Improve CORS handling

mark.george / httpcat

Browse code Improve CORS handling Closes #1
1 parent adaac98 commit 100c322f8ca391e0a1acb6a8c2a5d7fc0f29da1f Mark George authored on 16 Apr 2022

Patch

Showing 2 changed files

Ignore Space Show notes View src/parsing.go
/** Author: Mark George <mark.george@otago.ac.nz> License: Zero-Clause BSD License / package main import ( "errors" "strconv" "strings" ) var ( headers map[string]string = make(map[string]string) bodies map[string]string = make(map[string]string) statuses map[string]int = make(map[string]int) ) func parseHeader(header string) (string, string, error) { parts := strings.Split(header, ":") if len(parts) < 2 { return "", "", errors.New("header is not in the correct format") } else { name := strings.TrimSpace(parts[0]) value := strings.TrimSpace(parts[1]) // value had a ':' in it (probably a URL) so append the remaining part if len(parts) == 3 { value = value + ":" + strings.TrimSpace(parts[2]) } headers[name] = value return name, value, nil } } func parseRoute(route string) (string, string, int, error) { parts := strings.Split(route, "\|") if len(parts) != 3 { return "", "", 0, errors.New("route is not in the correct format") } else { path := parts[0] body := parts[1] status := parts[2] code, err := strconv.Atoi(status) if err != nil { return "", "", 0, errors.New("route is not in the correct format") } bodies[path] = body statuses[path] = code return path, body, code, nil } } /* Author: Mark George <mark.george@otago.ac.nz> License: Zero-Clause BSD License */ package main import ( "errors" "strconv" "strings" ) var ( headers map[string]string = make(map[string]string) bodies map[string]string = make(map[string]string) statuses map[string]int = make(map[string]int) ) func parseHeader(header string) (string, string, error) { parts := strings.Split(header, ":") if len(parts) != 2 { return "", "", errors.New("header is not in the correct format") } else { name := parts[0] value := parts[1] headers[name] = value return name, value, nil } } func parseRoute(route string) (string, string, int, error) { parts := strings.Split(route, "\|") if len(parts) != 3 { return "", "", 0, errors.New("route is not in the correct format") } else { path := parts[0] body := parts[1] status := parts[2] code, err := strconv.Atoi(status) if err != nil { return "", "", 0, errors.New("route is not in the correct format") } bodies[path] = body statuses[path] = code return path, body, code, nil } }

Ignore Space Show notes View

src/parsing.go

/**
  Author: Mark George <mark.george@otago.ac.nz>
  License: Zero-Clause BSD License
*/

package main

import (
	"errors"
	"strconv"
	"strings"
)

var (
	headers  map[string]string = make(map[string]string)
	bodies   map[string]string = make(map[string]string)
	statuses map[string]int    = make(map[string]int)
)

func parseHeader(header string) (string, string, error) {

parts := strings.Split(header, ":")

if len(parts) < 2 {
		return "", "", errors.New("header is not in the correct format")
	} else {
		name := strings.TrimSpace(parts[0])
		value := strings.TrimSpace(parts[1])

// value had a ':' in it (probably a URL) so append the remaining part
		if len(parts) == 3 {
			value = value + ":" + strings.TrimSpace(parts[2])
		}

headers[name] = value

return name, value, nil
	}

}

func parseRoute(route string) (string, string, int, error) {

parts := strings.Split(route, "|")

if len(parts) != 3 {
		return "", "", 0, errors.New("route is not in the correct format")
	} else {
		path := parts[0]
		body := parts[1]
		status := parts[2]
		code, err := strconv.Atoi(status)
		if err != nil {
			return "", "", 0, errors.New("route is not in the correct format")
		}

bodies[path] = body
		statuses[path] = code

return path, body, code, nil
	}

}

/**
  Author: Mark George <mark.george@otago.ac.nz>
  License: Zero-Clause BSD License
*/

package main

import (
	"errors"
	"strconv"
	"strings"
)

var (
	headers  map[string]string = make(map[string]string)
	bodies   map[string]string = make(map[string]string)
	statuses map[string]int    = make(map[string]int)
)

func parseHeader(header string) (string, string, error) {

parts := strings.Split(header, ":")

if len(parts) != 2 {
		return "", "", errors.New("header is not in the correct format")
	} else {
		name := parts[0]
		value := parts[1]

headers[name] = value

return name, value, nil
	}

}

func parseRoute(route string) (string, string, int, error) {

parts := strings.Split(route, "|")

bodies[path] = body
		statuses[path] = code

return path, body, code, nil
	}

}

Ignore Space Show notes View src/server.go
/** Author: Mark George <mark.george@otago.ac.nz> License: Zero-Clause BSD License / package main import ( "fmt" "net/http" "os" "strconv" ) type ServerCommand struct { Port int `short:"p" long:"port" description:"Port to listen on." default:"8080"` Routes []string `short:"r" long:"route" description:"Route which is made up of a path, a response body, and a response status, all separated by the pipe '\|' character. Repeat for additional routes." default:"/\|testing\|200"` Cors bool `short:"c" long:"cors" description:"Enable Cross Origin Resource Sharing (CORS)."` Headers []string `short:"H" long:"header" description:"A header to add to response in the form name:value. Repeat for additional headers."` } var ( serverOptions ServerCommand ) func (opts ServerCommand) Execute(args []string) error { serverOptions = opts // parse custom headers if provided if len(opts.Headers) > 0 { for _, header := range opts.Headers { if _, _, err := parseHeader(header); err != nil { fmt.Println("The following header is not in the correct format: " + header + "\nCorrect format is: 'name:value'") os.Exit(1) } } } fmt.Println("HTTP server listening on port " + strconv.Itoa(opts.Port) + "\n") if len(opts.Routes) > 0 { fmt.Println("Routes:") for _, route := range opts.Routes { if path, _, _, err := parseRoute(route); err == nil { fmt.Println(" " + path) http.HandleFunc(path, serverRequestHandler) } else { fmt.Println("The following route is not in the correct format: " + route + "\nCorrect format is: \"/path\|response body\|status code\"") os.Exit(1) } } } if err := http.ListenAndServe(":"+strconv.Itoa(opts.Port), nil); err != nil { fmt.Fprintf(os.Stderr, "Could not start server. Is port %d available?\n", opts.Port) os.Exit(1) } return nil } func serverRequestHandler(rsp http.ResponseWriter, req http.Request) { path := req.RequestURI body := bodies[path] code := statuses[path] showRequest(req) // CORS preflight if serverOptions.Cors && req.Method == http.MethodOptions { // was the OPTIONS request actually a CORS request? if secFetchMode := req.Header.Get("Sec-Fetch-Mode"); secFetchMode == "cors" { if globalOptions.Verbose { fmt.Println("Responding to CORS preflight") } if origin := req.Header.Get("Origin"); origin != "" { if globalOptions.Verbose { fmt.Println("Adding CORS response header - Access-Control-Allow-Origin: " + origin) } // allow the origin rsp.Header().Set("Access-Control-Allow-Origin", origin) if headers := req.Header.Get("Access-Control-Request-Headers"); headers != "" { if globalOptions.Verbose { fmt.Println("Adding CORS response header - Access-Control-Allow-Headers: " + headers) } // allow any requested headers rsp.Header().Set("Access-Control-Allow-Headers", headers) } if method := req.Header.Get("Access-Control-Request-Method"); method != "" { if globalOptions.Verbose { fmt.Println("Adding CORS response header - Access-Control-Allow-Methods: " + method) } // allow any requested methods rsp.Header().Set("Access-Control-Allow-Methods", method) } if globalOptions.Verbose { fmt.Println("Adding CORS response header - Access-Control-Max-Age: " + "600") } // allow browser to reuse the permissions for 10 minutes rsp.Header().Set("Access-Control-Max-Age", "600") rsp.WriteHeader(200) return } else { if globalOptions.Verbose { fmt.Println("CORS preflight did not contain 'Origin' header!") } rsp.Header().Set("Content-Type", "text/plain") rsp.WriteHeader(400) fmt.Fprint(rsp, "Origin header was not provided") return } } } // add custom headers if provided if len(serverOptions.Headers) > 0 { for name, value := range headers { if globalOptions.Verbose { fmt.Println("Adding response header - " + name + ": " + value) } rsp.Header().Set(name, value) } } // add CORS allow-origin header if serverOptions.Cors && req.Method != http.MethodOptions { if origin := req.Header.Get("Origin"); origin != "" { if globalOptions.Verbose { fmt.Println("Adding CORS response header - Access-Control-Allow-Origin: " + origin) } rsp.Header().Set("Access-Control-Allow-Origin", origin) } } // add status line rsp.WriteHeader(code) // add body fmt.Fprint(rsp, body) } /** Author: Mark George <mark.george@otago.ac.nz> License: Zero-Clause BSD License / package main import ( "fmt" "net/http" "os" "strconv" ) type ServerCommand struct { Port int `short:"p" long:"port" description:"Port to listen on." default:"8080"` Routes []string `short:"r" long:"route" description:"Route which is made up of a path, a response body, and a response status, all separated by the pipe '\|' character. Repeat for additional routes." default:"/\|testing\|200"` Cors bool `short:"c" long:"cors" description:"Enable Cross Origin Resource Sharing (CORS)."` Headers []string `short:"H" long:"header" description:"A header to add to response in the form name:value. Repeat for additional headers."` } var ( serverOptions ServerCommand ) func (opts ServerCommand) Execute(args []string) error { serverOptions = opts // parse custom headers if provided if len(opts.Headers) > 0 { for _, header := range opts.Headers { if _, _, err := parseHeader(header); err != nil { fmt.Println("The following header is not in the correct format: " + header + "\nCorrect format is: 'name:value'") os.Exit(1) } } } fmt.Println("HTTP server listening on port " + strconv.Itoa(opts.Port) + "\n") if len(opts.Routes) > 0 { fmt.Println("Routes:") for _, route := range opts.Routes { if path, _, _, err := parseRoute(route); err == nil { fmt.Println(" " + path) http.HandleFunc(path, serverRequestHandler) } else { fmt.Println("The following route is not in the correct format: " + route + "\nCorrect format is: \"/path\|response body\|status code\"") os.Exit(1) } } } if err := http.ListenAndServe(":"+strconv.Itoa(opts.Port), nil); err != nil { fmt.Fprintf(os.Stderr, "Could not start server. Is port %d available?\n", opts.Port) os.Exit(1) } return nil } func serverRequestHandler(rsp http.ResponseWriter, req http.Request) { path := req.RequestURI body := bodies[path] code := statuses[path] showRequest(req) // CORS if serverOptions.Cors && req.Method == http.MethodOptions { if globalOptions.Verbose { fmt.Println("CORS preflight") } if origin := req.Header.Get("Origin"); origin != "" { rsp.Header().Set("Access-Control-Allow-Origin", origin) if headers := req.Header.Get("Access-Control-Request-Headers"); headers != "" { rsp.Header().Set("Access-Control-Allow-Headers", headers) } if method := req.Header.Get("Access-Control-Request-Method"); method != "" { rsp.Header().Set("Access-Control-Allow-Method", method) } rsp.WriteHeader(200) return } else { fmt.Println("WARNING - CORS preflight did not contain 'Origin' header!") } } // add custom headers if provided if len(serverOptions.Headers) > 0 { for name, value := range headers { if globalOptions.Verbose { fmt.Println("Adding response header - " + name + ": " + value) } rsp.Header().Set(name, value) } } // add status line rsp.WriteHeader(code) // add body fmt.Fprintf(rsp, body) }

Ignore Space Show notes View

src/server.go

/**
  Author: Mark George <mark.george@otago.ac.nz>
  License: Zero-Clause BSD License
*/

package main

import (
	"fmt"
	"net/http"
	"os"
	"strconv"
)

type ServerCommand struct {
	Port    int      `short:"p" long:"port" description:"Port to listen on." default:"8080"`
	Routes  []string `short:"r" long:"route" description:"Route which is made up of a path, a response body, and a response status, all separated by the pipe '|' character.  Repeat for additional routes." default:"/|testing|200"`
	Cors    bool     `short:"c" long:"cors" description:"Enable Cross Origin Resource Sharing (CORS)."`
	Headers []string `short:"H" long:"header" description:"A header to add to response in the form name:value. Repeat for additional headers."`
}

var (
	serverOptions *ServerCommand
)

func (opts *ServerCommand) Execute(args []string) error {

serverOptions = opts

// parse custom headers if provided
	if len(opts.Headers) > 0 {
		for _, header := range opts.Headers {
			if _, _, err := parseHeader(header); err != nil {
				fmt.Println("The following header is not in the correct format: " + header + "\nCorrect format is: 'name:value'")
				os.Exit(1)
			}
		}
	}

fmt.Println("HTTP server listening on port " + strconv.Itoa(opts.Port) + "\n")

if len(opts.Routes) > 0 {
		fmt.Println("Routes:")
		for _, route := range opts.Routes {
			if path, _, _, err := parseRoute(route); err == nil {
				fmt.Println("  " + path)
				http.HandleFunc(path, serverRequestHandler)
			} else {
				fmt.Println("The following route is not in the correct format: " + route + "\nCorrect format is: \"/path|response body|status code\"")
				os.Exit(1)
			}
		}
	}

if err := http.ListenAndServe(":"+strconv.Itoa(opts.Port), nil); err != nil {
		fmt.Fprintf(os.Stderr, "Could not start server.  Is port %d available?\n", opts.Port)
		os.Exit(1)
	}

return nil
}

func serverRequestHandler(rsp http.ResponseWriter, req *http.Request) {

path := req.RequestURI
	body := bodies[path]
	code := statuses[path]

showRequest(req)

// CORS preflight
	if serverOptions.Cors && req.Method == http.MethodOptions {

// was the OPTIONS request actually a CORS request?
		if secFetchMode := req.Header.Get("Sec-Fetch-Mode"); secFetchMode == "cors" {

if globalOptions.Verbose {
				fmt.Println("Responding to CORS preflight")
			}

if origin := req.Header.Get("Origin"); origin != "" {

if globalOptions.Verbose {
					fmt.Println("Adding CORS response header - Access-Control-Allow-Origin: " + origin)
				}

// allow the origin
				rsp.Header().Set("Access-Control-Allow-Origin", origin)

if headers := req.Header.Get("Access-Control-Request-Headers"); headers != "" {

if globalOptions.Verbose {
						fmt.Println("Adding CORS response header - Access-Control-Allow-Headers: " + headers)
					}

// allow any requested headers
					rsp.Header().Set("Access-Control-Allow-Headers", headers)
				}

if method := req.Header.Get("Access-Control-Request-Method"); method != "" {
					if globalOptions.Verbose {
						fmt.Println("Adding CORS response header - Access-Control-Allow-Methods: " + method)
					}
					// allow any requested methods
					rsp.Header().Set("Access-Control-Allow-Methods", method)
				}

if globalOptions.Verbose {
					fmt.Println("Adding CORS response header - Access-Control-Max-Age: " + "600")
				}
				// allow browser to reuse the permissions for 10 minutes
				rsp.Header().Set("Access-Control-Max-Age", "600")

rsp.WriteHeader(200)

return

} else {
				if globalOptions.Verbose {
					fmt.Println("CORS preflight did not contain 'Origin' header!")
				}
				rsp.Header().Set("Content-Type", "text/plain")
				rsp.WriteHeader(400)
				fmt.Fprint(rsp, "Origin header was not provided")

return
			}
		}

}

// add custom headers if provided
	if len(serverOptions.Headers) > 0 {

for name, value := range headers {

if globalOptions.Verbose {
				fmt.Println("Adding response header - " + name + ": " + value)
			}

rsp.Header().Set(name, value)
		}
	}

// add CORS allow-origin header
	if serverOptions.Cors && req.Method != http.MethodOptions {
		if origin := req.Header.Get("Origin"); origin != "" {
			if globalOptions.Verbose {
				fmt.Println("Adding CORS response header - Access-Control-Allow-Origin: " + origin)
			}
			rsp.Header().Set("Access-Control-Allow-Origin", origin)
		}
	}

// add status line
	rsp.WriteHeader(code)

// add body
	fmt.Fprint(rsp, body)

}

/**
  Author: Mark George <mark.george@otago.ac.nz>
  License: Zero-Clause BSD License
*/

package main

import (
	"fmt"
	"net/http"
	"os"
	"strconv"
)

var (
	serverOptions *ServerCommand
)

func (opts *ServerCommand) Execute(args []string) error {

serverOptions = opts

fmt.Println("HTTP server listening on port " + strconv.Itoa(opts.Port) + "\n")

if err := http.ListenAndServe(":"+strconv.Itoa(opts.Port), nil); err != nil {
		fmt.Fprintf(os.Stderr, "Could not start server.  Is port %d available?\n", opts.Port)
		os.Exit(1)
	}

return nil
}

func serverRequestHandler(rsp http.ResponseWriter, req *http.Request) {

path := req.RequestURI
	body := bodies[path]
	code := statuses[path]

showRequest(req)

// CORS
	if serverOptions.Cors && req.Method == http.MethodOptions {

if globalOptions.Verbose {
			fmt.Println("CORS preflight")
		}

if origin := req.Header.Get("Origin"); origin != "" {

rsp.Header().Set("Access-Control-Allow-Origin", origin)

if headers := req.Header.Get("Access-Control-Request-Headers"); headers != "" {
				rsp.Header().Set("Access-Control-Allow-Headers", headers)
			}

if method := req.Header.Get("Access-Control-Request-Method"); method != "" {
				rsp.Header().Set("Access-Control-Allow-Method", method)
			}

rsp.WriteHeader(200)

return

} else {
			fmt.Println("WARNING - CORS preflight did not contain 'Origin' header!")
		}
	}

// add custom headers if provided
	if len(serverOptions.Headers) > 0 {

for name, value := range headers {

if globalOptions.Verbose {
				fmt.Println("Adding response header - " + name + ": " + value)
			}

rsp.Header().Set(name, value)
		}
	}

// add status line
	rsp.WriteHeader(code)

// add body
	fmt.Fprintf(rsp, body)

}

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