Oracles

1pragma solidity ^0.6.7;
2
3import "@chainlink/contracts/src/v0.6/interfaces/AggregatorV3Interface.sol";
4
5contract PriceConsumerV3 {
6
7    AggregatorV3Interface internal priceFeed;
8
9    /**
10     * Network: Kovan
11     * Aggregator: ETH/USD
12     * Address: 0x9326BFA02ADD2366b30bacB125260Af641031331
13     */
14    constructor() public {
15        priceFeed = AggregatorV3Interface(0x9326BFA02ADD2366b30bacB125260Af641031331);
16    }
17
18    /**
19     * Returns the latest price
20     */
21    function getLatestPrice() public view returns (int) {
22        (
23            uint80 roundID,
24            int price,
25            uint startedAt,
26            uint timeStamp,
27            uint80 answeredInRound
28        ) = priceFeed.latestRoundData();
29        return price;
30    }
31}
32
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1
2pragma solidity 0.6.6;
3
4import "@chainlink/contracts/src/v0.6/VRFConsumerBase.sol";
5
6contract RandomNumberConsumer is VRFConsumerBase {
7
8    bytes32 internal keyHash;
9    uint256 internal fee;
10
11    uint256 public randomResult;
12
13    /**
14     * Constructor inherits VRFConsumerBase
15     *
16     * Network: Kovan
17     * Chainlink VRF Coordinator address: 0xdD3782915140c8f3b190B5D67eAc6dc5760C46E9
18     * LINK token address:                0xa36085F69e2889c224210F603D836748e7dC0088
19     * Key Hash: 0x6c3699283bda56ad74f6b855546325b68d482e983852a7a82979cc4807b641f4
20     */
21    constructor()
22        VRFConsumerBase(
23            0xdD3782915140c8f3b190B5D67eAc6dc5760C46E9, // VRF Coordinator
24            0xa36085F69e2889c224210F603D836748e7dC0088  // LINK Token
25        ) public
26    {
27        keyHash = 0x6c3699283bda56ad74f6b855546325b68d482e983852a7a82979cc4807b641f4;
28        fee = 0.1 * 10 ** 18; // 0.1 LINK (varies by network)
29    }
30
31    /**
32     * Requests randomness from a user-provided seed
33     */
34    function getRandomNumber(uint256 userProvidedSeed) public returns (bytes32 requestId) {
35        require(LINK.balanceOf(address(this)) >= fee, "Not enough LINK - fill contract with faucet");
36        return requestRandomness(keyHash, fee, userProvidedSeed);
37    }
38
39    /**
40     * Callback function used by VRF Coordinator
41     */
42    function fulfillRandomness(bytes32 requestId, uint256 randomness) internal override {
43        randomResult = randomness;
44    }
45}
46
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1pragma solidity ^0.6.0;
2
3import "@chainlink/contracts/src/v0.6/ChainlinkClient.sol";
4
5contract APIConsumer is ChainlinkClient {
6
7    uint256 public volume;
8
9    address private oracle;
10    bytes32 private jobId;
11    uint256 private fee;
12
13    /**
14     * Network: Kovan
15     * Oracle: 0x2f90A6D021db21e1B2A077c5a37B3C7E75D15b7e
16     * Job ID: 29fa9aa13bf1468788b7cc4a500a45b8
17     * Fee: 0.1 LINK
18     */
19    constructor() public {
20        setPublicChainlinkToken();
21        oracle = 0x2f90A6D021db21e1B2A077c5a37B3C7E75D15b7e;
22        jobId = "29fa9aa13bf1468788b7cc4a500a45b8";
23        fee = 0.1 * 10 ** 18; // 0.1 LINK
24    }
25
26    /**
27     * Create a Chainlink request to retrieve API response, find the target
28     * data, then multiply by 1000000000000000000 (to remove decimal places from data).
29     */
30    function requestVolumeData() public returns (bytes32 requestId)
31    {
32        Chainlink.Request memory request = buildChainlinkRequest(jobId, address(this), this.fulfill.selector);
33
34        // Set the URL to perform the GET request on
35        request.add("get", "https://min-api.cryptocompare.com/data/pricemultifull?fsyms=ETH&tsyms=USD");
36
37        // Set the path to find the desired data in the API response, where the response format is:
38        // {"RAW":
39        //   {"ETH":
40        //    {"USD":
41        //     {
42        //      "VOLUME24HOUR": xxx.xxx,
43        //     }
44        //    }
45        //   }
46        //  }
47        request.add("path", "RAW.ETH.USD.VOLUME24HOUR");
48
49        // Multiply the result by 1000000000000000000 to remove decimals
50        int timesAmount = 10**18;
51        request.addInt("times", timesAmount);
52
53        // Sends the request
54        return sendChainlinkRequestTo(oracle, request, fee);
55    }
56
57    /**
58     * Receive the response in the form of uint256
59     */
60    function fulfill(bytes32 _requestId, uint256 _volume) public recordChainlinkFulfillment(_requestId)
61    {
62        volume = _volume;
63    }
64}
65
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1pragma solidity >=0.4.21 <0.6.0;
2
3contract Oracle {
4  Request[] requests; //list of requests made to the contract
5  uint currentId = 0; //increasing request id
6  uint minQuorum = 2; //minimum number of responses to receive before declaring final result
7  uint totalOracleCount = 3; // Hardcoded oracle count
8
9  // defines a general api request
10  struct Request {
11    uint id;                            //request id
12    string urlToQuery;                  //API url
13    string attributeToFetch;            //json attribute (key) to retrieve in the response
14    string agreedValue;                 //value from key
15    mapping(uint => string) anwers;     //answers provided by the oracles
16    mapping(address => uint) quorum;    //oracles which will query the answer (1=oracle hasn't voted, 2=oracle has voted)
17  }
18
19  //event that triggers oracle outside of the blockchain
20  event NewRequest (
21    uint id,
22    string urlToQuery,
23    string attributeToFetch
24  );
25
26  //triggered when there's a consensus on the final result
27  event UpdatedRequest (
28    uint id,
29    string urlToQuery,
30    string attributeToFetch,
31    string agreedValue
32  );
33
34  function createRequest (
35    string memory _urlToQuery,
36    string memory _attributeToFetch
37  )
38  public
39  {
40    uint lenght = requests.push(Request(currentId, _urlToQuery, _attributeToFetch, ""));
41    Request storage r = requests[lenght-1];
42
43    // Hardcoded oracles address
44    r.quorum[address(0x6c2339b46F41a06f09CA0051ddAD54D1e582bA77)] = 1;
45    r.quorum[address(0xb5346CF224c02186606e5f89EACC21eC25398077)] = 1;
46    r.quorum[address(0xa2997F1CA363D11a0a35bB1Ac0Ff7849bc13e914)] = 1;
47
48    // launch an event to be detected by oracle outside of blockchain
49    emit NewRequest (
50      currentId,
51      _urlToQuery,
52      _attributeToFetch
53    );
54
55    // increase request id
56    currentId++;
57  }
58
59  //called by the oracle to record its answer
60  function updateRequest (
61    uint _id,
62    string memory _valueRetrieved
63  ) public {
64
65    Request storage currRequest = requests[_id];
66
67    //check if oracle is in the list of trusted oracles
68    //and if the oracle hasn't voted yet
69    if(currRequest.quorum[address(msg.sender)] == 1){
70
71      //marking that this address has voted
72      currRequest.quorum[msg.sender] = 2;
73
74      //iterate through "array" of answers until a position if free and save the retrieved value
75      uint tmpI = 0;
76      bool found = false;
77      while(!found) {
78        //find first empty slot
79        if(bytes(currRequest.anwers[tmpI]).length == 0){
80          found = true;
81          currRequest.anwers[tmpI] = _valueRetrieved;
82        }
83        tmpI++;
84      }
85
86      uint currentQuorum = 0;
87
88      //iterate through oracle list and check if enough oracles(minimum quorum)
89      //have voted the same answer has the current one
90      for(uint i = 0; i < totalOracleCount; i++){
91        bytes memory a = bytes(currRequest.anwers[i]);
92        bytes memory b = bytes(_valueRetrieved);
93
94        if(keccak256(a) == keccak256(b)){
95          currentQuorum++;
96          if(currentQuorum >= minQuorum){
97            currRequest.agreedValue = _valueRetrieved;
98            emit UpdatedRequest (
99              currRequest.id,
100              currRequest.urlToQuery,
101              currRequest.attributeToFetch,
102              currRequest.agreedValue
103            );
104          }
105        }
106      }
107    }
108  }
109}
110
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