Add first version of gemini-grc.

gemini/gemini_url.go

@@ -0,0 +1,229 @@
+package gemini
+
+import (
+	"database/sql/driver"
+	"fmt"
+	"net/url"
+	"path"
+	"strconv"
+	"strings"
+)
+
+type URL struct {
+	Protocol string `json:"protocol,omitempty"`
+	Hostname string `json:"hostname,omitempty"`
+	Port     int    `json:"port,omitempty"`
+	Path     string `json:"path,omitempty"`
+	Descr    string `json:"descr,omitempty"`
+	Full     string `json:"full,omitempty"`
+}
+
+func (u *URL) Scan(value interface{}) error {
+	if value == nil {
+		// Clear the fields in the current GeminiUrl object (not the pointer itself)
+		*u = URL{}
+		return nil
+	}
+	b, ok := value.(string)
+	if !ok {
+		return fmt.Errorf("failed to scan GeminiUrl: expected string, got %T", value)
+	}
+	parsedURL, err := ParseURLNoNormalize(b, "")
+	if err != nil {
+		err = fmt.Errorf("failed to scan GeminiUrl %s: %v", b, err)
+		return err
+	}
+	*u = *parsedURL
+	return nil
+}
+
+func (u URL) String() string {
+	return u.Full
+}
+
+func (u URL) StringNoDefaultPort() string {
+	if u.Port == 1965 {
+		return fmt.Sprintf("%s://%s%s", u.Protocol, u.Hostname, u.Path)
+	}
+	return u.Full
+}
+
+func (u URL) Value() (driver.Value, error) {
+	if u.Full == "" {
+		return nil, nil
+	}
+	return u.Full, nil
+}
+
+func ParseURLNoNormalize(input string, descr string) (*URL, error) {
+	u, err := url.Parse(input)
+	if err != nil {
+		return nil, fmt.Errorf("%w: Input %s URL Parse Error: %w", ErrURLParse, input, err)
+	}
+	if u.Scheme != "gemini" {
+		return nil, fmt.Errorf("%w: URL scheme '%s' is not supported", ErrURLNotGemini, u.Scheme)
+	}
+	protocol := u.Scheme
+	hostname := u.Hostname()
+	strPort := u.Port()
+	urlPath := u.Path
+	if strPort == "" {
+		strPort = "1965"
+	}
+	port, err := strconv.Atoi(strPort)
+	if err != nil {
+		return nil, fmt.Errorf("%w: Input %s GeminiError %w", ErrURLParse, input, err)
+	}
+	full := fmt.Sprintf("%s://%s:%d%s", protocol, hostname, port, urlPath)
+	return &URL{Protocol: protocol, Hostname: hostname, Port: port, Path: urlPath, Descr: descr, Full: full}, nil
+}
+
+func ParseURL(input string, descr string) (*URL, error) {
+	u, err := NormalizeURL(input)
+	if err != nil {
+		return nil, fmt.Errorf("%w: Input %s URL Parse Error: %w", ErrURLParse, input, err)
+	}
+	if u.Scheme != "gemini" {
+		return nil, fmt.Errorf("%w: URL scheme '%s' is not supported", ErrURLNotGemini, u.Scheme)
+	}
+	protocol := u.Scheme
+	hostname := u.Hostname()
+	strPort := u.Port()
+	urlPath := u.Path
+	if strPort == "" {
+		strPort = "1965"
+	}
+	port, err := strconv.Atoi(strPort)
+	if err != nil {
+		return nil, fmt.Errorf("%w: Input %s GeminiError %w", ErrURLParse, input, err)
+	}
+	full := fmt.Sprintf("%s://%s:%d%s", protocol, hostname, port, urlPath)
+	return &URL{Protocol: protocol, Hostname: hostname, Port: port, Path: urlPath, Descr: descr, Full: full}, nil
+}
+
+// DeriveAbsoluteURL converts a (possibly) relative
+// URL to an absolute one. Used primarily to calculate
+// the full redirection URL target from a response header.
+func DeriveAbsoluteURL(currentURL URL, input string) (*URL, error) {
+	// If target URL is absolute, return just it
+	if strings.Contains(input, "://") {
+		return ParseURL(input, "")
+	}
+	// input is a relative path. Clean it and construct absolute.
+	var newPath string
+	// Handle weird cases found in the wild
+	if strings.HasPrefix(input, "/") {
+		newPath = path.Clean(input)
+	} else if input == "./" || input == "." {
+		newPath = path.Join(currentURL.Path, "/")
+	} else {
+		newPath = path.Join(currentURL.Path, "/", path.Clean(input))
+	}
+	strURL := fmt.Sprintf("%s://%s:%d%s", currentURL.Protocol, currentURL.Hostname, currentURL.Port, newPath)
+	return ParseURL(strURL, "")
+}
+
+// NormalizeURL takes a URL string and returns a normalized version.
+// Normalized meaning:
+// - Path normalization (removing redundant slashes, . and .. segments)
+// - Proper escaping of special characters
+// - Lowercase scheme and host
+// - Removal of default ports
+// - Empty path becomes "/"
+func NormalizeURL(rawURL string) (*url.URL, error) {
+	// Parse the URL
+	u, err := url.Parse(rawURL)
+	if err != nil {
+		return nil, fmt.Errorf("%w: %w", ErrURLParse, err)
+	}
+
+	// Convert scheme to lowercase
+	u.Scheme = strings.ToLower(u.Scheme)
+
+	// Convert hostname to lowercase
+	if u.Host != "" {
+		u.Host = strings.ToLower(u.Host)
+	}
+
+	// Remove default ports
+	if u.Port() != "" {
+		switch {
+		case u.Scheme == "http" && u.Port() == "80":
+			u.Host = u.Hostname()
+		case u.Scheme == "https" && u.Port() == "443":
+			u.Host = u.Hostname()
+		case u.Scheme == "gemini" && u.Port() == "1965":
+			u.Host = u.Hostname()
+		}
+	}
+
+	// Handle path normalization while preserving trailing slash
+	if u.Path != "" {
+		// Check if there was a trailing slash before cleaning
+		hadTrailingSlash := strings.HasSuffix(u.Path, "/")
+
+		u.Path = path.Clean(u.Path)
+		// If path was "/", path.Clean() will return "."
+		if u.Path == "." {
+			u.Path = "/"
+		} else if hadTrailingSlash && u.Path != "/" {
+			// Restore trailing slash if it existed and path isn't just "/"
+			u.Path += "/"
+		}
+	}
+
+	// Properly escape the path
+	// First split on '/' to avoid escaping them
+	parts := strings.Split(u.Path, "/")
+	for i, part := range parts {
+		parts[i] = url.PathEscape(part)
+	}
+	u.Path = strings.Join(parts, "/")
+
+	// Remove trailing fragment if empty
+	if u.Fragment == "" {
+		u.Fragment = ""
+	}
+
+	// Remove trailing query if empty
+	if u.RawQuery == "" {
+		u.RawQuery = ""
+	}
+
+	return u, nil
+}
+
+func EscapeURL(input string) string {
+	// Only escape if not already escaped
+	if strings.Contains(input, "%") && !strings.Contains(input, "% ") {
+		return input
+	}
+	// Split URL into parts (protocol, host, path)
+	parts := strings.SplitN(input, "://", 2)
+	if len(parts) != 2 {
+		return input
+	}
+
+	protocol := parts[0]
+	remainder := parts[1]
+
+	// If URL ends with just a slash, return as is
+	if strings.HasSuffix(remainder, "/") && !strings.Contains(remainder[:len(remainder)-1], "/") {
+		return input
+	}
+
+	// Split host and path
+	parts = strings.SplitN(remainder, "/", 2)
+	host := parts[0]
+	if len(parts) == 1 {
+		return protocol + "://" + host
+	}
+
+	path := parts[1]
+
+	// Escape the path portion
+	escapedPath := url.PathEscape(path)
+
+	// Reconstruct the URL
+	return protocol + "://" + host + "/" + escapedPath
+}