From 7f6e4ef17ddcbae9791dc2fb40e62a4c4602b8ad Mon Sep 17 00:00:00 2001
From: Ruben Perez <rubenperez038@gmail.com>
Date: Tue, 27 Jan 2026 20:08:52 +0100
Subject: [PATCH 01/11] Initial impl

---
 include/boost/redis/detail/connection_state.hpp   |  4 ++--
 include/boost/redis/impl/sentinel_resolve_fsm.ipp |  1 -
 include/boost/redis/impl/sentinel_utils.hpp       | 14 +++++++-------
 test/sansio_utils.cpp                             | 11 +++++------
 test/sansio_utils.hpp                             |  4 +++-
 5 files changed, 17 insertions(+), 17 deletions(-)

diff --git a/include/boost/redis/detail/connection_state.hpp b/include/boost/redis/detail/connection_state.hpp
index e8e091061..4c938a292 100644
--- a/include/boost/redis/detail/connection_state.hpp
+++ b/include/boost/redis/detail/connection_state.hpp
@@ -14,7 +14,7 @@
 #include <boost/redis/detail/subscription_tracker.hpp>
 #include <boost/redis/logger.hpp>
 #include <boost/redis/request.hpp>
-#include <boost/redis/resp3/node.hpp>
+#include <boost/redis/resp3/flat_tree.hpp>
 #include <boost/redis/response.hpp>
 
 #include <random>
@@ -56,7 +56,7 @@ struct connection_state {
    // Sentinel stuff
    lazy_random_engine eng{};
    std::vector<address> sentinels{};
-   std::vector<resp3::node> sentinel_resp_nodes{};  // for parsing
+   resp3::flat_tree sentinel_resp_nodes{};  // for parsing
 };
 
 }  // namespace boost::redis::detail
diff --git a/include/boost/redis/impl/sentinel_resolve_fsm.ipp b/include/boost/redis/impl/sentinel_resolve_fsm.ipp
index 96cf28f92..c4359e63b 100644
--- a/include/boost/redis/impl/sentinel_resolve_fsm.ipp
+++ b/include/boost/redis/impl/sentinel_resolve_fsm.ipp
@@ -141,7 +141,6 @@ sentinel_action sentinel_resolve_fsm::resume(
 
          update_sentinel_list(st.sentinels, idx_, resp.sentinels, st.cfg.sentinel.addresses);
 
-         st.sentinel_resp_nodes.clear();  // reduce memory consumption
          return system::error_code();
       }
 
diff --git a/include/boost/redis/impl/sentinel_utils.hpp b/include/boost/redis/impl/sentinel_utils.hpp
index b3df430ba..d8f187535 100644
--- a/include/boost/redis/impl/sentinel_utils.hpp
+++ b/include/boost/redis/impl/sentinel_utils.hpp
@@ -45,8 +45,8 @@ inline void compose_sentinel_request(config& cfg)
 
 // Parses a list of replicas or sentinels
 inline system::error_code parse_server_list(
-   const resp3::node*& first,
-   const resp3::node* last,
+   const resp3::node_view*& first,
+   const resp3::node_view* last,
    std::vector<address>& out)
 {
    const auto* it = first;
@@ -135,11 +135,11 @@ struct sentinel_response {
 //   * The node array originates from parsing a valid RESP3 message.
 //     E.g. we won't check that the first node has depth 0.
 inline system::error_code parse_sentinel_response(
-   span<const resp3::node> nodes,
+   span<const resp3::node_view> nodes,
    role server_role,
    sentinel_response& out)
 {
-   auto check_errors = [&out](const resp3::node& nd) {
+   auto check_errors = [&out](const resp3::node_view& nd) {
       switch (nd.data_type) {
          case resp3::type::simple_error:
             out.diagnostic = nd.value;
@@ -166,11 +166,11 @@ inline system::error_code parse_sentinel_response(
             return &*it;
       }
    };
-   const resp3::node* lib_first = find_first();
+   const resp3::node_view* lib_first = find_first();
 
    // Iterators
-   const resp3::node* it = nodes.begin();
-   const resp3::node* last = nodes.end();
+   const resp3::node_view* it = nodes.begin();
+   const resp3::node_view* last = nodes.end();
    ignore_unused(last);
 
    // Go through all the responses to user-supplied requests checking for errors
diff --git a/test/sansio_utils.cpp b/test/sansio_utils.cpp
index b3e446ac0..09dc9d947 100644
--- a/test/sansio_utils.cpp
+++ b/test/sansio_utils.cpp
@@ -6,6 +6,7 @@
 
 #include <boost/redis/adapter/any_adapter.hpp>
 #include <boost/redis/detail/multiplexer.hpp>
+#include <boost/redis/resp3/flat_tree.hpp>
 
 #include <boost/assert/source_location.hpp>
 #include <boost/core/ignore_unused.hpp>
@@ -74,12 +75,10 @@ logger log_fixture::make_logger()
    });
 }
 
-std::vector<resp3::node> nodes_from_resp3(
-   const std::vector<std::string_view>& msgs,
-   source_location loc)
+resp3::flat_tree nodes_from_resp3(const std::vector<std::string_view>& msgs, source_location loc)
 {
-   std::vector<resp3::node> nodes;
-   any_adapter adapter{nodes};
+   resp3::flat_tree res;
+   any_adapter adapter{res};
 
    for (std::string_view resp : msgs) {
       resp3::parser p;
@@ -91,7 +90,7 @@ std::vector<resp3::node> nodes_from_resp3(
          std::cerr << "Called from " << loc << std::endl;
    }
 
-   return nodes;
+   return res;
 }
 
 }  // namespace boost::redis::detail
diff --git a/test/sansio_utils.hpp b/test/sansio_utils.hpp
index cd4d7ebc6..8e97e09db 100644
--- a/test/sansio_utils.hpp
+++ b/test/sansio_utils.hpp
@@ -8,6 +8,7 @@
 #define BOOST_REDIS_TEST_SANSIO_UTILS_HPP
 
 #include <boost/redis/logger.hpp>
+#include <boost/redis/resp3/flat_tree.hpp>
 #include <boost/redis/resp3/node.hpp>
 
 #include <boost/assert/source_location.hpp>
@@ -55,7 +56,8 @@ constexpr auto to_milliseconds(std::chrono::steady_clock::duration d)
 // Creates a vector of nodes from a set of RESP3 messages.
 // Using the raw RESP values ensures that the correct
 // node tree is built, which is not always obvious
-std::vector<resp3::node> nodes_from_resp3(
+// TODO: rename this
+resp3::flat_tree nodes_from_resp3(
    const std::vector<std::string_view>& msgs,
    source_location loc = BOOST_CURRENT_LOCATION);
 

From 9acd67dede397b9ca81f07b0c62a322ef5350f18 Mon Sep 17 00:00:00 2001
From: Ruben Perez <rubenperez038@gmail.com>
Date: Tue, 27 Jan 2026 20:09:30 +0100
Subject: [PATCH 02/11] rename

---
 test/sansio_utils.cpp                 |  2 +-
 test/sansio_utils.hpp                 |  5 ++---
 test/test_parse_sentinel_response.cpp | 22 +++++++++---------
 test/test_sentinel_resolve_fsm.cpp    | 32 +++++++++++++--------------
 4 files changed, 30 insertions(+), 31 deletions(-)

diff --git a/test/sansio_utils.cpp b/test/sansio_utils.cpp
index 09dc9d947..90e5529a9 100644
--- a/test/sansio_utils.cpp
+++ b/test/sansio_utils.cpp
@@ -75,7 +75,7 @@ logger log_fixture::make_logger()
    });
 }
 
-resp3::flat_tree nodes_from_resp3(const std::vector<std::string_view>& msgs, source_location loc)
+resp3::flat_tree tree_from_resp3(const std::vector<std::string_view>& msgs, source_location loc)
 {
    resp3::flat_tree res;
    any_adapter adapter{res};
diff --git a/test/sansio_utils.hpp b/test/sansio_utils.hpp
index 8e97e09db..aba0f7f59 100644
--- a/test/sansio_utils.hpp
+++ b/test/sansio_utils.hpp
@@ -53,11 +53,10 @@ constexpr auto to_milliseconds(std::chrono::steady_clock::duration d)
    return std::chrono::duration_cast<std::chrono::milliseconds>(d).count();
 }
 
-// Creates a vector of nodes from a set of RESP3 messages.
+// Creates a collection of nodes from a set of RESP3 messages.
 // Using the raw RESP values ensures that the correct
 // node tree is built, which is not always obvious
-// TODO: rename this
-resp3::flat_tree nodes_from_resp3(
+resp3::flat_tree tree_from_resp3(
    const std::vector<std::string_view>& msgs,
    source_location loc = BOOST_CURRENT_LOCATION);
 
diff --git a/test/test_parse_sentinel_response.cpp b/test/test_parse_sentinel_response.cpp
index 00a83d752..40d78d6fa 100644
--- a/test/test_parse_sentinel_response.cpp
+++ b/test/test_parse_sentinel_response.cpp
@@ -25,7 +25,7 @@
 #include <vector>
 
 using namespace boost::redis;
-using detail::nodes_from_resp3;
+using detail::tree_from_resp3;
 using detail::parse_sentinel_response;
 using detail::sentinel_response;
 using boost::system::error_code;
@@ -80,7 +80,7 @@ void test_master()
 {
    // Setup
    fixture fix;
-   auto nodes = nodes_from_resp3({
+   auto nodes = tree_from_resp3({
       // clang-format off
       "*2\r\n$9\r\nlocalhost\r\n$4\r\n6380\r\n",
       "*2\r\n"
@@ -116,7 +116,7 @@ void test_master_no_sentinels()
 {
    // Setup
    fixture fix;
-   auto nodes = nodes_from_resp3({
+   auto nodes = tree_from_resp3({
       "*2\r\n$9\r\nlocalhost\r\n$4\r\n6380\r\n",
       "*0\r\n",
    });
@@ -132,7 +132,7 @@ void test_master_setup_request()
 {
    // Setup
    fixture fix;
-   auto nodes = nodes_from_resp3({
+   auto nodes = tree_from_resp3({
       // clang-format off
       "+OK\r\n",
       "%6\r\n$6\r\nserver\r\n$5\r\nredis\r\n$7\r\nversion\r\n$5\r\n7.4.2\r\n$5\r\nproto\r\n:3\r\n$2\r\nid\r\n:3\r\n$4\r\nmode\r\n$8\r\nsentinel\r\n$7\r\nmodules\r\n*0\r\n",
@@ -170,7 +170,7 @@ void test_master_ip_port_out_of_order()
 {
    // Setup
    fixture fix;
-   auto nodes = nodes_from_resp3({
+   auto nodes = tree_from_resp3({
       // clang-format off
       "*2\r\n$9\r\nlocalhost\r\n$4\r\n6380\r\n",
       "*1\r\n"
@@ -195,7 +195,7 @@ void test_replica()
 {
    // Setup
    fixture fix;
-   auto nodes = nodes_from_resp3({
+   auto nodes = tree_from_resp3({
       // clang-format off
       "*2\r\n$9\r\nlocalhost\r\n$4\r\n6380\r\n",
       "*2\r\n"
@@ -254,7 +254,7 @@ void test_replica_no_sentinels()
 {
    // Setup
    fixture fix;
-   auto nodes = nodes_from_resp3({
+   auto nodes = tree_from_resp3({
       // clang-format off
       "*2\r\n$9\r\nlocalhost\r\n$4\r\n6380\r\n",
       "*2\r\n"
@@ -283,7 +283,7 @@ void test_replica_no_replicas()
 {
    // Setup
    fixture fix;
-   auto nodes = nodes_from_resp3({
+   auto nodes = tree_from_resp3({
       // clang-format off
       "*2\r\n$9\r\nlocalhost\r\n$4\r\n6380\r\n",
       "*0\r\n",
@@ -304,7 +304,7 @@ void test_replica_setup_request()
 {
    // Setup
    fixture fix;
-   auto nodes = nodes_from_resp3({
+   auto nodes = tree_from_resp3({
       // clang-format off
       "*2\r\n+OK\r\n+OK\r\n",
       "*2\r\n$9\r\nlocalhost\r\n$4\r\n6380\r\n",
@@ -342,7 +342,7 @@ void test_replica_ip_port_out_of_order()
 {
    // Setup
    fixture fix;
-   auto nodes = nodes_from_resp3({
+   auto nodes = tree_from_resp3({
       // clang-format off
       "*2\r\n$9\r\ntest.host\r\n$4\r\n6389\r\n",
       "*1\r\n"
@@ -697,7 +697,7 @@ void test_errors()
       // Setup
       std::cerr << "Running error test case: " << tc.name << std::endl;
       fixture fix;
-      auto nodes = nodes_from_resp3(tc.responses);
+      auto nodes = tree_from_resp3(tc.responses);
 
       // Call the function
       auto ec = parse_sentinel_response(nodes, tc.server_role, fix.resp);
diff --git a/test/test_sentinel_resolve_fsm.cpp b/test/test_sentinel_resolve_fsm.cpp
index 4eb847d93..d3046819a 100644
--- a/test/test_sentinel_resolve_fsm.cpp
+++ b/test/test_sentinel_resolve_fsm.cpp
@@ -26,7 +26,7 @@ namespace asio = boost::asio;
 using detail::sentinel_resolve_fsm;
 using detail::sentinel_action;
 using detail::connection_state;
-using detail::nodes_from_resp3;
+using detail::tree_from_resp3;
 using boost::system::error_code;
 using boost::asio::cancellation_type_t;
 
@@ -115,7 +115,7 @@ void test_success()
    // Now send the request
    act = fix.fsm.resume(fix.st, error_code(), cancellation_type_t::none);
    BOOST_TEST_EQ(act, sentinel_action::request());
-   fix.st.sentinel_resp_nodes = nodes_from_resp3({
+   fix.st.sentinel_resp_nodes = tree_from_resp3({
       // clang-format off
       "*2\r\n$9\r\ntest.host\r\n$4\r\n6380\r\n",
       "*1\r\n"
@@ -166,7 +166,7 @@ void test_success_replica()
    // Now send the request
    act = fix.fsm.resume(fix.st, error_code(), cancellation_type_t::none);
    BOOST_TEST_EQ(act, sentinel_action::request());
-   fix.st.sentinel_resp_nodes = nodes_from_resp3({
+   fix.st.sentinel_resp_nodes = tree_from_resp3({
       // clang-format off
       "*2\r\n$9\r\ntest.host\r\n$4\r\n6380\r\n",
       "*3\r\n"
@@ -215,7 +215,7 @@ void test_one_connect_error()
    // Now send the request
    act = fix.fsm.resume(fix.st, error_code(), cancellation_type_t::none);
    BOOST_TEST_EQ(act, sentinel_action::request());
-   fix.st.sentinel_resp_nodes = nodes_from_resp3({
+   fix.st.sentinel_resp_nodes = tree_from_resp3({
       "*2\r\n$9\r\ntest.host\r\n$4\r\n6380\r\n",
       "*0\r\n",
    });
@@ -257,7 +257,7 @@ void test_one_request_network_error()
    BOOST_TEST_EQ(act, (address{"host2", "2000"}));
    act = fix.fsm.resume(fix.st, error_code(), cancellation_type_t::none);
    BOOST_TEST_EQ(act, sentinel_action::request());
-   fix.st.sentinel_resp_nodes = nodes_from_resp3({
+   fix.st.sentinel_resp_nodes = tree_from_resp3({
       "*2\r\n$9\r\ntest.host\r\n$4\r\n6380\r\n",
       "*0\r\n",
    });
@@ -292,7 +292,7 @@ void test_one_request_parse_error()
    BOOST_TEST_EQ(act, (address{"host1", "1000"}));
    act = fix.fsm.resume(fix.st, error_code(), cancellation_type_t::none);
    BOOST_TEST_EQ(act, sentinel_action::request());
-   fix.st.sentinel_resp_nodes = nodes_from_resp3({
+   fix.st.sentinel_resp_nodes = tree_from_resp3({
       "+OK\r\n",
       "+OK\r\n",
    });
@@ -302,7 +302,7 @@ void test_one_request_parse_error()
    BOOST_TEST_EQ(act, (address{"host2", "2000"}));
    act = fix.fsm.resume(fix.st, error_code(), cancellation_type_t::none);
    BOOST_TEST_EQ(act, sentinel_action::request());
-   fix.st.sentinel_resp_nodes = nodes_from_resp3({
+   fix.st.sentinel_resp_nodes = tree_from_resp3({
       "*2\r\n$9\r\ntest.host\r\n$4\r\n6380\r\n",
       "*0\r\n",
    });
@@ -338,7 +338,7 @@ void test_one_request_error_node()
    BOOST_TEST_EQ(act, (address{"host1", "1000"}));
    act = fix.fsm.resume(fix.st, error_code(), cancellation_type_t::none);
    BOOST_TEST_EQ(act, sentinel_action::request());
-   fix.st.sentinel_resp_nodes = nodes_from_resp3({
+   fix.st.sentinel_resp_nodes = tree_from_resp3({
       "-ERR needs authentication\r\n",
       "-ERR needs authentication\r\n",
    });
@@ -348,7 +348,7 @@ void test_one_request_error_node()
    BOOST_TEST_EQ(act, (address{"host2", "2000"}));
    act = fix.fsm.resume(fix.st, error_code(), cancellation_type_t::none);
    BOOST_TEST_EQ(act, sentinel_action::request());
-   fix.st.sentinel_resp_nodes = nodes_from_resp3({
+   fix.st.sentinel_resp_nodes = tree_from_resp3({
       "*2\r\n$9\r\ntest.host\r\n$4\r\n6380\r\n",
       "*0\r\n",
    });
@@ -383,7 +383,7 @@ void test_one_master_unknown()
    BOOST_TEST_EQ(act, (address{"host1", "1000"}));
    act = fix.fsm.resume(fix.st, error_code(), cancellation_type_t::none);
    BOOST_TEST_EQ(act, sentinel_action::request());
-   fix.st.sentinel_resp_nodes = nodes_from_resp3({
+   fix.st.sentinel_resp_nodes = tree_from_resp3({
       "_\r\n",
       "-ERR unknown master\r\n",
    });
@@ -394,7 +394,7 @@ void test_one_master_unknown()
    BOOST_TEST_EQ(act, (address{"host2", "2000"}));
    act = fix.fsm.resume(fix.st, error_code(), cancellation_type_t::none);
    BOOST_TEST_EQ(act, sentinel_action::request());
-   fix.st.sentinel_resp_nodes = nodes_from_resp3({
+   fix.st.sentinel_resp_nodes = tree_from_resp3({
       "*2\r\n$9\r\ntest.host\r\n$4\r\n6380\r\n",
       "*0\r\n",
    });
@@ -430,7 +430,7 @@ void test_one_no_replicas()
    BOOST_TEST_EQ(act, (address{"host1", "1000"}));
    act = fix.fsm.resume(fix.st, error_code(), cancellation_type_t::none);
    BOOST_TEST_EQ(act, sentinel_action::request());
-   fix.st.sentinel_resp_nodes = nodes_from_resp3({
+   fix.st.sentinel_resp_nodes = tree_from_resp3({
       "*2\r\n$9\r\ntest.host\r\n$4\r\n6380\r\n",
       "*0\r\n",
       "*0\r\n",
@@ -441,7 +441,7 @@ void test_one_no_replicas()
    BOOST_TEST_EQ(act, (address{"host2", "2000"}));
    act = fix.fsm.resume(fix.st, error_code(), cancellation_type_t::none);
    BOOST_TEST_EQ(act, sentinel_action::request());
-   fix.st.sentinel_resp_nodes = nodes_from_resp3({
+   fix.st.sentinel_resp_nodes = tree_from_resp3({
       // clang-format off
       "*2\r\n$9\r\ntest.host\r\n$4\r\n6380\r\n",
       "*1\r\n"
@@ -481,7 +481,7 @@ void test_error()
    BOOST_TEST_EQ(act, (address{"host1", "1000"}));
    act = fix.fsm.resume(fix.st, error_code(), cancellation_type_t::none);
    BOOST_TEST_EQ(act, sentinel_action::request());
-   fix.st.sentinel_resp_nodes = nodes_from_resp3({
+   fix.st.sentinel_resp_nodes = tree_from_resp3({
       "_\r\n",
       "-ERR unknown master\r\n",
    });
@@ -495,7 +495,7 @@ void test_error()
    BOOST_TEST_EQ(act, (address{"host3", "3000"}));
    act = fix.fsm.resume(fix.st, error_code(), cancellation_type_t::none);
    BOOST_TEST_EQ(act, sentinel_action::request());
-   fix.st.sentinel_resp_nodes = nodes_from_resp3({
+   fix.st.sentinel_resp_nodes = tree_from_resp3({
       "-ERR unauthorized\r\n",
       "-ERR unauthorized\r\n",
    });
@@ -546,7 +546,7 @@ void test_error_replica()
    BOOST_TEST_EQ(act, (address{"host1", "1000"}));
    act = fix.fsm.resume(fix.st, error_code(), cancellation_type_t::none);
    BOOST_TEST_EQ(act, sentinel_action::request());
-   fix.st.sentinel_resp_nodes = nodes_from_resp3({
+   fix.st.sentinel_resp_nodes = tree_from_resp3({
       "*2\r\n$9\r\ntest.host\r\n$4\r\n6380\r\n",
       "*0\r\n",
       "*0\r\n",

From 063c713305100a4e4c01093cd8ab61848b350279 Mon Sep 17 00:00:00 2001
From: Ruben Perez <rubenperez038@gmail.com>
Date: Tue, 27 Jan 2026 20:30:08 +0100
Subject: [PATCH 03/11] use get_num_messages

---
 include/boost/redis/impl/sentinel_utils.hpp | 37 +++++++++++----------
 1 file changed, 20 insertions(+), 17 deletions(-)

diff --git a/include/boost/redis/impl/sentinel_utils.hpp b/include/boost/redis/impl/sentinel_utils.hpp
index d8f187535..e16b184cd 100644
--- a/include/boost/redis/impl/sentinel_utils.hpp
+++ b/include/boost/redis/impl/sentinel_utils.hpp
@@ -11,6 +11,7 @@
 
 #include <boost/redis/config.hpp>
 #include <boost/redis/error.hpp>
+#include <boost/redis/resp3/flat_tree.hpp>
 #include <boost/redis/resp3/node.hpp>
 #include <boost/redis/resp3/type.hpp>
 
@@ -135,7 +136,7 @@ struct sentinel_response {
 //   * The node array originates from parsing a valid RESP3 message.
 //     E.g. we won't check that the first node has depth 0.
 inline system::error_code parse_sentinel_response(
-   span<const resp3::node_view> nodes,
+   const resp3::flat_tree& tree,
    role server_role,
    sentinel_response& out)
 {
@@ -156,27 +157,29 @@ inline system::error_code parse_sentinel_response(
    out.sentinels.clear();
    out.replicas.clear();
 
-   // Find the first root node of interest. It's the 2nd or 3rd, starting with the end
-   auto find_first = [nodes, server_role] {
-      const std::size_t expected_roots = server_role == role::master ? 2u : 3u;
-      std::size_t roots_seen = 0u;
-      for (auto it = nodes.rbegin();; ++it) {
-         BOOST_ASSERT(it != nodes.rend());
-         if (it->depth == 0u && ++roots_seen == expected_roots)
-            return &*it;
-      }
-   };
-   const resp3::node_view* lib_first = find_first();
+   // User-supplied commands are before the ones added by us.
+   // Find out how many responses should we skip
+   const std::size_t num_lib_msgs = server_role == role::master ? 2u : 3u;
+   BOOST_ASSERT(tree.get_total_msgs() >= num_lib_msgs);
+   const std::size_t num_user_msgs = tree.get_total_msgs() - num_lib_msgs;
 
    // Iterators
-   const resp3::node_view* it = nodes.begin();
-   const resp3::node_view* last = nodes.end();
+   const resp3::node_view* it = tree.begin();
+   const resp3::node_view* last = tree.end();
    ignore_unused(last);
 
    // Go through all the responses to user-supplied requests checking for errors
-   for (; it != lib_first; ++it) {
-      if (auto ec = check_errors(*it))
-         return ec;
+   BOOST_ASSERT(it != last);
+   BOOST_ASSERT(it->depth == 0u);
+   for (std::size_t i = 0u; i < num_user_msgs; ++i) {
+      while (true) {
+         if (auto ec = check_errors(*it))
+            return ec;
+         ++it;
+         BOOST_ASSERT(it != last);
+         if (it->depth == 0u)
+            break;
+      }
    }
 
    // SENTINEL GET-MASTER-ADDR-BY-NAME

From 17d4132ddd8f9748312451f4d1b1f35912747e74 Mon Sep 17 00:00:00 2001
From: Ruben Perez <rubenperez038@gmail.com>
Date: Tue, 27 Jan 2026 20:43:13 +0100
Subject: [PATCH 04/11] Use indices and at

---
 include/boost/redis/impl/sentinel_utils.hpp | 109 +++++++++-----------
 1 file changed, 51 insertions(+), 58 deletions(-)

diff --git a/include/boost/redis/impl/sentinel_utils.hpp b/include/boost/redis/impl/sentinel_utils.hpp
index e16b184cd..c28021f76 100644
--- a/include/boost/redis/impl/sentinel_utils.hpp
+++ b/include/boost/redis/impl/sentinel_utils.hpp
@@ -16,7 +16,6 @@
 #include <boost/redis/resp3/type.hpp>
 
 #include <boost/assert.hpp>
-#include <boost/core/ignore_unused.hpp>
 #include <boost/core/span.hpp>
 #include <boost/system/error_code.hpp>
 
@@ -46,60 +45,57 @@ inline void compose_sentinel_request(config& cfg)
 
 // Parses a list of replicas or sentinels
 inline system::error_code parse_server_list(
-   const resp3::node_view*& first,
-   const resp3::node_view* last,
+   const resp3::flat_tree& tree,
+   std::size_t& index,
    std::vector<address>& out)
 {
-   const auto* it = first;
-   ignore_unused(last);
-
    // The root node must be an array
-   BOOST_ASSERT(it != last);
-   BOOST_ASSERT(it->depth == 0u);
-   if (it->data_type != resp3::type::array)
+   const auto& root = tree.at(index);
+   BOOST_ASSERT(root.depth == 0u);
+   if (root.data_type != resp3::type::array)
       return {error::expects_resp3_array};
-   const std::size_t num_servers = it->aggregate_size;
-   ++it;
+   const std::size_t num_servers = root.aggregate_size;
+   ++index;
 
    // Each element in the array represents a server
    out.resize(num_servers);
    for (std::size_t i = 0u; i < num_servers; ++i) {
       // A server is a map (resp3) or array (resp2, currently unsupported)
-      BOOST_ASSERT(it != last);
-      BOOST_ASSERT(it->depth == 1u);
-      if (it->data_type != resp3::type::map)
+      const auto& server_node = tree.at(index);
+      BOOST_ASSERT(server_node.depth == 1u);
+      if (server_node.data_type != resp3::type::map)
          return {error::expects_resp3_map};
-      const std::size_t num_key_values = it->aggregate_size;
-      ++it;
+      const std::size_t num_key_values = server_node.aggregate_size;
+      ++index;
 
       // The server object is composed by a set of key/value pairs.
       // Skip everything except for the ones we care for.
       bool ip_seen = false, port_seen = false;
       for (std::size_t j = 0; j < num_key_values; ++j) {
          // Key. It should be a string
-         BOOST_ASSERT(it != last);
-         BOOST_ASSERT(it->depth == 2u);
-         if (it->data_type != resp3::type::blob_string)
+         const auto& key_node = tree.at(index);
+         BOOST_ASSERT(key_node.depth == 2u);
+         if (key_node.data_type != resp3::type::blob_string)
             return {error::expects_resp3_string};
-         const std::string_view key = it->value;
-         ++it;
+         const std::string_view key = key_node.value;
+         ++index;
 
          // Value. All values seem to be strings, too.
-         BOOST_ASSERT(it != last);
-         BOOST_ASSERT(it->depth == 2u);
-         if (it->data_type != resp3::type::blob_string)
+         const auto& value_node = tree.at(index);
+         BOOST_ASSERT(value_node.depth == 2u);
+         if (value_node.data_type != resp3::type::blob_string)
             return {error::expects_resp3_string};
 
          // Record it
          if (key == "ip") {
             ip_seen = true;
-            out[i].host = it->value;
+            out[i].host = tree.at(index).value;
          } else if (key == "port") {
             port_seen = true;
-            out[i].port = it->value;
+            out[i].port = tree.at(index).value;
          }
 
-         ++it;
+         ++index;
       }
 
       // Check that the response actually contained the fields we wanted
@@ -108,7 +104,6 @@ inline system::error_code parse_server_list(
    }
 
    // Done
-   first = it;
    return system::error_code();
 }
 
@@ -160,62 +155,60 @@ inline system::error_code parse_sentinel_response(
    // User-supplied commands are before the ones added by us.
    // Find out how many responses should we skip
    const std::size_t num_lib_msgs = server_role == role::master ? 2u : 3u;
-   BOOST_ASSERT(tree.get_total_msgs() >= num_lib_msgs);
+   BOOST_ASSERT(tree.get_total_msgs() >= num_lib_msgs);  // TODO
    const std::size_t num_user_msgs = tree.get_total_msgs() - num_lib_msgs;
 
-   // Iterators
-   const resp3::node_view* it = tree.begin();
-   const resp3::node_view* last = tree.end();
-   ignore_unused(last);
+   // Index-based access
+   std::size_t index = 0;
 
    // Go through all the responses to user-supplied requests checking for errors
-   BOOST_ASSERT(it != last);
-   BOOST_ASSERT(it->depth == 0u);
+   BOOST_ASSERT(tree.at(index).depth == 0u);
    for (std::size_t i = 0u; i < num_user_msgs; ++i) {
       while (true) {
-         if (auto ec = check_errors(*it))
+         if (auto ec = check_errors(tree.at(index)))
             return ec;
-         ++it;
-         BOOST_ASSERT(it != last);
-         if (it->depth == 0u)
+         ++index;
+         if (tree.at(index).depth == 0u)
             break;
       }
    }
 
    // SENTINEL GET-MASTER-ADDR-BY-NAME
+   // TODO: move
 
    // Check for errors
-   if (auto ec = check_errors(*it))
+   const auto& root_node = tree.at(index);
+   if (auto ec = check_errors(root_node))
       return ec;
 
    // If the root node is NULL, Sentinel doesn't know about this master.
    // We use resp3_null to signal this fact. This doesn't reach the end user.
-   if (it->data_type == resp3::type::null) {
+   if (root_node.data_type == resp3::type::null) {
       return {error::resp3_null};
    }
 
    // If the root node is an array, an IP and port follow
-   if (it->data_type != resp3::type::array)
+   if (root_node.data_type != resp3::type::array)
       return {error::expects_resp3_array};
-   if (it->aggregate_size != 2u)
+   if (root_node.aggregate_size != 2u)
       return {error::incompatible_size};
-   ++it;
+   ++index;
 
    // IP
-   BOOST_ASSERT(it != last);
-   BOOST_ASSERT(it->depth == 1u);
-   if (it->data_type != resp3::type::blob_string)
+   const auto& ip_node = tree.at(index);
+   BOOST_ASSERT(ip_node.depth == 1u);
+   if (ip_node.data_type != resp3::type::blob_string)
       return {error::expects_resp3_string};
-   out.master_addr.host = it->value;
-   ++it;
+   out.master_addr.host = ip_node.value;
+   ++index;
 
    // Port
-   BOOST_ASSERT(it != last);
-   BOOST_ASSERT(it->depth == 1u);
-   if (it->data_type != resp3::type::blob_string)
+   const auto& port_node = tree.at(index);
+   BOOST_ASSERT(port_node.depth == 1u);
+   if (port_node.data_type != resp3::type::blob_string)
       return {error::expects_resp3_string};
-   out.master_addr.port = it->value;
-   ++it;
+   out.master_addr.port = port_node.value;
+   ++index;
 
    if (server_role == role::replica) {
       // SENTINEL REPLICAS
@@ -223,11 +216,11 @@ inline system::error_code parse_sentinel_response(
       // This request fails if Sentinel doesn't know about this master.
       // However, that's not the case if we got here.
       // Check for other errors.
-      if (auto ec = check_errors(*it))
+      if (auto ec = check_errors(tree.at(index)))
          return ec;
 
       // Actual parsing
-      if (auto ec = parse_server_list(it, last, out.replicas))
+      if (auto ec = parse_server_list(tree, index, out.replicas))
          return ec;
    }
 
@@ -236,11 +229,11 @@ inline system::error_code parse_sentinel_response(
    // This request fails if Sentinel doesn't know about this master.
    // However, that's not the case if we got here.
    // Check for other errors.
-   if (auto ec = check_errors(*it))
+   if (auto ec = check_errors(tree.at(index)))
       return ec;
 
    // Actual parsing
-   if (auto ec = parse_server_list(it, last, out.sentinels))
+   if (auto ec = parse_server_list(tree, index, out.sentinels))
       return ec;
 
    // Done

From dbca826c484aa17ef9df728918d8f7b207295d38 Mon Sep 17 00:00:00 2001
From: Ruben Perez <rubenperez038@gmail.com>
Date: Tue, 27 Jan 2026 20:49:04 +0100
Subject: [PATCH 05/11] add a response length check

---
 include/boost/redis/impl/sentinel_utils.hpp | 29 ++++++++++-----------
 1 file changed, 14 insertions(+), 15 deletions(-)

diff --git a/include/boost/redis/impl/sentinel_utils.hpp b/include/boost/redis/impl/sentinel_utils.hpp
index c28021f76..05e0d5241 100644
--- a/include/boost/redis/impl/sentinel_utils.hpp
+++ b/include/boost/redis/impl/sentinel_utils.hpp
@@ -53,7 +53,7 @@ inline system::error_code parse_server_list(
    const auto& root = tree.at(index);
    BOOST_ASSERT(root.depth == 0u);
    if (root.data_type != resp3::type::array)
-      return {error::expects_resp3_array};
+      return error::expects_resp3_array;
    const std::size_t num_servers = root.aggregate_size;
    ++index;
 
@@ -64,7 +64,7 @@ inline system::error_code parse_server_list(
       const auto& server_node = tree.at(index);
       BOOST_ASSERT(server_node.depth == 1u);
       if (server_node.data_type != resp3::type::map)
-         return {error::expects_resp3_map};
+         return error::expects_resp3_map;
       const std::size_t num_key_values = server_node.aggregate_size;
       ++index;
 
@@ -76,7 +76,7 @@ inline system::error_code parse_server_list(
          const auto& key_node = tree.at(index);
          BOOST_ASSERT(key_node.depth == 2u);
          if (key_node.data_type != resp3::type::blob_string)
-            return {error::expects_resp3_string};
+            return error::expects_resp3_string;
          const std::string_view key = key_node.value;
          ++index;
 
@@ -84,7 +84,7 @@ inline system::error_code parse_server_list(
          const auto& value_node = tree.at(index);
          BOOST_ASSERT(value_node.depth == 2u);
          if (value_node.data_type != resp3::type::blob_string)
-            return {error::expects_resp3_string};
+            return error::expects_resp3_string;
 
          // Record it
          if (key == "ip") {
@@ -100,7 +100,7 @@ inline system::error_code parse_server_list(
 
       // Check that the response actually contained the fields we wanted
       if (!ip_seen || !port_seen)
-         return {error::empty_field};
+         return error::empty_field;
    }
 
    // Done
@@ -126,10 +126,8 @@ struct sentinel_response {
 // This means that we can't use generic_response, since its adapter errors on error nodes.
 // SENTINEL GET-MASTER-ADDR-BY-NAME is sent even when connecting to replicas
 //    for better diagnostics when the master name is unknown.
-// Preconditions:
-//   * There are at least 2 (master)/3 (replica) root nodes.
-//   * The node array originates from parsing a valid RESP3 message.
-//     E.g. we won't check that the first node has depth 0.
+// Note that the tree should originate from a valid RESP3 message
+//   (i.e. we won't check that the first node has depth 0.)
 inline system::error_code parse_sentinel_response(
    const resp3::flat_tree& tree,
    role server_role,
@@ -155,7 +153,8 @@ inline system::error_code parse_sentinel_response(
    // User-supplied commands are before the ones added by us.
    // Find out how many responses should we skip
    const std::size_t num_lib_msgs = server_role == role::master ? 2u : 3u;
-   BOOST_ASSERT(tree.get_total_msgs() >= num_lib_msgs);  // TODO
+   if (tree.get_total_msgs() < num_lib_msgs)
+      return error::incompatible_size;
    const std::size_t num_user_msgs = tree.get_total_msgs() - num_lib_msgs;
 
    // Index-based access
@@ -184,21 +183,21 @@ inline system::error_code parse_sentinel_response(
    // If the root node is NULL, Sentinel doesn't know about this master.
    // We use resp3_null to signal this fact. This doesn't reach the end user.
    if (root_node.data_type == resp3::type::null) {
-      return {error::resp3_null};
+      return error::resp3_null;
    }
 
    // If the root node is an array, an IP and port follow
    if (root_node.data_type != resp3::type::array)
-      return {error::expects_resp3_array};
+      return error::expects_resp3_array;
    if (root_node.aggregate_size != 2u)
-      return {error::incompatible_size};
+      return error::incompatible_size;
    ++index;
 
    // IP
    const auto& ip_node = tree.at(index);
    BOOST_ASSERT(ip_node.depth == 1u);
    if (ip_node.data_type != resp3::type::blob_string)
-      return {error::expects_resp3_string};
+      return error::expects_resp3_string;
    out.master_addr.host = ip_node.value;
    ++index;
 
@@ -206,7 +205,7 @@ inline system::error_code parse_sentinel_response(
    const auto& port_node = tree.at(index);
    BOOST_ASSERT(port_node.depth == 1u);
    if (port_node.data_type != resp3::type::blob_string)
-      return {error::expects_resp3_string};
+      return error::expects_resp3_string;
    out.master_addr.port = port_node.value;
    ++index;
 

From 5bb388e59b1cad1bee073aed1fe8db5db651b8b4 Mon Sep 17 00:00:00 2001
From: Ruben Perez <rubenperez038@gmail.com>
Date: Tue, 27 Jan 2026 20:51:43 +0100
Subject: [PATCH 06/11] size check tests

---
 test/test_parse_sentinel_response.cpp | 35 ++++++++++++++++++++++++++-
 1 file changed, 34 insertions(+), 1 deletion(-)

diff --git a/test/test_parse_sentinel_response.cpp b/test/test_parse_sentinel_response.cpp
index 40d78d6fa..b77c6abf5 100644
--- a/test/test_parse_sentinel_response.cpp
+++ b/test/test_parse_sentinel_response.cpp
@@ -688,7 +688,40 @@ void test_errors()
          },
          "",
          error::empty_field
-      }
+      },
+      {
+         "not_enough_messages_1",
+         role::master,
+         {},
+         "",
+         error::incompatible_size
+      },
+      {
+         "not_enough_messages_2",
+         role::master,
+         {
+            "*2\r\n$9\r\nlocalhost\r\n$4\r\n6380\r\n",
+         },
+         "",
+         error::incompatible_size
+      },
+      {
+         "not_enough_messages_replica_1",
+         role::replica,
+         {},
+         "",
+         error::incompatible_size
+      },
+      {
+         "not_enough_messages_replica_2",
+         role::replica,
+         {
+            "*2\r\n$9\r\nlocalhost\r\n$4\r\n6380\r\n",
+            "*0\r\n",
+         },
+         "",
+         error::incompatible_size
+      },
 
       // clang-format on
    };

From edbca64b33f57bf807bf004437decf99ef71708e Mon Sep 17 00:00:00 2001
From: Ruben Perez <rubenperez038@gmail.com>
Date: Tue, 27 Jan 2026 21:03:26 +0100
Subject: [PATCH 07/11] simplify skip loop

---
 include/boost/redis/impl/sentinel_utils.hpp | 23 +++++++++++----------
 1 file changed, 12 insertions(+), 11 deletions(-)

diff --git a/include/boost/redis/impl/sentinel_utils.hpp b/include/boost/redis/impl/sentinel_utils.hpp
index 05e0d5241..7fe933efd 100644
--- a/include/boost/redis/impl/sentinel_utils.hpp
+++ b/include/boost/redis/impl/sentinel_utils.hpp
@@ -150,6 +150,9 @@ inline system::error_code parse_sentinel_response(
    out.sentinels.clear();
    out.replicas.clear();
 
+   // Index-based access
+   std::size_t index = 0;
+
    // User-supplied commands are before the ones added by us.
    // Find out how many responses should we skip
    const std::size_t num_lib_msgs = server_role == role::master ? 2u : 3u;
@@ -157,19 +160,17 @@ inline system::error_code parse_sentinel_response(
       return error::incompatible_size;
    const std::size_t num_user_msgs = tree.get_total_msgs() - num_lib_msgs;
 
-   // Index-based access
-   std::size_t index = 0;
-
    // Go through all the responses to user-supplied requests checking for errors
    BOOST_ASSERT(tree.at(index).depth == 0u);
-   for (std::size_t i = 0u; i < num_user_msgs; ++i) {
-      while (true) {
-         if (auto ec = check_errors(tree.at(index)))
-            return ec;
-         ++index;
-         if (tree.at(index).depth == 0u)
-            break;
-      }
+   for (std::size_t remaining_roots = num_user_msgs + 1u;; ++index) {
+      // Exit at node N+1
+      const auto& node = tree.at(index);
+      if (node.depth == 0u && --remaining_roots == 0u)
+         break;
+
+      // This is a user-supplied message. Check for errors
+      if (auto ec = check_errors(node))
+         return ec;
    }
 
    // SENTINEL GET-MASTER-ADDR-BY-NAME

From cea85360231dd65c5962df473cadb79ea6f37a01 Mon Sep 17 00:00:00 2001
From: Ruben Perez <rubenperez038@gmail.com>
Date: Tue, 27 Jan 2026 21:04:53 +0100
Subject: [PATCH 08/11] remove TODO

---
 include/boost/redis/impl/sentinel_utils.hpp | 1 -
 1 file changed, 1 deletion(-)

diff --git a/include/boost/redis/impl/sentinel_utils.hpp b/include/boost/redis/impl/sentinel_utils.hpp
index 7fe933efd..bbbe93326 100644
--- a/include/boost/redis/impl/sentinel_utils.hpp
+++ b/include/boost/redis/impl/sentinel_utils.hpp
@@ -174,7 +174,6 @@ inline system::error_code parse_sentinel_response(
    }
 
    // SENTINEL GET-MASTER-ADDR-BY-NAME
-   // TODO: move
 
    // Check for errors
    const auto& root_node = tree.at(index);

From d38a4b0577a70fe336fcfae5ced2ec3abfb8dec9 Mon Sep 17 00:00:00 2001
From: Ruben Perez <rubenperez038@gmail.com>
Date: Tue, 27 Jan 2026 21:08:09 +0100
Subject: [PATCH 09/11] don't access value node

---
 include/boost/redis/impl/sentinel_utils.hpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/boost/redis/impl/sentinel_utils.hpp b/include/boost/redis/impl/sentinel_utils.hpp
index bbbe93326..54083abd3 100644
--- a/include/boost/redis/impl/sentinel_utils.hpp
+++ b/include/boost/redis/impl/sentinel_utils.hpp
@@ -89,10 +89,10 @@ inline system::error_code parse_server_list(
          // Record it
          if (key == "ip") {
             ip_seen = true;
-            out[i].host = tree.at(index).value;
+            out[i].host = value_node.value;
          } else if (key == "port") {
             port_seen = true;
-            out[i].port = tree.at(index).value;
+            out[i].port = value_node.value;
          }
 
          ++index;

From 58f790cdd35c4d5a9105b560ee810ec6de4c2932 Mon Sep 17 00:00:00 2001
From: Ruben Perez <rubenperez038@gmail.com>
Date: Tue, 27 Jan 2026 21:20:46 +0100
Subject: [PATCH 10/11] movbe check_errors

---
 include/boost/redis/impl/sentinel_utils.hpp | 55 +++++++++------------
 1 file changed, 23 insertions(+), 32 deletions(-)

diff --git a/include/boost/redis/impl/sentinel_utils.hpp b/include/boost/redis/impl/sentinel_utils.hpp
index 54083abd3..bb991fa7f 100644
--- a/include/boost/redis/impl/sentinel_utils.hpp
+++ b/include/boost/redis/impl/sentinel_utils.hpp
@@ -43,15 +43,31 @@ inline void compose_sentinel_request(config& cfg)
    // Note that we don't care about request flags because this is a one-time request
 }
 
+// Helper
+inline system::error_code sentinel_check_errors(const resp3::node_view& nd, std::string& diag)
+{
+   switch (nd.data_type) {
+      case resp3::type::simple_error: diag = nd.value; return error::resp3_simple_error;
+      case resp3::type::blob_error:   diag = nd.value; return error::resp3_blob_error;
+      default:                        return system::error_code();
+   }
+};
+
 // Parses a list of replicas or sentinels
 inline system::error_code parse_server_list(
    const resp3::flat_tree& tree,
    std::size_t& index,
+   std::string& diag,
    std::vector<address>& out)
 {
-   // The root node must be an array
    const auto& root = tree.at(index);
    BOOST_ASSERT(root.depth == 0u);
+
+   // If the command failed, this will be an error
+   if (auto ec = sentinel_check_errors(root, diag))
+      return ec;
+
+   // The root node must be an array
    if (root.data_type != resp3::type::array)
       return error::expects_resp3_array;
    const std::size_t num_servers = root.aggregate_size;
@@ -133,18 +149,6 @@ inline system::error_code parse_sentinel_response(
    role server_role,
    sentinel_response& out)
 {
-   auto check_errors = [&out](const resp3::node_view& nd) {
-      switch (nd.data_type) {
-         case resp3::type::simple_error:
-            out.diagnostic = nd.value;
-            return system::error_code(error::resp3_simple_error);
-         case resp3::type::blob_error:
-            out.diagnostic = nd.value;
-            return system::error_code(error::resp3_blob_error);
-         default: return system::error_code();
-      }
-   };
-
    // Clear the output
    out.diagnostic.clear();
    out.sentinels.clear();
@@ -169,7 +173,7 @@ inline system::error_code parse_sentinel_response(
          break;
 
       // This is a user-supplied message. Check for errors
-      if (auto ec = check_errors(node))
+      if (auto ec = sentinel_check_errors(node, out.diagnostic))
          return ec;
    }
 
@@ -177,11 +181,13 @@ inline system::error_code parse_sentinel_response(
 
    // Check for errors
    const auto& root_node = tree.at(index);
-   if (auto ec = check_errors(root_node))
+   if (auto ec = sentinel_check_errors(root_node, out.diagnostic))
       return ec;
 
    // If the root node is NULL, Sentinel doesn't know about this master.
    // We use resp3_null to signal this fact. This doesn't reach the end user.
+   // If this is the case, SENTINEL REPLICAS and SENTINEL SENTINELS will fail.
+   // We exit here so the diagnostic is clean.
    if (root_node.data_type == resp3::type::null) {
       return error::resp3_null;
    }
@@ -211,28 +217,13 @@ inline system::error_code parse_sentinel_response(
 
    if (server_role == role::replica) {
       // SENTINEL REPLICAS
-
-      // This request fails if Sentinel doesn't know about this master.
-      // However, that's not the case if we got here.
-      // Check for other errors.
-      if (auto ec = check_errors(tree.at(index)))
-         return ec;
-
-      // Actual parsing
-      if (auto ec = parse_server_list(tree, index, out.replicas))
+      if (auto ec = parse_server_list(tree, index, out.diagnostic, out.replicas))
          return ec;
    }
 
    // SENTINEL SENTINELS
 
-   // This request fails if Sentinel doesn't know about this master.
-   // However, that's not the case if we got here.
-   // Check for other errors.
-   if (auto ec = check_errors(tree.at(index)))
-      return ec;
-
-   // Actual parsing
-   if (auto ec = parse_server_list(tree, index, out.sentinels))
+   if (auto ec = parse_server_list(tree, index, out.diagnostic, out.sentinels))
       return ec;
 
    // Done

From f7304ae5558e65628ce938c4adebf6951e223901 Mon Sep 17 00:00:00 2001
From: Ruben Perez <rubenperez038@gmail.com>
Date: Tue, 27 Jan 2026 21:24:01 +0100
Subject: [PATCH 11/11] extract get-master-addr

---
 include/boost/redis/impl/sentinel_utils.hpp | 87 ++++++++++++---------
 1 file changed, 50 insertions(+), 37 deletions(-)

diff --git a/include/boost/redis/impl/sentinel_utils.hpp b/include/boost/redis/impl/sentinel_utils.hpp
index bb991fa7f..6b52ce7ea 100644
--- a/include/boost/redis/impl/sentinel_utils.hpp
+++ b/include/boost/redis/impl/sentinel_utils.hpp
@@ -123,6 +123,54 @@ inline system::error_code parse_server_list(
    return system::error_code();
 }
 
+// Parses the output of SENTINEL GET-MASTER-ADDR-BY-NAME
+inline system::error_code parse_get_master_addr_by_name(
+   const resp3::flat_tree& tree,
+   std::size_t& index,
+   std::string& diag,
+   address& out)
+{
+   const auto& root_node = tree.at(index);
+   BOOST_ASSERT(root_node.depth == 0u);
+
+   // Check for errors
+   if (auto ec = sentinel_check_errors(root_node, diag))
+      return ec;
+
+   // If the root node is NULL, Sentinel doesn't know about this master.
+   // We use resp3_null to signal this fact. This doesn't reach the end user.
+   // If this is the case, SENTINEL REPLICAS and SENTINEL SENTINELS will fail.
+   // We exit here so the diagnostic is clean.
+   if (root_node.data_type == resp3::type::null) {
+      return error::resp3_null;
+   }
+
+   // If the root node is an array, an IP and port follow
+   if (root_node.data_type != resp3::type::array)
+      return error::expects_resp3_array;
+   if (root_node.aggregate_size != 2u)
+      return error::incompatible_size;
+   ++index;
+
+   // IP
+   const auto& ip_node = tree.at(index);
+   BOOST_ASSERT(ip_node.depth == 1u);
+   if (ip_node.data_type != resp3::type::blob_string)
+      return error::expects_resp3_string;
+   out.host = ip_node.value;
+   ++index;
+
+   // Port
+   const auto& port_node = tree.at(index);
+   BOOST_ASSERT(port_node.depth == 1u);
+   if (port_node.data_type != resp3::type::blob_string)
+      return error::expects_resp3_string;
+   out.port = port_node.value;
+   ++index;
+
+   return system::error_code();
+}
+
 // The output type of parse_sentinel_response
 struct sentinel_response {
    std::string diagnostic;         // In case the server returned an error
@@ -178,51 +226,16 @@ inline system::error_code parse_sentinel_response(
    }
 
    // SENTINEL GET-MASTER-ADDR-BY-NAME
-
-   // Check for errors
-   const auto& root_node = tree.at(index);
-   if (auto ec = sentinel_check_errors(root_node, out.diagnostic))
+   if (auto ec = parse_get_master_addr_by_name(tree, index, out.diagnostic, out.master_addr))
       return ec;
 
-   // If the root node is NULL, Sentinel doesn't know about this master.
-   // We use resp3_null to signal this fact. This doesn't reach the end user.
-   // If this is the case, SENTINEL REPLICAS and SENTINEL SENTINELS will fail.
-   // We exit here so the diagnostic is clean.
-   if (root_node.data_type == resp3::type::null) {
-      return error::resp3_null;
-   }
-
-   // If the root node is an array, an IP and port follow
-   if (root_node.data_type != resp3::type::array)
-      return error::expects_resp3_array;
-   if (root_node.aggregate_size != 2u)
-      return error::incompatible_size;
-   ++index;
-
-   // IP
-   const auto& ip_node = tree.at(index);
-   BOOST_ASSERT(ip_node.depth == 1u);
-   if (ip_node.data_type != resp3::type::blob_string)
-      return error::expects_resp3_string;
-   out.master_addr.host = ip_node.value;
-   ++index;
-
-   // Port
-   const auto& port_node = tree.at(index);
-   BOOST_ASSERT(port_node.depth == 1u);
-   if (port_node.data_type != resp3::type::blob_string)
-      return error::expects_resp3_string;
-   out.master_addr.port = port_node.value;
-   ++index;
-
+   // SENTINEL REPLICAS
    if (server_role == role::replica) {
-      // SENTINEL REPLICAS
       if (auto ec = parse_server_list(tree, index, out.diagnostic, out.replicas))
          return ec;
    }
 
    // SENTINEL SENTINELS
-
    if (auto ec = parse_server_list(tree, index, out.diagnostic, out.sentinels))
       return ec;