Merge dev: devianter v0.3.1 migration, DA throttle, fixes

Migrate to github.com/zerolabsco/devianter v0.3.1 and adapt to its
reordered return values, throttle outbound DeviantArt requests, harden
the random-art retry loop, and fix the darwin build.

9 files changed, 246 insertions, 18 deletions

diff --git a/app/api.go b/app/api.go
index d2a5655..0398d3c 100755
--- a/app/api.go
+++ b/app/api.go
@@ -3,9 +3,10 @@ package app
 import (
 	"encoding/json"
 	"math/rand"
+	"strconv"
 	"strings"
 
-	"git.macaw.me/skunky/devianter"
+	"github.com/zerolabsco/devianter"
 )
 
 type API struct {
@@ -58,25 +59,32 @@ func (a API) sendMedia(d *devianter.Deviation) {
 
 // TODO: сделать фильтры
 func (a API) Random() {
-	for attempt := 1; ; {
-		if attempt > 3 {
-			a.Error("Sorry, butt NSFW on this are disabled, and the instance failed to find a random art without NSFW", 500)
-		}
+	// Bounded retries: the loop used to be unbounded, and the DeviantArt-error
+	// path never incremented attempt, so a single request could spin forever
+	// hammering the API (and get this instance's egress IP banned).
+	const maxAttempts = 3
 
-		s, err, daErr := devianter.PerformSearch(string(rand.Intn(999)), rand.Intn(30), 'a')
+	for attempt := 0; attempt < maxAttempts; attempt++ {
+		// strconv.Itoa, not string(): string(65) is "A", not "65".
+		s, daErr, err := devianter.PerformSearch(strconv.Itoa(rand.Intn(999)), rand.Intn(30), 'a')
 		try(err)
 		if daErr.RAW != nil {
 			continue
 		}
 
-		deviation := &s.Results[rand.Intn(len(s.Results))]
+		// rand.Intn panics on 0, so an empty result set must be skipped.
+		if len(s.Results) == 0 {
+			continue
+		}
 
+		deviation := &s.Results[rand.Intn(len(s.Results))]
 		if deviation.NSFW && !CFG.Nsfw {
-			attempt++
 			continue
 		}
 
 		a.sendMedia(deviation)
 		return
 	}
+
+	a.Error("Sorry, butt NSFW on this are disabled, and the instance failed to find a random art without NSFW", 500)
 }
diff --git a/app/config.go b/app/config.go
index 813453c..2d32d19 100755
--- a/app/config.go
+++ b/app/config.go
@@ -8,7 +8,7 @@ import (
 	"strconv"
 	"time"
 
-	"git.macaw.me/skunky/devianter"
+	"github.com/zerolabsco/devianter"
 )
 
 var Release struct {
diff --git a/app/httpclient.go b/app/httpclient.go
new file mode 100644
index 0000000..d3e5d50
--- /dev/null
+++ b/app/httpclient.go
@@ -0,0 +1,68 @@
+package app
+
+import (
+	"net/http"
+	"strings"
+	"sync"
+	"time"
+)
+
+// DeviantArt fronts its API with AWS CloudFront + WAF, which bans egress IPs that
+// hit it too hard. Under a bot flood, unbounded concurrent handlers each fetch
+// ~150-200 KB of DA JSON, which both hammers that IP (risking a ban) and can OOM
+// the process. devianter makes its requests with a bare &http.Client{}, so they go
+// through http.DefaultTransport — we wrap it here to bound the rate and concurrency
+// of calls to deviantart.com and to add timeouts. Requests to other hosts (e.g.
+// wixmp image CDN) are passed straight through, so media stays fast.
+//
+// http.ProxyFromEnvironment is preserved, so HTTPS_PROXY (VPN egress) still applies.
+
+// Tunables (kept in source; safe defaults). Lower is gentler on the DA IP.
+var (
+	daMinInterval   = 400 * time.Millisecond // minimum gap between DA request starts
+	daMaxConcurrent = 2                      // max simultaneous in-flight DA requests
+)
+
+type daThrottle struct {
+	base http.RoundTripper
+	sem  chan struct{}
+	mu   sync.Mutex
+	last time.Time
+}
+
+func (t *daThrottle) RoundTrip(req *http.Request) (*http.Response, error) {
+	// Only throttle DeviantArt's WAF-protected API host; let everything else fly.
+	if !strings.Contains(req.URL.Hostname(), "deviantart.com") {
+		return t.base.RoundTrip(req)
+	}
+
+	// Concurrency cap: block until a slot frees up (backpressure under floods).
+	t.sem <- struct{}{}
+	defer func() { <-t.sem }()
+
+	// Rate cap: enforce a minimum interval between request starts.
+	t.mu.Lock()
+	if wait := daMinInterval - time.Since(t.last); wait > 0 {
+		time.Sleep(wait)
+	}
+	t.last = time.Now()
+	t.mu.Unlock()
+
+	return t.base.RoundTrip(req)
+}
+
+// InstallDAThrottle wraps http.DefaultTransport with the rate/concurrency limits and
+// timeouts above. Call once at startup, before any DeviantArt request is made.
+func InstallDAThrottle() {
+	// Clone the default transport so we keep its Proxy (ProxyFromEnvironment) and
+	// connection-pool defaults, then tighten timeouts to bound hung connections.
+	base := http.DefaultTransport.(*http.Transport).Clone()
+	base.TLSHandshakeTimeout = 10 * time.Second
+	base.ResponseHeaderTimeout = 20 * time.Second
+	base.ExpectContinueTimeout = 2 * time.Second
+
+	http.DefaultTransport = &daThrottle{
+		base: base,
+		sem:  make(chan struct{}, daMaxConcurrent),
+	}
+}
diff --git a/app/httpclient_test.go b/app/httpclient_test.go
new file mode 100644
index 0000000..650360e
--- /dev/null
+++ b/app/httpclient_test.go
@@ -0,0 +1,137 @@
+package app
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"sync"
+	"testing"
+	"time"
+)
+
+// stubTransport records how many requests reached it and returns an empty 200.
+type stubTransport struct {
+	mu sync.Mutex
+	n  int
+}
+
+func (s *stubTransport) RoundTrip(req *http.Request) (*http.Response, error) {
+	s.mu.Lock()
+	s.n++
+	s.mu.Unlock()
+	return httptest.NewRecorder().Result(), nil
+}
+
+func newTestThrottle(base http.RoundTripper, gap time.Duration, max int) *daThrottle {
+	return &daThrottle{base: base, sem: make(chan struct{}, max)}
+}
+
+// DeviantArt requests must be spaced by at least daMinInterval.
+func TestThrottleRateLimitsDeviantArt(t *testing.T) {
+	stub := &stubTransport{}
+	tr := newTestThrottle(stub, daMinInterval, daMaxConcurrent)
+
+	start := time.Now()
+	const n = 3
+	for i := 0; i < n; i++ {
+		req, _ := http.NewRequest("GET", "https://www.deviantart.com/_puppy/x", nil)
+		if _, err := tr.RoundTrip(req); err != nil {
+			t.Fatalf("unexpected error: %v", err)
+		}
+	}
+	elapsed := time.Since(start)
+
+	// n requests => at least (n-1) gaps between them.
+	if want := time.Duration(n-1) * daMinInterval; elapsed < want {
+		t.Errorf("DA requests were not throttled: %d requests took %v, want >= %v", n, elapsed, want)
+	}
+	if stub.n != n {
+		t.Errorf("expected all %d requests to reach the base transport, got %d", n, stub.n)
+	}
+}
+
+// Non-DA hosts (e.g. the wixmp image CDN) must not be slowed down.
+func TestThrottleSkipsOtherHosts(t *testing.T) {
+	stub := &stubTransport{}
+	tr := newTestThrottle(stub, daMinInterval, daMaxConcurrent)
+
+	start := time.Now()
+	for i := 0; i < 5; i++ {
+		req, _ := http.NewRequest("GET", "https://images-wixmp-ed30a86b8c4ca887773594c2.wixmp.com/f/x.jpg", nil)
+		if _, err := tr.RoundTrip(req); err != nil {
+			t.Fatalf("unexpected error: %v", err)
+		}
+	}
+
+	if elapsed := time.Since(start); elapsed >= daMinInterval {
+		t.Errorf("non-DA host was throttled: 5 requests took %v, want < %v", elapsed, daMinInterval)
+	}
+	if stub.n != 5 {
+		t.Errorf("expected 5 requests through, got %d", stub.n)
+	}
+}
+
+// Concurrent callers must never exceed daMaxConcurrent in-flight DA requests.
+func TestThrottleCapsConcurrency(t *testing.T) {
+	var (
+		mu       sync.Mutex
+		inFlight int
+		peak     int
+	)
+	counting := roundTripFunc(func(req *http.Request) (*http.Response, error) {
+		mu.Lock()
+		inFlight++
+		if inFlight > peak {
+			peak = inFlight
+		}
+		mu.Unlock()
+
+		time.Sleep(20 * time.Millisecond) // hold the slot
+
+		mu.Lock()
+		inFlight--
+		mu.Unlock()
+		return httptest.NewRecorder().Result(), nil
+	})
+
+	tr := newTestThrottle(counting, daMinInterval, daMaxConcurrent)
+
+	var wg sync.WaitGroup
+	for i := 0; i < 6; i++ {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			req, _ := http.NewRequest("GET", "https://www.deviantart.com/_puppy/x", nil)
+			tr.RoundTrip(req)
+		}()
+	}
+	wg.Wait()
+
+	if peak > daMaxConcurrent {
+		t.Errorf("concurrency cap breached: peak %d in-flight DA requests, max %d", peak, daMaxConcurrent)
+	}
+}
+
+type roundTripFunc func(*http.Request) (*http.Response, error)
+
+func (f roundTripFunc) RoundTrip(r *http.Request) (*http.Response, error) { return f(r) }
+
+// InstallDAThrottle must preserve proxy-from-environment so HTTPS_PROXY (VPN
+// egress) keeps working, and must not panic on a repeat call.
+func TestInstallDAThrottlePreservesProxy(t *testing.T) {
+	orig := http.DefaultTransport
+	defer func() { http.DefaultTransport = orig }()
+
+	InstallDAThrottle()
+
+	th, ok := http.DefaultTransport.(*daThrottle)
+	if !ok {
+		t.Fatalf("DefaultTransport was not wrapped, got %T", http.DefaultTransport)
+	}
+	base, ok := th.base.(*http.Transport)
+	if !ok {
+		t.Fatalf("base transport is not *http.Transport, got %T", th.base)
+	}
+	if base.Proxy == nil {
+		t.Error("base transport lost its Proxy func: HTTPS_PROXY / VPN egress would break")
+	}
+}
diff --git a/app/parsers.go b/app/parsers.go
index 192a88d..229b4b5 100755
--- a/app/parsers.go
+++ b/app/parsers.go
@@ -5,7 +5,7 @@ import (
 	"strconv"
 	"strings"
 
-	"git.macaw.me/skunky/devianter"
+	"github.com/zerolabsco/devianter"
 	"golang.org/x/net/html"
 )
 
diff --git a/app/stat-darwin.go b/app/stat-darwin.go
new file mode 100644
index 0000000..f3e05bc
--- /dev/null
+++ b/app/stat-darwin.go
@@ -0,0 +1,15 @@
+//go:build darwin
+// +build darwin
+
+package app
+
+import (
+	"syscall"
+	"time"
+)
+
+// macOS names the ctime field Ctimespec rather than Ctim, so it needs its own
+// variant to let the project build and test on a Mac (deploys are Linux).
+func statTime(stat *syscall.Stat_t) int64 {
+	return time.Unix(stat.Ctimespec.Unix()).UnixMilli()
+}
diff --git a/app/stat.go b/app/stat.go
index a5bebcc..8f0d231 100755
--- a/app/stat.go
+++ b/app/stat.go
@@ -1,5 +1,5 @@
-//go:build !freebsd
-// +build !freebsd
+//go:build !freebsd && !darwin
+// +build !freebsd,!darwin
 
 package app
 
diff --git a/app/util.go b/app/util.go
index 6ece2e8..493997b 100755
--- a/app/util.go
+++ b/app/util.go
@@ -12,7 +12,7 @@ import (
 	"text/template"
 	"time"
 
-	"git.macaw.me/skunky/devianter"
+	"github.com/zerolabsco/devianter"
 	"golang.org/x/net/html"
 )
 
diff --git a/app/wrapper.go b/app/wrapper.go
index ef1fb31..0f69159 100755
--- a/app/wrapper.go
+++ b/app/wrapper.go
@@ -6,7 +6,7 @@ import (
 	"strings"
 	"time"
 
-	"git.macaw.me/skunky/devianter"
+	"github.com/zerolabsco/devianter"
 	"golang.org/x/net/html"
 )
 
@@ -20,7 +20,7 @@ func (s skunkyart) GRUser() {
 	var daError devianter.Error
 	g.Name = s.Query
 	var err error
-	s.Templates.GroupUser.GR, err, daError = g.Get()
+	s.Templates.GroupUser.GR, daError, err = g.Get()
 	try(err)
 	if daError.RAW != nil {
 		s.Error(daError)
@@ -98,7 +98,7 @@ func (s skunkyart) GRUser() {
 		if s.Type == 'f' {
 			content, daError = g.Favourites(s.Page, all, folderid)
 		} else {
-			content, err, daError = g.Gallery(s.Page, folderid)
+			content, daError, err = g.Gallery(s.Page, folderid)
 			try(err)
 		}
 
@@ -267,9 +267,9 @@ func (s skunkyart) Search() {
 	ss := &s.Templates.Search
 	switch s.Type {
 	case 'a', 't':
-		ss.Content, err, daError = devianter.PerformSearch(s.Query, s.Page, s.Type)
+		ss.Content, daError, err = devianter.PerformSearch(s.Query, s.Page, s.Type)
 	case 'g', 'f':
-		ss.Content, err, daError = devianter.PerformSearch(s.Query, s.Page, s.Type, s.Args.Get("usr"))
+		ss.Content, daError, err = devianter.PerformSearch(s.Query, s.Page, s.Type, s.Args.Get("usr"))
 	case 'r': // скраппер, поскольку девиантартовцы зажопили гостевое API для поиска групп
 		var (
 			usernames = make(map[int]string)