Add decompression middleware and tests for gzip handling

internal/middleware/decompress.go

@@ -0,0 +1,77 @@
+package middleware
+
+import (
+	"compress/gzip"
+	"io"
+	"net/http"
+	"strings"
+)
+
+// DecompressOptions configures the decompression middleware
+type DecompressOptions struct {
+	// MaxSize is the maximum size of the decompressed body in bytes
+	// Zero means no limit
+	MaxSize int64
+}
+
+// DefaultDecompressOptions provides sensible default options
+func DefaultDecompressOptions() *DecompressOptions {
+	return &DecompressOptions{
+		MaxSize: 10 << 20, // 10MB
+	}
+}
+
+// Decompress creates a middleware that decompresses HTTP requests with gzip content encoding
+func Decompress(opts *DecompressOptions) Middleware {
+	// Use default options if none provided
+	if opts == nil {
+		opts = DefaultDecompressOptions()
+	}
+
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			// Check if the request has Content-Encoding header
+			contentEncoding := r.Header.Get("Content-Encoding")
+			
+			// If not compressed, pass through
+			if contentEncoding == "" {
+				next.ServeHTTP(w, r)
+				return
+			}
+			
+			// Check if gzip encoded
+			if strings.Contains(contentEncoding, "gzip") {
+				// Create a gzip reader
+				gz, err := gzip.NewReader(r.Body)
+				if err != nil {
+					http.Error(w, "Invalid gzip body", http.StatusBadRequest)
+					return
+				}
+				defer gz.Close()
+				
+				// Add limit reader if max size is specified
+				var bodyReader io.Reader = gz
+				if opts.MaxSize > 0 {
+					bodyReader = io.LimitReader(gz, opts.MaxSize)
+				}
+				
+				// Replace the body with a decompressed reader
+				r.Body = io.NopCloser(bodyReader)
+				
+				// Remove the content-encoding header to signal that the body is now decompressed
+				r.Header.Del("Content-Encoding")
+				
+				// Adjust content length because the body has been decompressed
+				r.Header.Del("Content-Length")
+			}
+			
+			// Call the next handler with the decompressed body
+			next.ServeHTTP(w, r)
+		})
+	}
+}
+
+// DecompressDefault creates a middleware that decompresses HTTP requests with default options
+func DecompressDefault() Middleware {
+	return Decompress(nil)
+}