image proxying

lib/proxy_images/init.go

@@ -0,0 +1,66 @@
+package proxyimages
+
+import (
+	"bytes"
+
+	"github.com/gofiber/fiber/v2"
+	"github.com/maid-zone/soundcloak/lib/cfg"
+	"github.com/maid-zone/soundcloak/lib/sc"
+	"github.com/valyala/fasthttp"
+)
+
+var sndcdn = []byte(".sndcdn.com")
+
+// seems soundcloud has 4 of these (i1, i2, i3, i4)
+// they point to the same ip from my observations, and they all serve the same files
+const cdn = "i1.sndcdn.com"
+
+var httpc = &fasthttp.HostClient{
+	Addr:                cdn + ":443",
+	IsTLS:               true,
+	DialDualStack:       true,
+	Dial:                (&fasthttp.TCPDialer{DNSCacheDuration: cfg.DNSCacheTTL}).Dial,
+	MaxIdleConnDuration: 1<<63 - 1,
+}
+
+func Load(r fiber.Router) {
+	r.Get("/proxy/images", func(c *fiber.Ctx) error {
+		url := c.Query("url")
+		if url == "" {
+			return fiber.ErrBadRequest
+		}
+
+		parsed := fasthttp.AcquireURI()
+		defer fasthttp.ReleaseURI(parsed)
+
+		err := parsed.Parse(nil, []byte(url))
+		if err != nil {
+			return err
+		}
+
+		if !bytes.HasSuffix(parsed.Host(), sndcdn) {
+			return fiber.ErrBadRequest
+		}
+
+		parsed.SetHost(cdn)
+
+		req := fasthttp.AcquireRequest()
+		defer fasthttp.ReleaseRequest(req)
+
+		req.SetURI(parsed)
+		req.Header.Set("User-Agent", cfg.UserAgent)
+		req.Header.Set("Accept-Encoding", "gzip, deflate, br, zstd")
+
+		resp := fasthttp.AcquireResponse()
+		defer fasthttp.ReleaseResponse(resp)
+
+		err = sc.DoWithRetry(httpc, req, resp)
+		if err != nil {
+			return err
+		}
+
+		c.Response().Header.SetBytesV("Content-Type", resp.Header.Peek("Content-Type"))
+		c.Set("Cache-Control", cfg.ImageCacheControl)
+		return c.Send(resp.Body())
+	})
+}