pages-server/handler.go
2021-03-17 01:16:57 +01:00

275 lines
9.7 KiB
Go

package main
import (
"bytes"
"fmt"
"github.com/valyala/fasthttp"
"github.com/valyala/fastjson"
"mime"
"net/url"
"path"
"strconv"
"strings"
"time"
)
// handler handles a single HTTP request to the web server.
func handler(ctx *fasthttp.RequestCtx) {
ctx.Response.Header.Set("Server", "Codeberg Pages")
// Force new default from specification (since November 2020) - see https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Referrer-Policy#strict-origin-when-cross-origin
ctx.Response.Header.Set("Referrer-Policy", "strict-origin-when-cross-origin")
// Enable caching, but require revalidation to reduce confusion
ctx.Response.Header.Set("Cache-Control", "must-revalidate")
// Block all methods not required for static pages
if !ctx.IsGet() && !ctx.IsHead() && !ctx.IsOptions() {
ctx.Response.Header.Set("Allow", "GET, HEAD, OPTIONS")
ctx.Error("Method not allowed", fasthttp.StatusMethodNotAllowed)
return
}
// Block blacklisted paths (like ACME challenges)
for _, blacklistedPath := range BlacklistedPaths {
if bytes.HasPrefix(ctx.Path(), blacklistedPath) {
returnErrorPage(ctx, fasthttp.StatusForbidden)
return
}
}
// Allow CORS for specified domains
if ctx.IsOptions() {
allowCors := false
for _, allowedCorsDomain := range AllowedCorsDomains {
if bytes.Equal(ctx.Request.Host(), allowedCorsDomain) {
allowCors = true
break
}
}
if allowCors {
ctx.Response.Header.Set("Access-Control-Allow-Origin", "*")
ctx.Response.Header.Set("Access-Control-Allow-Methods", "GET, HEAD")
}
ctx.Response.Header.Set("Allow", "GET, HEAD, OPTIONS")
ctx.Response.Header.SetStatusCode(fasthttp.StatusNoContent)
return
}
// Prepare request information to Gitea
var targetOwner, targetRepo, targetBranch, targetPath string
var targetOptions = &upstreamOptions{
ForbiddenMimeTypes: map[string]struct{}{},
TryIndexPages: true,
}
if RawDomain != nil && bytes.Equal(ctx.Request.Host(), RawDomain) {
// Serve raw content from RawDomain
targetOptions.TryIndexPages = false
targetOptions.ForbiddenMimeTypes["text/html"] = struct{}{}
targetOptions.DefaultMimeType = "text/plain; charset=utf-8"
pathElements := strings.SplitN(string(bytes.Trim(ctx.Request.URI().Path(), "/")), "/", 4)
if len(pathElements) < 2 {
// https://{RawDomain}/{owner}/{repo}[/@{branch}]/{path} is required
ctx.Redirect(RawInfoPage, fasthttp.StatusTemporaryRedirect)
return
}
targetOwner = pathElements[0]
targetRepo = pathElements[1]
if len(pathElements) > 3 {
targetPath = strings.Trim(pathElements[2]+"/"+pathElements[3], "/")
} else if len(pathElements) > 2 {
targetPath = pathElements[2]
}
// raw.codeberg.page/example/myrepo/@main/index.html
if len(pathElements) > 3 && strings.HasPrefix(pathElements[2], "@") {
branch, _ := url.PathUnescape(pathElements[2][1:])
if branch == "" {
branch = pathElements[2][1:]
}
// Check if the branch exists, otherwise treat it as a file path
targetBranch, targetOptions.BranchTimestamp = getBranchTimestamp(targetOwner, targetRepo, branch)
if targetOptions.BranchTimestamp != (time.Time{}) {
targetPath = strings.Trim(pathElements[3], "/") // branch exists, use it
} else {
targetBranch = "" // branch doesn't exist, use default branch
}
}
} else if bytes.HasSuffix(ctx.Request.Host(), MainDomainSuffix) {
// Serve pages from subdomains of MainDomainSuffix
pathElements := strings.SplitN(string(bytes.Trim(ctx.Request.URI().Path(), "/")), "/", 2)
targetOwner = string(bytes.TrimSuffix(ctx.Request.Host(), MainDomainSuffix))
targetRepo = pathElements[0]
if len(pathElements) > 1 {
targetPath = strings.Trim(pathElements[1], "/")
}
// Check if the first directory is a repo with a "pages" branch
targetBranch, targetOptions.BranchTimestamp = getBranchTimestamp(targetOwner, targetRepo, "pages")
if targetOptions.BranchTimestamp == (time.Time{}) {
targetRepo = "pages"
targetBranch = ""
targetPath = strings.Trim(pathElements[0]+"/"+targetPath, "/")
}
} else {
// Serve pages from external domains
targetOwner, targetRepo, targetBranch, targetPath = getTargetFromDNS(ctx)
if targetOwner == "" {
ctx.Redirect(BrokenDNSPage, fasthttp.StatusTemporaryRedirect)
return
}
}
// Check if a username can't exist because it's reserved (we'd risk to hit a Gitea route in that case)
if _, ok := ReservedUsernames[targetOwner]; ok {
returnErrorPage(ctx, fasthttp.StatusForbidden)
return
}
// Check for blob path
if strings.HasPrefix(targetPath, "blob/") {
returnErrorPage(ctx, fasthttp.StatusForbidden)
return
}
// Try to request the file from the Gitea API
if !upstream(ctx, targetOwner, targetRepo, targetBranch, targetPath, targetOptions) {
returnErrorPage(ctx, ctx.Response.StatusCode())
}
}
// returnErrorPage sets the response status code and writes NotFoundPage to the response body, with "%status" replaced
// with the provided status code.
func returnErrorPage(ctx *fasthttp.RequestCtx, code int) {
ctx.Response.SetStatusCode(code)
ctx.Response.Header.SetContentType("text/html; charset=utf-8")
ctx.Response.SetBody(bytes.ReplaceAll(NotFoundPage, []byte("%status"), []byte(strconv.Itoa(code) + " " + fasthttp.StatusMessage(code))))
}
// getBranchTimestamp finds the default branch (if branch is "") and returns the last modification time of the branch
// (or an empty time.Time if the branch doesn't exist)
func getBranchTimestamp(owner, repo, branch string) (branchWithFallback string, t time.Time) {
branchWithFallback = branch
if branch == "" {
var body = make([]byte, 0)
status, body, err := fasthttp.GetTimeout(body, string(GiteaRoot)+"/api/v1/repos/"+owner+"/"+repo, 10*time.Second)
if err != nil || status != 200 {
branchWithFallback = ""
return
}
branch = fastjson.GetString(body, "default_branch")
branchWithFallback = branch
}
var body = make([]byte, 0)
status, body, err := fasthttp.GetTimeout(body, string(GiteaRoot)+"/api/v1/repos/"+owner+"/"+repo+"/branches/"+branch, 10*time.Second)
if err != nil || status != 200 {
branchWithFallback = ""
return
}
t, _ = time.Parse(time.RFC3339, fastjson.GetString(body, "commit", "timestamp"))
return
}
// upstream requests a file from the Gitea API at GiteaRoot and writes it to the request context.
func upstream(ctx *fasthttp.RequestCtx, targetOwner string, targetRepo string, targetBranch string, targetPath string, options *upstreamOptions) (success bool) {
if options.ForbiddenMimeTypes == nil {
options.ForbiddenMimeTypes = map[string]struct{}{}
}
// Check if the branch exists and when it was modified
if options.BranchTimestamp == (time.Time{}) {
targetBranch, options.BranchTimestamp = getBranchTimestamp(targetOwner, targetRepo, targetBranch)
}
// Handle repositories with no/broken pages setup
if options.BranchTimestamp == (time.Time{}) || targetBranch == "" {
ctx.Response.SetStatusCode(fasthttp.StatusNotFound)
ctx.Response.Header.SetContentType("text/html; charset=utf-8")
ctx.Response.SetBody(bytes.ReplaceAll(NotFoundPage, []byte("%status"), []byte("pages not set up for this repo")))
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
}
}
// Make a GET request to the upstream URL
req := fasthttp.AcquireRequest()
req.SetRequestURI(string(GiteaRoot) + "/api/v1/repos/" + targetOwner + "/" + targetRepo + "/raw/" + targetBranch + "/" + targetPath)
res := fasthttp.AcquireResponse()
err := fasthttp.DoTimeout(req, res, 10*time.Second)
// Handle errors
if 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 IndexPages {
if upstream(ctx, targetOwner, targetRepo, targetBranch, strings.TrimSuffix(targetPath, "/")+"/"+indexPage, &optionsForIndexPages) {
return true
}
}
}
ctx.Response.SetStatusCode(fasthttp.StatusNotFound)
return false
}
if err != nil || res.StatusCode() != fasthttp.StatusOK {
fmt.Printf("Couldn't fetch contents from \"%s\": %s (status code %d)\n", req.RequestURI(), err, res.StatusCode())
returnErrorPage(ctx, fasthttp.StatusInternalServerError)
return true
}
// Append trailing slash if missing (for index files)
if options.AppendTrailingSlash && !bytes.HasSuffix(ctx.Request.URI().Path(), []byte{'/'}) {
ctx.Redirect(string(ctx.Request.URI().Path())+"/", fasthttp.StatusTemporaryRedirect)
return true
}
// 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)
// Write the response to the original request
ctx.Response.SetStatusCode(fasthttp.StatusOK)
ctx.Response.Header.SetLastModified(options.BranchTimestamp)
err = res.BodyWriteTo(ctx.Response.BodyWriter())
if err != nil {
fmt.Printf("Couldn't write body for \"%s\": %s\n", req.RequestURI(), err)
returnErrorPage(ctx, fasthttp.StatusInternalServerError)
return true
}
return true
}
// upstreamOptions provides various options for the upstream request.
type upstreamOptions struct {
DefaultMimeType string
ForbiddenMimeTypes map[string]struct{}
TryIndexPages bool
AppendTrailingSlash bool
BranchTimestamp time.Time
}