Code Quality: Silent error handling hides failures

[sgaunet]

Description

Errors are silently discarded throughout the codebase using _, violating Go idioms and hiding real issues like broken connections, write failures, and parse errors.

Location

Multiple locations:

• http-echo.go:57-58 - fmt.Fprintf write errors ignored
• http-echo.go:63 - ParseForm errors ignored
• http-echo.go:66 - ReadAll errors ignored
• http-echo.go:107-236 - All print functions ignore write errors

// Line 57-58: Write errors silently ignored
_, _ = fmt.Fprintf(w, "\n=== REQUEST COMPLETED ===")
_, _ = fmt.Fprintf(w, "\nProcessing Time: %v\n", time.Since(startTime))

// Line 63: Parse errors ignored
_ = r.ParseForm()

// Line 66: Read errors ignored
body, _ := io.ReadAll(r.Body)

Impact

• Severity: MEDIUM
• Write failures go undetected (broken connections, client timeouts)
• Form parsing issues hidden (size limits, corrupted data)
• Body read errors masked (size limits, I/O errors)
• Difficult to debug production issues
• Violates Go error handling best practices

Scenarios Where This Matters

1. Client Disconnects: Client closes connection mid-response, writes fail silently
2. Proxy Timeouts: Reverse proxy times out, write errors not logged
3. Resource Limits: Form data exceeds limits, silently ignored
4. I/O Errors: Disk/network issues during body read, not detected

Recommended Fix

For Write Errors (Low-Priority Logging)

func (h helloWorldhandler) printRequestSummary(w http.ResponseWriter, info requestInfo) {
    if _, err := fmt.Fprintf(w, "=== REQUEST SUMMARY ===\n"); err != nil {
        log.Printf("Write error: %v", err)
        return // Stop writing if client disconnected
    }
    // ... continue with other writes, checking errors
}

Or create a helper:

type errorWriter struct {
    w   http.ResponseWriter
    err error
}

func (ew *errorWriter) fprintf(format string, args ...interface{}) {
    if ew.err != nil {
        return // Already failed, don't continue writing
    }
    _, ew.err = fmt.Fprintf(ew.w, format, args...)
    if ew.err != nil {
        log.Printf("Write error: %v", ew.err)
    }
}

// Usage in ServeHTTP:
ew := &errorWriter{w: w}
h.printRequestSummary(ew, info)
if ew.err != nil {
    return // Client disconnected
}

For Parse Errors

if err := r.ParseForm(); err != nil {
    log.Printf("Form parse error: %v", err)
    // Continue anyway for diagnostic purposes, but log the issue
}

For Body Read Errors

body, err := io.ReadAll(io.LimitReader(r.Body, maxBodySize))
if err != nil {
    log.Printf("Body read error: %v", err)
    body = []byte(fmt.Sprintf("(error reading body: %v)", err))
}

Benefits

• Early detection of broken connections (stop processing)
• Visibility into client-side issues
• Better debugging in production
• Follows Go best practices
• Helps identify infrastructure issues (proxies, timeouts)

Testing

• Test with client that disconnects mid-request
• Test with very slow clients (write timeout scenarios)
• Test with malformed form data
• Review logs for error messages

Priority

Medium - Code quality issue that improves observability and debugging.

Related Issues

• Update badges #3 (Unbounded body reading)
• Add coverage CI #4 (Unbounded form parsing)

References

• Effective Go: Errors
• Go Code Review Comments: Error Handling