fix: Degrade instead of dying on multiple/relative servers; remove package die()

cmd/automate.go

@@ -1,6 +1,7 @@
 package cmd
 
 import (
+	"fmt"
 	"io"
 	"os"
 	"path/filepath"
@@ -22,10 +23,10 @@ var automateCmd = &cobra.Command{
 	Long: `The automate command sends a request to each discovered endpoint and returns the status code of the result.
 This enables the user to get a quick look at which endpoints require authentication and which ones do not. If a request
 responds in an abnormal way, manual testing should be conducted (prepare manual tests using the "prepare" command).`,
-	Run: func(cmd *cobra.Command, args []string) {
+	RunE: func(cmd *cobra.Command, args []string) error {
 		if outfile != "" && strings.ToLower(outputFormat) != "" {
 			if !strings.HasSuffix(strings.ToLower(outfile), "json") && strings.ToLower(outputFormat) != "json" {
-				die("Only the JSON output format is supported at the moment.")
+				return fmt.Errorf("only the JSON output format is supported at the moment")
 			} else if strings.HasSuffix(strings.ToLower(outfile), "json") && strings.ToLower(outputFormat) == "console" {
 				outputFormat = "json"
 			}
@@ -45,12 +46,15 @@ responds in an abnormal way, manual testing should be conducted (prepare manual
 
 		_, err := time.Parse("2006-01-02", customDate)
 		if err != nil {
-			die("An invalid date was supplied. Please supply a date in '2006-01-02' format.")
+			return fmt.Errorf("an invalid date was supplied. Please supply a date in '2006-01-02' format")
 		}
 
 		var bodyBytes []byte
 
-		client, replayClient := CheckAndConfigureProxy()
+		client, replayClient, err := CheckAndConfigureProxy()
+		if err != nil {
+			return err
+		}
 
 		if strings.ToLower(outputFormat) != "json" {
 			printInfo("\n")
@@ -58,11 +62,14 @@ responds in an abnormal way, manual testing should be conducted (prepare manual
 		}
 
 		if swaggerURL != "" {
-			bodyBytes, _, _ = MakeRequest(client, "GET", swaggerURL, timeout, nil)
+			bodyBytes, _, _, err = MakeRequest(client, "GET", swaggerURL, timeout, nil)
+			if err != nil {
+				return err
+			}
 		} else {
 			specFile, err := os.Open(localFile)
 			if err != nil {
-				die("Error opening file: %v", err)
+				return fmt.Errorf("error opening file: %v", err)
 			}
 			// Set the base directory for resolving external refs
 			specBaseDir = filepath.Dir(localFile)
@@ -79,7 +86,7 @@ responds in an abnormal way, manual testing should be conducted (prepare manual
 			log.Info("Sending requests at a rate of ", rateLimit, " requests per second.")
 		}
 		*/
-		GenerateRequests(bodyBytes, client, replayClient)
+		return GenerateRequests(bodyBytes, client, replayClient)
 	},
 }
 

cmd/brute.go

@@ -44,7 +44,7 @@ var bruteCmd = &cobra.Command{
 	Use:   "brute",
 	Short: "Sends a series of automated requests to discover hidden API operation definitions.",
 	Long:  `The brute command sends requests to the target to find operation definitions based on commonly used file locations.`,
-	Run: func(cmd *cobra.Command, args []string) {
+	RunE: func(cmd *cobra.Command, args []string) error {
 
 		/* // NEED TO RE-IMPLEMENT RATE LIMIT
 		if rateLimit <= 0 {
@@ -58,7 +58,10 @@ var bruteCmd = &cobra.Command{
 			}
 		}
 
-		client, _ := CheckAndConfigureProxy()
+		client, _, err := CheckAndConfigureProxy()
+		if err != nil {
+			return err
+		}
 
 		var allURLs []string
 		u, err := url.Parse(swaggerURL)
@@ -80,7 +83,7 @@ var bruteCmd = &cobra.Command{
 		} else {
 			endpointList, err := os.Open(endpointWordlist)
 			if err != nil {
-				die("failed to open file: %s", err)
+				return fmt.Errorf("failed to open file: %s", err)
 			}
 			defer endpointList.Close()
 
@@ -92,7 +95,7 @@ var bruteCmd = &cobra.Command{
 			}
 
 			if err := scanner.Err(); err != nil {
-				die("failed to read words from file: %s", err)
+				return fmt.Errorf("failed to read words from file: %s", err)
 			}
 		}
 		if rateLimit > 0 && strings.ToLower(outputFormat) != "json" {
@@ -101,7 +104,10 @@ var bruteCmd = &cobra.Command{
 			printInfo("Sending %d requests. This could take a while...\n", len(allURLs))
 		}
 
-		specFound, definitionFile := findDefinitionFile(allURLs, client)
+		specFound, definitionFile, err := findDefinitionFile(allURLs, client)
+		if err != nil {
+			return err
+		}
 		if specFound {
 			definedOperations, err := json.Marshal(definitionFile)
 			if err != nil {
@@ -126,7 +132,7 @@ var bruteCmd = &cobra.Command{
 				}
 			} else {
 				if endpointOnly {
-					return
+					return nil
 				} else {
 					fmt.Println(string(definedOperations))
 				}
@@ -135,6 +141,7 @@ var bruteCmd = &cobra.Command{
 		} else {
 			printErr("\nNo definition file found for:\t%s", swaggerURL)
 		}
+		return nil
 	},
 }
 
@@ -166,45 +173,52 @@ func makeURLs(target string, basePath string, endpoints []string, fileExtension
 // maxFollowDepth bounds how far brute chases discovered spec references.
 const maxFollowDepth = 3
 
-func findDefinitionFile(urls []string, client http.Client) (bool, *openapi3.T) {
+func findDefinitionFile(urls []string, client http.Client) (bool, *openapi3.T, error) {
 	seen := make(map[string]bool)
 	for i, url := range urls {
-		if found, checkSpec := checkURLForSpec(url, client, seen, 0); found {
-			return true, checkSpec
+		found, checkSpec, err := checkURLForSpec(url, client, seen, 0)
+		if err != nil {
+			return false, nil, err
+		}
+		if found {
+			return true, checkSpec, nil
 		}
 		writeProgress("Request: %d", i+1)
 	}
-	return false, nil
+	return false, nil, nil
 }
 
 // checkURLForSpec fetches one URL and validates it as an OpenAPI/Swagger
 // definition. For a Swagger UI page, initializer script, or swagger-config JSON,
 // it follows the referenced URLs (bounded by maxFollowDepth and a shared visited
 // set) so specs on non-standard paths are still found.
-func checkURLForSpec(target string, client http.Client, seen map[string]bool, depth int) (bool, *openapi3.T) {
+func checkURLForSpec(target string, client http.Client, seen map[string]bool, depth int) (bool, *openapi3.T, error) {
 	if depth > maxFollowDepth || seen[target] || isExternalDemoSpecURL(target) {
-		return false, nil
+		return false, nil, nil
 	}
 	seen[target] = true
 
 	// One request so body and Content-Type come from the same response (two
 	// separate requests can desync behind a WAF/CDN).
-	bodyBytes, bodyString, _, ctRaw, _ := MakeRequestFull(client, "GET", target, timeout, nil)
+	bodyBytes, bodyString, _, ctRaw, _, reqErr := MakeRequestFull(client, "GET", target, timeout, nil)
+	if reqErr != nil {
+		return false, nil, reqErr
+	}
 	if bodyBytes == nil {
-		return false, nil
+		return false, nil, nil
 	}
 	ct := strings.ToLower(ctRaw)
 
 	// Skip content types that cannot be a spec or reference one.
 	for _, skip := range []string{"image/", "video/", "audio/", "font/", "text/css", "application/zip", "application/pdf"} {
 		if strings.Contains(ct, skip) {
-			return false, nil
+			return false, nil, nil
 		}
 	}
 
 	if looksLikeChallengeResponse(bodyString) {
 		warnWAFChallengeOnce()
-		return false, nil
+		return false, nil, nil
 	}
 
 	// Swagger UI HTML page: follow the references it declares.
@@ -216,14 +230,14 @@ func checkURLForSpec(target string, client http.Client, seen map[string]bool, de
 	// Library bundles are excluded to avoid their internal url: strings.
 	if strings.Contains(ct, "javascript") || strings.HasSuffix(strings.ToLower(urlPath(target)), ".js") {
 		if !looksLikeSwaggerInitCandidate(target) {
-			return false, nil
+			return false, nil, nil
 		}
 		if bodyHasEmbeddedSpec(bodyString) {
 			if jsonContent, ok := ExtractJSONFromJSSpec(bodyBytes); ok {
-				checkSpec := UnmarshalSpec(jsonContent)
+				checkSpec, _ := UnmarshalSpec(jsonContent)
 				if strings.HasPrefix(checkSpec.OpenAPI, "2") || strings.HasPrefix(checkSpec.OpenAPI, "3") {
 					printInfo("Found operation definitions embedded in JavaScript file at %s\n", target)
-					return true, checkSpec
+					return true, checkSpec, nil
 				}
 			}
 		}
@@ -240,10 +254,10 @@ func checkURLForSpec(target string, client http.Client, seen map[string]bool, de
 	}
 
 	// Otherwise treat the body as a candidate spec and validate by parsing.
-	checkSpec := UnmarshalSpec(bodyBytes)
+	checkSpec, _ := UnmarshalSpec(bodyBytes)
 	if (strings.HasPrefix(checkSpec.OpenAPI, "2") || strings.HasPrefix(checkSpec.OpenAPI, "3")) && checkSpec.Paths != nil {
 		printInfo("Definition file found: %s\n", target)
-		return true, checkSpec
+		return true, checkSpec, nil
 	}
 
 	// Not a spec: may be a swagger-config document that references one.
@@ -251,13 +265,17 @@ func checkURLForSpec(target string, client http.Client, seen map[string]bool, de
 }
 
 // followReferences recurses into a set of discovered spec/reference URLs.
-func followReferences(refs []string, client http.Client, seen map[string]bool, depth int) (bool, *openapi3.T) {
+func followReferences(refs []string, client http.Client, seen map[string]bool, depth int) (bool, *openapi3.T, error) {
 	for _, ref := range refs {
-		if found, checkSpec := checkURLForSpec(ref, client, seen, depth+1); found {
-			return true, checkSpec
+		found, checkSpec, err := checkURLForSpec(ref, client, seen, depth+1)
+		if err != nil {
+			return false, nil, err
+		}
+		if found {
+			return true, checkSpec, nil
 		}
 	}
-	return false, nil
+	return false, nil, nil
 }
 
 func init() {
@@ -357,7 +375,7 @@ func ExtractSpecFromJS(bodyBytes []byte) []byte {
 	return bodyBytes
 }
 
-func UnmarshalSpec(bodyBytes []byte) (newDoc *openapi3.T) {
+func UnmarshalSpec(bodyBytes []byte) (*openapi3.T, error) {
 	var doc openapi2.T
 	var doc3 openapi3.T
 
@@ -373,19 +391,19 @@ func UnmarshalSpec(bodyBytes []byte) (newDoc *openapi3.T) {
 	_ = json.Unmarshal(bodyBytes, &doc3)
 
 	if strings.HasPrefix(doc3.OpenAPI, "3") {
-		newDoc := &doc3
-		return newDoc
+		return &doc3, nil
 	} else if strings.HasPrefix(doc.Swagger, "2") {
 		newDoc, err := openapi2conv.ToV3(&doc)
 		if err != nil {
 			printErr("Error converting v2 document to v3: %s", err)
 		}
-		return newDoc
+		return newDoc, nil
 	} else if Mode == "brute" {
 		var noDoc openapi3.T
-		return &noDoc
+		return &noDoc, nil
 	} else {
-		die("Error parsing definition file.")
-		return nil
+		// Return a non-nil doc alongside the error so callers that ignore the
+		// error don't dereference nil.
+		return &openapi3.T{}, fmt.Errorf("error parsing definition file")
 	}
 }

cmd/convert.go

@@ -19,7 +19,7 @@ var convertCmd = &cobra.Command{
 	Use:   "convert",
 	Short: "Converts a Swagger definition file to an OpenAPI v3 definition file.",
 	Long:  `The convert command converts a provided definition file from the Swagger specification (v2) to the OpenAPI specification (v3) and stores it into an output file.`,
-	Run: func(cmd *cobra.Command, args []string) {
+	RunE: func(cmd *cobra.Command, args []string) error {
 
 		var bodyBytes []byte
 
@@ -29,7 +29,10 @@ var convertCmd = &cobra.Command{
 			}
 		}
 
-		client, _ := CheckAndConfigureProxy()
+		client, _, err := CheckAndConfigureProxy()
+		if err != nil {
+			return err
+		}
 
 		if strings.ToLower(outputFormat) != "json" {
 			printInfo("\n")
@@ -37,11 +40,14 @@ var convertCmd = &cobra.Command{
 		}
 
 		if swaggerURL != "" {
-			bodyBytes, _, _ = MakeRequest(client, "GET", swaggerURL, timeout, nil)
+			bodyBytes, _, _, err = MakeRequest(client, "GET", swaggerURL, timeout, nil)
+			if err != nil {
+				return err
+			}
 		} else {
 			specFile, err := os.Open(localFile)
 			if err != nil {
-				die("Error opening definition file: %v", err)
+				return fmt.Errorf("error opening definition file: %v", err)
 			}
 
 			bodyBytes, _ = io.ReadAll(specFile)
@@ -75,7 +81,7 @@ var convertCmd = &cobra.Command{
 				}
 				converted, err := json.Marshal(newDoc)
 				if err != nil {
-					die("Error converting definition file to v3: %v", err)
+					return fmt.Errorf("error converting definition file to v3: %v", err)
 				}
 				if !strings.HasSuffix(string(converted), "}") {
 					if outfile == "" {
@@ -94,7 +100,7 @@ var convertCmd = &cobra.Command{
 			case "yaml", "yml":
 				converted, err := yaml.Marshal(newDoc)
 				if err != nil {
-					die("Error converting definition file to v3: %v", err)
+					return fmt.Errorf("error converting definition file to v3: %v", err)
 				}
 				if outfile == "" {
 					fmt.Println(string(converted))
@@ -104,8 +110,9 @@ var convertCmd = &cobra.Command{
 			}
 
 		} else {
-			die("Error parsing definition file.")
+			return fmt.Errorf("error parsing definition file")
 		}
+		return nil
 	},
 }
 

cmd/endpoints.go

@@ -1,6 +1,7 @@
 package cmd
 
 import (
+	"fmt"
 	"io"
 	"os"
 	"path/filepath"
@@ -13,14 +14,17 @@ var endpointsCmd = &cobra.Command{
 	Short: "Prints a list of endpoints from the target.",
 	Long: `The endpoints command allows you to pull a list of endpoints out of a Swagger definition file.
 This list contains the raw endpoints (parameter values will not be appended or modified).`,
-	Run: func(cmd *cobra.Command, args []string) {
+	RunE: func(cmd *cobra.Command, args []string) error {
 		if randomUserAgent {
 			if UserAgent != "Swagger Jacker (github.com/BishopFox/sj)" {
 				printWarn("A supplied User Agent was detected (%s) while supplying the 'random-user-agent' flag.", UserAgent)
 			}
 		}
 
-		client, _ := CheckAndConfigureProxy()
+		client, _, err := CheckAndConfigureProxy()
+		if err != nil {
+			return err
+		}
 
 		var bodyBytes []byte
 
@@ -28,22 +32,25 @@ This list contains the raw endpoints (parameter values will not be appended or m
 		printInfo("Gathering endpoints.\n\n")
 
 		if swaggerURL != "" {
-			bodyBytes, _, _ = MakeRequest(client, "GET", swaggerURL, timeout, nil)
-			GenerateRequests(bodyBytes, client, nil)
-		} else {
-			specFile, err := os.Open(localFile)
+			bodyBytes, _, _, err = MakeRequest(client, "GET", swaggerURL, timeout, nil)
 			if err != nil {
-				die("Error opening file: %v", err)
+				return err
 			}
-			// Set the base directory for resolving external refs
-			specBaseDir = filepath.Dir(localFile)
-			if specBaseDir == "." {
-				if absPath, err := filepath.Abs(localFile); err == nil {
-					specBaseDir = filepath.Dir(absPath)
-				}
-			}
-			bodyBytes, _ = io.ReadAll(specFile)
-			GenerateRequests(bodyBytes, client, nil)
+			return GenerateRequests(bodyBytes, client, nil)
 		}
+
+		specFile, err := os.Open(localFile)
+		if err != nil {
+			return fmt.Errorf("error opening file: %v", err)
+		}
+		// Set the base directory for resolving external refs
+		specBaseDir = filepath.Dir(localFile)
+		if specBaseDir == "." {
+			if absPath, err := filepath.Abs(localFile); err == nil {
+				specBaseDir = filepath.Dir(absPath)
+			}
+		}
+		bodyBytes, _ = io.ReadAll(specFile)
+		return GenerateRequests(bodyBytes, client, nil)
 	},
 }

cmd/log.go

@@ -80,11 +80,6 @@ func printErr(format string, args ...interface{}) {
 	fmt.Fprintf(os.Stderr, "%s %s\n", red("[✗]"), msg)
 }
 
-func die(format string, args ...interface{}) {
-	printErr(format, args...)
-	os.Exit(1)
-}
-
 // writeLog is the main dispatch function for endpoint results.
 func writeLog(sc int, target, method, errorMsg, response, security string, missingAuth bool) {
 	var out io.Writer = os.Stdout
@@ -97,14 +92,16 @@ func writeLog(sc int, target, method, errorMsg, response, security string, missi
 	if outfile != "" {
 		file, err := os.OpenFile(outfile, os.O_RDWR|os.O_APPEND|os.O_CREATE, 0644)
 		if err != nil {
-			fmt.Fprintln(os.Stderr, "Output file does not exist or cannot be created")
-			os.Exit(1)
+			// Package code must not exit the process; fall back to stdout so the
+			// results are still emitted.
+			printErr("Output file '%s' cannot be opened; writing to stdout instead.", outfile)
+		} else {
+			defer file.Close()
+			out = file
+			// Disable color when writing to a file.
+			color.NoColor = true
+			defer func() { color.NoColor = false }()
 		}
-		defer file.Close()
-		out = file
-		// Disable color when writing to a file.
-		color.NoColor = true
-		defer func() { color.NoColor = false }()
 	}
 
 	preview := ""

cmd/prepare.go

@@ -1,6 +1,7 @@
 package cmd
 
 import (
+	"fmt"
 	"io"
 	"os"
 	"path/filepath"
@@ -14,7 +15,7 @@ var prepareCmd = &cobra.Command{
 	Short: "Prepares a set of commands for manual testing of each endpoint.",
 	Long: `The prepare command prepares a set of commands for manual testing of each endpoint.
 This enables you to test specific API functions for common vulnerabilities or misconfigurations.`,
-	Run: func(cmd *cobra.Command, args []string) {
+	RunE: func(cmd *cobra.Command, args []string) error {
 
 		if randomUserAgent {
 			if UserAgent != "Swagger Jacker (github.com/BishopFox/sj)" {
@@ -24,32 +25,38 @@ This enables you to test specific API functions for common vulnerabilities or mi
 
 		_, err := time.Parse("2006-01-02", customDate)
 		if err != nil {
-			die("An invalid date was supplied. Please supply a date in '2006-01-02' format.")
+			return fmt.Errorf("an invalid date was supplied. Please supply a date in '2006-01-02' format")
 		}
 
-		client, _ := CheckAndConfigureProxy()
+		client, _, err := CheckAndConfigureProxy()
+		if err != nil {
+			return err
+		}
 
 		printInfo("\n")
 		printInfo("Gathering API details.\n\n")
 		if swaggerURL != "" {
-			bodyBytes, _, _ := MakeRequest(client, "GET", swaggerURL, timeout, nil)
-			GenerateRequests(bodyBytes, client, nil)
-		} else {
-			specFile, err := os.Open(localFile)
+			bodyBytes, _, _, err := MakeRequest(client, "GET", swaggerURL, timeout, nil)
 			if err != nil {
-				die("Error opening file: %v", err)
+				return err
 			}
-			// Set the base directory for resolving external refs
-			specBaseDir = filepath.Dir(localFile)
-			if specBaseDir == "." {
-				if absPath, err := filepath.Abs(localFile); err == nil {
-					specBaseDir = filepath.Dir(absPath)
-				}
-			}
-
-			specBytes, _ := io.ReadAll(specFile)
-			GenerateRequests(specBytes, client, nil)
+			return GenerateRequests(bodyBytes, client, nil)
 		}
+
+		specFile, err := os.Open(localFile)
+		if err != nil {
+			return fmt.Errorf("error opening file: %v", err)
+		}
+		// Set the base directory for resolving external refs
+		specBaseDir = filepath.Dir(localFile)
+		if specBaseDir == "." {
+			if absPath, err := filepath.Abs(localFile); err == nil {
+				specBaseDir = filepath.Dir(absPath)
+			}
+		}
+
+		specBytes, _ := io.ReadAll(specFile)
+		return GenerateRequests(specBytes, client, nil)
 	},
 }
 var prepareFor string

cmd/requests.go

@@ -157,9 +157,9 @@ func dangerousRequestDeclined(target string) bool {
 
 // MakeRequest returns the body bytes, body string, and status code. It wraps
 // MakeRequestFull for callers that do not need the Content-Type.
-func MakeRequest(client http.Client, method, target string, timeout int64, reqData io.Reader) ([]byte, string, int) {
-	bodyBytes, bodyString, status, _, _ := MakeRequestFull(client, method, target, timeout, reqData)
-	return bodyBytes, bodyString, status
+func MakeRequest(client http.Client, method, target string, timeout int64, reqData io.Reader) ([]byte, string, int, error) {
+	bodyBytes, bodyString, status, _, _, err := MakeRequestFull(client, method, target, timeout, reqData)
+	return bodyBytes, bodyString, status, err
 }
 
 // splitWords lowercases s and splits it into words on non-alphanumeric
@@ -217,7 +217,7 @@ func requestWords(u *url.URL) map[string]bool {
 
 // MakeRequestFull also returns the response Content-Type and the User-Agent sent.
 // Taking body and Content-Type from one response avoids a second request per URL.
-func MakeRequestFull(client http.Client, method, target string, timeout int64, reqData io.Reader) ([]byte, string, int, string, string) {
+func MakeRequestFull(client http.Client, method, target string, timeout int64, reqData io.Reader) ([]byte, string, int, string, string, error) {
 	if quiet {
 		avoidDangerousRequests = "y"
 	}
@@ -226,10 +226,10 @@ func MakeRequestFull(client http.Client, method, target string, timeout int64, r
 	u, err := url.Parse(target)
 	if err != nil || u == nil {
 		printWarn("Error parsing URL '%s': %v - skipping request.", target, err)
-		return nil, "", 0, "", ""
+		return nil, "", 0, "", "", nil
 	}
 	if Mode == "automate" && target != approvedTarget && dangerousRequestDeclined(target) {
-		return nil, "", 0, "", ""
+		return nil, "", 0, "", "", nil
 	}
 
 	ctx, cancel := context.WithTimeout(context.Background(), time.Duration(timeout)*time.Second)
@@ -247,9 +247,9 @@ func MakeRequestFull(client http.Client, method, target string, timeout int64, r
 	req, err := http.NewRequest(method, target, body)
 	if err != nil {
 		if err != context.Canceled && err != io.EOF {
-			die("Error: could not create HTTP request - %v", err)
+			return nil, "", 0, "", "", fmt.Errorf("could not create HTTP request - %v", err)
 		}
-		return nil, "", 0, "", ""
+		return nil, "", 0, "", "", nil
 	}
 
 	sentUserAgent := applyHeaders(req, "")
@@ -257,18 +257,18 @@ func MakeRequestFull(client http.Client, method, target string, timeout int64, r
 	resp, err := client.Do(req.WithContext(ctx))
 	if err == context.DeadlineExceeded {
 		printWarn("Error: %s - skipping request.", err)
-		return nil, "", 0, "", ""
+		return nil, "", 0, "", "", nil
 	} else if err != nil && err != context.Canceled && err != io.EOF {
 		if (strings.Contains(fmt.Sprint(err), "tls") || strings.Contains(fmt.Sprint(err), "x509")) && !strings.Contains(fmt.Sprint(err), "user canceled") {
-			die("Try supplying the --insecure flag.")
+			return nil, "", 0, "", "", fmt.Errorf("Try supplying the --insecure flag.")
 		} else if strings.Contains(fmt.Sprint(err), "tcp") && strings.Contains(fmt.Sprint(err), "no such host") {
-			die("The target '%s' is not reachable. Check the declared host(s) and supply a target manually using -T if needed.", u.Scheme+"://"+u.Host)
+			return nil, "", 0, "", "", fmt.Errorf("The target '%s' is not reachable. Check the declared host(s) and supply a target manually using -T if needed.", u.Scheme+"://"+u.Host)
 		} else if strings.Contains(fmt.Sprint(err), "user canceled") {
-			return nil, "skipped", 1, "", ""
+			return nil, "skipped", 1, "", "", nil
 		} else {
 			printErr("Error: response not received.\n%v", err)
 		}
-		return nil, "", 0, "", ""
+		return nil, "", 0, "", "", nil
 	}
 
 	bodyBytes, _ := io.ReadAll(resp.Body)
@@ -281,23 +281,24 @@ func MakeRequestFull(client http.Client, method, target string, timeout int64, r
 		if locErr != nil || redirect == nil {
 			requestStatus = resp.StatusCode
 			depth = 0
-			return bodyBytes, bodyString, requestStatus, contentTypeHeader, sentUserAgent
+			return bodyBytes, bodyString, requestStatus, contentTypeHeader, sentUserAgent, nil
 		}
 		depth += 1
 		var ct, ua string
+		var rerr error
 		// redirect.String() keeps the query string, and the buffered body is
 		// replayed through a fresh reader.
-		bodyBytes, bodyString, requestStatus, ct, ua = MakeRequestFull(client, method, redirect.String(), timeout, bytes.NewReader(reqBody))
-		return bodyBytes, bodyString, requestStatus, ct, ua
+		bodyBytes, bodyString, requestStatus, ct, ua, rerr = MakeRequestFull(client, method, redirect.String(), timeout, bytes.NewReader(reqBody))
+		return bodyBytes, bodyString, requestStatus, ct, ua, rerr
 	}
 
 	requestStatus = resp.StatusCode
 	depth = 0
 
-	return bodyBytes, bodyString, requestStatus, contentTypeHeader, sentUserAgent
+	return bodyBytes, bodyString, requestStatus, contentTypeHeader, sentUserAgent, nil
 }
 
-func CheckAndConfigureProxy() (client http.Client, replayClient *http.Client) {
+func CheckAndConfigureProxy() (client http.Client, replayClient *http.Client, err error) {
 	var proxyUrl *url.URL
 
 	transport := &http.Transport{}
@@ -323,9 +324,9 @@ func CheckAndConfigureProxy() (client http.Client, replayClient *http.Client) {
 		if insecure {
 			replayTransport.TLSClientConfig = &tls.Config{InsecureSkipVerify: true}
 		}
-		replayProxyUrl, err := url.Parse(replayProxy)
-		if err != nil {
-			die("Error parsing replay proxy URL: %v", err)
+		replayProxyUrl, parseErr := url.Parse(replayProxy)
+		if parseErr != nil {
+			return client, replayClient, fmt.Errorf("error parsing replay proxy URL: %v", parseErr)
 		}
 		replayTransport.Proxy = http.ProxyURL(replayProxyUrl)
 		replayClient = &http.Client{
@@ -336,7 +337,7 @@ func CheckAndConfigureProxy() (client http.Client, replayClient *http.Client) {
 		}
 	}
 
-	return client, replayClient
+	return client, replayClient, nil
 }
 
 // userAgent is the one the replayed request carried, so the copy reproduces it.

cmd/requests_test.go

@@ -112,7 +112,7 @@ func TestRedirectPreservesBodyAndQuery(t *testing.T) {
 	}}
 
 	want := `{"name":"bishopfox"}`
-	_, _, sc, _, _ := MakeRequestFull(client, "PUT", redirector.URL+"/first", 30, bytes.NewReader([]byte(want)))
+	_, _, sc, _, _, _ := MakeRequestFull(client, "PUT", redirector.URL+"/first", 30, bytes.NewReader([]byte(want)))
 
 	if sc != http.StatusOK {
 		t.Errorf("redirect not followed: status %d, want %d", sc, http.StatusOK)

cmd/root.go

@@ -1,6 +1,9 @@
 package cmd
 
 import (
+	"fmt"
+	"os"
+
 	"github.com/spf13/cobra"
 )
 
@@ -58,16 +61,27 @@ $ sj convert -u https://petstore.swagger.io/v2/swagger.json -o openapi.json`,
 	PersistentPreRun: func(cmd *cobra.Command, args []string) {
 		Mode = cmd.Name()
 	},
-	Run: func(cmd *cobra.Command, args []string) {
+	RunE: func(cmd *cobra.Command, args []string) error {
 		if len(args) < 1 {
-			printErr("Command not specified. See the --help flag for usage.")
+			return fmt.Errorf("command not specified. See the --help flag for usage")
 		}
+		return nil
 	},
 	Version: "2.8.2",
+	// Errors and usage are surfaced once by Execute() with our own styling, so
+	// cobra should not also print them on a RunE failure.
+	SilenceErrors: true,
+	SilenceUsage:  true,
 }
 
+// Execute runs the root command. It is the single place in the package that
+// terminates the process: command and library code return errors up to here
+// instead of calling os.Exit, which keeps that logic testable and reusable.
 func Execute() {
-	cobra.CheckErr(rootCmd.Execute())
+	if err := rootCmd.Execute(); err != nil {
+		printErr("%v", err)
+		os.Exit(1)
+	}
 }
 
 func init() {

cmd/utils.go

@@ -40,10 +40,10 @@ type SchemaNode struct {
 	AdditionalProperties *SchemaNode
 }
 
-func BuildRequestsFromPaths(spec map[string]interface{}, client http.Client, replayClient *http.Client) {
+func BuildRequestsFromPaths(spec map[string]interface{}, client http.Client, replayClient *http.Client) error {
 	paths, ok := spec["paths"].(map[string]interface{})
 	if !ok || paths == nil {
-		die("Could not find any defined operations. Review the file manually.")
+		return fmt.Errorf("could not find any defined operations. Review the file manually")
 	}
 
 	pathKeys := make([]string, 0, len(paths))
@@ -364,7 +364,10 @@ func BuildRequestsFromPaths(spec map[string]interface{}, client http.Client, rep
 								// the wire cannot disagree.
 								sentBody := []byte(v.body)
 
-								_, resp, sc, _, sentUA := MakeRequestFull(client, strings.ToUpper(method), targetURL, timeout, bytes.NewReader(sentBody))
+								_, resp, sc, _, sentUA, reqErr := MakeRequestFull(client, strings.ToUpper(method), targetURL, timeout, bytes.NewReader(sentBody))
+								if reqErr != nil {
+									return reqErr
+								}
 
 								tempResponsePreviewLength := responsePreviewLength
 								if len(resp) <= responsePreviewLength {
@@ -456,19 +459,20 @@ func BuildRequestsFromPaths(spec map[string]interface{}, client http.Client, rep
 			if verbose {
 				err := json.Unmarshal([]byte(strings.TrimPrefix(jsonResultsStringArray[r], ",")), &verboseResult)
 				if err != nil {
-					die("Error marshalling JSON: %v", err)
+					return fmt.Errorf("error unmarshalling JSON: %v", err)
 				}
 				jsonVerboseResultArray = append(jsonVerboseResultArray, verboseResult)
 			} else {
 				err := json.Unmarshal([]byte(strings.TrimPrefix(jsonResultsStringArray[r], ",")), &result)
 				if err != nil {
-					die("Error marshalling JSON: %v", err)
+					return fmt.Errorf("error unmarshalling JSON: %v", err)
 				}
 				jsonResultArray = append(jsonResultArray, result)
 			}
 		}
 		writeLog(8899, "", "", "", "", "", false)
 	}
+	return nil
 }
 
 func EnforceSingleContentType(newContentType string) {
@@ -679,7 +683,7 @@ func GenerateExample(node *SchemaNode) interface{} {
 	}
 }
 
-func GenerateRequests(bodyBytes []byte, client http.Client, replayClient *http.Client) {
+func GenerateRequests(bodyBytes []byte, client http.Client, replayClient *http.Client) error {
 	// Swagger UI bundles serve the spec wrapped in JavaScript (e.g.
 	// swagger-ui-init.js). Detect that and unwrap before parsing so the
 	// downstream YAML/JSON unmarshal succeeds.
@@ -690,7 +694,10 @@ func GenerateRequests(bodyBytes []byte, client http.Client, replayClient *http.C
 	}
 
 	// Ingests the specification file
-	spec := SafelyUnmarshalSpec(bodyBytes)
+	spec, err := SafelyUnmarshalSpec(bodyBytes)
+	if err != nil {
+		return err
+	}
 
 	// Checks defined security schemes and prompts for authentication
 	CheckSecuritySchemes(spec)
@@ -741,44 +748,42 @@ func GenerateRequests(bodyBytes []byte, client http.Client, replayClient *http.C
 	} else if v, ok := spec["openapi"].(string); ok && strings.HasPrefix(v, "3") {
 		// OpenAPI (v3)
 		if servers, ok := spec["servers"].([]interface{}); ok && len(servers) > 0 {
-			if len(servers) > 1 {
-				if !quiet && (Mode != "endpoints") && apiTarget == "" {
-					printWarn("Multiple servers detected in documentation. You can manually set a server to test with the -T flag.\nThe detected servers are as follows:")
-					for i := range servers {
-						if srv, ok := servers[i].(map[string]interface{}); ok {
-							if serverURL, ok := srv["url"].(string); ok {
-								printInfo("%s\n", serverURL)
-							}
+			// When several servers are declared and the user hasn't pinned one
+			// with -T, warn and fall through to the first declared server rather
+			// than aborting the run.
+			if len(servers) > 1 && !quiet && Mode != "endpoints" && apiTarget == "" {
+				printWarn("Multiple servers detected in documentation. Defaulting to the first; set a specific server with the -T flag.\nThe detected servers are as follows:")
+				for i := range servers {
+					if srv, ok := servers[i].(map[string]interface{}); ok {
+						if serverURL, ok := srv["url"].(string); ok {
+							printInfo("%s\n", serverURL)
 						}
 					}
 				}
-			} else {
-				if srv, ok := servers[0].(map[string]interface{}); ok {
-					if serverURL, ok := srv["url"].(string); ok {
-						if strings.Contains(serverURL, "://") {
-							// Full URL in server
-							if parsedServerURL, err := url.Parse(serverURL); err == nil {
-								basePath = normalizeBasePath(parsedServerURL.Path)
-								if apiTarget == "" {
-									apiTarget = parsedServerURL.Scheme + "://" + parsedServerURL.Host
-								}
-							}
-						} else if serverURL == "/" {
-							basePath = ""
-						} else {
-							// Relative URL - this becomes the basePath
-							basePath = normalizeBasePath(serverURL)
-							// Only try to construct apiTarget if -T wasn't used
+			}
+			if srv, ok := servers[0].(map[string]interface{}); ok {
+				if serverURL, ok := srv["url"].(string); ok {
+					if strings.Contains(serverURL, "://") {
+						// Full URL in server
+						if parsedServerURL, err := url.Parse(serverURL); err == nil {
+							basePath = normalizeBasePath(parsedServerURL.Path)
 							if apiTarget == "" {
-								if u.Scheme != "" && u.Host != "" {
-									apiTarget = u.Scheme + "://" + u.Host
-								} else {
-									// Local file with relative server URL and no -T flag
-									// Only fail for commands that need full URLs
-									if Mode != "endpoints" {
-										die("Spec has relative server URL '%s' but no base URL available. Use -T to specify target server.", serverURL)
-									}
-								}
+								apiTarget = parsedServerURL.Scheme + "://" + parsedServerURL.Host
+							}
+						}
+					} else if serverURL == "/" {
+						basePath = ""
+					} else {
+						// Relative URL - this becomes the basePath
+						basePath = normalizeBasePath(serverURL)
+						// Only try to construct apiTarget if -T wasn't used
+						if apiTarget == "" {
+							if u.Scheme != "" && u.Host != "" {
+								apiTarget = u.Scheme + "://" + u.Host
+							} else if Mode != "endpoints" {
+								// Local file with relative server URL and no -T flag:
+								// there is no host to resolve, so this can't proceed.
+								return fmt.Errorf("spec has relative server URL '%s' but no base URL available. Use -T to specify target server", serverURL)
 							}
 						}
 					}
@@ -791,12 +796,10 @@ func GenerateRequests(bodyBytes []byte, client http.Client, replayClient *http.C
 	if apiTarget == "" {
 		if u.Scheme != "" && u.Host != "" {
 			apiTarget = u.Scheme + "://" + u.Host
-		} else {
-			// No server info and no URL to parse - require user to specify target
-			// Only fail for commands that need full URLs
-			if Mode != "endpoints" {
-				die("No server information found in spec and no URL provided. Use -T to specify target server.")
-			}
+		} else if Mode != "endpoints" {
+			// No server info and no URL to parse - require user to specify target.
+			// Only fail for commands that need full URLs.
+			return fmt.Errorf("no server information found in spec and no URL provided. Use -T to specify target server")
 		}
 	}
 
@@ -806,7 +809,7 @@ func GenerateRequests(bodyBytes []byte, client http.Client, replayClient *http.C
 	}
 
 	// Reviews all defined API routes and builds requests as defined
-	BuildRequestsFromPaths(spec, client, replayClient)
+	return BuildRequestsFromPaths(spec, client, replayClient)
 }
 
 func ResolveRef(spec map[string]interface{}, ref string) map[string]interface{} {
@@ -975,8 +978,8 @@ func ResolveExternalRef(ref string, baseDir string) map[string]interface{} {
 		return nil
 	}
 
-	externalSpec := SafelyUnmarshalSpec(fileData)
-	if externalSpec == nil {
+	externalSpec, err := SafelyUnmarshalSpec(fileData)
+	if err != nil || externalSpec == nil {
 		return nil
 	}
 
@@ -1052,14 +1055,14 @@ func looksLikeJSSpec(b []byte) bool {
 	return false
 }
 
-func SafelyUnmarshalSpec(data []byte) map[string]interface{} {
+func SafelyUnmarshalSpec(data []byte) (map[string]interface{}, error) {
 
 	var doc map[string]interface{}
 	if err := yaml.Unmarshal(data, &doc); err != nil {
-		die("Failed to unmarshal API documentation: %v", err)
+		return nil, fmt.Errorf("failed to unmarshal API documentation: %v", err)
 	}
 
-	return doc
+	return doc, nil
 }
 
 /*

cmd/utils_test.go

@@ -34,7 +34,7 @@ func TestSwaggerV2SchemeHandling(t *testing.T) {
 		return
 	}
 
-	spec := SafelyUnmarshalSpec(data)
+	spec, _ := SafelyUnmarshalSpec(data)
 	if spec == nil {
 		t.Fatal("Failed to unmarshal spec")
 	}
@@ -75,7 +75,7 @@ func TestExternalReferenceResolution(t *testing.T) {
 		return
 	}
 
-	spec := SafelyUnmarshalSpec(data)
+	spec, _ := SafelyUnmarshalSpec(data)
 	if spec == nil {
 		t.Fatal("Failed to unmarshal spec")
 	}
@@ -122,7 +122,7 @@ func TestNestedExternalReferences(t *testing.T) {
 		return
 	}
 
-	externalSpec := SafelyUnmarshalSpec(data)
+	externalSpec, _ := SafelyUnmarshalSpec(data)
 	if externalSpec == nil {
 		t.Fatal("Failed to unmarshal external schema")
 	}
@@ -180,7 +180,7 @@ func TestQueryObjectParameterHandling(t *testing.T) {
 		return
 	}
 
-	spec := SafelyUnmarshalSpec(data)
+	spec, _ := SafelyUnmarshalSpec(data)
 	if spec == nil {
 		t.Fatal("Failed to unmarshal spec")
 	}
@@ -243,7 +243,7 @@ func TestRequestBodyContextPreservation(t *testing.T) {
 		return
 	}
 
-	spec := SafelyUnmarshalSpec(data)
+	spec, _ := SafelyUnmarshalSpec(data)
 	if spec == nil {
 		t.Fatal("Failed to unmarshal spec")
 	}
@@ -298,7 +298,7 @@ func TestDefaultValueHandling(t *testing.T) {
 		return
 	}
 
-	spec := SafelyUnmarshalSpec(data)
+	spec, _ := SafelyUnmarshalSpec(data)
 	if spec == nil {
 		t.Fatal("Failed to unmarshal spec")
 	}
@@ -366,7 +366,7 @@ func TestJSONCurlQuoting(t *testing.T) {
 		return
 	}
 
-	spec := SafelyUnmarshalSpec(data)
+	spec, _ := SafelyUnmarshalSpec(data)
 	if spec == nil {
 		t.Fatal("Failed to unmarshal spec")
 	}
@@ -467,7 +467,7 @@ func TestRelativeServerURLHandling(t *testing.T) {
 		return
 	}
 
-	spec := SafelyUnmarshalSpec(data)
+	spec, _ := SafelyUnmarshalSpec(data)
 	if spec == nil {
 		t.Fatal("Failed to unmarshal spec")
 	}
@@ -546,7 +546,7 @@ func TestTargetFlagPreservesSpecBasePath(t *testing.T) {
 		return
 	}
 
-	spec := SafelyUnmarshalSpec(data)
+	spec, _ := SafelyUnmarshalSpec(data)
 	if spec == nil {
 		t.Fatal("Failed to unmarshal spec")
 	}
@@ -599,7 +599,7 @@ func TestOpenAPIv3AbsoluteServerURLWithTargetFlag(t *testing.T) {
 		return
 	}
 
-	spec := SafelyUnmarshalSpec(data)
+	spec, _ := SafelyUnmarshalSpec(data)
 	if spec == nil {
 		t.Fatal("Failed to unmarshal spec")
 	}
@@ -669,7 +669,7 @@ func TestOpenAPIv3AbsoluteServerURLWithoutTargetFlag(t *testing.T) {
 		return
 	}
 
-	spec := SafelyUnmarshalSpec(data)
+	spec, _ := SafelyUnmarshalSpec(data)
 	if spec == nil {
 		t.Fatal("Failed to unmarshal spec")
 	}
@@ -704,6 +704,87 @@ func TestOpenAPIv3AbsoluteServerURLWithoutTargetFlag(t *testing.T) {
 	}
 }
 
+// withResolveGlobals saves and restores the globals GenerateRequests reads while
+// resolving a target, so these tests don't leak state into one another.
+func withResolveGlobals(t *testing.T, mode string, fn func()) {
+	t.Helper()
+	oldMode, oldSwaggerURL, oldAPITarget, oldBasePath, oldQuiet := Mode, swaggerURL, apiTarget, basePath, quiet
+	defer func() {
+		Mode, swaggerURL, apiTarget, basePath, quiet = oldMode, oldSwaggerURL, oldAPITarget, oldBasePath, oldQuiet
+	}()
+	Mode = mode
+	swaggerURL = ""
+	apiTarget = ""
+	basePath = ""
+	quiet = true
+	fn()
+}
+
+// TestGenerateRequestsMultipleServersDefaultsToFirst verifies that a spec
+// declaring several servers no longer aborts the run (previously a fatal die()):
+// GenerateRequests resolves against the first declared server instead.
+func TestGenerateRequestsMultipleServersDefaultsToFirst(t *testing.T) {
+	spec := []byte(`{"openapi":"3.0.0","info":{"title":"t","version":"1"},"servers":[{"url":"https://api1.example.com/v1"},{"url":"https://api2.example.com/v2"}],"paths":{"/users":{"get":{"responses":{"200":{"description":"ok"}}}}}}`)
+
+	withResolveGlobals(t, "endpoints", func() {
+		var err error
+		_ = captureStdout(t, func() { err = GenerateRequests(spec, http.Client{}, nil) })
+		if err != nil {
+			t.Fatalf("expected no error for multiple servers, got: %v", err)
+		}
+		if apiTarget != "https://api1.example.com" {
+			t.Errorf("expected apiTarget to default to first server host, got '%s'", apiTarget)
+		}
+		if basePath != "/v1" {
+			t.Errorf("expected basePath from first server, got '%s'", basePath)
+		}
+	})
+}
+
+// TestGenerateRequestsRelativeServerURLWithoutTargetReturnsError verifies the
+// relative-server-URL-with-no-base case now returns an error (it used to die()
+// and exit the process), so callers can surface it gracefully.
+func TestGenerateRequestsRelativeServerURLWithoutTargetReturnsError(t *testing.T) {
+	spec := []byte(`{"openapi":"3.0.0","info":{"title":"t","version":"1"},"servers":[{"url":"/api"}],"paths":{"/users":{"get":{"responses":{"200":{"description":"ok"}}}}}}`)
+
+	withResolveGlobals(t, "automate", func() {
+		var err error
+		_ = captureStdout(t, func() { err = GenerateRequests(spec, http.Client{}, nil) })
+		if err == nil {
+			t.Fatal("expected an error for relative server URL with no base and no -T, got nil")
+		}
+	})
+}
+
+// TestGenerateRequestsRelativeServerURLEndpointsModeNoError confirms the
+// endpoints-mode exemption is preserved: listing endpoints needs no host, so the
+// same ambiguous spec resolves without error.
+func TestGenerateRequestsRelativeServerURLEndpointsModeNoError(t *testing.T) {
+	spec := []byte(`{"openapi":"3.0.0","info":{"title":"t","version":"1"},"servers":[{"url":"/api"}],"paths":{"/users":{"get":{"responses":{"200":{"description":"ok"}}}}}}`)
+
+	withResolveGlobals(t, "endpoints", func() {
+		var err error
+		_ = captureStdout(t, func() { err = GenerateRequests(spec, http.Client{}, nil) })
+		if err != nil {
+			t.Fatalf("expected no error in endpoints mode, got: %v", err)
+		}
+	})
+}
+
+// TestGenerateRequestsNoServerNoURLReturnsError verifies the no-server-info and
+// no-URL case now returns an error rather than exiting the process.
+func TestGenerateRequestsNoServerNoURLReturnsError(t *testing.T) {
+	spec := []byte(`{"openapi":"3.0.0","info":{"title":"t","version":"1"},"paths":{"/users":{"get":{"responses":{"200":{"description":"ok"}}}}}}`)
+
+	withResolveGlobals(t, "automate", func() {
+		var err error
+		_ = captureStdout(t, func() { err = GenerateRequests(spec, http.Client{}, nil) })
+		if err == nil {
+			t.Fatal("expected an error when no server info and no URL are available, got nil")
+		}
+	})
+}
+
 func TestNormalizeBasePath(t *testing.T) {
 	cases := []struct {
 		in   string