feat(openapi/swagger): direct fuzzing using target url

internal/runner/runner.go

@@ -254,8 +254,12 @@ func New(options *types.Options) (*Runner, error) {
 		os.Exit(0)
 	}
 
+	if tmpDir, err := os.MkdirTemp("", "nuclei-tmp-*"); err == nil {
+		runner.tmpDir = tmpDir
+	}
+
 	// create the input provider and load the inputs
-	inputProvider, err := provider.NewInputProvider(provider.InputOptions{Options: options})
+	inputProvider, err := provider.NewInputProvider(provider.InputOptions{Options: options, TempDir: runner.tmpDir})
 	if err != nil {
 		return nil, errors.Wrap(err, "could not create input provider")
 	}
@@ -386,10 +390,6 @@ func New(options *types.Options) (*Runner, error) {
 	}
 	runner.rateLimiter = utils.GetRateLimiter(context.Background(), options.RateLimit, options.RateLimitDuration)
 
-	if tmpDir, err := os.MkdirTemp("", "nuclei-tmp-*"); err == nil {
-		runner.tmpDir = tmpDir
-	}
-
 	return runner, nil
 }
 

pkg/input/formats/formats.go

@@ -47,6 +47,15 @@ type Format interface {
 	SetOptions(options InputFormatOptions)
 }
 
+// SpecDownloader is an interface for downloading API specifications from URLs
+type SpecDownloader interface {
+	// Download downloads the spec from the given URL and saves it to tmpDir
+	// Returns the path to the downloaded file
+	Download(url, tmpDir string) (string, error)
+	// SupportedExtensions returns the list of supported file extensions
+	SupportedExtensions() []string
+}
+
 var (
 	DefaultVarDumpFileName = "required_openapi_params.yaml"
 	ErrNoVarsDumpFile      = errors.New("no required params file found")

pkg/input/formats/openapi/downloader.go

@@ -0,0 +1,120 @@
+package openapi
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"os"
+	"path/filepath"
+	"strings"
+	"time"
+
+	"github.com/pkg/errors"
+	"github.com/projectdiscovery/nuclei/v3/pkg/input/formats"
+)
+
+// OpenAPIDownloader implements the SpecDownloader interface for OpenAPI 3.0 specs
+type OpenAPIDownloader struct{}
+
+// NewDownloader creates a new OpenAPI downloader
+func NewDownloader() formats.SpecDownloader {
+	return &OpenAPIDownloader{}
+}
+
+// This function downloads an OpenAPI 3.0 spec from the given URL and saves it to tmpDir
+func (d *OpenAPIDownloader) Download(urlStr, tmpDir string) (string, error) {
+	// Validate URL format, OpenAPI 3.0 specs are typically JSON
+	if !strings.HasSuffix(urlStr, ".json") && !strings.Contains(urlStr, "openapi") {
+		return "", fmt.Errorf("URL does not appear to be an OpenAPI JSON spec")
+	}
+
+	client := &http.Client{Timeout: 30 * time.Second}
+
+	resp, err := client.Get(urlStr)
+	if err != nil {
+		return "", errors.Wrap(err, "failed to download OpenAPI spec")
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return "", fmt.Errorf("HTTP %d when downloading OpenAPI spec", resp.StatusCode)
+	}
+
+	bodyBytes, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return "", errors.Wrap(err, "failed to read response body")
+	}
+
+	// Validate it's a valid JSON and has OpenAPI structure
+	var spec map[string]interface{}
+	if err := json.Unmarshal(bodyBytes, &spec); err != nil {
+		return "", fmt.Errorf("downloaded content is not valid JSON: %w", err)
+	}
+
+	// Check if it's an OpenAPI 3.0 spec
+	if openapi, exists := spec["openapi"]; exists {
+		if openapiStr, ok := openapi.(string); ok && strings.HasPrefix(openapiStr, "3.") {
+			// Valid OpenAPI 3.0 spec
+		} else {
+			return "", fmt.Errorf("not a valid OpenAPI 3.0 spec (found version: %v)", openapi)
+		}
+	} else {
+		return "", fmt.Errorf("not an OpenAPI spec (missing 'openapi' field)")
+	}
+
+	// Extract host from URL for server configuration
+	parsedURL, err := url.Parse(urlStr)
+	if err != nil {
+		return "", errors.Wrap(err, "failed to parse URL")
+	}
+	host := parsedURL.Host
+
+	// Add servers section if missing or empty
+	servers, exists := spec["servers"]
+	if !exists || servers == nil {
+		spec["servers"] = []map[string]interface{}{
+			{"url": "https://" + host},
+		}
+	} else if serversList, ok := servers.([]interface{}); ok && len(serversList) == 0 {
+		spec["servers"] = []map[string]interface{}{
+			{"url": "https://" + host},
+		}
+	}
+
+	// Marshal back to JSON
+	modifiedJSON, err := json.Marshal(spec)
+	if err != nil {
+		return "", errors.Wrap(err, "failed to marshal modified spec")
+	}
+
+	// Create output directory
+	openapiDir := filepath.Join(tmpDir, "openapi")
+	if err := os.MkdirAll(openapiDir, 0755); err != nil {
+		return "", errors.Wrap(err, "failed to create openapi directory")
+	}
+
+	// Generate filename
+	filename := fmt.Sprintf("openapi-spec-%d.json", time.Now().Unix())
+	filePath := filepath.Join(openapiDir, filename)
+
+	// Write file
+	file, err := os.Create(filePath)
+	if err != nil {
+		return "", fmt.Errorf("failed to create file: %w", err)
+	}
+	defer file.Close()
+
+	if _, err := file.Write(modifiedJSON); err != nil {
+		os.Remove(filePath)
+		return "", errors.Wrap(err, "failed to write OpenAPI spec to file")
+	}
+
+	return filePath, nil
+}
+
+// SupportedExtensions returns the list of supported file extensions for OpenAPI
+func (d *OpenAPIDownloader) SupportedExtensions() []string {
+	return []string{".json"}
+}

pkg/input/formats/openapi/downloader_test.go

@@ -0,0 +1,240 @@
+package openapi
+
+import (
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"strings"
+	"testing"
+	"time"
+)
+
+func TestOpenAPIDownloader_SupportedExtensions(t *testing.T) {
+	downloader := &OpenAPIDownloader{}
+	extensions := downloader.SupportedExtensions()
+
+	expected := []string{".json"}
+	if len(extensions) != len(expected) {
+		t.Errorf("Expected %d extensions, got %d", len(expected), len(extensions))
+	}
+
+	for i, ext := range extensions {
+		if ext != expected[i] {
+			t.Errorf("Expected extension %s, got %s", expected[i], ext)
+		}
+	}
+}
+
+func TestOpenAPIDownloader_Download_Success(t *testing.T) {
+	// Create a mock OpenAPI spec
+	mockSpec := map[string]interface{}{
+		"openapi": "3.0.0",
+		"info": map[string]interface{}{
+			"title":   "Test API",
+			"version": "1.0.0",
+		},
+		"paths": map[string]interface{}{
+			"/test": map[string]interface{}{
+				"get": map[string]interface{}{
+					"summary": "Test endpoint",
+				},
+			},
+		},
+	}
+
+	// Create mock server
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+		json.NewEncoder(w).Encode(mockSpec)
+	}))
+	defer server.Close()
+
+	// Create temp directory
+	tmpDir, err := os.MkdirTemp("", "openapi_test")
+	if err != nil {
+		t.Fatalf("Failed to create temp dir: %v", err)
+	}
+	defer os.RemoveAll(tmpDir)
+
+	// Test download
+	downloader := &OpenAPIDownloader{}
+	filePath, err := downloader.Download(server.URL+"/openapi.json", tmpDir)
+	if err != nil {
+		t.Fatalf("Download failed: %v", err)
+	}
+
+	// Verify file exists
+	if !fileExists(filePath) {
+		t.Errorf("Downloaded file does not exist: %s", filePath)
+	}
+
+	// Verify file content
+	content, err := os.ReadFile(filePath)
+	if err != nil {
+		t.Fatalf("Failed to read downloaded file: %v", err)
+	}
+
+	var downloadedSpec map[string]interface{}
+	if err := json.Unmarshal(content, &downloadedSpec); err != nil {
+		t.Fatalf("Failed to parse downloaded JSON: %v", err)
+	}
+
+	// Verify servers field was added
+	servers, exists := downloadedSpec["servers"]
+	if !exists {
+		t.Error("Servers field was not added to the spec")
+	}
+
+	if serversList, ok := servers.([]interface{}); ok {
+		if len(serversList) == 0 {
+			t.Error("Servers list is empty")
+		}
+	} else {
+		t.Error("Servers field is not a list")
+	}
+}
+
+func TestOpenAPIDownloader_Download_NonJSONURL(t *testing.T) {
+	tmpDir, err := os.MkdirTemp("", "openapi_test")
+	if err != nil {
+		t.Fatalf("Failed to create temp dir: %v", err)
+	}
+	defer os.RemoveAll(tmpDir)
+
+	downloader := &OpenAPIDownloader{}
+	_, err = downloader.Download("http://example.com/spec.yaml", tmpDir)
+	if err == nil {
+		t.Error("Expected error for non-JSON URL, but got none")
+	}
+
+	if !strings.Contains(err.Error(), "URL does not appear to be an OpenAPI JSON spec") {
+		t.Errorf("Unexpected error message: %v", err)
+	}
+}
+
+func TestOpenAPIDownloader_Download_HTTPError(t *testing.T) {
+	// Create mock server that returns 404
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusNotFound)
+	}))
+	defer server.Close()
+
+	tmpDir, err := os.MkdirTemp("", "openapi_test")
+	if err != nil {
+		t.Fatalf("Failed to create temp dir: %v", err)
+	}
+	defer os.RemoveAll(tmpDir)
+
+	downloader := &OpenAPIDownloader{}
+	_, err = downloader.Download(server.URL+"/openapi.json", tmpDir)
+	if err == nil {
+		t.Error("Expected error for HTTP 404, but got none")
+	}
+}
+
+func TestOpenAPIDownloader_Download_InvalidJSON(t *testing.T) {
+	// Create mock server that returns invalid JSON
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+		w.Write([]byte("invalid json"))
+	}))
+	defer server.Close()
+
+	tmpDir, err := os.MkdirTemp("", "openapi_test")
+	if err != nil {
+		t.Fatalf("Failed to create temp dir: %v", err)
+	}
+	defer os.RemoveAll(tmpDir)
+
+	downloader := &OpenAPIDownloader{}
+	_, err = downloader.Download(server.URL+"/openapi.json", tmpDir)
+	if err == nil {
+		t.Error("Expected error for invalid JSON, but got none")
+	}
+}
+
+func TestOpenAPIDownloader_Download_Timeout(t *testing.T) {
+	// Create mock server with delay
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		time.Sleep(35 * time.Second) // Longer than 30 second timeout
+		json.NewEncoder(w).Encode(map[string]interface{}{"test": "data"})
+	}))
+	defer server.Close()
+
+	tmpDir, err := os.MkdirTemp("", "openapi_test")
+	if err != nil {
+		t.Fatalf("Failed to create temp dir: %v", err)
+	}
+	defer os.RemoveAll(tmpDir)
+
+	downloader := &OpenAPIDownloader{}
+	_, err = downloader.Download(server.URL+"/openapi.json", tmpDir)
+	if err == nil {
+		t.Error("Expected timeout error, but got none")
+	}
+}
+
+func TestOpenAPIDownloader_Download_WithExistingServers(t *testing.T) {
+	// Create a mock OpenAPI spec with existing servers
+	mockSpec := map[string]interface{}{
+		"openapi": "3.0.0",
+		"info": map[string]interface{}{
+			"title":   "Test API",
+			"version": "1.0.0",
+		},
+		"servers": []interface{}{
+			map[string]interface{}{
+				"url": "https://existing-server.com",
+			},
+		},
+		"paths": map[string]interface{}{},
+	}
+
+	// Create mock server
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+		json.NewEncoder(w).Encode(mockSpec)
+	}))
+	defer server.Close()
+
+	tmpDir, err := os.MkdirTemp("", "openapi_test")
+	if err != nil {
+		t.Fatalf("Failed to create temp dir: %v", err)
+	}
+	defer os.RemoveAll(tmpDir)
+
+	downloader := &OpenAPIDownloader{}
+	filePath, err := downloader.Download(server.URL+"/openapi.json", tmpDir)
+	if err != nil {
+		t.Fatalf("Download failed: %v", err)
+	}
+
+	// Verify existing servers are preserved
+	content, err := os.ReadFile(filePath)
+	if err != nil {
+		t.Fatalf("Failed to read downloaded file: %v", err)
+	}
+
+	var downloadedSpec map[string]interface{}
+	if err := json.Unmarshal(content, &downloadedSpec); err != nil {
+		t.Fatalf("Failed to parse downloaded JSON: %v", err)
+	}
+
+	servers, exists := downloadedSpec["servers"]
+	if !exists {
+		t.Error("Servers field was removed from the spec")
+	}
+
+	if serversList, ok := servers.([]interface{}); ok {
+		if len(serversList) != 1 {
+			t.Errorf("Expected 1 server, got %d", len(serversList))
+		}
+	}
+}
+
+// Helper function to check if file exists
+func fileExists(filename string) bool {
+	_, err := os.Stat(filename)
+	return !os.IsNotExist(err)
+}

pkg/input/formats/swagger/downloader.go

@@ -0,0 +1,148 @@
+package swagger
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"os"
+	"path/filepath"
+	"strings"
+	"time"
+
+	"github.com/pkg/errors"
+	"github.com/projectdiscovery/nuclei/v3/pkg/input/formats"
+	"gopkg.in/yaml.v3"
+)
+
+// SwaggerDownloader implements the SpecDownloader interface for Swagger 2.0 specs
+type SwaggerDownloader struct{}
+
+// NewDownloader creates a new Swagger downloader
+func NewDownloader() formats.SpecDownloader {
+	return &SwaggerDownloader{}
+}
+
+// This function downloads a Swagger 2.0 spec from the given URL and saves it to tmpDir
+func (d *SwaggerDownloader) Download(urlStr, tmpDir string) (string, error) {
+	// Swagger can be JSON or YAML
+	supportedExts := []string{".json", ".yaml", ".yml"}
+	isSupported := false
+	for _, ext := range supportedExts {
+		if strings.HasSuffix(urlStr, ext) {
+			isSupported = true
+			break
+		}
+	}
+	if !isSupported && !strings.Contains(urlStr, "swagger") {
+		return "", fmt.Errorf("URL does not appear to be a Swagger spec (supported: %v)", supportedExts)
+	}
+
+	client := &http.Client{Timeout: 30 * time.Second}
+
+	resp, err := client.Get(urlStr)
+	if err != nil {
+		return "", errors.Wrap(err, "failed to download Swagger spec")
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return "", fmt.Errorf("HTTP %d when downloading Swagger spec", resp.StatusCode)
+	}
+
+	bodyBytes, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return "", errors.Wrap(err, "failed to read response body")
+	}
+
+	// Determine format and parse
+	var spec map[string]interface{}
+	var isYAML bool
+
+	// Try JSON first
+	if err := json.Unmarshal(bodyBytes, &spec); err != nil {
+		// Then try YAML
+		if err := yaml.Unmarshal(bodyBytes, &spec); err != nil {
+			return "", fmt.Errorf("downloaded content is neither valid JSON nor YAML: %w", err)
+		}
+		isYAML = true
+	}
+
+	// Validate it's a Swagger 2.0 spec
+	if swagger, exists := spec["swagger"]; exists {
+		if swaggerStr, ok := swagger.(string); ok && strings.HasPrefix(swaggerStr, "2.") {
+			// Valid Swagger 2.0 spec
+		} else {
+			return "", fmt.Errorf("not a valid Swagger 2.0 spec (found version: %v)", swagger)
+		}
+	} else {
+		return "", fmt.Errorf("not a Swagger spec (missing 'swagger' field)")
+	}
+
+	// Extract host from URL for host configuration
+	parsedURL, err := url.Parse(urlStr)
+	if err != nil {
+		return "", errors.Wrap(err, "failed to parse URL")
+	}
+	host := parsedURL.Host
+
+	// Add host if missing
+	if _, exists := spec["host"]; !exists {
+		spec["host"] = host
+	}
+
+	// Add schemes if missing
+	if _, exists := spec["schemes"]; !exists {
+		scheme := parsedURL.Scheme
+		if scheme == "" {
+			scheme = "https"
+		}
+		spec["schemes"] = []string{scheme}
+	}
+
+	// Create output directory
+	swaggerDir := filepath.Join(tmpDir, "swagger")
+	if err := os.MkdirAll(swaggerDir, 0755); err != nil {
+		return "", errors.Wrap(err, "failed to create swagger directory")
+	}
+
+	// Generate filename and content based on original format
+	var filename string
+	var content []byte
+
+	if isYAML {
+		filename = fmt.Sprintf("swagger-spec-%d.yaml", time.Now().Unix())
+		content, err = yaml.Marshal(spec)
+		if err != nil {
+			return "", errors.Wrap(err, "failed to marshal modified YAML spec")
+		}
+	} else {
+		filename = fmt.Sprintf("swagger-spec-%d.json", time.Now().Unix())
+		content, err = json.Marshal(spec)
+		if err != nil {
+			return "", errors.Wrap(err, "failed to marshal modified JSON spec")
+		}
+	}
+
+	filePath := filepath.Join(swaggerDir, filename)
+
+	// Write file
+	file, err := os.Create(filePath)
+	if err != nil {
+		return "", errors.Wrap(err, "failed to create file")
+	}
+	defer file.Close()
+
+	if _, err := file.Write(content); err != nil {
+		os.Remove(filePath)
+		return "", errors.Wrap(err, "failed to write file")
+	}
+
+	return filePath, nil
+}
+
+// SupportedExtensions returns the list of supported file extensions for Swagger
+func (d *SwaggerDownloader) SupportedExtensions() []string {
+	return []string{".json", ".yaml", ".yml"}
+}

pkg/input/formats/swagger/downloader_test.go

@@ -0,0 +1,306 @@
+package swagger
+
+import (
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"strings"
+	"testing"
+	"time"
+
+	"gopkg.in/yaml.v3"
+)
+
+func TestSwaggerDownloader_SupportedExtensions(t *testing.T) {
+	downloader := &SwaggerDownloader{}
+	extensions := downloader.SupportedExtensions()
+
+	expected := []string{".json", ".yaml", ".yml"}
+	if len(extensions) != len(expected) {
+		t.Errorf("Expected %d extensions, got %d", len(expected), len(extensions))
+	}
+
+	for i, ext := range extensions {
+		if ext != expected[i] {
+			t.Errorf("Expected extension %s, got %s", expected[i], ext)
+		}
+	}
+}
+
+func TestSwaggerDownloader_Download_JSON_Success(t *testing.T) {
+	// Create a mock Swagger spec (JSON)
+	mockSpec := map[string]interface{}{
+		"swagger": "2.0",
+		"info": map[string]interface{}{
+			"title":   "Test API",
+			"version": "1.0.0",
+		},
+		"paths": map[string]interface{}{
+			"/test": map[string]interface{}{
+				"get": map[string]interface{}{
+					"summary": "Test endpoint",
+				},
+			},
+		},
+	}
+
+	// Create mock server
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+		json.NewEncoder(w).Encode(mockSpec)
+	}))
+	defer server.Close()
+
+	// Create temp directory
+	tmpDir, err := os.MkdirTemp("", "swagger_test")
+	if err != nil {
+		t.Fatalf("Failed to create temp dir: %v", err)
+	}
+	defer os.RemoveAll(tmpDir)
+
+	// Test download
+	downloader := &SwaggerDownloader{}
+	filePath, err := downloader.Download(server.URL+"/swagger.json", tmpDir)
+	if err != nil {
+		t.Fatalf("Download failed: %v", err)
+	}
+
+	// Verify file exists
+	if !fileExists(filePath) {
+		t.Errorf("Downloaded file does not exist: %s", filePath)
+	}
+
+	// Verify file content
+	content, err := os.ReadFile(filePath)
+	if err != nil {
+		t.Fatalf("Failed to read downloaded file: %v", err)
+	}
+
+	var downloadedSpec map[string]interface{}
+	if err := json.Unmarshal(content, &downloadedSpec); err != nil {
+		t.Fatalf("Failed to parse downloaded JSON: %v", err)
+	}
+
+	// Verify host field was added
+	_, exists := downloadedSpec["host"]
+	if !exists {
+		t.Error("Host field was not added to the spec")
+	}
+}
+
+func TestSwaggerDownloader_Download_YAML_Success(t *testing.T) {
+	// Create a mock Swagger spec (YAML)
+	mockSpecYAML := `
+swagger: "2.0"
+info:
+  title: "Test API"
+  version: "1.0.0"
+paths:
+  /test:
+    get:
+      summary: "Test endpoint"
+`
+
+	// Create mock server
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/yaml")
+		w.Write([]byte(mockSpecYAML))
+	}))
+	defer server.Close()
+
+	// Create temp directory
+	tmpDir, err := os.MkdirTemp("", "swagger_test")
+	if err != nil {
+		t.Fatalf("Failed to create temp dir: %v", err)
+	}
+	defer os.RemoveAll(tmpDir)
+
+	// Test download
+	downloader := &SwaggerDownloader{}
+	filePath, err := downloader.Download(server.URL+"/swagger.yaml", tmpDir)
+	if err != nil {
+		t.Fatalf("Download failed: %v", err)
+	}
+
+	// Verify file exists
+	if !fileExists(filePath) {
+		t.Errorf("Downloaded file does not exist: %s", filePath)
+	}
+
+	// Verify file content
+	content, err := os.ReadFile(filePath)
+	if err != nil {
+		t.Fatalf("Failed to read downloaded file: %v", err)
+	}
+
+	var downloadedSpec map[string]interface{}
+	if err := yaml.Unmarshal(content, &downloadedSpec); err != nil {
+		t.Fatalf("Failed to parse downloaded YAML: %v", err)
+	}
+
+	// Verify host field was added
+	_, exists := downloadedSpec["host"]
+	if !exists {
+		t.Error("Host field was not added to the spec")
+	}
+}
+
+func TestSwaggerDownloader_Download_UnsupportedExtension(t *testing.T) {
+	tmpDir, err := os.MkdirTemp("", "swagger_test")
+	if err != nil {
+		t.Fatalf("Failed to create temp dir: %v", err)
+	}
+	defer os.RemoveAll(tmpDir)
+
+	downloader := &SwaggerDownloader{}
+	_, err = downloader.Download("http://example.com/spec.xml", tmpDir)
+	if err == nil {
+		t.Error("Expected error for unsupported extension, but got none")
+	}
+
+	if !strings.Contains(err.Error(), "URL does not appear to be a Swagger spec") {
+		t.Errorf("Unexpected error message: %v", err)
+	}
+}
+
+func TestSwaggerDownloader_Download_HTTPError(t *testing.T) {
+	// Create mock server that returns 404
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusNotFound)
+	}))
+	defer server.Close()
+
+	tmpDir, err := os.MkdirTemp("", "swagger_test")
+	if err != nil {
+		t.Fatalf("Failed to create temp dir: %v", err)
+	}
+	defer os.RemoveAll(tmpDir)
+
+	downloader := &SwaggerDownloader{}
+	_, err = downloader.Download(server.URL+"/swagger.json", tmpDir)
+	if err == nil {
+		t.Error("Expected error for HTTP 404, but got none")
+	}
+}
+
+func TestSwaggerDownloader_Download_InvalidJSON(t *testing.T) {
+	// Create mock server that returns invalid JSON
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+		w.Write([]byte("invalid json"))
+	}))
+	defer server.Close()
+
+	tmpDir, err := os.MkdirTemp("", "swagger_test")
+	if err != nil {
+		t.Fatalf("Failed to create temp dir: %v", err)
+	}
+	defer os.RemoveAll(tmpDir)
+
+	downloader := &SwaggerDownloader{}
+	_, err = downloader.Download(server.URL+"/swagger.json", tmpDir)
+	if err == nil {
+		t.Error("Expected error for invalid JSON, but got none")
+	}
+}
+
+func TestSwaggerDownloader_Download_InvalidYAML(t *testing.T) {
+	// Create mock server that returns invalid YAML
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/yaml")
+		w.Write([]byte("invalid: yaml: content: ["))
+	}))
+	defer server.Close()
+
+	tmpDir, err := os.MkdirTemp("", "swagger_test")
+	if err != nil {
+		t.Fatalf("Failed to create temp dir: %v", err)
+	}
+	defer os.RemoveAll(tmpDir)
+
+	downloader := &SwaggerDownloader{}
+	_, err = downloader.Download(server.URL+"/swagger.yaml", tmpDir)
+	if err == nil {
+		t.Error("Expected error for invalid YAML, but got none")
+	}
+}
+
+func TestSwaggerDownloader_Download_Timeout(t *testing.T) {
+	// Create mock server with delay
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		time.Sleep(35 * time.Second) // Longer than 30 second timeout
+		json.NewEncoder(w).Encode(map[string]interface{}{"test": "data"})
+	}))
+	defer server.Close()
+
+	tmpDir, err := os.MkdirTemp("", "swagger_test")
+	if err != nil {
+		t.Fatalf("Failed to create temp dir: %v", err)
+	}
+	defer os.RemoveAll(tmpDir)
+
+	downloader := &SwaggerDownloader{}
+	_, err = downloader.Download(server.URL+"/swagger.json", tmpDir)
+	if err == nil {
+		t.Error("Expected timeout error, but got none")
+	}
+}
+
+func TestSwaggerDownloader_Download_WithExistingHost(t *testing.T) {
+	// Create a mock Swagger spec with existing host
+	mockSpec := map[string]interface{}{
+		"swagger": "2.0",
+		"info": map[string]interface{}{
+			"title":   "Test API",
+			"version": "1.0.0",
+		},
+		"host":  "existing-host.com",
+		"paths": map[string]interface{}{},
+	}
+
+	// Create mock server
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+		json.NewEncoder(w).Encode(mockSpec)
+	}))
+	defer server.Close()
+
+	tmpDir, err := os.MkdirTemp("", "swagger_test")
+	if err != nil {
+		t.Fatalf("Failed to create temp dir: %v", err)
+	}
+	defer os.RemoveAll(tmpDir)
+
+	downloader := &SwaggerDownloader{}
+	filePath, err := downloader.Download(server.URL+"/swagger.json", tmpDir)
+	if err != nil {
+		t.Fatalf("Download failed: %v", err)
+	}
+
+	// Verify existing host is preserved
+	content, err := os.ReadFile(filePath)
+	if err != nil {
+		t.Fatalf("Failed to read downloaded file: %v", err)
+	}
+
+	var downloadedSpec map[string]interface{}
+	if err := json.Unmarshal(content, &downloadedSpec); err != nil {
+		t.Fatalf("Failed to parse downloaded JSON: %v", err)
+	}
+
+	host, exists := downloadedSpec["host"]
+	if !exists {
+		t.Error("Host field was removed from the spec")
+	}
+
+	if hostStr, ok := host.(string); !ok || hostStr != "existing-host.com" {
+		t.Errorf("Expected host 'existing-host.com', got '%v'", host)
+	}
+}
+
+// Helper function to check if file exists
+func fileExists(filename string) bool {
+	_, err := os.Stat(filename)
+	return !os.IsNotExist(err)
+}

pkg/input/provider/interface.go

@@ -7,6 +7,8 @@ import (
 
 	"github.com/projectdiscovery/gologger"
 	"github.com/projectdiscovery/nuclei/v3/pkg/input/formats"
+	"github.com/projectdiscovery/nuclei/v3/pkg/input/formats/openapi"
+	"github.com/projectdiscovery/nuclei/v3/pkg/input/formats/swagger"
 	"github.com/projectdiscovery/nuclei/v3/pkg/input/provider/http"
 	"github.com/projectdiscovery/nuclei/v3/pkg/input/provider/list"
 	"github.com/projectdiscovery/nuclei/v3/pkg/input/types"
@@ -74,6 +76,8 @@ type InputProvider interface {
 type InputOptions struct {
 	// Options for global config
 	Options *configTypes.Options
+	// TempDir is the temporary directory for storing files
+	TempDir string
 	// NotFoundCallback is the callback to call when input is not found
 	// only supported in list input provider
 	NotFoundCallback func(template string) bool
@@ -107,20 +111,49 @@ func NewInputProvider(opts InputOptions) (InputProvider, error) {
 			Options:          opts.Options,
 			NotFoundCallback: opts.NotFoundCallback,
 		})
-	} else {
-		// use HttpInputProvider
-		return http.NewHttpInputProvider(&http.HttpMultiFormatOptions{
-			InputFile: opts.Options.TargetsFilePath,
-			InputMode: opts.Options.InputFileMode,
-			Options: formats.InputFormatOptions{
-				Variables:            generators.MergeMaps(extraVars, opts.Options.Vars.AsMap()),
-				SkipFormatValidation: opts.Options.SkipFormatValidation,
-				RequiredOnly:         opts.Options.FormatUseRequiredOnly,
-				VarsTextTemplating:   opts.Options.VarsTextTemplating,
-				VarsFilePaths:        opts.Options.VarsFilePaths,
-			},
-		})
+	} else if len(opts.Options.Targets) > 0 &&
+		(strings.EqualFold(opts.Options.InputFileMode, "openapi") || strings.EqualFold(opts.Options.InputFileMode, "swagger")) {
+
+		if len(opts.Options.Targets) > 1 {
+			return nil, fmt.Errorf("only one target URL is supported in %s input mode", opts.Options.InputFileMode)
+		}
+
+		target := opts.Options.Targets[0]
+		if strings.HasPrefix(target, "http://") || strings.HasPrefix(target, "https://") {
+			var downloader formats.SpecDownloader
+			var tempFile string
+			var err error
+
+			switch strings.ToLower(opts.Options.InputFileMode) {
+			case "openapi":
+				downloader = openapi.NewDownloader()
+				tempFile, err = downloader.Download(target, opts.TempDir)
+			case "swagger":
+				downloader = swagger.NewDownloader()
+				tempFile, err = downloader.Download(target, opts.TempDir)
+			default:
+				return nil, fmt.Errorf("unsupported input mode: %s", opts.Options.InputFileMode)
+			}
+
+			if err != nil {
+				return nil, fmt.Errorf("failed to download %s spec from url %s: %w", opts.Options.InputFileMode, target, err)
+			}
+
+			opts.Options.TargetsFilePath = tempFile
+		}
 	}
+
+	return http.NewHttpInputProvider(&http.HttpMultiFormatOptions{
+		InputFile: opts.Options.TargetsFilePath,
+		InputMode: opts.Options.InputFileMode,
+		Options: formats.InputFormatOptions{
+			Variables:            generators.MergeMaps(extraVars, opts.Options.Vars.AsMap()),
+			SkipFormatValidation: opts.Options.SkipFormatValidation,
+			RequiredOnly:         opts.Options.FormatUseRequiredOnly,
+			VarsTextTemplating:   opts.Options.VarsTextTemplating,
+			VarsFilePaths:        opts.Options.VarsFilePaths,
+		},
+	})
 }
 
 // SupportedInputFormats returns all supported input formats of nuclei