nghttpx: Add sni keyword to --backend option

The --backend-tls-sni-field is deprecated in favor of sni keyword.
--backend-tls-sni-field still works, and it overrides all sni keyword
in --backend option.  But it will be removed in the future release.

src/shrpx.cc

@@ -1263,13 +1263,13 @@ Connections:
 
               Several parameters <PARAM> are accepted after <PATTERN>.
               The  parameters are  delimited  by  ";".  The  available
-              parameters are: "proto=<PROTO>",  "tls", "fall=<N>", and
-              "rise=<N>".   The  parameter  consists of  keyword,  and
-              optionally followed by "="  and value.  For example, the
-              parameter "proto=h2" consists of the keyword "proto" and
-              value "h2".  The parameter "tls" consists of the keyword
-              "tls"  without value.   Each parameter  is described  as
-              follows.
+              parameters       are:      "proto=<PROTO>",       "tls",
+              "sni=<SNI_HOST>",   "fall=<N>",  and   "rise=<N>".   The
+              parameter consists  of keyword, and  optionally followed
+              by "=" and value.  For example, the parameter "proto=h2"
+              consists  of the  keyword "proto"  and value  "h2".  The
+              parameter "tls"  consists of  the keyword  "tls" without
+              value.  Each parameter is described as follows.
 
               The backend application protocol  can be specified using
               optional   "proto"  keyword,   and   in   the  form   of
@@ -1284,6 +1284,10 @@ Connections:
               TLS can be enabled by specifying optional "tls" keyword.
               TLS is not enabled by default.
 
+              With "sni=<SNI_HOST>" parameter, it can override the TLS
+              SNI  field  value  with  given  <SNI_HOST>.   This  will
+              default to the backend <HOST> name
+
               The  feature  to detect  whether  backend  is online  or
               offline can be enabled  using optional "fall" and "rise"
               parameters.   Using  "fall=<N>"  parameter,  if  nghttpx
@@ -1503,9 +1507,6 @@ SSL/TLS:
               indicated  by  client  using TLS  SNI  extension.   This
               option  can  be  used  multiple  times.   To  make  OCSP
               stapling work, <CERTPATH> must be absolute path.
-  --backend-tls-sni-field=<HOST>
-              Explicitly  set the  content of  the TLS  SNI extension.
-              This will default to the backend HOST name.
   --dh-param-file=<PATH>
               Path to file that contains  DH parameters in PEM format.
               Without  this   option,  DHE   cipher  suites   are  not
@@ -2168,6 +2169,17 @@ void process_options(int argc, char **argv,
     }
   }
 
+  // backward compatibility: override all SNI fields with the option
+  // value --backend-tls-sni-field
+  if (!tlsconf.backend_sni_name.empty()) {
+    auto &sni = tlsconf.backend_sni_name;
+    for (auto &addr_group : addr_groups) {
+      for (auto &addr : addr_group.addrs) {
+        addr.sni = sni;
+      }
+    }
+  }
+
   if (LOG_ENABLED(INFO)) {
     LOG(INFO) << "Resolving backend address";
   }

src/shrpx_config.cc

@@ -644,6 +644,7 @@ int parse_upstream_params(UpstreamParams &out, const StringRef &src_params) {
 } // namespace
 
 struct DownstreamParams {
+  StringRef sni;
   size_t fall;
   size_t rise;
   shrpx_proto proto;
@@ -709,6 +710,8 @@ int parse_downstream_params(DownstreamParams &out,
       out.tls = true;
     } else if (util::strieq_l("no-tls", param)) {
       out.tls = false;
+    } else if (util::istarts_with_l(param, "sni=")) {
+      out.sni = StringRef{first + str_size("sni="), end};
     } else if (!param.empty()) {
       LOG(ERROR) << "backend: " << param << ": unknown keyword";
       return -1;
@@ -750,6 +753,7 @@ int parse_mapping(DownstreamAddrConfig addr, const StringRef &src_pattern,
 
   addr.fall = params.fall;
   addr.rise = params.rise;
+  addr.sni = ImmutableString{std::begin(params.sni), std::end(params.sni)};
 
   for (const auto &raw_pattern : mapping) {
     auto done = false;
@@ -2050,6 +2054,9 @@ int parse_config(const StringRef &opt, const StringRef &optarg,
                         "default.  See also " << SHRPX_OPT_BACKEND_TLS;
     return 0;
   case SHRPX_OPTID_BACKEND_TLS_SNI_FIELD:
+    LOG(WARN) << opt << ": deprecated.  Use sni keyword in --backend option.  "
+                        "For now, all sni values of all backends are "
+                        "overridden by the given value " << optarg;
     mod_config()->tls.backend_sni_name = optarg.str();
 
     return 0;

src/shrpx_config.h

@@ -327,6 +327,8 @@ struct DownstreamAddrConfig {
   // <HOST>:<PORT>.  This does not treat 80 and 443 specially.  If
   // |host_unix| is true, this is "localhost".
   ImmutableString hostport;
+  // hostname sent as SNI field
+  ImmutableString sni;
   size_t fall;
   size_t rise;
   // backend port.  0 if |host_unix| is true.

src/shrpx_http2_session.cc

@@ -360,9 +360,8 @@ int Http2Session::initiate_connection() {
 
       conn_.set_ssl(ssl);
 
-      auto sni_name = !get_config()->tls.backend_sni_name.empty()
-                          ? StringRef(get_config()->tls.backend_sni_name)
-                          : StringRef(addr_->host);
+      auto sni_name =
+          addr_->sni.empty() ? StringRef{addr_->host} : StringRef{addr_->sni};
 
       if (!util::numeric_host(sni_name.c_str())) {
         // TLS extensions: SNI. There is no documentation about the return

src/shrpx_http_downstream_connection.cc

@@ -239,9 +239,8 @@ int HttpDownstreamConnection::attach_downstream(Downstream *downstream) {
       addr_ = &addr;
 
       if (ssl_ctx_) {
-        auto sni_name = !get_config()->tls.backend_sni_name.empty()
-                            ? StringRef(get_config()->tls.backend_sni_name)
-                            : StringRef(addr_->host);
+        auto sni_name =
+            addr_->sni.empty() ? StringRef{addr_->host} : StringRef{addr_->sni};
         if (!util::numeric_host(sni_name.c_str())) {
           SSL_set_tlsext_host_name(conn_.tls.ssl, sni_name.c_str());
         }

src/shrpx_live_check.cc

@@ -192,9 +192,8 @@ int LiveCheck::initiate_connection() {
   }
 
   if (ssl_ctx_) {
-    auto sni_name = !get_config()->tls.backend_sni_name.empty()
-                        ? StringRef(get_config()->tls.backend_sni_name)
-                        : StringRef(addr_->host);
+    auto sni_name =
+        addr_->sni.empty() ? StringRef{addr_->host} : StringRef{addr_->sni};
     if (!util::numeric_host(sni_name.c_str())) {
       SSL_set_tlsext_host_name(conn_.tls.ssl, sni_name.c_str());
     }

src/shrpx_ssl.cc

@@ -1064,10 +1064,8 @@ int check_cert(SSL *ssl, const Address *addr, const StringRef &host) {
 }
 
 int check_cert(SSL *ssl, const DownstreamAddr *addr) {
-  auto &backend_sni_name = get_config()->tls.backend_sni_name;
-
-  auto hostname = !backend_sni_name.empty() ? StringRef(backend_sni_name)
-                                            : StringRef(addr->host);
+  auto hostname =
+      addr->sni.empty() ? StringRef{addr->host} : StringRef{addr->sni};
   return check_cert(ssl, &addr->addr, hostname);
 }
 

src/shrpx_worker.cc

@@ -83,7 +83,7 @@ bool match_shared_downstream_addr(
 
       auto &b = rhs->addrs[i];
       if (a.host == b.host && a.port == b.port && a.host_unix == b.host_unix &&
-          a.fall == b.fall && a.rise == b.rise) {
+          a.sni == b.sni && a.fall == b.fall && a.rise == b.rise) {
         break;
       }
     }
@@ -159,6 +159,7 @@ Worker::Worker(struct ev_loop *loop, SSL_CTX *sv_ssl_ctx, SSL_CTX *cl_ssl_ctx,
       dst_addr.hostport = src_addr.hostport;
       dst_addr.port = src_addr.port;
       dst_addr.host_unix = src_addr.host_unix;
+      dst_addr.sni = src_addr.sni;
       dst_addr.fall = src_addr.fall;
       dst_addr.rise = src_addr.rise;
 

src/shrpx_worker.h

@@ -80,6 +80,9 @@ struct DownstreamAddr {
   // true if |host| contains UNIX domain socket path.
   bool host_unix;
 
+  // sni field to send remote server if TLS is enabled.
+  ImmutableString sni;
+
   std::unique_ptr<ConnectBlocker> connect_blocker;
   std::unique_ptr<LiveCheck> live_check;
   size_t fall;

src/template.h

@@ -254,15 +254,15 @@ public:
 
   ImmutableString() : len(0), base("") {}
   ImmutableString(const char *s, size_t slen)
-      : len(slen), base(copystr(s, len)) {}
-  ImmutableString(const char *s) : len(strlen(s)), base(copystr(s, len)) {}
+      : len(slen), base(copystr(s, s + len)) {}
+  ImmutableString(const char *s) : len(strlen(s)), base(copystr(s, s + len)) {}
   ImmutableString(const std::string &s)
-      : len(s.size()), base(copystr(s.c_str(), s.size())) {}
+      : len(s.size()), base(copystr(std::begin(s), std::end(s))) {}
   template <typename InputIt>
   ImmutableString(InputIt first, InputIt last)
-      : len(std::distance(first, last)), base(copystr(first, len)) {}
+      : len(std::distance(first, last)), base(copystr(first, last)) {}
   ImmutableString(const ImmutableString &other)
-      : len(other.len), base(copystr(other.base, other.len)) {}
+      : len(other.len), base(copystr(std::begin(other), std::end(other))) {}
   ImmutableString(ImmutableString &&other) noexcept : len(other.len),
                                                       base(other.base) {
     other.len = 0;
@@ -282,7 +282,7 @@ public:
       delete[] base;
     }
     len = other.len;
-    base = copystr(other.base, other.len);
+    base = copystr(std::begin(other), std::end(other));
     return *this;
   }
   ImmutableString &operator=(ImmutableString &&other) noexcept {
@@ -325,12 +325,12 @@ public:
   const_reference operator[](size_type pos) const { return *(base + pos); }
 
 private:
-  const char *copystr(const char *s, size_t slen) {
-    if (slen == 0) {
+  template <typename InputIt> const char *copystr(InputIt first, InputIt last) {
+    if (first == last) {
       return "";
     }
-    auto res = new char[slen + 1];
-    *std::copy_n(s, slen, res) = '\0';
+    auto res = new char[std::distance(first, last) + 1];
+    *std::copy(first, last, res) = '\0';
     return res;
   }