Move tracker-specific logic out of http/query and into http

http/tracker.go

@@ -5,7 +5,11 @@
 package http
 
 import (
+	"errors"
+	"net"
 	"net/http"
+	"strconv"
+	"strings"
 
 	"github.com/julienschmidt/httprouter"
 
@@ -23,7 +27,7 @@ func NewAnnounce(cfg *config.Config, r *http.Request, p httprouter.Params) (*mod
 
 	compact := q.Params["compact"] != "0"
 	event, _ := q.Params["event"]
-	numWant := q.RequestedPeerCount(cfg.NumWantFallback)
+	numWant := requestedPeerCount(q, cfg.NumWantFallback)
 
 	infohash, exists := q.Params["info_hash"]
 	if !exists {
@@ -35,7 +39,7 @@ func NewAnnounce(cfg *config.Config, r *http.Request, p httprouter.Params) (*mod
 		return nil, models.ErrMalformedRequest
 	}
 
-	ipv4, ipv6, err := q.RequestedIP(r, &cfg.NetConfig)
+	ipv4, ipv6, err := requestedIP(q, r, &cfg.NetConfig)
 	if err != nil {
 		return nil, models.ErrMalformedRequest
 	}
@@ -99,3 +103,90 @@ func NewScrape(cfg *config.Config, r *http.Request, p httprouter.Params) (*model
 		Infohashes: q.Infohashes,
 	}, nil
 }
+
+// requestedPeerCount returns the wanted peer count or the provided fallback.
+func requestedPeerCount(q *query.Query, fallback int) int {
+	if numWantStr, exists := q.Params["numwant"]; exists {
+		numWant, err := strconv.Atoi(numWantStr)
+		if err != nil {
+			return fallback
+		}
+		return numWant
+	}
+
+	return fallback
+}
+
+// requestedIP returns the IP addresses for a request. If there are multiple
+// IP addresses in the request, one IPv4 and one IPv6 will be returned.
+func requestedIP(q *query.Query, r *http.Request, cfg *config.NetConfig) (v4, v6 net.IP, err error) {
+	var done bool
+
+	if cfg.AllowIPSpoofing {
+		if str, ok := q.Params["ip"]; ok {
+			if v4, v6, done = getIPs(str, v4, v6, cfg); done {
+				return
+			}
+		}
+
+		if str, ok := q.Params["ipv4"]; ok {
+			if v4, v6, done = getIPs(str, v4, v6, cfg); done {
+				return
+			}
+		}
+
+		if str, ok := q.Params["ipv6"]; ok {
+			if v4, v6, done = getIPs(str, v4, v6, cfg); done {
+				return
+			}
+		}
+	}
+
+	if cfg.RealIPHeader != "" {
+		if xRealIPs, ok := q.Params[cfg.RealIPHeader]; ok {
+			if v4, v6, done = getIPs(string(xRealIPs[0]), v4, v6, cfg); done {
+				return
+			}
+		}
+	} else {
+		if r.RemoteAddr == "" {
+			if v4 == nil {
+				v4 = net.ParseIP("127.0.0.1")
+			}
+			return
+		}
+
+		if idx := strings.LastIndex(r.RemoteAddr, ":"); idx != -1 {
+			if v4, v6, done = getIPs(r.RemoteAddr[0:idx], v4, v6, cfg); done {
+				return
+			}
+		}
+	}
+
+	if v4 == nil && v6 == nil {
+		err = errors.New("failed to parse IP address")
+	}
+	return
+}
+
+func getIPs(ipstr string, ipv4, ipv6 net.IP, cfg *config.NetConfig) (net.IP, net.IP, bool) {
+	var done bool
+
+	if ip := net.ParseIP(ipstr); ip != nil {
+		newIPv4 := ip.To4()
+
+		if ipv4 == nil && newIPv4 != nil {
+			ipv4 = newIPv4
+		} else if ipv6 == nil && newIPv4 == nil {
+			ipv6 = ip
+		}
+	}
+
+	if cfg.DualStackedPeers {
+		done = ipv4 != nil && ipv6 != nil
+	} else {
+		done = ipv4 != nil || ipv6 != nil
+	}
+
+	return ipv4, ipv6, done
+}