http: build the Host header from an address in authority form

include/seastar/http/request.hh

@@ -422,6 +422,28 @@ public:
      */
     static request make(httpd::operation_type type, sstring host, sstring path);
 
+    /**
+     * \brief Make simple request to an address
+     *
+     * \param method - method to use, e.g. "GET"
+     * \param addr - the address to contact. The "Host" header is its RFC 3986
+     *               authority form, i.e. an IPv6 address is bracketed.
+     * \path - the URL to send the request to
+     *
+     */
+    static request make(sstring method, const socket_address& addr, sstring path);
+
+    /**
+     * \brief Make simple request to an address
+     *
+     * \param method - method to use, e.g. operation_type::GET
+     * \param addr - the address to contact. The "Host" header is its RFC 3986
+     *               authority form, i.e. an IPv6 address is bracketed.
+     * \path - the URL to send the request to
+     *
+     */
+    static request make(httpd::operation_type type, const socket_address& addr, sstring path);
+
     sstring request_line() const;
     future<> write_request_headers(output_stream<char>& out) const;
 private:
@@ -430,6 +452,11 @@ private:
 };
 
 namespace internal {
+
+/// The RFC 3986 §3.2.2 authority for \param addr: "host:port", with an IPv6
+/// address bracketed. A zone index is not part of an authority and is dropped.
+sstring format_authority(const socket_address& addr);
+
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wdeprecated-declarations"
 inline sstring& deprecated_content(request& req) noexcept { return req.content; }

src/http/request.cc

@@ -25,6 +25,7 @@
 #include <utility>
 
 #include <seastar/http/request.hh>
+#include <seastar/net/inet_address.hh>
 #include <seastar/http/url.hh>
 #include <seastar/http/common.hh>
 #include <seastar/util/assert.hh>
@@ -168,5 +169,23 @@ request request::make(httpd::operation_type type, sstring host, sstring path) {
     return make(httpd::type2str(type), std::move(host), std::move(path));
 }
 
+request request::make(sstring method, const socket_address& addr, sstring path) {
+    return make(std::move(method), internal::format_authority(addr), std::move(path));
+}
+
+request request::make(httpd::operation_type type, const socket_address& addr, sstring path) {
+    return make(httpd::type2str(type), internal::format_authority(addr), std::move(path));
+}
+
+sstring internal::format_authority(const socket_address& addr) {
+    auto ip = addr.addr();
+    if (ip.is_ipv6()) {
+        // inet_address prints a scope as "%<index>", which an authority cannot
+        // carry; build the address without one.
+        return format("[{}]:{:d}", net::inet_address(static_cast<::in6_addr>(ip)), addr.port());
+    }
+    return format("{}:{:d}", ip, addr.port());
+}
+
 } // http namespace
 } // seastar namespace

tests/unit/httpd_test.cc

@@ -2434,6 +2434,22 @@ BOOST_AUTO_TEST_CASE(test_http_status_classification) {
     BOOST_REQUIRE_EQUAL(unclassified, 300);
 }
 
+SEASTAR_TEST_CASE(test_format_authority) {
+    BOOST_REQUIRE_EQUAL(http::internal::format_authority(socket_address(ipv4_addr("10.0.0.1", 80))), "10.0.0.1:80");
+    BOOST_REQUIRE_EQUAL(http::internal::format_authority(socket_address(ipv6_addr("2001:db8::1", 8080))), "[2001:db8::1]:8080");
+    BOOST_REQUIRE_EQUAL(http::internal::format_authority(socket_address(ipv6_addr("::1", 0))), "[::1]:0");
+    // a zone belongs to the host, not to the authority
+    BOOST_REQUIRE_EQUAL(http::internal::format_authority(socket_address(ipv6_addr("fe80::1", 8080), 2)), "[fe80::1]:8080");
+
+    // and the request overload puts exactly that in the Host header
+    auto v6 = http::request::make("GET", socket_address(ipv6_addr("::1", 8080)), "/test");
+    BOOST_REQUIRE_EQUAL(v6.get_header("Host"), "[::1]:8080");
+    BOOST_REQUIRE_EQUAL(v6.get_url(), "http://[::1]:8080/test");
+    auto v4 = http::request::make(GET, socket_address(ipv4_addr("127.0.0.1", 80)), "/test");
+    BOOST_REQUIRE_EQUAL(v4.get_header("Host"), "127.0.0.1:80");
+    return make_ready_future();
+}
+
 // An IPv4 client of a `[::]` listener is an IPv4 client to the handler, not the
 // ::ffff:a.b.c.d the kernel reports.
 SEASTAR_THREAD_TEST_CASE(test_dual_stack_listener_reports_ipv4_client) {