hmn/src/website/requesthandling.go

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package website
import (
"bytes"
"context"
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"fmt"
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"html"
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"io"
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"net"
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"net/http"
"net/url"
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"path"
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"regexp"
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"strings"
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"git.handmade.network/hmn/hmn/src/logging"
"git.handmade.network/hmn/hmn/src/models"
"git.handmade.network/hmn/hmn/src/oops"
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"git.handmade.network/hmn/hmn/src/perf"
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"git.handmade.network/hmn/hmn/src/templates"
"github.com/jackc/pgx/v4/pgxpool"
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"github.com/rs/zerolog"
)
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type Router struct {
Routes []Route
}
type Route struct {
Method string
Regex *regexp.Regexp
Handler Handler
}
type RouteBuilder struct {
Router *Router
Middleware Middleware
}
type Handler func(c *RequestContext) ResponseData
type Middleware func(h Handler) Handler
func (rb *RouteBuilder) Handle(methods []string, regex *regexp.Regexp, h Handler) {
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h = rb.Middleware(h)
for _, method := range methods {
rb.Router.Routes = append(rb.Router.Routes, Route{
Method: method,
Regex: regex,
Handler: h,
})
}
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}
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func (rb *RouteBuilder) AnyMethod(regex *regexp.Regexp, h Handler) {
rb.Handle([]string{""}, regex, h)
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}
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func (rb *RouteBuilder) GET(regex *regexp.Regexp, h Handler) {
rb.Handle([]string{http.MethodGet}, regex, h)
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}
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func (rb *RouteBuilder) POST(regex *regexp.Regexp, h Handler) {
rb.Handle([]string{http.MethodPost}, regex, h)
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}
func (r *Router) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
path := req.URL.Path
for _, route := range r.Routes {
if route.Method != "" && req.Method != route.Method {
continue
}
match := route.Regex.FindStringSubmatch(path)
if match == nil {
continue
}
c := &RequestContext{
Route: route.Regex.String(),
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Logger: logging.GlobalLogger(),
Req: req,
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Res: rw,
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}
if len(match) > 0 {
params := map[string]string{}
subexpNames := route.Regex.SubexpNames()
for i, paramValue := range match {
paramName := subexpNames[i]
if paramName == "" {
continue
}
params[paramName] = paramValue
}
c.PathParams = params
}
doRequest(rw, c, route.Handler)
return
}
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// TODO(asaf): Replace this with a 404 handler? Isn't this going to crash the server?
// We're doing panic recovery in doRequest, but not here. I don't think we should have this line in production.
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panic(fmt.Sprintf("Path '%s' did not match any routes! Make sure to register a wildcard route to act as a 404.", path))
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}
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type RequestContext struct {
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Route string
Logger *zerolog.Logger
Req *http.Request
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PathParams map[string]string
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// NOTE(asaf): This is the http package's internal response object. Not just a ResponseWriter.
// We sometimes need the original response object so that some functions of the http package can set connection-management flags on it.
Res http.ResponseWriter
Conn *pgxpool.Pool
CurrentProject *models.Project
CurrentUser *models.User
CurrentSession *models.Session
Theme string
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Perf *perf.RequestPerf
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}
func (c *RequestContext) Context() context.Context {
return c.Req.Context()
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}
func (c *RequestContext) URL() *url.URL {
return c.Req.URL
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}
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func (c *RequestContext) FullUrl() string {
var scheme string // TODO(asaf): BEFORE RELEASE!! Fetch scheme from X-Forwarded-* headers or Forwarded header
if c.Req.TLS != nil {
scheme = "https://"
} else {
scheme = "http://"
}
return scheme + c.Req.Host + c.Req.URL.String()
}
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func (c *RequestContext) GetIP() *net.IPNet {
ipString := ""
if ipString == "" {
cf, hasCf := c.Req.Header["CF-Connecting-IP"]
if hasCf {
ipString = cf[0]
}
}
if ipString == "" {
forwarded, hasForwarded := c.Req.Header["X-Forwarded-For"]
if hasForwarded {
ipString = forwarded[0]
}
}
if ipString == "" {
ipString = c.Req.RemoteAddr
}
if ipString != "" {
_, res, err := net.ParseCIDR(fmt.Sprintf("%s/32", ipString))
if err == nil {
return res
}
}
return nil
}
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func (c *RequestContext) GetFormValues() (url.Values, error) {
err := c.Req.ParseForm()
if err != nil {
return nil, err
}
return c.Req.PostForm, nil
}
// The logic of this function is copy-pasted from the Go standard library.
// https://golang.org/pkg/net/http/#Redirect
func (c *RequestContext) Redirect(dest string, code int) ResponseData {
var res ResponseData
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if u, err := url.Parse(dest); err == nil {
// If url was relative, make its path absolute by
// combining with request path.
// The client would probably do this for us,
// but doing it ourselves is more reliable.
// See RFC 7231, section 7.1.2
if u.Scheme == "" && u.Host == "" {
oldpath := c.Req.URL.Path
if oldpath == "" { // should not happen, but avoid a crash if it does
oldpath = "/"
}
// no leading http://server
if dest == "" || dest[0] != '/' {
// make relative path absolute
olddir, _ := path.Split(oldpath)
dest = olddir + dest
}
var query string
if i := strings.Index(dest, "?"); i != -1 {
dest, query = dest[:i], dest[i:]
}
// clean up but preserve trailing slash
trailing := strings.HasSuffix(dest, "/")
dest = path.Clean(dest)
if trailing && !strings.HasSuffix(dest, "/") {
dest += "/"
}
dest += query
}
}
// Escape stuff
destUrl, _ := url.Parse(dest)
dest = destUrl.String()
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res.Header().Set("Location", dest)
if c.Req.Method == "GET" || c.Req.Method == "HEAD" {
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res.Header().Set("Content-Type", "text/html; charset=utf-8")
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}
res.StatusCode = code
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// Shouldn't send the body for POST or HEAD; that leaves GET.
if c.Req.Method == "GET" {
res.Write([]byte("<a href=\"" + html.EscapeString(dest) + "\">" + http.StatusText(code) + "</a>.\n"))
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}
return res
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}
type ResponseData struct {
StatusCode int
Body *bytes.Buffer
Errors []error
header http.Header
}
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var _ http.ResponseWriter = &ResponseData{}
func (rd *ResponseData) Header() http.Header {
if rd.header == nil {
rd.header = make(http.Header)
}
return rd.header
}
func (rd *ResponseData) Write(p []byte) (n int, err error) {
if rd.Body == nil {
rd.Body = new(bytes.Buffer)
}
return rd.Body.Write(p)
}
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func (rd *ResponseData) WriteHeader(status int) {
rd.StatusCode = status
}
func (rd *ResponseData) SetCookie(cookie *http.Cookie) {
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rd.Header().Add("Set-Cookie", cookie.String())
}
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func (rd *ResponseData) WriteTemplate(name string, data interface{}, rp *perf.RequestPerf) error {
if rp != nil {
rp.StartBlock("TEMPLATE", name)
defer rp.EndBlock()
}
template, hasTemplate := templates.Templates[name]
if !hasTemplate {
panic(oops.New(nil, "Template not found: %s", name))
}
return template.Execute(rd, data)
}
func (rd *ResponseData) MustWriteTemplate(name string, data interface{}, rp *perf.RequestPerf) {
err := rd.WriteTemplate(name, data, rp)
if err != nil {
panic(err)
}
}
func ErrorResponse(status int, errs ...error) ResponseData {
return ResponseData{
StatusCode: status,
Errors: errs,
}
}
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func doRequest(rw http.ResponseWriter, c *RequestContext, h Handler) {
defer func() {
/*
This panic recovery is the last resort. If you want to render
an error page or something, make it a request wrapper.
*/
if recovered := recover(); recovered != nil {
rw.WriteHeader(http.StatusInternalServerError)
logging.LogPanicValue(c.Logger, recovered, "request panicked and was not handled")
}
}()
res := h(c)
if res.StatusCode == 0 {
res.StatusCode = http.StatusOK
}
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for name, vals := range res.Header() {
for _, val := range vals {
rw.Header().Add(name, val)
}
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}
rw.WriteHeader(res.StatusCode)
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if res.Body != nil {
io.Copy(rw, res.Body)
}
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}