caddyfile: Less strict URL parsing; allows placeholders

See https://caddy.community/t/caddy-v2-reusable-snippets/6744/11?u=matt

caddyconfig/httpcaddyfile/addresses.go

@@ -17,7 +17,6 @@ package httpcaddyfile
 import (
 	"fmt"
 	"net"
-	"net/url"
 	"reflect"
 	"strconv"
 	"strings"
@@ -209,44 +208,69 @@ type Address struct {
 // ParseAddress parses an address string into a structured format with separate
 // scheme, host, port, and path portions, as well as the original input string.
 func ParseAddress(str string) (Address, error) {
+	const maxLen = 4096
+	if len(str) > maxLen {
+		str = str[:maxLen]
+	}
+	remaining := strings.TrimSpace(str)
+	a := Address{Original: remaining}
+
+	// extract scheme
+	splitScheme := strings.SplitN(remaining, "://", 2)
+	switch len(splitScheme) {
+	case 0:
+		return a, nil
+	case 1:
+		remaining = splitScheme[0]
+	case 2:
+		a.Scheme = splitScheme[0]
+		remaining = splitScheme[1]
+	}
+
+	// extract host and port
+	hostSplit := strings.SplitN(remaining, "/", 2)
+	if len(hostSplit) > 0 {
+		host, port, err := net.SplitHostPort(hostSplit[0])
+		if err != nil {
+			host, port, err = net.SplitHostPort(hostSplit[0] + ":")
+			if err != nil {
+				host = hostSplit[0]
+			}
+		}
+		a.Host = host
+		a.Port = port
+	}
+	if len(hostSplit) == 2 {
+		// all that remains is the path
+		a.Path = "/" + hostSplit[1]
+	}
+
 	httpPort, httpsPort := strconv.Itoa(certmagic.HTTPPort), strconv.Itoa(certmagic.HTTPSPort)
 
-	input := str
-
-	// Split input into components (prepend with // to force host portion by default)
-	if !strings.Contains(str, "//") && !strings.HasPrefix(str, "/") {
-		str = "//" + str
-	}
-
-	u, err := url.Parse(str)
-	if err != nil {
-		return Address{}, err
-	}
-
-	// separate host and port
-	host, port, err := net.SplitHostPort(u.Host)
-	if err != nil {
-		host, port, err = net.SplitHostPort(u.Host + ":")
-		if err != nil {
-			host = u.Host
-		}
-	}
-
 	// see if we can set port based off scheme
-	if port == "" {
-		if u.Scheme == "http" {
-			port = httpPort
-		} else if u.Scheme == "https" {
-			port = httpsPort
+	if a.Port == "" {
+		if a.Scheme == "http" {
+			a.Port = httpPort
+		} else if a.Scheme == "https" {
+			a.Port = httpsPort
+		}
+	}
+
+	// make sure port is valid
+	if a.Port != "" {
+		if portNum, err := strconv.Atoi(a.Port); err != nil {
+			return Address{}, fmt.Errorf("invalid port '%s': %v", a.Port, err)
+		} else if portNum < 0 || portNum > 65535 {
+			return Address{}, fmt.Errorf("port %d is out of range", portNum)
 		}
 	}
 
 	// error if scheme and port combination violate convention
-	if (u.Scheme == "http" && port == httpsPort) || (u.Scheme == "https" && port == httpPort) {
-		return Address{}, fmt.Errorf("[%s] scheme and port violate convention", input)
+	if (a.Scheme == "http" && a.Port == httpsPort) || (a.Scheme == "https" && a.Port == httpPort) {
+		return Address{}, fmt.Errorf("[%s] scheme and port violate convention", str)
 	}
 
-	return Address{Original: input, Scheme: u.Scheme, Host: host, Port: port, Path: u.Path}, err
+	return a, nil
 }
 
 // TODO: which of the methods on Address are even used?

caddyconfig/httpcaddyfile/addresses_test.go

@@ -11,6 +11,7 @@ func TestParseAddress(t *testing.T) {
 		scheme, host, port, path string
 		shouldErr                bool
 	}{
+		{``, "", "", "", "", false},
 		{`localhost`, "", "localhost", "", "", false},
 		{`localhost:1234`, "", "localhost", "1234", "", false},
 		{`localhost:`, "", "localhost", "", "", false},
@@ -31,6 +32,10 @@ func TestParseAddress(t *testing.T) {
 		{`https://localhost:80`, "", "", "", "", true}, // not conventional
 		{`http://localhost`, "http", "localhost", "80", "", false},
 		{`https://localhost`, "https", "localhost", "443", "", false},
+		{`http://{env.APP_DOMAIN}`, "http", "{env.APP_DOMAIN}", "80", "", false},
+		{`{env.APP_DOMAIN}:80`, "", "{env.APP_DOMAIN}", "80", "", false},
+		{`{env.APP_DOMAIN}/path`, "", "{env.APP_DOMAIN}", "", "/path", false},
+		{`example.com/{env.APP_PATH}`, "", "example.com", "", "/{env.APP_PATH}", false},
 		{`http://127.0.0.1`, "http", "127.0.0.1", "80", "", false},
 		{`https://127.0.0.1`, "https", "127.0.0.1", "443", "", false},
 		{`http://[::1]`, "http", "::1", "80", "", false},
@@ -38,12 +43,12 @@ func TestParseAddress(t *testing.T) {
 		{`https://127.0.0.1:1234`, "https", "127.0.0.1", "1234", "", false},
 		{`http://[::1]:1234`, "http", "::1", "1234", "", false},
 		{``, "", "", "", "", false},
-		{`::1`, "", "::1", "", "", true},
-		{`localhost::`, "", "localhost::", "", "", true},
-		{`#$%@`, "", "", "", "", true},
+		{`::1`, "", "::1", "", "", false},
+		{`localhost::`, "", "localhost::", "", "", false},
+		{`#$%@`, "", "#$%@", "", "", false}, // don't want to presume what the hostname could be
 		{`host/path`, "", "host", "", "/path", false},
 		{`http://host/`, "http", "host", "80", "/", false},
-		{`//asdf`, "", "asdf", "", "", false},
+		{`//asdf`, "", "", "", "//asdf", false},
 		{`:1234/asdf`, "", "", "1234", "/asdf", false},
 		{`http://host/path`, "http", "host", "80", "/path", false},
 		{`https://host:443/path/foo`, "https", "host", "443", "/path/foo", false},
@@ -56,7 +61,7 @@ func TestParseAddress(t *testing.T) {
 			t.Errorf("Test %d (%s): Expected no error, but had error: %v", i, test.input, err)
 		}
 		if err == nil && test.shouldErr {
-			t.Errorf("Test %d (%s): Expected error, but had none", i, test.input)
+			t.Errorf("Test %d (%s): Expected error, but had none (%#v)", i, test.input, actual)
 		}
 
 		if !test.shouldErr && actual.Original != test.input {