refactor(#130): move IsBlockedIP to internal/netutil to remove gitea import in validateurl.go

validateurl.go is VCS-generic but imported gitea.IsBlockedIP, creating an unexpected generic→Gitea-specific dependency. Extract IsBlockedIP and its CIDR list to internal/netutil/ipcheck.go (a neutral shared package). - gitea/ipcheck.go becomes a thin forwarding wrapper (preserves API compat for callers within the gitea package) - gitea/ipcheck_test.go replaced with a forwarding smoke test; full coverage moves to internal/netutil/ipcheck_test.go - validateurl.go now imports internal/netutil directly
2026-05-15 08:38:48 +00:00
parent 1e50a22caa
commit f7008ab86b
5 changed files with 278 additions and 215 deletions
@@ -0,0 +1,97 @@
+// Package netutil provides shared network utilities for review-bot.
+// ipcheck.go implements IP-level SSRF protection by checking resolved addresses
+// against known blocked CIDR ranges (RFC1918, loopback, link-local, etc.).
+package netutil
+
+import (
+	"fmt"
+	"net"
+)
+
+// blockedCIDRStrings is the canonical list of CIDR strings that should never
+// be contacted by review-bot. See IsBlockedIP for the full list of covered
+// address families.
+//
+// These are hard-coded literals: any parse failure is a programming error.
+// Validity is verified by TestBlockedCIDRsValid in ipcheck_test.go.
+var blockedCIDRStrings = []string{
+	// IPv4 loopback
+	"127.0.0.0/8",
+	// IPv4 unspecified / "this network"
+	"0.0.0.0/8",
+	// RFC1918 private ranges
+	"10.0.0.0/8",
+	"172.16.0.0/12",
+	"192.168.0.0/16",
+	// IPv4 link-local (APIPA, also used by AWS instance metadata 169.254.169.254)
+	"169.254.0.0/16",
+	// IPv4 shared address space (RFC6598, carrier-grade NAT)
+	"100.64.0.0/10",
+	// IPv4 multicast
+	"224.0.0.0/4",
+	// IPv4 reserved / broadcast
+	"240.0.0.0/4",
+	// IPv6 loopback
+	"::1/128",
+	// IPv6 unspecified
+	"::/128",
+	// IPv6 link-local
+	"fe80::/10",
+	// IPv6 unique local (ULA) — RFC4193
+	"fc00::/7",
+	// IPv6 multicast
+	"ff00::/8",
+}
+
+// blockedCIDRs is the parsed form of blockedCIDRStrings.
+// Any entry that fails to parse is recorded in blockedCIDRParseErrors instead
+// of panicking; tests verify this slice is always empty via TestBlockedCIDRsValid.
+var (
+	blockedCIDRs           []*net.IPNet
+	blockedCIDRParseErrors []string
+)
+
+func init() {
+	blockedCIDRs = make([]*net.IPNet, 0, len(blockedCIDRStrings))
+	for _, r := range blockedCIDRStrings {
+		_, cidr, err := net.ParseCIDR(r)
+		if err != nil {
+			// Record the error rather than panicking; TestBlockedCIDRsValid
+			// will catch this during tests, and the CI build will fail.
+			blockedCIDRParseErrors = append(blockedCIDRParseErrors,
+				fmt.Sprintf("ipcheck: invalid built-in CIDR %q: %v", r, err))
+			continue
+		}
+		blockedCIDRs = append(blockedCIDRs, cidr)
+	}
+}
+
+// BlockedCIDRParseErrors returns any errors encountered parsing the built-in
+// CIDR list. In correct code this will always be empty; tests assert it is.
+func BlockedCIDRParseErrors() []string {
+	return blockedCIDRParseErrors
+}
+
+// IsBlockedIP reports whether ip is in a blocked address range.
+// It is exported for use by the gitea package's safe dialer, the validate-url
+// subcommand, and tests outside this package.
+//
+// IPv6-mapped IPv4 addresses (e.g. ::ffff:192.168.1.1) are normalized to their
+// IPv4 form before checking so that IPv4 CIDRs catch them.
+//
+// Based on:
+//   - RFC1918 private ranges
+//   - RFC5735 / RFC4193 special-use IPv4/IPv6 ranges
+//   - RFC4291 IPv6 link-local / loopback
+func IsBlockedIP(ip net.IP) bool {
+	// Normalize IPv6-mapped IPv4 addresses (::ffff:x.x.x.x) to plain IPv4.
+	if v4 := ip.To4(); v4 != nil {
+		ip = v4
+	}
+	for _, cidr := range blockedCIDRs {
+		if cidr.Contains(ip) {
+			return true
+		}
+	}
+	return false
+}