Parse github webhook requests into suitable HTML messages

Verifies requests using an optional secret token. This commit doesn't
implement sending of these messages.

src/github.com/matrix-org/go-neb/services/echo/echo.go

@@ -4,6 +4,7 @@ import (
 	"github.com/matrix-org/go-neb/matrix"
 	"github.com/matrix-org/go-neb/plugin"
 	"github.com/matrix-org/go-neb/types"
+	"net/http"
 	"strings"
 )
 
@@ -29,6 +30,9 @@ func (e *echoService) Plugin(roomID string) plugin.Plugin {
 		},
 	}
 }
+func (e *echoService) OnReceiveWebhook(w http.ResponseWriter, req http.Request) {
+	w.WriteHeader(200) // Do nothing
+}
 
 func init() {
 	types.RegisterService(func(serviceID string) types.Service {

src/github.com/matrix-org/go-neb/services/github/github.go

@@ -6,8 +6,10 @@ import (
 	"github.com/google/go-github/github"
 	"github.com/matrix-org/go-neb/matrix"
 	"github.com/matrix-org/go-neb/plugin"
+	"github.com/matrix-org/go-neb/services/github/webhook"
 	"github.com/matrix-org/go-neb/types"
 	"golang.org/x/oauth2"
+	"net/http"
 	"regexp"
 	"strconv"
 )
@@ -60,6 +62,10 @@ func (s *githubService) Plugin(roomID string) plugin.Plugin {
 		},
 	}
 }
+func (s *githubService) OnReceiveWebhook(w http.ResponseWriter, req http.Request) {
+	// defer entirely to the webhook package
+	webhook.OnReceiveRequest(w, req, "")
+}
 
 // githubClient returns a github Client which can perform Github API operations.
 // If `token` is empty, a non-authenticated client will be created. This should be

src/github.com/matrix-org/go-neb/services/github/webhook/webhook.go

@@ -0,0 +1,259 @@
+package webhook
+
+import (
+	"crypto/hmac"
+	"crypto/sha1"
+	"encoding/hex"
+	"encoding/json"
+	"fmt"
+	log "github.com/Sirupsen/logrus"
+	"github.com/google/go-github/github"
+	"html"
+	"io/ioutil"
+	"net/http"
+	"strings"
+)
+
+// OnReceiveRequest processes incoming github webhook requests. The secretToken
+// parameter is optional.
+func OnReceiveRequest(w http.ResponseWriter, r http.Request, secretToken string) {
+	// Verify the HMAC signature if NEB was configured with a secret token
+	eventType := r.Header.Get("X-GitHub-Event")
+	signatureSHA1 := r.Header.Get("X-Hub-Signature")
+	content, err := ioutil.ReadAll(r.Body)
+	if err != nil {
+		log.WithError(err).Print("Failed to read Github webhook body")
+		w.WriteHeader(400)
+		return
+	}
+	// Verify request if a secret token has been supplied.
+	if secretToken != "" {
+		sigHex := strings.Split(signatureSHA1, "=")[1]
+		var sigBytes []byte
+		sigBytes, err = hex.DecodeString(sigHex)
+		if err != nil {
+			log.WithError(err).WithField("X-Hub-Signature", sigHex).Print(
+				"Failed to decode signature as hex.")
+			w.WriteHeader(400)
+			return
+		}
+
+		if !checkMAC([]byte(content), sigBytes, []byte(secretToken)) {
+			log.WithFields(log.Fields{
+				"X-Hub-Signature": signatureSHA1,
+			}).Print("Received Github event which failed MAC check.")
+			w.WriteHeader(403)
+			return
+		}
+	}
+
+	log.WithFields(log.Fields{
+		"event_type": eventType,
+		"signature":  signatureSHA1,
+	}).Print("Received Github event")
+
+	htmlStr, repo, err := parseGithubEvent(eventType, content)
+	if err != nil {
+		log.WithError(err).Print("Failed to parse github event")
+		w.WriteHeader(500)
+		return
+	}
+
+	if err := handleWebhookEvent(eventType, htmlStr, repo); err != nil {
+		log.WithError(err).Print("Failed to handle Github webhook event")
+		w.WriteHeader(500)
+		return
+	}
+	w.WriteHeader(200)
+}
+
+// checkMAC reports whether messageMAC is a valid HMAC tag for message.
+func checkMAC(message, messageMAC, key []byte) bool {
+	mac := hmac.New(sha1.New, key)
+	mac.Write(message)
+	expectedMAC := mac.Sum(nil)
+	return hmac.Equal(messageMAC, expectedMAC)
+}
+
+// parseGithubEvent parses a github event type and JSON data and returns an explanatory
+// HTML string and the github repository this event affects, or an error.
+func parseGithubEvent(eventType string, data []byte) (string, *github.Repository, error) {
+	if eventType == "pull_request" {
+		var ev github.PullRequestEvent
+		if err := json.Unmarshal(data, &ev); err != nil {
+			return "", nil, err
+		}
+		return pullRequestHTMLMessage(ev), ev.Repo, nil
+	} else if eventType == "issues" {
+		var ev github.IssuesEvent
+		if err := json.Unmarshal(data, &ev); err != nil {
+			return "", nil, err
+		}
+		return issueHTMLMessage(ev), ev.Repo, nil
+	} else if eventType == "push" {
+		var ev github.PushEvent
+		if err := json.Unmarshal(data, &ev); err != nil {
+			return "", nil, err
+		}
+
+		// The 'push' event repository format is subtly different from normal, so munge the bits we need.
+		fullName := *ev.Repo.Owner.Name + "/" + *ev.Repo.Name
+		repo := github.Repository{
+			Owner: &github.User{
+				Login: ev.Repo.Owner.Name,
+			},
+			Name:     ev.Repo.Name,
+			FullName: &fullName,
+		}
+		return pushHTMLMessage(ev), &repo, nil
+	} else if eventType == "issue_comment" {
+		var ev github.IssueCommentEvent
+		if err := json.Unmarshal(data, &ev); err != nil {
+			return "", nil, err
+		}
+		return issueCommentHTMLMessage(ev), ev.Repo, nil
+	} else if eventType == "pull_request_review_comment" {
+		var ev github.PullRequestReviewCommentEvent
+		if err := json.Unmarshal(data, &ev); err != nil {
+			return "", nil, err
+		}
+		return prReviewCommentHTMLMessage(ev), ev.Repo, nil
+	}
+	return "", nil, fmt.Errorf("Unrecognized event type")
+}
+
+func handleWebhookEvent(eventType string, htmlStr string, repo *github.Repository) error {
+	return nil
+}
+
+func pullRequestHTMLMessage(p github.PullRequestEvent) string {
+	var actionTarget string
+	if p.PullRequest.Assignee != nil && p.PullRequest.Assignee.Login != nil {
+		actionTarget = fmt.Sprintf(" to %s", *p.PullRequest.Assignee.Login)
+	}
+	return fmt.Sprintf(
+		"[<u>%s</u>] %s %s <b>pull request #%d</b>: %s [%s]%s - %s",
+		html.EscapeString(*p.Repo.FullName),
+		html.EscapeString(*p.Sender.Login),
+		html.EscapeString(*p.Action),
+		*p.Number,
+		html.EscapeString(*p.PullRequest.Title),
+		html.EscapeString(*p.PullRequest.State),
+		html.EscapeString(actionTarget),
+		html.EscapeString(*p.PullRequest.HTMLURL),
+	)
+}
+
+func issueHTMLMessage(p github.IssuesEvent) string {
+	var actionTarget string
+	if p.Issue.Assignee != nil && p.Issue.Assignee.Login != nil {
+		actionTarget = fmt.Sprintf(" to %s", *p.Issue.Assignee.Login)
+	}
+	return fmt.Sprintf(
+		"[<u>%s</u>] %s %s <b>issue #%d</b>: %s [%s]%s - %s",
+		html.EscapeString(*p.Repo.FullName),
+		html.EscapeString(*p.Sender.Login),
+		html.EscapeString(*p.Action),
+		*p.Issue.Number,
+		html.EscapeString(*p.Issue.Title),
+		html.EscapeString(*p.Issue.State),
+		html.EscapeString(actionTarget),
+		html.EscapeString(*p.Issue.HTMLURL),
+	)
+}
+
+func issueCommentHTMLMessage(p github.IssueCommentEvent) string {
+	var kind string
+	if p.Issue.PullRequestLinks == nil {
+		kind = "issue"
+	} else {
+		kind = "pull request"
+	}
+
+	return fmt.Sprintf(
+		"[<u>%s</u>] %s commented on %s's <b>%s #%d</b>: %s - %s",
+		html.EscapeString(*p.Repo.FullName),
+		html.EscapeString(*p.Comment.User.Login),
+		html.EscapeString(*p.Issue.User.Login),
+		kind,
+		*p.Issue.Number,
+		html.EscapeString(*p.Issue.Title),
+		html.EscapeString(*p.Issue.HTMLURL),
+	)
+}
+
+func prReviewCommentHTMLMessage(p github.PullRequestReviewCommentEvent) string {
+	assignee := "None"
+	if p.PullRequest.Assignee != nil {
+		assignee = html.EscapeString(*p.PullRequest.Assignee.Login)
+	}
+	return fmt.Sprintf(
+		"[<u>%s</u>] %s made a line comment on %s's <b>pull request #%d</b> (assignee: %s): %s - %s",
+		html.EscapeString(*p.Repo.FullName),
+		html.EscapeString(*p.Sender.Login),
+		html.EscapeString(*p.PullRequest.User.Login),
+		*p.PullRequest.Number,
+		assignee,
+		html.EscapeString(*p.PullRequest.Title),
+		html.EscapeString(*p.Comment.HTMLURL),
+	)
+}
+
+func pushHTMLMessage(p github.PushEvent) string {
+	// /refs/heads/alice/branch-name => alice/branch-name
+	branch := strings.Replace(*p.Ref, "refs/heads/", "", -1)
+
+	// this branch was deleted, no HeadCommit object and deleted=true
+	if p.HeadCommit == nil && p.Deleted != nil && *p.Deleted {
+		return fmt.Sprintf(
+			`[<u>%s</u>] %s <font color="red"><b>deleted</font> %s</b>`,
+			html.EscapeString(*p.Repo.FullName),
+			html.EscapeString(*p.Pusher.Name),
+			html.EscapeString(branch),
+		)
+	}
+
+	if p.Commits != nil && len(p.Commits) > 1 {
+		// multi-commit message
+		// [<repo>] <username> pushed <num> commits to <branch>: <git.io link>
+		// <up to 3 commits>
+		var cList []string
+		for _, c := range p.Commits {
+			cList = append(cList, fmt.Sprintf(
+				`%s: %s`,
+				html.EscapeString(nameForAuthor(c.Author)),
+				html.EscapeString(*c.Message),
+			))
+		}
+		return fmt.Sprintf(
+			`[<u>%s</u>] %s pushed %d commits to <b>%s</b>: %s<br>%s`,
+			html.EscapeString(*p.Repo.FullName),
+			html.EscapeString(nameForAuthor(p.HeadCommit.Committer)),
+			len(p.Commits),
+			html.EscapeString(branch),
+			html.EscapeString(*p.HeadCommit.URL),
+			strings.Join(cList, "<br>"),
+		)
+	}
+
+	// single commit message
+	// [<repo>] <username> pushed to <branch>: <msg> - <git.io link>
+	return fmt.Sprintf(
+		`[<u>%s</u>] %s pushed to <b>%s</b>: %s  - %s`,
+		html.EscapeString(*p.Repo.FullName),
+		html.EscapeString(nameForAuthor(p.HeadCommit.Committer)),
+		html.EscapeString(branch),
+		html.EscapeString(*p.HeadCommit.Message),
+		html.EscapeString(*p.HeadCommit.URL),
+	)
+}
+
+func nameForAuthor(a *github.CommitAuthor) string {
+	if a == nil {
+		return ""
+	}
+	if a.Login != nil { // prefer to use their GH username than the name they commited as
+		return *a.Login
+	}
+	return *a.Name
+}

src/github.com/matrix-org/go-neb/types/types.go

@@ -3,7 +3,7 @@ package types
 import (
 	"errors"
 	"github.com/matrix-org/go-neb/plugin"
-	// "net/http"
+	"net/http"
 	"net/url"
 )
 
@@ -32,7 +32,7 @@ type Service interface {
 	ServiceType() string
 	RoomIDs() []string
 	Plugin(roomID string) plugin.Plugin
-	// OnReceiveWebhook(req http.Request)
+	OnReceiveWebhook(w http.ResponseWriter, req http.Request)
 }
 
 var servicesByType = map[string]func(string) Service{}