short-d/short

package google

import (
    "encoding/json"
    "fmt"
    "net/http"

    "github.com/short-d/app/fw/webreq"
    "github.com/short-d/short/backend/app/usecase/risk"
)

var _ risk.BlackList = (*SafeBrowsing)(nil)

const safeBrowsingLookupAPI = "https://safebrowsing.googleapis.com/v4/threatMatches:find"

type threatType string

const (
    unknown               threatType = "THREAT_TYPE_UNSPECIFIED"
    malware               threatType = "MALWARE"
    socialEngineering     threatType = "SOCIAL_ENGINEERING"
    potentiallyHarmfulApp threatType = "POTENTIALLY_HARMFUL_APPLICATION"
    unwantedSoftware      threatType = "UNWANTED_SOFTWARE"
)

type platformType string

const (
    allPlatforms platformType = "ALL_PLATFORMS"
    anyPlatform  platformType = "ANY_PLATFORM"
    window       platformType = "WINDOWS"
    linux        platformType = "LINUX"
    osx          platformType = "OSX"
    chrome       platformType = "CHROME"
    ios          platformType = "IOS"
    android      platformType = "Android"
)

type threatEntryType string

const (
    unspecified  threatEntryType = "THREAT_ENTRY_TYPE_UNSPECIFIED"
    maliciousURL threatEntryType = "URL"
    executable   threatEntryType = "EXECUTABLE"
)

type threat struct {
    URL string `json:"url"`
}

type lookupAPIRequest struct {
    ThreatInfo threatInfo `json:"threatInfo"`
}

type threatInfo struct {
    ThreatTypes   []threatType   `json:"threatTypes"`
    PlatformTypes []platformType `json:"platformTypes"`
    ThreatEntries []threat       `json:"threatEntries"`
}

type lookupAPIResponse struct {
    Matches []match `json:"matches"`
}

type match struct {
    ThreatType      threatType      `json:"threatType"`
    PlatformType    platformType    `json:"platformType"`
    Threat          threat          `json:"threat"`
    CacheDuration   string          `json:"cacheDuration"`
    ThreatEntryType threatEntryType `json:"threatEntryType"`
}

// SafeBrowsing represents Googles SafeBrowsing APIs.
type SafeBrowsing struct {
    apiKey      string
    httpRequest webreq.HTTP
}

// HasURL checks whether a given URL is blacklisted by Google.
func (s SafeBrowsing) HasURL(url string) (bool, error) {
    api := s.auth(safeBrowsingLookupAPI)
    body := lookupAPIRequest{
        ThreatInfo: threatInfo{
            ThreatTypes: []threatType{
                malware,
                socialEngineering,
                potentiallyHarmfulApp,
                unwantedSoftware,
            },
            PlatformTypes: []platformType{
                allPlatforms,
            },
            ThreatEntries: []threat{
                {URL: url},
            },
        },
    }

    buf, err := json.Marshal(body)
    if err != nil {
        return false, err
    }

    headers := map[string]string{
        "Content-Type": "application/json",
    }

    res := lookupAPIResponse{}
    err = s.httpRequest.JSON(http.MethodPost, api, headers, string(buf), &res)
    if err != nil {
        return false, err
    }
    return len(res.Matches) > 0, nil
}

func (s SafeBrowsing) auth(baseURL string) string {
    return fmt.Sprintf("%s/?key=%s", baseURL, s.apiKey)
}

// NewSafeBrowsing initializes Google's SafeBrowsing API client.
func NewSafeBrowsing(apiKey string, req webreq.HTTP) SafeBrowsing {
    return SafeBrowsing{
        apiKey:      apiKey,
        httpRequest: req,
    }
}