move upstream into own package

server/upstream/upstream.go

@@ -0,0 +1,193 @@
+package upstream
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"mime"
+	"path"
+	"strconv"
+	"strings"
+	"time"
+
+	"codeberg.org/codeberg/pages/html"
+
+	"github.com/rs/zerolog/log"
+	"github.com/valyala/fasthttp"
+)
+
+// upstreamIndexPages lists pages that may be considered as index pages for directories.
+var upstreamIndexPages = []string{
+	"index.html",
+}
+
+// Options provides various options for the upstream request.
+type Options struct {
+	DefaultMimeType     string
+	ForbiddenMimeTypes  map[string]struct{}
+	TryIndexPages       bool
+	AppendTrailingSlash bool
+	RedirectIfExists    string
+	BranchTimestamp     time.Time
+}
+
+var Client = fasthttp.Client{
+	ReadTimeout:        10 * time.Second,
+	MaxConnDuration:    60 * time.Second,
+	MaxConnWaitTimeout: 1000 * time.Millisecond,
+	MaxConnsPerHost:    128 * 16, // TODO: adjust bottlenecks for best performance with Gitea!
+}
+
+// Upstream requests a file from the Gitea API at GiteaRoot and writes it to the request context.
+func Upstream(ctx *fasthttp.RequestCtx, targetOwner, targetRepo, targetBranch, targetPath, giteaRoot, giteaApiToken string, options *Options) (final bool) {
+	log := log.With().Strs("upstream", []string{targetOwner, targetRepo, targetBranch, targetPath}).Logger()
+
+	if options.ForbiddenMimeTypes == nil {
+		options.ForbiddenMimeTypes = map[string]struct{}{}
+	}
+
+	// Check if the branch exists and when it was modified
+	if options.BranchTimestamp == (time.Time{}) {
+		branch := GetBranchTimestamp(targetOwner, targetRepo, targetBranch, giteaRoot, giteaApiToken)
+
+		if branch == nil {
+			html.ReturnErrorPage(ctx, fasthttp.StatusFailedDependency)
+			return true
+		}
+		targetBranch = branch.Branch
+		options.BranchTimestamp = branch.Timestamp
+	}
+
+	if targetOwner == "" || targetRepo == "" || targetBranch == "" {
+		html.ReturnErrorPage(ctx, fasthttp.StatusBadRequest)
+		return true
+	}
+
+	// Check if the browser has a cached version
+	if ifModifiedSince, err := time.Parse(time.RFC1123, string(ctx.Request.Header.Peek("If-Modified-Since"))); err == nil {
+		if !ifModifiedSince.Before(options.BranchTimestamp) {
+			ctx.Response.SetStatusCode(fasthttp.StatusNotModified)
+			return true
+		}
+	}
+	log.Debug().Msg("preparations")
+
+	// Make a GET request to the upstream URL
+	uri := targetOwner + "/" + targetRepo + "/raw/" + targetBranch + "/" + targetPath
+	var req *fasthttp.Request
+	var res *fasthttp.Response
+	var cachedResponse fileResponse
+	var err error
+	if cachedValue, ok := fileResponseCache.Get(uri + "?timestamp=" + strconv.FormatInt(options.BranchTimestamp.Unix(), 10)); ok && len(cachedValue.(fileResponse).body) > 0 {
+		cachedResponse = cachedValue.(fileResponse)
+	} else {
+		req = fasthttp.AcquireRequest()
+		req.SetRequestURI(giteaRoot + "/api/v1/repos/" + uri + "?access_token=" + giteaApiToken)
+		res = fasthttp.AcquireResponse()
+		res.SetBodyStream(&strings.Reader{}, -1)
+		err = Client.Do(req, res)
+	}
+	log.Debug().Msg("acquisition")
+
+	// Handle errors
+	if (res == nil && !cachedResponse.exists) || (res != nil && res.StatusCode() == fasthttp.StatusNotFound) {
+		if options.TryIndexPages {
+			// copy the options struct & try if an index page exists
+			optionsForIndexPages := *options
+			optionsForIndexPages.TryIndexPages = false
+			optionsForIndexPages.AppendTrailingSlash = true
+			for _, indexPage := range upstreamIndexPages {
+				if Upstream(ctx, targetOwner, targetRepo, targetBranch, strings.TrimSuffix(targetPath, "/")+"/"+indexPage, giteaRoot, giteaApiToken, &optionsForIndexPages) {
+					_ = fileResponseCache.Set(uri+"?timestamp="+strconv.FormatInt(options.BranchTimestamp.Unix(), 10), fileResponse{
+						exists: false,
+					}, FileCacheTimeout)
+					return true
+				}
+			}
+			// compatibility fix for GitHub Pages (/example → /example.html)
+			optionsForIndexPages.AppendTrailingSlash = false
+			optionsForIndexPages.RedirectIfExists = string(ctx.Request.URI().Path()) + ".html"
+			if Upstream(ctx, targetOwner, targetRepo, targetBranch, targetPath+".html", giteaRoot, giteaApiToken, &optionsForIndexPages) {
+				_ = fileResponseCache.Set(uri+"?timestamp="+strconv.FormatInt(options.BranchTimestamp.Unix(), 10), fileResponse{
+					exists: false,
+				}, FileCacheTimeout)
+				return true
+			}
+		}
+		ctx.Response.SetStatusCode(fasthttp.StatusNotFound)
+		if res != nil {
+			// Update cache if the request is fresh
+			_ = fileResponseCache.Set(uri+"?timestamp="+strconv.FormatInt(options.BranchTimestamp.Unix(), 10), fileResponse{
+				exists: false,
+			}, FileCacheTimeout)
+		}
+		return false
+	}
+	if res != nil && (err != nil || res.StatusCode() != fasthttp.StatusOK) {
+		fmt.Printf("Couldn't fetch contents from \"%s\": %s (status code %d)\n", req.RequestURI(), err, res.StatusCode())
+		html.ReturnErrorPage(ctx, fasthttp.StatusInternalServerError)
+		return true
+	}
+
+	// Append trailing slash if missing (for index files), and redirect to fix filenames in general
+	// options.AppendTrailingSlash is only true when looking for index pages
+	if options.AppendTrailingSlash && !bytes.HasSuffix(ctx.Request.URI().Path(), []byte{'/'}) {
+		ctx.Redirect(string(ctx.Request.URI().Path())+"/", fasthttp.StatusTemporaryRedirect)
+		return true
+	}
+	if bytes.HasSuffix(ctx.Request.URI().Path(), []byte("/index.html")) {
+		ctx.Redirect(strings.TrimSuffix(string(ctx.Request.URI().Path()), "index.html"), fasthttp.StatusTemporaryRedirect)
+		return true
+	}
+	if options.RedirectIfExists != "" {
+		ctx.Redirect(options.RedirectIfExists, fasthttp.StatusTemporaryRedirect)
+		return true
+	}
+	log.Debug().Msg("error handling")
+
+	// Set the MIME type
+	mimeType := mime.TypeByExtension(path.Ext(targetPath))
+	mimeTypeSplit := strings.SplitN(mimeType, ";", 2)
+	if _, ok := options.ForbiddenMimeTypes[mimeTypeSplit[0]]; ok || mimeType == "" {
+		if options.DefaultMimeType != "" {
+			mimeType = options.DefaultMimeType
+		} else {
+			mimeType = "application/octet-stream"
+		}
+	}
+	ctx.Response.Header.SetContentType(mimeType)
+
+	// Everything's okay so far
+	ctx.Response.SetStatusCode(fasthttp.StatusOK)
+	ctx.Response.Header.SetLastModified(options.BranchTimestamp)
+
+	log.Debug().Msg("response preparations")
+
+	// Write the response body to the original request
+	var cacheBodyWriter bytes.Buffer
+	if res != nil {
+		if res.Header.ContentLength() > FileCacheSizeLimit {
+			err = res.BodyWriteTo(ctx.Response.BodyWriter())
+		} else {
+			// TODO: cache is half-empty if request is cancelled - does the ctx.Err() below do the trick?
+			err = res.BodyWriteTo(io.MultiWriter(ctx.Response.BodyWriter(), &cacheBodyWriter))
+		}
+	} else {
+		_, err = ctx.Write(cachedResponse.body)
+	}
+	if err != nil {
+		fmt.Printf("Couldn't write body for \"%s\": %s\n", req.RequestURI(), err)
+		html.ReturnErrorPage(ctx, fasthttp.StatusInternalServerError)
+		return true
+	}
+	log.Debug().Msg("response")
+
+	if res != nil && ctx.Err() == nil {
+		cachedResponse.exists = true
+		cachedResponse.mimeType = mimeType
+		cachedResponse.body = cacheBodyWriter.Bytes()
+		_ = fileResponseCache.Set(uri+"?timestamp="+strconv.FormatInt(options.BranchTimestamp.Unix(), 10), cachedResponse, FileCacheTimeout)
+	}
+
+	return true
+}