[security] transport.Controller{} and transport.Transport{} security and performance improvements (#564)

* cache transports in controller by privkey-generated pubkey, add retry logic to transport requests

Signed-off-by: kim <grufwub@gmail.com>

* update code comments, defer mutex unlocks

Signed-off-by: kim <grufwub@gmail.com>

* add count to 'performing request' log message

Signed-off-by: kim <grufwub@gmail.com>

* reduce repeated conversions of same url.URL object

Signed-off-by: kim <grufwub@gmail.com>

* move worker.Worker to concurrency subpackage, add WorkQueue type, limit transport http client use by WorkQueue

Signed-off-by: kim <grufwub@gmail.com>

* fix security advisories regarding max outgoing conns, max rsp body size

- implemented by a new httpclient.Client{} that wraps an underlying
  client with a queue to limit connections, and limit reader wrapping
  a response body with a configured maximum size
- update pub.HttpClient args passed around to be this new httpclient.Client{}

Signed-off-by: kim <grufwub@gmail.com>

* add httpclient tests, move ip validation to separate package + change mechanism

Signed-off-by: kim <grufwub@gmail.com>

* fix merge conflicts

Signed-off-by: kim <grufwub@gmail.com>

* use singular mutex in transport rather than separate signer mus

Signed-off-by: kim <grufwub@gmail.com>

* improved useragent string

Signed-off-by: kim <grufwub@gmail.com>

* add note regarding missing test

Signed-off-by: kim <grufwub@gmail.com>

* remove useragent field from transport (instead store in controller)

Signed-off-by: kim <grufwub@gmail.com>

* shutup linter

Signed-off-by: kim <grufwub@gmail.com>

* reset other signing headers on each loop iteration

Signed-off-by: kim <grufwub@gmail.com>

* respect request ctx during retry-backoff sleep period

Signed-off-by: kim <grufwub@gmail.com>

* use external pkg with docs explaining performance "hack"

Signed-off-by: kim <grufwub@gmail.com>

* use http package constants instead of string method literals

Signed-off-by: kim <grufwub@gmail.com>

* add license file headers

Signed-off-by: kim <grufwub@gmail.com>

* update code comment to match new func names

Signed-off-by: kim <grufwub@gmail.com>

* updates to user-agent string

Signed-off-by: kim <grufwub@gmail.com>

* update signed testrig models to fit with new transport logic (instead uses separate signer now)

Signed-off-by: kim <grufwub@gmail.com>

* fuck you linter

Signed-off-by: kim <grufwub@gmail.com>

internal/federation/federatingdb/db.go

@@ -24,10 +24,10 @@ import (
 	"codeberg.org/gruf/go-mutexes"
 	"github.com/superseriousbusiness/activity/pub"
 	"github.com/superseriousbusiness/activity/streams/vocab"
+	"github.com/superseriousbusiness/gotosocial/internal/concurrency"
 	"github.com/superseriousbusiness/gotosocial/internal/db"
 	"github.com/superseriousbusiness/gotosocial/internal/messages"
 	"github.com/superseriousbusiness/gotosocial/internal/typeutils"
-	"github.com/superseriousbusiness/gotosocial/internal/worker"
 )
 
 // DB wraps the pub.Database interface with a couple of custom functions for GoToSocial.
@@ -44,12 +44,12 @@ type DB interface {
 type federatingDB struct {
 	locks         mutexes.MutexMap
 	db            db.DB
-	fedWorker     *worker.Worker[messages.FromFederator]
+	fedWorker     *concurrency.WorkerPool[messages.FromFederator]
 	typeConverter typeutils.TypeConverter
 }
 
 // New returns a DB interface using the given database and config
-func New(db db.DB, fedWorker *worker.Worker[messages.FromFederator]) DB {
+func New(db db.DB, fedWorker *concurrency.WorkerPool[messages.FromFederator]) DB {
 	fdb := federatingDB{
 		locks:         mutexes.NewMap(-1, -1), // use defaults
 		db:            db,

internal/federation/federatingdb/federatingdb_test.go

@@ -23,12 +23,12 @@ import (
 
 	"github.com/stretchr/testify/suite"
 	"github.com/superseriousbusiness/gotosocial/internal/ap"
+	"github.com/superseriousbusiness/gotosocial/internal/concurrency"
 	"github.com/superseriousbusiness/gotosocial/internal/db"
 	"github.com/superseriousbusiness/gotosocial/internal/federation/federatingdb"
 	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
 	"github.com/superseriousbusiness/gotosocial/internal/messages"
 	"github.com/superseriousbusiness/gotosocial/internal/typeutils"
-	"github.com/superseriousbusiness/gotosocial/internal/worker"
 	"github.com/superseriousbusiness/gotosocial/testrig"
 )
 
@@ -36,7 +36,7 @@ type FederatingDBTestSuite struct {
 	suite.Suite
 	db            db.DB
 	tc            typeutils.TypeConverter
-	fedWorker     *worker.Worker[messages.FromFederator]
+	fedWorker     *concurrency.WorkerPool[messages.FromFederator]
 	fromFederator chan messages.FromFederator
 	federatingDB  federatingdb.DB
 
@@ -65,7 +65,7 @@ func (suite *FederatingDBTestSuite) SetupSuite() {
 func (suite *FederatingDBTestSuite) SetupTest() {
 	testrig.InitTestLog()
 	testrig.InitTestConfig()
-	suite.fedWorker = worker.New[messages.FromFederator](-1, -1)
+	suite.fedWorker = concurrency.NewWorkerPool[messages.FromFederator](-1, -1)
 	suite.fromFederator = make(chan messages.FromFederator, 10)
 	suite.fedWorker.SetProcessor(func(ctx context.Context, msg messages.FromFederator) error {
 		suite.fromFederator <- msg