retry on "connection reset by peer" (#3138)

retry when we receive a "connection reset by peer" error

---

#### Does this PR need a docs update or release note?

- [x] ✅ Yes, it's included

#### Type of change

- [x] 🐛 Bugfix

#### Issue(s)

* #3129

#### Test Plan

- [x] 💪 Manual
- [x] ⚡ Unit test

CHANGELOG.md

@@ -23,6 +23,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Skip OneNote items bigger than 2GB (Graph API prevents us from downloading them)
 - ParentPath of json output for Exchange calendar now shows names instead of IDs.
 - Fixed failure when downloading huge amount of attachments
+- Graph API requests that return an ECONNRESET error are now retried.
 
 ### Known Issues
 - Restoring a OneDrive or SharePoint file with the same name as a file with that name as its M365 ID may restore both items.

src/internal/connector/graph/errors.go

@@ -8,6 +8,7 @@ import (
 	"net/url"
 	"os"
 	"strings"
+	"syscall"
 
 	"github.com/alcionai/clues"
 	"github.com/microsoftgraph/msgraph-sdk-go/models"
@@ -116,6 +117,10 @@ func IsErrTimeout(err error) bool {
 		os.IsTimeout(err)
 }
 
+func IsErrConnectionReset(err error) bool {
+	return errors.Is(err, syscall.ECONNRESET)
+}
+
 func IsErrUnauthorized(err error) bool {
 	// TODO: refine this investigation.  We don't currently know if
 	// a specific item download url expired, or if the full connection

src/internal/connector/graph/errors_test.go

@@ -3,6 +3,7 @@ package graph
 import (
 	"context"
 	"net/http"
+	"syscall"
 	"testing"
 
 	"github.com/alcionai/clues"
@@ -32,6 +33,35 @@ func odErr(code string) *odataerrors.ODataError {
 	return odErr
 }
 
+func (suite *GraphErrorsUnitSuite) TestIsErrConnectionReset() {
+	table := []struct {
+		name   string
+		err    error
+		expect assert.BoolAssertionFunc
+	}{
+		{
+			name:   "nil",
+			err:    nil,
+			expect: assert.False,
+		},
+		{
+			name:   "non-matching",
+			err:    assert.AnError,
+			expect: assert.False,
+		},
+		{
+			name:   "matching",
+			err:    syscall.ECONNRESET,
+			expect: assert.True,
+		},
+	}
+	for _, test := range table {
+		suite.Run(test.name, func() {
+			test.expect(suite.T(), IsErrConnectionReset(test.err))
+		})
+	}
+}
+
 func (suite *GraphErrorsUnitSuite) TestIsErrDeletedInFlight() {
 	table := []struct {
 		name   string

src/internal/connector/graph/middleware.go

@@ -213,7 +213,7 @@ func (middleware RetryHandler) retryRequest(
 		}
 
 		response, err := pipeline.Next(req, middlewareIndex)
-		if err != nil && !IsErrTimeout(err) {
+		if err != nil && !IsErrTimeout(err) && !IsErrConnectionReset(err) {
 			return response, Stack(ctx, err).With("retry_count", executionCount)
 		}