprintf("SWAP arrangement with <%v>: %v; %v)", proto, buy, sell))

    return
}

func (self *SwapParams) Chequebook() *chequebook.Chequebook {
    defer self.lock.Unlock()
    self.lock.Lock()
    return self.chbook
}

func (self *SwapParams) PrivateKey() *ecdsa.PrivateKey {
    return self.privateKey
}

// func (self *SwapParams) PublicKey() *ecdsa.PublicKey {
//  return self.publicKey
// }

func (self *SwapParams) SetKey(prvkey *ecdsa.PrivateKey) {
    self.privateKey = prvkey
    self.publicKey = &prvkey.PublicKey
}

// setChequebook(path, backend) wraps the
// chequebook initialiser and sets up autoDeposit to cover spending.
func (self *SwapParams) SetChequebook(ctx context.Context, backend chequebook.Backend, path string) error {
    self.lock.Lock()
    contract := self.Contract
    self.lock.Unlock()

    valid, err := chequebook.ValidateCode(ctx, backend, contract)
    if err != nil {
        return err
    } else if valid {
        return self.newChequebookFromContract(path, backend)
    }
    return self.deployChequebook(ctx, backend, path)
}

func (self *SwapParams) deployChequebook(ctx context.Context, backend chequebook.Backend, path string) error {
    opts := bind.NewKeyedTransactor(self.privateKey)
    opts.Value = self.AutoDepositBuffer
    opts.Context = ctx

    log.Info(fmt.Sprintf("Deploying new chequebook (owner: %v)", opts.From.Hex()))
    contract, err := deployChequebookLoop(opts, backend)
    if err != nil {
        log.Error(fmt.Sprintf("unable to deploy new chequebook: %v", err))
        return err
    }
    log.Info(fmt.Sprintf("new chequebook deployed at %v (owner: %v)", contract.Hex(), opts.From.Hex()))

    // need to save config at this point
    self.lock.Lock()
    self.Contract = contract
    err = self.newChequebookFromContract(path, backend)
    self.lock.Unlock()
    if err != nil {
        log.Warn(fmt.Sprintf("error initialising cheque book (owner: %v): %v", opts.From.Hex(), err))
    }
    return err
}

// repeatedly tries to deploy a chequebook.
func deployChequebookLoop(opts *bind.TransactOpts, backend chequebook.Backend) (addr common.Address, err error) {
    var tx *types.Transaction
    for try := 0; try < chequebookDeployRetries; try++ {
        if try > 0 {
            time.Sleep(chequebookDeployDelay)
        }
        if _, tx, _, err = contract.DeployChequebook(opts, backend); err != nil {
            log.Warn(fmt.Sprintf("can't send chequebook deploy tx (try %d): %v", try, err))
            continue
        }
        if addr, err = bind.WaitDeployed(opts.Context, backend, tx); err != nil {
            log.Warn(fmt.Sprintf("chequebook deploy error (try %d): %v", try, err))
            continue
        }
        return addr, nil
    }
    return addr, err
}

// initialise the chequebook from a persisted json file or create a new one
// caller holds the lock
func (self *SwapParams) newChequebookFromContract(path string, backend chequebook.Backend) error {
    hexkey := common.Bytes2Hex(self.Contract.Bytes())
    err := os.MkdirAll(filepath.Join(path, "chequebooks"), os.ModePerm)
    if err != nil {
        return fmt.Errorf("unable to create directory for chequebooks: %v", err)
    }

    chbookpath := filepath.Join(path, "chequebooks", hexkey+".json")
    self.chbook, err = chequebook.LoadChequebook(chbookpath, self.privateKey, backend, true)

    if err != nil {
        self.chbook, err = chequebook.NewChequebook(chbookpath, self.Contract, self.privateKey, backend)
        if err != nil {
            log.Warn(fmt.Sprintf("unable to initialise chequebook (owner: %v): %v", self.owner.Hex(), err))
            return fmt.Errorf("unable to initialise chequebook (owner: %v): %v", self.owner.Hex(), err)
        }
    }

    self.chbook.AutoDeposit(self.AutoDepositInterval, self.AutoDepositThreshold, self.AutoDepositBuffer)
    log.Info(fmt.Sprintf("auto deposit ON for %v -> %v: interval = %v, threshold = %v, buffer = %v)", crypto.PubkeyToAddress(*(self.publicKey)).Hex()[:8], self.Contract.Hex()[:8], self.AutoDepositInterval, self.AutoDepositThreshold, self.AutoDepositBuffer))

    return nil
}