[WIP] handle edge cases in the name query parameter

hello_server.go

@@ -6,6 +6,8 @@ import (
 	"net/http"
 	"os"
 	"os/signal"
+	"regexp"
+	"strings"
 	"syscall"
 	"time"
 
@@ -15,14 +17,34 @@ import (
 func handler(w http.ResponseWriter, r *http.Request) {
 	query := r.URL.Query()
 	name := query.Get("name")
-	log.Printf("Received request for %s\n", name)
+
+	// Sanitize name for logging by removing control characters
+	controlCharsRegex := regexp.MustCompile(`[\x00-\x1F\x7F]`)
+	sanitizedName := controlCharsRegex.ReplaceAllString(name, " ")
+
+	log.Printf("Received request for %s\n", sanitizedName)
 	w.Write([]byte(CreateGreeting(name)))
 }
 
 func CreateGreeting(name string) string {
+	// Trim leading and trailing whitespace
+	name = strings.TrimSpace(name)
+
+	// Return "Hello, Guest" if input is empty after trim
 	if name == "" {
-		name = "Guest"
+		return "Hello, Guest\n"
 	}
+
+	// Limit accepted name length to 100 characters
+	if len(name) > 100 {
+		name = name[:100]
+	}
+
+	// Strip newline and control characters, replace with space
+	// This regex matches control characters (ASCII 0-31) except space (32)
+	controlCharsRegex := regexp.MustCompile(`[\x00-\x1F\x7F]`)
+	name = controlCharsRegex.ReplaceAllString(name, " ")
+
 	return "Hello, " + name + "\n"
 }
 

hello_server_test.go

@@ -36,6 +36,95 @@ func TestGreetingDefault(t *testing.T) {
 		t.Errorf("Greeting was incorrect, got: %s, want: %s.", greeting, "Hello, Guest\n")
 	}
 }
-
 
+func TestGreeting_WhitespaceOnly(t *testing.T) {
+	testCases := []string{
+		"   ",           // spaces
+		"\t",            // tab
+		"\n",            // newline
+		"\r",            // carriage return
+		" \t\n\r ",      // mixed whitespace
+	}
+
+	for _, name := range testCases {
+		greeting := CreateGreeting(name)
+		if greeting != "Hello, Guest\n" {
+			t.Errorf("Greeting for whitespace-only name '%s' was incorrect, got: %s, want: %s.", name, greeting, "Hello, Guest\n")
+		}
+	}
+}
+
+func TestGreeting_LongName(t *testing.T) {
+	// Test name longer than 100 characters
+	longName := "a"
+	for i := 0; i < 120; i++ {
+		longName += "a"
+	}
+
+	greeting := CreateGreeting(longName)
+	// Should truncate to 100 characters
+	expectedName := longName[:100]
+	expected := "Hello, " + expectedName + "\n"
+
+	if greeting != expected {
+		t.Errorf("Greeting for long name was incorrect, got length %d, want length %d", len(greeting)-8-1, 100) // -8 for "Hello, " and -1 for "\n"
+	}
+}
+
+func TestGreeting_NewlineInjection(t *testing.T) {
+	testCases := []struct {
+		input    string
+		expected string
+	}{
+		{"John\nAdmin", "Hello, John Admin\n"},          // newline should be replaced with space
+		{"Jane\r\nDoe", "Hello, Jane  Doe\n"},           // carriage return + newline
+		{"Test\tUser", "Hello, Test User\n"},            // tab should be replaced with space
+		{"User\x00", "Hello, User \n"},                  // null character
+		{"Test\x01\x02", "Hello, Test  \n"},             // control characters
+	}
+
+	for _, tc := range testCases {
+		greeting := CreateGreeting(tc.input)
+		if greeting != tc.expected {
+			t.Errorf("Greeting for input '%s' was incorrect, got: %s, want: %s.", tc.input, greeting, tc.expected)
+		}
+	}
+}
+
+func TestGreeting_SpecialSymbols(t *testing.T) {
+	testCases := []struct {
+		input    string
+		expected string
+	}{
+		{"Jane!@#", "Hello, Jane!@#\n"},
+		{"User$%^&*()", "Hello, User$%^&*()\n"},
+		{"Test-User_123", "Hello, Test-User_123\n"},
+		{"João", "Hello, João\n"}, // Unicode characters should be preserved
+	}
+
+	for _, tc := range testCases {
+		greeting := CreateGreeting(tc.input)
+		if greeting != tc.expected {
+			t.Errorf("Greeting for input '%s' was incorrect, got: %s, want: %s.", tc.input, greeting, tc.expected)
+		}
+	}
+}
+
+func TestGreeting_TrimWhitespace(t *testing.T) {
+	testCases := []struct {
+		input    string
+		expected string
+	}{
+		{"  John  ", "Hello, John\n"},
+		{"\tJane\t", "Hello, Jane\n"},
+		{" \n Test \r ", "Hello, Test\n"},
+	}
+
+	for _, tc := range testCases {
+		greeting := CreateGreeting(tc.input)
+		if greeting != tc.expected {
+			t.Errorf("Greeting for input '%s' was incorrect, got: %s, want: %s.", tc.input, greeting, tc.expected)
+		}
+	}
+}