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a5ebec0041
Previously, all matchers in a route would be evaluated before any handlers were executed, and a composite route of the matching routes would be created. This made rewrites especially tricky, since the only way to defer later matchers' evaluation was to wrap them in a subroute, or to invoke a "rehandle" which often caused bugs. Instead, this new sequential design evaluates each route's matchers then its handlers in lock-step; matcher-handlers-matcher-handlers... If the first matching route consists of a rewrite, then the second route will be evaluated against the rewritten request, rather than the original one, and so on. This should do away with any need for rehandling. I've also taken this opportunity to avoid adding new values to the request context in the handler chain, as this creates a copy of the Request struct, which may possibly lead to bugs like it has in the past (see PR #1542, PR #1481, and maybe issue #2463). We now add all the expected context values in the top-level handler at the server, then any new values can be added to the variable table via the VarsCtxKey context key, or just the GetVar/SetVar functions. In particular, we are using this facility to convey dial information in the reverse proxy. Had to be careful in one place as the middleware compilation logic has changed, and moved a bit. We no longer compile a middleware chain per- request; instead, we can compile it at provision-time, and defer only the evaluation of matchers to request-time, which should slightly improve performance. Doing this, however, we take advantage of multiple function closures, and we also changed the use of HandlerFunc (function pointer) to Handler (interface)... this led to a situation where, if we aren't careful, allows one request routed a certain way to permanently change the "next" handler for all/most other requests! We avoid this by making a copy of the interface value (which is a lightweight pointer copy) and using exclusively that within our wrapped handlers. This way, the original stack frame is preserved in a "read-only" fashion. The comments in the code describe this phenomenon. This may very well be a breaking change for some configurations, however I do not expect it to impact many people. I will make it clear in the release notes that this change has occurred.
105 lines
3.1 KiB
Go
105 lines
3.1 KiB
Go
// Copyright 2015 Matthew Holt and The Caddy Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package caddyhttp
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import (
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"context"
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"net/http"
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"github.com/caddyserver/caddy/v2"
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)
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func init() {
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caddy.RegisterModule(VarsMiddleware{})
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caddy.RegisterModule(VarsMatcher{})
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}
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// VarsMiddleware is an HTTP middleware which sets variables
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// in the context, mainly for use by placeholders. The
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// placeholders have the form: `{http.vars.variable_name}`
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type VarsMiddleware map[string]string
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// CaddyModule returns the Caddy module information.
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func (VarsMiddleware) CaddyModule() caddy.ModuleInfo {
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return caddy.ModuleInfo{
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ID: "http.handlers.vars",
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New: func() caddy.Module { return new(VarsMiddleware) },
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}
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}
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func (t VarsMiddleware) ServeHTTP(w http.ResponseWriter, r *http.Request, next Handler) error {
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vars := r.Context().Value(VarsCtxKey).(map[string]interface{})
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repl := r.Context().Value(caddy.ReplacerCtxKey).(*caddy.Replacer)
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for k, v := range t {
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keyExpanded := repl.ReplaceAll(k, "")
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valExpanded := repl.ReplaceAll(v, "")
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vars[keyExpanded] = valExpanded
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}
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return next.ServeHTTP(w, r)
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}
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// VarsMatcher is an HTTP request matcher which can match
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// requests based on variables in the context.
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type VarsMatcher map[string]string
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// CaddyModule returns the Caddy module information.
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func (VarsMatcher) CaddyModule() caddy.ModuleInfo {
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return caddy.ModuleInfo{
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ID: "http.matchers.vars",
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New: func() caddy.Module { return new(VarsMatcher) },
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}
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}
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// Match matches a request based on variables in the context.
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func (m VarsMatcher) Match(r *http.Request) bool {
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vars := r.Context().Value(VarsCtxKey).(map[string]string)
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repl := r.Context().Value(caddy.ReplacerCtxKey).(*caddy.Replacer)
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for k, v := range m {
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keyExpanded := repl.ReplaceAll(k, "")
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valExpanded := repl.ReplaceAll(v, "")
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if vars[keyExpanded] != valExpanded {
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return false
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}
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}
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return true
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}
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// GetVar gets a value out of the context's variable table by key.
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// If the key does not exist, the return value will be nil.
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func GetVar(ctx context.Context, key string) interface{} {
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varMap, ok := ctx.Value(VarsCtxKey).(map[string]interface{})
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if !ok {
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return nil
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}
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return varMap[key]
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}
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// SetVar sets a value in the context's variable table with
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// the given key. It overwrites any previous value with the
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// same key.
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func SetVar(ctx context.Context, key string, value interface{}) {
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varMap, ok := ctx.Value(VarsCtxKey).(map[string]interface{})
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if !ok {
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return
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}
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varMap[key] = value
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}
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// Interface guards
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var (
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_ MiddlewareHandler = (*VarsMiddleware)(nil)
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_ RequestMatcher = (*VarsMatcher)(nil)
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)
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