pkg/sr: improve base URL and resource path joining

* use `url.JoinPath()` to join the base URL with the path for cleaning any ./ or ../ element
* also move hardDelete to a request context query parameter

pkg/sr/api.go

@@ -404,7 +404,7 @@ func (cl *Client) DeleteSubject(ctx context.Context, subject string, how DeleteH
 	// DELETE /subjects/{subject}?permanent={x}
 	path := pathSubject(subject)
 	if how == HardDelete {
-		path += "?permanent=true"
+		ctx = WithParams(ctx, hardDelete)
 	}
 	var versions []int
 	defer func() { sort.Ints(versions) }()
@@ -419,7 +419,7 @@ func (cl *Client) DeleteSchema(ctx context.Context, subject string, version int,
 	// DELETE /subjects/{subject}/versions/{version}?permanent={x}
 	path := pathSubjectVersion(subject, version)
 	if how == HardDelete {
-		path += "?permanent=true"
+		ctx = WithParams(ctx, hardDelete)
 	}
 	return cl.delete(ctx, path, nil)
 }

pkg/sr/client.go

@@ -24,6 +24,7 @@ import (
 	"fmt"
 	"io"
 	"net/http"
+	"net/url"
 	"time"
 )
 
@@ -100,21 +101,25 @@ func (cl *Client) do(ctx context.Context, method, path string, v, into any) erro
 	urls := cl.urls
 
 start:
-	url := fmt.Sprintf("%s%s", urls[0], path)
+	reqURL, err := url.JoinPath(urls[0], path)
+	if err != nil {
+		return fmt.Errorf("unable to join path for %q and %q: %w", urls[0], path, err)
+	}
+
 	urls = urls[1:]
 
 	var reqBody io.Reader
 	if v != nil {
 		marshaled, err := json.Marshal(v)
 		if err != nil {
-			return fmt.Errorf("unable to encode body for %s %q: %w", method, url, err)
+			return fmt.Errorf("unable to encode body for %s %q: %w", method, reqURL, err)
 		}
 		reqBody = bytes.NewReader(marshaled)
 	}
 
-	req, err := http.NewRequestWithContext(ctx, method, url, reqBody)
+	req, err := http.NewRequestWithContext(ctx, method, reqURL, reqBody)
 	if err != nil {
-		return fmt.Errorf("unable to create request for %s %q: %v", method, url, err)
+		return fmt.Errorf("unable to create request for %s %q: %v", method, reqURL, err)
 	}
 	req.Header.Set("Content-Type", "application/vnd.schemaregistry.v1+json")
 	req.Header.Set("Accept", "application/vnd.schemaregistry.v1+json")
@@ -127,21 +132,21 @@ start:
 	resp, err := cl.httpcl.Do(req)
 	if err != nil {
 		if len(urls) == 0 {
-			return fmt.Errorf("unable to %s %q: %w", method, url, err)
+			return fmt.Errorf("unable to %s %q: %w", method, reqURL, err)
 		}
 		goto start
 	}
 
 	body, err := io.ReadAll(resp.Body)
 	resp.Body.Close()
 	if err != nil {
-		return fmt.Errorf("unable to read response body from %s %q: %w", method, url, err)
+		return fmt.Errorf("unable to read response body from %s %q: %w", method, reqURL, err)
 	}
 
 	if resp.StatusCode >= 300 {
 		e := &ResponseError{
 			Method: method,
-			URL:    url,
+			URL:    reqURL,
 			Raw:    body,
 		}
 		_ = json.Unmarshal(body, e) // best effort
@@ -154,7 +159,7 @@ start:
 			*into = body // return raw body to caller
 		default:
 			if err := json.Unmarshal(body, into); err != nil {
-				return fmt.Errorf("unable to decode ok response body from %s %q: %w", method, url, err)
+				return fmt.Errorf("unable to decode ok response body from %s %q: %w", method, reqURL, err)
 			}
 		}
 	}

pkg/sr/params.go

@@ -22,6 +22,7 @@ type Param struct {
 	subject         string
 	page            *int
 	limit           int
+	hardDelete      bool
 }
 
 // WithParams adds query parameters to the given context. This is a merge
@@ -83,6 +84,9 @@ func (p Param) apply(req *http.Request) {
 	if p.limit > 0 {
 		q.Set("limit", fmt.Sprintf("%d", p.limit))
 	}
+	if p.hardDelete {
+		q.Set("permanent", "true")
+	}
 	req.URL.RawQuery = q.Encode()
 }
 
@@ -130,6 +134,9 @@ func mergeParams(p ...Param) Param {
 		if p.limit > 0 {
 			merged.limit = p.limit
 		}
+		if p.hardDelete {
+			merged.hardDelete = p.hardDelete
+		}
 	}
 	return merged
 }
@@ -167,6 +174,9 @@ var (
 	// DeletedOnly is a Param that configures whether to return only
 	// deleted schemas or subjects in certain get operations.
 	DeletedOnly = Param{deletedOnly: true}
+
+	// hardDelete is internal, and set when DeleteHow == HardDelete.
+	hardDelete = Param{hardDelete: true}
 )
 
 // Format returns a Param that configures how schema's are returned in certain