[feature] add rate limit middleware (#741)

* feat: add rate limit middleware

* chore: update vendor dir

* chore: update readme with new dependency

* chore: add rate limit infos to swagger.md file

* refactor: add ipv6 mask limiter option

Add IPv6 CIDR /64 mask

* refactor: increase rate limit to 1000

Address https://github.com/superseriousbusiness/gotosocial/pull/741#discussion_r945584800

Co-authored-by: tobi <31960611+tsmethurst@users.noreply.github.com>

vendor/github.com/ulule/limiter/v3/network.go

@@ -0,0 +1,137 @@
+package limiter
+
+import (
+	"net"
+	"net/http"
+	"strings"
+)
+
+var (
+	// DefaultIPv4Mask defines the default IPv4 mask used to obtain user IP.
+	DefaultIPv4Mask = net.CIDRMask(32, 32)
+	// DefaultIPv6Mask defines the default IPv6 mask used to obtain user IP.
+	DefaultIPv6Mask = net.CIDRMask(128, 128)
+)
+
+// GetIP returns IP address from request.
+// If options is defined and either TrustForwardHeader is true or ClientIPHeader is defined,
+// it will lookup IP in HTTP headers.
+// Please be advised that using this option could be insecure (ie: spoofed) if your reverse
+// proxy is not configured properly to forward a trustworthy client IP.
+// Please read the section "Limiter behind a reverse proxy" in the README for further information.
+func (limiter *Limiter) GetIP(r *http.Request) net.IP {
+	return GetIP(r, limiter.Options)
+}
+
+// GetIPWithMask returns IP address from request by applying a mask.
+// If options is defined and either TrustForwardHeader is true or ClientIPHeader is defined,
+// it will lookup IP in HTTP headers.
+// Please be advised that using this option could be insecure (ie: spoofed) if your reverse
+// proxy is not configured properly to forward a trustworthy client IP.
+// Please read the section "Limiter behind a reverse proxy" in the README for further information.
+func (limiter *Limiter) GetIPWithMask(r *http.Request) net.IP {
+	return GetIPWithMask(r, limiter.Options)
+}
+
+// GetIPKey extracts IP from request and returns hashed IP to use as store key.
+// If options is defined and either TrustForwardHeader is true or ClientIPHeader is defined,
+// it will lookup IP in HTTP headers.
+// Please be advised that using this option could be insecure (ie: spoofed) if your reverse
+// proxy is not configured properly to forward a trustworthy client IP.
+// Please read the section "Limiter behind a reverse proxy" in the README for further information.
+func (limiter *Limiter) GetIPKey(r *http.Request) string {
+	return limiter.GetIPWithMask(r).String()
+}
+
+// GetIP returns IP address from request.
+// If options is defined and either TrustForwardHeader is true or ClientIPHeader is defined,
+// it will lookup IP in HTTP headers.
+// Please be advised that using this option could be insecure (ie: spoofed) if your reverse
+// proxy is not configured properly to forward a trustworthy client IP.
+// Please read the section "Limiter behind a reverse proxy" in the README for further information.
+func GetIP(r *http.Request, options ...Options) net.IP {
+	if len(options) >= 1 {
+		if options[0].ClientIPHeader != "" {
+			ip := getIPFromHeader(r, options[0].ClientIPHeader)
+			if ip != nil {
+				return ip
+			}
+		}
+		if options[0].TrustForwardHeader {
+			ip := getIPFromXFFHeader(r)
+			if ip != nil {
+				return ip
+			}
+
+			ip = getIPFromHeader(r, "X-Real-IP")
+			if ip != nil {
+				return ip
+			}
+		}
+	}
+
+	remoteAddr := strings.TrimSpace(r.RemoteAddr)
+	host, _, err := net.SplitHostPort(remoteAddr)
+	if err != nil {
+		return net.ParseIP(remoteAddr)
+	}
+
+	return net.ParseIP(host)
+}
+
+// GetIPWithMask returns IP address from request by applying a mask.
+// If options is defined and either TrustForwardHeader is true or ClientIPHeader is defined,
+// it will lookup IP in HTTP headers.
+// Please be advised that using this option could be insecure (ie: spoofed) if your reverse
+// proxy is not configured properly to forward a trustworthy client IP.
+// Please read the section "Limiter behind a reverse proxy" in the README for further information.
+func GetIPWithMask(r *http.Request, options ...Options) net.IP {
+	if len(options) == 0 {
+		return GetIP(r)
+	}
+
+	ip := GetIP(r, options[0])
+	if ip.To4() != nil {
+		return ip.Mask(options[0].IPv4Mask)
+	}
+	if ip.To16() != nil {
+		return ip.Mask(options[0].IPv6Mask)
+	}
+	return ip
+}
+
+func getIPFromXFFHeader(r *http.Request) net.IP {
+	headers := r.Header.Values("X-Forwarded-For")
+	if len(headers) == 0 {
+		return nil
+	}
+
+	parts := []string{}
+	for _, header := range headers {
+		parts = append(parts, strings.Split(header, ",")...)
+	}
+
+	for i := range parts {
+		part := strings.TrimSpace(parts[i])
+		ip := net.ParseIP(part)
+		if ip != nil {
+			return ip
+		}
+	}
+
+	return nil
+}
+
+func getIPFromHeader(r *http.Request, name string) net.IP {
+	header := strings.TrimSpace(r.Header.Get(name))
+	if header == "" {
+		return nil
+	}
+
+	ip := net.ParseIP(header)
+	if ip != nil {
+		return ip
+	}
+
+	return nil
+}