magellan/internal/util/net.go

package util

import (
	"bytes"
	"crypto/tls"
	"fmt"
	"io"
	"net"
	"net/http"
	"net/url"
	"strings"

	"github.com/rs/zerolog/log"
)

// HTTP aliases for readibility
type HTTPHeader map[string]string
type HTTPBody []byte

func (h HTTPHeader) Authorization(accessToken string) HTTPHeader {
	if accessToken != "" {
		h["Authorization"] = fmt.Sprintf("Bearer %s", accessToken)
	}
	return h
}

func (h HTTPHeader) ContentType(contentType string) HTTPHeader {
	h["Content-Type"] = contentType
	return h
}

// GetNextIP() returns the next IP address, but does not account
// for net masks.
func GetNextIP(ip *net.IP, inc uint) *net.IP {
	if ip == nil {
		return &net.IP{}
	}
	i := ip.To4()
	v := uint(i[0])<<24 + uint(i[1])<<16 + uint(i[2])<<8 + uint(i[3])
	v += inc
	v3 := byte(v & 0xFF)
	v2 := byte((v >> 8) & 0xFF)
	v1 := byte((v >> 16) & 0xFF)
	v0 := byte((v >> 24) & 0xFF)
	// return &net.IP{[]byte{v0, v1, v2, v3}}
	r := net.IPv4(v0, v1, v2, v3)
	return &r
}

// MakeRequest() is a wrapper function that condenses simple HTTP
// requests done to a single call. It expects an optional HTTP client,
// URL, HTTP method, request body, and request headers. This function
// is useful when making many requests where only these few arguments
// are changing.
//
// Returns a HTTP response object, response body as byte array, and any
// error that may have occurred with making the request.
func MakeRequest(client *http.Client, url string, httpMethod string, body HTTPBody, header HTTPHeader) (*http.Response, HTTPBody, error) {
	// use defaults if no client provided
	if client == nil {
		client = http.DefaultClient
		client.Transport = &http.Transport{
			TLSClientConfig: &tls.Config{InsecureSkipVerify: true},
		}
	}
	req, err := http.NewRequest(httpMethod, url, bytes.NewBuffer(body))
	if err != nil {
		return nil, nil, fmt.Errorf("failed to create new HTTP request: %v", err)
	}
	req.Header.Add("User-Agent", "magellan")
	for k, v := range header {
		req.Header.Add(k, v)
	}
	res, err := client.Do(req)
	if err != nil {
		return nil, nil, fmt.Errorf("failed to make request: %v", err)
	}
	b, err := io.ReadAll(res.Body)
	res.Body.Close()
	if err != nil {
		return nil, nil, fmt.Errorf("failed to read response body: %v", err)
	}
	return res, b, err
}

// FormatHostUrls() takes a list of hosts and ports and builds full URLs in the
// form of scheme://host:port. If no scheme is provided, it will use "https" by
// default.
//
// Returns a 2D string slice where each slice contains URL host strings for each
// port. The intention is to have all of the URLs for a single host combined into
// a single slice to initiate one goroutine per host, but making request to multiple
// ports.
func FormatHostUrls(hosts []string, ports []int, scheme string, verbose bool) [][]string {
	// format each positional arg as a complete URL
	var formattedHosts [][]string
	for _, host := range hosts {
		uri, err := url.ParseRequestURI(host)
		if err != nil {
			if verbose {
				log.Warn().Msgf("invalid URI parsed: %s", host)
			}
			continue
		}

		// check if scheme is set, if not set it with flag or default value ('https' if flag is not set)
		if uri.Scheme == "" {
			if scheme != "" {
				uri.Scheme = scheme
			} else {
				// hardcoded assumption
				uri.Scheme = "https"
			}
		}

		// tidy up slashes and update arg with new value
		uri.Path = strings.TrimSuffix(uri.Path, "/")
		uri.Path = strings.ReplaceAll(uri.Path, "//", "/")

		// for hosts with unspecified ports, add ports to scan from flag
		if uri.Port() == "" {
			var tmp []string
			for _, port := range ports {
				uri.Host += fmt.Sprintf(":%d", port)
				tmp = append(tmp, uri.String())
			}
			formattedHosts = append(formattedHosts, tmp)
		} else {
			formattedHosts = append(formattedHosts, []string{uri.String()})
		}

	}
	return formattedHosts
}

// FormatIPUrls() takes a list of IP addresses and ports and builds full URLs in the
// form of scheme://host:port. If no scheme is provided, it will use "https" by
// default.
//
// Returns a 2D string slice where each slice contains URL host strings for each
// port. The intention is to have all of the URLs for a single host combined into
// a single slice to initiate one goroutine per host, but making request to multiple
// ports.
func FormatIPUrls(ips []string, ports []int, scheme string, verbose bool) [][]string {
	// format each positional arg as a complete URL
	var formattedHosts [][]string
	for _, ip := range ips {
		// if parsing completely fails, try to build new URL object
		uri := &url.URL{
			Scheme: scheme,
			Host:   ip,
		}

		// check if scheme is set, if not set it with flag or default value ('https' if flag is not set)
		if uri.Scheme == "" {
			if scheme != "" {
				uri.Scheme = scheme
			} else {
				// hardcoded assumption
				uri.Scheme = "https"
			}
		}

		// tidy up slashes and update arg with new value
		uri.Path = strings.TrimSuffix(uri.Path, "/")
		uri.Path = strings.ReplaceAll(uri.Path, "//", "/")

		// for hosts with unspecified ports, add ports to scan from flag
		if uri.Port() == "" {
			var tmp []string
			for _, port := range ports {
				uri.Host = fmt.Sprintf("%s:%d", ip, port)
				tmp = append(tmp, uri.String())
			}
			formattedHosts = append(formattedHosts, tmp)
		} else {
			formattedHosts = append(formattedHosts, []string{uri.String()})
		}

	}
	return formattedHosts
}