[PubSubClient3] Update to latest MQTT Client PubSubClient3

lib/pubsubclient3/.github/ISSUE_TEMPLATE/bug_report.yml

@@ -0,0 +1,105 @@
+name: Bug Report
+description: Create a report to help improve PubSubClient3
+labels: ["bug"]
+body:
+  - type: markdown
+    attributes:
+      value: |
+        Thanks for taking the time to fill out this bug report!
+
+  - type: textarea
+    id: description
+    attributes:
+      label: Describe the bug
+      description: A clear and concise description of what the bug is.
+      placeholder: Tell us what happened...
+    validations:
+      required: true
+
+  - type: textarea
+    id: reproduction
+    attributes:
+      label: Steps to reproduce
+      description: Steps to reproduce the behavior
+      placeholder: |
+        1. Connect to '...'
+        2. Publish message to '...'
+        3. See error
+    validations:
+      required: true
+
+  - type: textarea
+    id: expected
+    attributes:
+      label: Expected behavior
+      description: A clear and concise description of what you expected to happen.
+    validations:
+      required: true
+
+  - type: input
+    id: version
+    attributes:
+      label: Library version
+      description: What version of PubSubClient3 are you running?
+      placeholder: v3.3.0
+    validations:
+      required: true
+
+  - type: dropdown
+    id: platform
+    attributes:
+      label: Platform
+      description: What platform are you using?
+      options:
+        - Arduino AVR
+        - ESP32
+        - ESP8266
+        - Other (specify in environment)
+    validations:
+      required: true
+
+  - type: textarea
+    id: environment
+    attributes:
+      label: Environment
+      description: |
+        Provide details about your hardware and software environment, including:
+        - Board: (e.g., Arduino Uno, ESP12E, ESP32, NodeMCU, etc.)
+        - Framework Version: (e.g., Arduino AVR 5.2.0, ESP32 Arduino 3.3.2, ESP8266 Core 3.1.2 / 3.2.0-git)
+        - Development Environment: (e.g., Arduino IDE 2.3.6, PlatformIO Core 6.1.8)
+        - Platform: (if Other was selected above)
+      placeholder: |
+        - Board:
+        - Framework Version:
+        - Development Environment:
+      render: markdown
+    validations:
+      required: true
+
+  - type: textarea
+    id: example_code
+    attributes:
+      label: Minimal reproducible example (MVP)
+      description: Provide the smallest code/config and exact steps that reproduce the bug. Paste complete minimal sketch or commands.
+      placeholder: |
+        ```cpp
+        #include <ESP8266WiFi.h>
+        #include <PubSubClient.h>
+
+        // minimal setup showing the bug
+        void setup() {
+          // ...
+        }
+
+        void loop() {
+          // ...
+        }
+        ```
+      render: markdown
+
+  - type: textarea
+    id: logs
+    attributes:
+      label: Relevant log output
+      description: Please copy and paste any relevant log output
+      render: shell

lib/pubsubclient3/.github/ISSUE_TEMPLATE/feature_request.yml

@@ -0,0 +1,32 @@
+name: Feature Request
+description: Suggest a new feature for PubSubClient3
+labels: ["enhancement"]
+body:
+  - type: markdown
+    attributes:
+      value: |
+        Thanks for taking the time to suggest a new feature!
+
+  - type: textarea
+    id: reason
+    attributes:
+      label: Describe the reason of your feature request
+      description: A clear and concise description of what the problem is.
+      placeholder: I want to do [...]
+    validations:
+      required: true
+
+  - type: textarea
+    id: solution
+    attributes:
+      label: Describe the solution you'd like
+      description: A clear and concise description of what you want to happen.
+    validations:
+      required: true
+
+  - type: textarea
+    id: context
+    attributes:
+      label: Additional context
+      description: Add any other context or code examples about the feature request here.
+      render: markdown

lib/pubsubclient3/.github/build-arduino.sh

@@ -29,7 +29,7 @@ ln -s $GITHUB_WORKSPACE $HOME/Arduino/libraries/CI_Test_Library
 
 # Compile all *.ino files for the Arduino
 for f in **/*.ino ; do
-    if [[ "$f" != *mqtt_esp8266.ino && "$f" != *mqtt_large_message.ino ]]; then
+    if [[ "$f" != *"mqtt_esp"* ]]; then
         echo "################################################################"
         echo "Arduino Uno compiling file ${f}"
         arduino-cli compile -b arduino:avr:uno $f

lib/pubsubclient3/.github/clang-lint.sh

@@ -9,7 +9,7 @@ cd $GITHUB_WORKSPACE
 #command -v clang-format >/dev/null 2>&1 || sudo apt-get -y install clang-format
 # need Ubuntu clang-format version 19.1.1 (1ubuntu1~24.04.2)
 # default Ubuntu clang-format version 18.1.3 (1ubuntu1) is not working
-sudo apt-get -y install clang-format-19
+#sudo apt-get -y install clang-format-19
 # Check clang-format output
 for f in **/*.{h,c,hpp,cpp,ino} ; do
     #if [ -f "$f" ] && [[ "$f" != "tests/"* ]]; then

lib/pubsubclient3/.github/dependabot.yaml

@@ -0,0 +1,7 @@
+version: 2
+updates:
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: weekly
+      time: "06:00"

lib/pubsubclient3/.github/workflows/compile-examples.yml

@@ -0,0 +1,103 @@
+name: Compile examples
+
+# See: https://docs.github.com/en/free-pro-team@latest/actions/reference/events-that-trigger-workflows
+on:
+  push:
+    paths:
+      - ".github/workflows/compile-examples.yml"
+      - 'examples/**'
+      - 'src/**'
+  pull_request:
+    paths:
+      - ".github/workflows/compile-examples.yml"
+      - 'examples/**'
+      - 'src/**'
+
+jobs:
+  build:
+    name: ${{ matrix.board.fqbn }}
+    runs-on: ubuntu-latest
+
+    env:
+      SKETCHES_REPORTS_PATH: sketches-reports
+
+    strategy:
+      fail-fast: false
+
+      matrix:
+        board:
+          - fqbn: arduino:avr:uno
+            platforms: |
+              - name: arduino:avr
+            libraries: ""
+            artifact-name-suffix: arduino-avr-uno
+          - fqbn: arduino:megaavr:uno2018
+            platforms: |
+              - name: arduino:megaavr
+            libraries: |
+              - name: WiFiNINA
+            artifact-name-suffix: arduino-megaavr-uno2018
+          - fqbn: arduino:samd:mkr1000
+            platforms: |
+              - name: arduino:samd
+            libraries: |
+              - name: WiFi101
+            artifact-name-suffix: arduino-samd-mkr1000
+          - fqbn: esp8266:esp8266:generic
+            platforms: |
+              - name: esp8266:esp8266
+                source-url: https://arduino.esp8266.com/stable/package_esp8266com_index.json
+            libraries: ""
+            artifact-name-suffix: esp8266-esp8266-generic
+          - fqbn: "esp32:esp32:esp32"
+            platforms: |
+              - name: esp32:esp32
+            libraries: ""
+            artifact-name-suffix: esp32-esp32-esp32
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v6
+
+      - name: Download SRAM library
+        run: |
+          mkdir -p ./arduino-libraries
+          git -C ./arduino-libraries clone https://github.com/ennui2342/arduino-sram.git
+
+      - name: Filter examples
+        if: success()
+        run: |
+          if [[ "${{ matrix.board.fqbn }}" == esp32:esp32:* ]]; then
+            echo "Removing non-ESP32 specific examples"
+            rm -rf examples/mqtt_stream
+          fi
+          if [[ ! "${{ matrix.board.fqbn }}" == *:esp*:* ]]; then
+            echo "Removing ESP specific examples"
+            rm -rf examples/mqtt_esp*
+          fi
+
+      - name: Compile examples
+        uses: arduino/compile-sketches@v1
+        with:
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          fqbn: ${{ matrix.board.fqbn }}
+          platforms: ${{ matrix.board.platforms }}
+          libraries: |
+            # Install the library from the local path
+            - source-path: ./
+            - source-path: ./arduino-libraries/arduino-sram
+            # Install libraries from GitHub
+            #- source-url: https://github.com/ennui2342/arduino-sram
+            - name: Ethernet
+            ${{ matrix.board.libraries }}
+          sketch-paths: |
+            - examples
+          enable-deltas-report: true
+          sketches-report-path: ${{ env.SKETCHES_REPORTS_PATH }}
+
+      - name: Save sketches report as workflow artifact
+        uses: actions/upload-artifact@v7
+        with:
+          if-no-files-found: error
+          path: ${{ env.SKETCHES_REPORTS_PATH }}
+          name: sketches-report-${{ matrix.board.artifact-name-suffix }}

lib/pubsubclient3/.github/workflows/gh-pages.yml

@@ -7,7 +7,7 @@ name: Generate Doxygen API and deploy content to GitHub Pages
 on:
   # Runs on pushes targeting the default branch
   push:
-    branches: ["master"]
+    branches: ["release"]
 
   # Allows you to run this workflow manually from the Actions tab
   workflow_dispatch:
@@ -34,12 +34,11 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
       - name: Update Doxyfile PROJECT_NUMBER
         run: bash .github/doxygen-update-version.sh
       - name: Doxygenize
-        #uses: langroodi/doxygenize@v1.7.1 # waiting for update ...
-        uses: langroodi/doxygenize@6e920681c5d838e9a1b5cd273b814d1e4023b63d
+        uses: langroodi/doxygenize@v1.7.1
         #uses: hmueller01/doxygenize@update-alpine-linux+patches
         with:
           # Doxygen configuration file path
@@ -54,12 +53,12 @@ jobs:
       #   run: |
       #     find ./site
       - name: Setup Pages
-        uses: actions/configure-pages@v5
+        uses: actions/configure-pages@v6
       - name: Upload artifact
-        uses: actions/upload-pages-artifact@v3
+        uses: actions/upload-pages-artifact@v5
         with:
           #path: '.' # Upload entire repository
           path: './site'
       - name: Deploy to GitHub Pages
         id: deployment
-        uses: actions/deploy-pages@v4
+        uses: actions/deploy-pages@v5

lib/pubsubclient3/.github/workflows/lint.yml

@@ -0,0 +1,28 @@
+name: Lint
+
+on:
+  push:
+    branches: [ "master" ]
+    paths:
+      - 'examples/**'
+      - 'src/**'
+      - 'tests/**'
+  pull_request:
+    branches: [ "master" ]
+
+jobs:
+  run-checks:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v6
+
+    - name: Install deps
+      # need Ubuntu clang-format version 19.1.1 (1ubuntu1~24.04.2)
+      # default Ubuntu clang-format version 18.1.3 (1ubuntu1) is not working
+      run: |
+        sudo apt-get update
+        sudo apt-get install -y clang-format-19
+
+    - name: Check clang-format conformity
+      run: bash .github/clang-lint.sh

lib/pubsubclient3/.github/workflows/report-size-deltas.yml

@@ -0,0 +1,24 @@
+name: Report Size Deltas
+
+# See: https://docs.github.com/en/free-pro-team@latest/actions/reference/events-that-trigger-workflows
+on:
+  push:
+    paths:
+      - ".github/workflows/report-size-deltas.yml"
+  schedule:
+    # Run at the minimum interval allowed by GitHub Actions.
+    # Note: GitHub Actions periodically has outages which result in workflow failures.
+    # In this event, the workflows will start passing again once the service recovers.
+    - cron: "*/5 * * * *"
+  workflow_dispatch:
+  repository_dispatch:
+
+jobs:
+  report:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Comment size deltas reports to PRs
+        uses: arduino/report-size-deltas@v1
+        with:
+          # Regex matching the names of the workflow artifacts created by the "Compile Examples" workflow
+          sketches-reports-source: ^sketches-report-.+

lib/pubsubclient3/.github/workflows/unit-tests.yml

@@ -1,4 +1,4 @@
-name: build
+name: Unit tests
 
 on:
   push:
@@ -11,14 +11,11 @@ on:
     branches: [ "master" ]
 
 jobs:
-  build:
+  run-tests:
     runs-on: ubuntu-latest
     steps:
     - name: Checkout
-      uses: actions/checkout@v2
-
-    - name: Check clang-format conformity
-      run: bash .github/clang-lint.sh
+      uses: actions/checkout@v6
 
     - name: Build tests
       # Build / Execute tests defined in tests folder
@@ -31,5 +28,5 @@ jobs:
       #run: make test
       run: bin/connect_spec && bin/publish_spec && bin/receive_spec && bin/subscribe_spec
 
-    - name: Build on Arduino CLI
-      run: bash .github/build-arduino.sh
+#    - name: Build on Arduino CLI
+#      run: bash .github/build-arduino.sh

lib/pubsubclient3/.gitignore

@@ -1,6 +1,8 @@
-tests/bin
-.pioenvs
-.piolibdeps
 .clang_complete
 .gcc-flags.json
+.pio/
+.pioenvs
+.piolibdeps
+.vscode/
 site/api
+tests/bin

lib/pubsubclient3/CHANGELOG.md

@@ -0,0 +1,192 @@
+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/), and this project adheres to
+[Semantic Versioning](https://semver.org/).
+
+## Unreleased
+
+### Changed
+
+* Improved test coverage for all QoS levels (0, 1, 2)
+* Increased robustness and correctness in client-side handling of QoS 1 and QoS 2 messages (proper handling of PUBACK, PUBREC, PUBREL, PUBCOMP sequences)
+* Merged and cleaned up tests to ensure MQTT protocol compliance for all QoS scenarios
+
+## [3.3.0] - 2025-12-14
+
+### Added
+
+* Speedup publish large messages by using a buffer by @TD-er in [#59](https://github.com/hmueller01/pubsubclient3/pull/59)
+* Support `PROGMEM` and `__FlashStringHelper` topics by @hmueller01 in [#72](https://github.com/hmueller01/pubsubclient3/pull/72)
+* Added issue template by @hmueller01 in [#76](https://github.com/hmueller01/pubsubclient3/pull/76)
+* Report delta sizes in pull requests by @hmueller01 in [#77](https://github.com/hmueller01/pubsubclient3/pull/77)
+
+### Changed
+
+* Refactored private members by @hmueller01 in [#68](https://github.com/hmueller01/pubsubclient3/pull/68)
+* Refactored private functions by @hmueller01 in [#70](https://github.com/hmueller01/pubsubclient3/pull/70)
+* Do not crash if `_client` not set by @hmueller01 in [#69](https://github.com/hmueller01/pubsubclient3/pull/69)
+* Minor updates that come across by @hmueller01 in [#73](https://github.com/hmueller01/pubsubclient3/pull/73)
+* Inline optimisation by @hmueller01 in [#75](https://github.com/hmueller01/pubsubclient3/pull/75)
+* Bump actions/upload-pages-artifact from 3 to 4 by @dependabot[bot] in [#78](https://github.com/hmueller01/pubsubclient3/pull/78)
+* Bump actions/checkout from 2 to 5 by @dependabot[bot] in [#79](https://github.com/hmueller01/pubsubclient3/pull/79)
+* Tag unused parameter to avoid warnings by @hmueller01 in [#82](https://github.com/hmueller01/pubsubclient3/pull/82)
+* Fix compile warning at strnlen bound by @hmueller01 in [#83](https://github.com/hmueller01/pubsubclient3/pull/83)
+* Fix deprecated `BUILTIN_LED` by @hmueller01 in [#84](https://github.com/hmueller01/pubsubclient3/pull/84)
+* Bump actions/checkout from 5 to 6 by @dependabot[bot] in [#85](https://github.com/hmueller01/pubsubclient3/pull/85)
+* Update workflows by @hmueller01 in [#86](https://github.com/hmueller01/pubsubclient3/pull/86)
+
+## [3.2.1] - 2025-09-11
+
+### Fixed
+
+- Fixed bug introduced with QoS > 0 support (#65)
+
+## [3.2.0] - 2025-07-20
+
+### Added
+
+- Support publish at QoS 1 and 2 (by @hmueller01) (#49)
+- Doxygen API documentation on gh-pages (by @hmueller01) (#51)
+
+### Changed
+
+- Add check for nullptr in `CHECK_STRING_LENGTH` (by @TD-er) (#48)
+- Move `CHECK_STRING_LENGTH` to `PubSubClient.cpp` (by @hmueller01) (#50)
+- Get rid of lazy calling parameter (by @hmueller01) (#53)
+- Implemented `writeNextMsgId()` (by @hmueller01) (#54)
+- Cleanup `writeString()` (by @hmueller01) (#55)
+
+## [3.1.0] - 2025-03-20
+
+### Added
+
+- Added `ERROR_PSC_PRINTF` and `ERROR_PSC_PRINTF_P` outputs (#25)
+
+### Changed
+
+- Fix `setServer(domain, ...)` by copying domain string to an internal buffer (prevent potential dangling pointer) (#10)
+- Connect to broker only if port != 0 (protect against incorrect initialization) (#10)
+- Refactored buffer length types to `size_t` (#11)
+- Added warnings and `-Werror` to tests Makefile (#11)
+- Reformatted tests code using Google style (see `.clang-format`) (#11)
+- Fix keepalive handling (thanks to @uschnindler) (#14)
+- Use initializer lists for constructors (#15)
+- Fix `DEBUG_PSC_PRINTF` outputs (#18)
+- Introduce `MQTTRETAINED` flag (#21)
+- Added documentation on `readByte()` and `readPacket()` (#23)
+- Refactored `buildHeader()`, `readPacket()`, `readByte()`, `beginPublish()`/`endPublish()`, `publish()`/`publish_P()`, `connect()`, `connected()`, `subscribe()`/`unsubscribe()` and internal timing handling (#22, #23, #28, #30, #31, #33, #34, #37, #38, #39, #40, #44)
+- Fixed potential memory corruption in `MQTTPUBLISH` callback preparation (#25)
+- Fixed a missing failure test on `_client->read()` in `readByte()` (#32)
+- Switch from constructor init-lists to class member initialization (C++ core guideline C.45) (#42)
+
+## [3.0.2] - 2025-02-27
+
+### Added
+
+- GitHub workflow to execute tests
+- GitHub workflow to compile examples using Arduino CLI
+- Examples: Use a better source of randomness (#9)
+- Optionally deactivate `std::function` usage (#7)
+
+## [3.0.1] - 2025-02-20
+
+### Added
+
+- Added `.editorconfig`
+- Added GitHub workflow to check code style on push/PR
+
+### Changed
+
+- Reformatted code using Google style
+- Fixes for tests: missing def for `strlen_P` & Python libs
+
+## [3.0] - 2025-02-17
+
+Maintenance taken over by Holger Mueller
+
+### Added
+
+- In-source documentation added to `PubSubClient` header
+- Add flag for enabling debugging of library
+
+### Changed
+
+- Always use `PubSubClient()` constructor
+- Use `bool` instead of `boolean`
+- Add `yield()` calls in `connect()` and `write()` to avoid watchdog resets
+- Fix bug in `publish_P` handling of PROGMEM payload length
+- Fix increase `bytesToWrite` to `uint16_t` to prevent overflow
+- Remove compiler warning about unsigned `expectedLength`
+- Extend usage of `std::function` where available
+- Fix for keep alive zero
+
+## [2.8] - 2020-05-20
+
+### Added
+
+- `setBufferSize()` to override `MQTT_MAX_PACKET_SIZE`
+- `setKeepAlive()` to override `MQTT_KEEPALIVE`
+- `setSocketTimeout()` to override `MQTT_SOCKET_TIMEOUT`
+- Check to prevent subscribe/unsubscribe to empty topics
+- Declare WiFi mode prior to connect in ESP example
+- Use `strnlen` to avoid overruns
+- Support pre-connected `Client` objects
+
+## [2.7] - 2018-11-02
+
+### Added
+
+- Added large-payload API: `beginPublish`/`write`/`publish`/`endPublish`
+- Added `yield` calls to improve reliability on ESP
+- Added Clean Session flag to connect options
+- Added ESP32 support for functional callback signature
+
+### Fixed
+
+- Fixed remaining-length handling to prevent buffer overrun
+
+## [2.4] - 2015-11-21
+
+### Added
+
+- `MQTT_SOCKET_TIMEOUT` to avoid blocking indefinitely while waiting for inbound data
+
+### Fixed
+
+- Fixed return code when publishing >256 bytes
+
+## [2.3] - 2015-09-11
+
+### Added
+
+- `publish(topic,payload,retained)` convenience overload
+
+## [2.2] - 2015-09-07
+
+### Changed
+
+- Changed code layout to match Arduino Library requirements
+
+## [2.1] - 2015-09-07
+
+### Added
+
+- `MAX_TRANSFER_SIZE` to chunk messages if needed
+- Reject topic/payloads that exceed `MQTT_MAX_PACKET_SIZE`
+
+## [2.0] - 2015-08-28
+
+### Added
+
+- MQTT 3.1.1 support
+- Fix PROGMEM handling for Intel Galileo/ESP8266
+- Overloaded constructors for convenience
+- Chainable setters for server/callback/client/stream
+- `state()` function to return CONNACK code
+
+## [1.0] - 2009-02-02
+
+- Initial release notes: QoS 0 only, 128 byte max message size, keepalive 30s, no Will messages
+

lib/pubsubclient3/CHANGES.txt

@@ -1,136 +0,0 @@
-3.1.0
-   * Fix setServer(domain, ...) by copy domain string to own buffer (prevent potential dangling string pointer) #10
-   * Connect to broker only if port != 0 (e.g. in case of incorrect PubSubClient initialization) #10
-   * Refactored different buffer length types to size_t #11
-   * Added a bunch of warnings and -Werror to tests Makefile #11
-   * Reformatted tests code using Google sytle (see .clang-format) #11
-   * Fix keepalive handling, thanks to @uschnindler providing this to thingsboard #14
-   * Use initializer lists instead of assigning global members in constructor #15
-   * Fix DEBUG_PSC_PRINTF outputs #18
-   * Added ERROR_PSC_PRINTF and ERROR_PSC_PRINTF_P outputs #25
-   * Introduce MQTTRETAINED flag instead of hard coding #21
-   * Added documentation on readByte() and readPacket() functions #23
-   * Refactored buildHeader() (change return type, use MQTT_MAX_HEADER_SIZE, locals) #22, #34, #37
-   * Refactored readPacket() (changed return type to size_t, used MQTT_MAX_HEADER_SIZE, locals) #23
-   * Refactored readByte() #23
-   * Refactored beginPublish() and endPublish() #28
-   * Refactored publish() #31
-   * Refactored publish_P() #30
-   * Refactored connect() #40
-   * Refactored connected() (mostly rewritten and simplified, added setting pingOutstanding, don't need flush()) #44
-   * Refactored subscribe() and unsubscribe() #44
-   * Refactored internal socketTimeout and keepAlive to millis to improve performance #33, #38, #39
-   * Fix potential memory corruption in MQTTPUBLISH callback preparation #25
-   * Fix potential error in readByte() (missing failure test on _client->read()) #32
-   * Switch from constructor init-lists to class member initialization, see C++ core guideline C.45 #42
-
-3.0.2
-   * Added github workflow to execute tests
-   * Added github workflow to compile examples using arduino-cli
-   * Examples: Use a better source of random #9
-   * Deactivate use of std::function on demand #7
-
-3.0.1
-   * Reformatted code using Google sytle (see .clang-format)
-   * Added .editorconfig
-   * Added github workflow to check code sytle on push and pull request
-   * Fix-tests: missing def for strlen_P & Python libs
-
-3.0
-   * Maintenance taken over by Holger Mueller
-   * Adds in-source documentation to PubSubClient header.
-   * Add flag for enabling debugging of library
-   * Always use PubSubClient() constructor
-   * Use bool instead of boolean
-   * Add yield() calls in connect() and write() to avoid wdt resets if either blocks for too long
-   * Fix bug in publish_P which will always treat the payload length as 0 when used with PROGMEM
-   * Fix increase `bytesToWrite` to uint16_t to prevent overflow
-   * Remove compiler warning `expectedLength` should be unsigned
-   * Extend usage of std::function on all the platforms where it's available
-   * Fix for keep alive zero
-
-2.8
-   * Add setBufferSize() to override MQTT_MAX_PACKET_SIZE
-   * Add setKeepAlive() to override MQTT_KEEPALIVE
-   * Add setSocketTimeout() to overide MQTT_SOCKET_TIMEOUT
-   * Added check to prevent subscribe/unsubscribe to empty topics
-   * Declare wifi mode prior to connect in ESP example
-   * Use `strnlen` to avoid overruns
-   * Support pre-connected Client objects
-
-2.7
-   * Fix remaining-length handling to prevent buffer overrun
-   * Add large-payload API - beginPublish/write/publish/endPublish
-   * Add yield call to improve reliability on ESP
-   * Add Clean Session flag to connect options
-   * Add ESP32 support for functional callback signature
-   * Various other fixes
-
-2.4
-   * Add MQTT_SOCKET_TIMEOUT to prevent it blocking indefinitely
-     whilst waiting for inbound data
-   * Fixed return code when publishing >256 bytes
-
-2.3
-   * Add publish(topic,payload,retained) function
-
-2.2
-   * Change code layout to match Arduino Library reqs
-
-2.1
-   * Add MAX_TRANSFER_SIZE def to chunk messages if needed
-   * Reject topic/payloads that exceed MQTT_MAX_PACKET_SIZE
-
-2.0
-   * Add (and default to) MQTT 3.1.1 support
-   * Fix PROGMEM handling for Intel Galileo/ESP8266
-   * Add overloaded constructors for convenience
-   * Add chainable setters for server/callback/client/stream
-   * Add state function to return connack return code
-
-1.9
-   * Do not split MQTT packets over multiple calls to _client->write()
-   * API change: All constructors now require an instance of Client
-      to be passed in.
-   * Fixed example to match 1.8 api changes - dpslwk
-   * Added username/password support - WilHall
-   * Added publish_P - publishes messages from PROGMEM - jobytaffey
-
-1.8
-    * KeepAlive interval is configurable in PubSubClient.h
-    * Maximum packet size is configurable in PubSubClient.h
-    * API change: Return boolean rather than int from various functions
-    * API change: Length parameter in message callback changed
-       from int to unsigned int
-    * Various internal tidy-ups around types
-
-1.7
-    * Improved keepalive handling
-    * Updated to the Arduino-1.0 API
-
-1.6
-    * Added the ability to publish a retained message
-
-1.5
-    * Added default constructor
-    * Fixed compile error when used with arduino-0021 or later
-
-1.4
-    * Fixed connection lost handling
-
-1.3
-    * Fixed packet reading bug in PubSubClient.readPacket
-
-1.2
-    * Fixed compile error when used with arduino-0016 or later
-
-1.1
-    * Reduced size of library
-    * Added support for Will messages
-    * Clarified licensing - see LICENSE.txt
-
-1.0
-    * Only Quality of Service (QOS) 0 messaging is supported
-    * The maximum message size, including header, is 128 bytes
-    * The keepalive interval is set to 30 seconds
-    * No support for Will messages

lib/pubsubclient3/README.md

@@ -29,7 +29,7 @@ Full API documentation is available here: https://hmueller01.github.io/pubsubcli
 ## Limitations
 
  - The client is based on the [MQTT Version 3.1.1 specification](https://docs.oasis-open.org/mqtt/mqtt/v3.1.1/os/mqtt-v3.1.1-os.html) with some limitations.
- - It can publish at QoS 0, 1 or 2.
+ - It can publish at QoS 0 and since [v3.2.0](https://github.com/hmueller01/pubsubclient3/releases/tag/v3.2.0) also at QoS 1 or 2.
 
    **WARNING:** No retransmission is supported to keep the library as much memory friendly as possible.
 
@@ -45,7 +45,17 @@ Full API documentation is available here: https://hmueller01.github.io/pubsubcli
    `PubSubClient::setKeepAlive(keepAlive)`.
  - The client uses MQTT 3.1.1 by default. It can be changed to use MQTT 3.1 by
    changing value of `MQTT_VERSION` in `PubSubClient.h`.
-
+ - Since [v3.3.0](https://github.com/hmueller01/pubsubclient3/releases/tag/v3.3.0) it can publish and subscribe to `PROGMEM` or `__FlashStringHelper` topics.
+   Details see [mqtt_progmem](https://github.com/hmueller01/pubsubclient3/blob/aae84e4d1aa65e752e19e30239b5796b4fe2705b/examples/mqtt_progmem/src/mqtt_progmem.cpp#L39-L48) example.
+   But if you like to publish `PROGMEM` topics you have to use
+   ```c
+   const char TOPIC[] PROGMEM = "test";
+   const char HELLO_WORLD[] PROGMEM = "hello world";
+   client.beginPublish_P(TOPIC, strlen_P(HELLO_WORLD), MQTT_QOS0, false);
+   client.write_P(HELLO_WORLD);
+   client.endPublish();
+   ```
+   as `client.publish_P(...)` is already used for `PROGMEM` payloads.
 
 ## Compatible Hardware
 
@@ -69,6 +79,10 @@ The library cannot currently be used with hardware based on the ENC28J60 chip
 such as the Nanode or the Nuelectronics Ethernet Shield. For those, there is an
 [alternative library](https://github.com/njh/NanodeMQTT) available.
 
+## Changelog
+
+See [CHANGELOG.md](CHANGELOG.md)
+
 ## License
 
-This code is released under the MIT License.
+This code is released under the [MIT License](LICENSE.txt).

lib/pubsubclient3/examples/mqtt_auth/mqtt_auth.ino

@@ -11,12 +11,14 @@
 #include <PubSubClient.h>
 #include <SPI.h>
 
+#define _UNUSED_ __attribute__((unused))
+
 // Update these with values suitable for your network.
 byte mac[] = {0xDE, 0xED, 0xBA, 0xFE, 0xFE, 0xED};
 IPAddress ip(172, 16, 0, 100);
 IPAddress server(172, 16, 0, 2);
 
-void callback(char* topic, uint8_t* payload, size_t plength) {
+void callback(_UNUSED_ char* topic, _UNUSED_ uint8_t* payload, _UNUSED_ size_t plength) {
     // handle message arrived
 }
 

lib/pubsubclient3/examples/mqtt_esp/mqtt_esp.ino

@@ -23,7 +23,7 @@
 #elif defined(ESP32)
 #include <WiFi.h>
 #include <esp_random.h>
-#define BUILTIN_LED A0
+#define LED_BUILTIN A0
 #define RANDOM_REG32 esp_random()
 #else
 #error Platform not supported.
@@ -77,11 +77,11 @@ void callback(char* topic, uint8_t* payload, size_t plength) {
 
     // Switch on the LED if an 1 was received as first character
     if ((char)payload[0] == '1') {
-        digitalWrite(BUILTIN_LED, LOW);  // Turn the LED on (Note that LOW is the voltage level
+        digitalWrite(LED_BUILTIN, LOW);  // Turn the LED on (Note that LOW is the voltage level
                                          // but actually the LED is on; this is because
                                          // it is active low on the ESP-01)
     } else {
-        digitalWrite(BUILTIN_LED, HIGH);  // Turn the LED off by making the voltage HIGH
+        digitalWrite(LED_BUILTIN, HIGH);  // Turn the LED off by making the voltage HIGH
     }
 }
 
@@ -110,7 +110,7 @@ void reconnect() {
 }
 
 void setup() {
-    pinMode(BUILTIN_LED, OUTPUT);  // Initialize the BUILTIN_LED pin as an output
+    pinMode(LED_BUILTIN, OUTPUT);  // Initialize the LED_BUILTIN pin as an output
     Serial.begin(115200);
     setup_wifi();
     client.setServer(mqtt_server, 1883);
@@ -127,7 +127,7 @@ void loop() {
     if (now - lastMsg > 2000) {
         lastMsg = now;
         ++value;
-        snprintf(msg, MSG_BUFFER_SIZE, "hello world #%ld", value);
+        snprintf(msg, MSG_BUFFER_SIZE, "hello world #%d", value);
         Serial.print("Publish message: ");
         Serial.println(msg);
         client.publish("outTopic", msg);

lib/pubsubclient3/examples/mqtt_esp_large_message/mqtt_esp_large_message.ino

@@ -28,7 +28,6 @@
 #elif defined(ESP32)
 #include <WiFi.h>
 #include <esp_random.h>
-#define BUILTIN_LED A0
 #define RANDOM_REG32 esp_random()
 #else
 #error Platform not supported.
@@ -170,7 +169,6 @@ void reconnect() {
 }
 
 void setup() {
-    pinMode(BUILTIN_LED, OUTPUT);  // Initialize the BUILTIN_LED pin as an output
     Serial.begin(115200);
     setup_wifi();
     client.setServer(mqtt_server, 1883);

lib/pubsubclient3/examples/mqtt_progmem/mqtt_progmem.ino

@@ -0,0 +1,3 @@
+// Example sketch showing how to use PubSubClient with strings stored in PROGMEM.
+// This needs to be an empty file to satisfy the arduino-cli build system.
+// See src/mqtt_progmem.cpp for the actual example code.

lib/pubsubclient3/examples/mqtt_progmem/platformio.ini

@@ -0,0 +1,40 @@
+; PlatformIO Project Configuration File
+;
+;   Build options: build flags, source filter
+;   Upload options: custom upload port, speed and extra flags
+;   Library options: dependencies, extra library storages
+;   Advanced options: extra scripting
+;
+; Please visit documentation for the other options and examples
+; https://docs.platformio.org/page/projectconf.html
+; https://docs.platformio.org/en/latest/boards/atmelavr/uno.html
+
+[platformio]
+description = Basic MQTT example with Authentication and Progmem strings
+
+[env]
+framework = arduino
+lib_deps =
+	arduino-libraries/Ethernet @ ^2.0.2
+	hmueller01/PubSubClient3 @ ^3.3.0
+build_flags =
+;	-D DEBUG_ESP_PORT=Serial
+;	-D DEBUG_PUBSUBCLIENT
+;	-D MQTT_MAX_PACKET_SIZE=512
+;	-D MQTT_KEEPALIVE=120
+
+[env:uno]
+platform = atmelavr
+board = uno
+
+[env:esp8266]
+platform = espressif8266
+platform_packages = platformio/framework-arduinoespressif8266 @ https://github.com/esp8266/Arduino.git
+board = esp12e
+build_flags =
+	${env.build_flags}
+	-D PIO_FRAMEWORK_ARDUINO_ESPRESSIF_SDK305
+
+[env:esp32]
+platform = espressif32
+board = esp32dev

lib/pubsubclient3/examples/mqtt_progmem/src/mqtt_progmem.cpp

@@ -0,0 +1,54 @@
+/*
+ Basic MQTT example with Authentication
+
+  - connects to an MQTT server, providing username
+    and password
+  - publishes "hello world" to the topic "outTopic"
+  - subscribes to the topic "inTopic"
+*/
+
+#include <Ethernet.h>
+#include <PubSubClient.h>
+#include <SPI.h>
+
+#define _UNUSED_ __attribute__((unused))
+
+// Update these with values suitable for your network.
+byte mac[] = {0xDE, 0xED, 0xBA, 0xFE, 0xFE, 0xED};
+IPAddress ip(172, 16, 0, 100);
+IPAddress server(172, 16, 0, 2);
+const char HELLO_WORLD_3[] PROGMEM = "hello world 3";
+const char HELLO_WORLD_4[] PROGMEM = "hello world 4";
+const char SUBSCRIBE_TOPIC[] PROGMEM = "inTopic1";
+
+void callback(_UNUSED_ char* topic, _UNUSED_ uint8_t* payload, _UNUSED_ size_t plength) {
+    // handle message arrived
+}
+
+EthernetClient ethClient;
+PubSubClient client(server, 1883, callback, ethClient);
+
+void setup() {
+    Ethernet.begin(mac, ip);
+    // Note - the default maximum packet size is 128 bytes. If the
+    // combined length of clientId, username and password exceed this use the
+    // following to increase the buffer size:
+    // client.setBufferSize(255);
+
+    if (client.connect("arduinoClient", "testuser", "testpass")) {
+        client.publish(F("outTopic"), "hello world 1", MQTT_QOS0, false);
+        client.publish(F("outTopic"), F("hello world 2"), MQTT_QOS1, false);
+        client.publish_P(F("outTopic"), HELLO_WORLD_3, MQTT_QOS2, false);
+
+        client.beginPublish(F("outTopic"), strlen_P(HELLO_WORLD_4), MQTT_QOS1, false);
+        client.write_P(HELLO_WORLD_4);
+        client.endPublish();
+
+        client.subscribe(F("inTopic"));
+        client.subscribe_P(SUBSCRIBE_TOPIC, MQTT_QOS1);
+    }
+}
+
+void loop() {
+    client.loop();
+}

lib/pubsubclient3/examples/mqtt_publish_in_callback/mqtt_publish_in_callback.ino

@@ -17,6 +17,8 @@
 #include <PubSubClient.h>
 #include <SPI.h>
 
+#define _UNUSED_ __attribute__((unused))
+
 // Update these with values suitable for your network.
 byte mac[] = {0xDE, 0xED, 0xBA, 0xFE, 0xFE, 0xED};
 IPAddress ip(172, 16, 0, 100);
@@ -29,7 +31,7 @@ EthernetClient ethClient;
 PubSubClient client(server, 1883, callback, ethClient);
 
 // Callback function
-void callback(char* topic, uint8_t* payload, size_t plength) {
+void callback(_UNUSED_ char* topic, uint8_t* payload, size_t plength) {
     // In order to republish this payload, a copy must be made
     // as the orignal payload buffer will be overwritten whilst
     // constructing the PUBLISH packet.

lib/pubsubclient3/examples/mqtt_reconnect_nonblocking/mqtt_reconnect_nonblocking.ino

@@ -11,12 +11,14 @@
 #include <PubSubClient.h>
 #include <SPI.h>
 
+#define _UNUSED_ __attribute__((unused))
+
 // Update these with values suitable for your hardware/network.
 byte mac[] = {0xDE, 0xED, 0xBA, 0xFE, 0xFE, 0xED};
 IPAddress ip(172, 16, 0, 100);
 IPAddress server(172, 16, 0, 2);
 
-void callback(char* topic, uint8_t* payload, size_t plength) {
+void callback(_UNUSED_ char* topic, _UNUSED_ uint8_t* payload, _UNUSED_ size_t plength) {
     // handle message arrived
 }
 

lib/pubsubclient3/examples/mqtt_stream/mqtt_stream.ino

@@ -14,6 +14,8 @@
 #include <SPI.h>
 #include <SRAM.h>
 
+#define _UNUSED_ __attribute__((unused))
+
 // Update these with values suitable for your network.
 byte mac[] = {0xDE, 0xED, 0xBA, 0xFE, 0xFE, 0xED};
 IPAddress ip(172, 16, 0, 100);
@@ -21,7 +23,7 @@ IPAddress server(172, 16, 0, 2);
 
 SRAM sram(4, SRAM_1024);
 
-void callback(char* topic, uint8_t* payload, size_t plength) {
+void callback(_UNUSED_ char* topic, _UNUSED_ uint8_t* payload, size_t plength) {
     sram.seek(1);
 
     // do something with the message

lib/pubsubclient3/keywords.txt

@@ -17,9 +17,12 @@ disconnect 	KEYWORD2
 publish 	KEYWORD2
 publish_P 	KEYWORD2
 beginPublish 	KEYWORD2
+beginPublish_P 	KEYWORD2
 endPublish 	KEYWORD2
 write	 	KEYWORD2
+write_P	 	KEYWORD2
 subscribe 	KEYWORD2
+subscribe_P 	KEYWORD2
 unsubscribe 	KEYWORD2
 loop 	KEYWORD2
 connected 	KEYWORD2

lib/pubsubclient3/library.json

@@ -6,13 +6,15 @@
         "type": "git",
         "url": "https://github.com/hmueller01/pubsubclient3.git"
     },
-    "version": "3.1.0",
+    "version": "3.3.0",
     "license": "MIT",
     "exclude": "tests",
     "examples": "examples/*/*.ino",
     "frameworks": "arduino",
     "platforms": [
         "atmelavr",
+        "atmelsam",
+        "atmelmegaavr",
         "espressif8266",
         "espressif32"
     ]

lib/pubsubclient3/library.properties

@@ -1,5 +1,5 @@
 name=PubSubClient3
-version=3.1.0
+version=3.3.0
 author=Nick O'Leary <nick.oleary@gmail.com>
 maintainer=Holger Mueller <github@euhm.de>
 license=MIT

lib/pubsubclient3/src/PubSubClient.h

@@ -34,7 +34,7 @@
  * @brief Maximum packet size defined by MQTT protocol.
  */
 #ifndef MQTT_MAX_POSSIBLE_PACKET_SIZE
-#define MQTT_MAX_POSSIBLE_PACKET_SIZE 268435455
+#define MQTT_MAX_POSSIBLE_PACKET_SIZE ((size_t)268435455)  // might be limited to 65535 if size_t is 16-bit (unsigned int)
 #endif
 
 /**
@@ -176,36 +176,39 @@
 class PubSubClient : public Print {
    private:
     Client* _client{};
-    uint8_t* buffer{};
-    size_t bufferSize{};
-    unsigned long keepAliveMillis{};
-    unsigned long socketTimeoutMillis{};
-    uint16_t nextMsgId{};
-    unsigned long lastOutActivity{};
-    unsigned long lastInActivity{};
-    bool pingOutstanding{};
-    MQTT_CALLBACK_SIGNATURE{};
-    IPAddress ip{};
-    char* domain{};
-    uint16_t port{};
-    Stream* stream{};
-    int _state{MQTT_DISCONNECTED};
+    uint8_t* _buffer{};
+    size_t _bufferSize{};
     size_t _bufferWritePos{};
-    uint8_t _qos{MQTT_QOS0};
+    unsigned long _keepAliveMillis{};
+    unsigned long _socketTimeoutMillis{};
+    uint16_t _nextMsgId{};
+    unsigned long _lastOutActivity{};
+    unsigned long _lastInActivity{};
+    bool _pingOutstanding{};
+    MQTT_CALLBACK_SIGNATURE{};
+    IPAddress _ip{};
+    char* _domain{};
+    uint16_t _port{};
+    Stream* _stream{};
+    int _state{MQTT_DISCONNECTED};
 
     size_t readPacket(uint8_t* hdrLen);
     bool handlePacket(uint8_t hdrLen, size_t len);
     bool readByte(uint8_t* result);
     bool readByte(uint8_t* result, size_t* pos);
-    uint8_t buildHeader(uint8_t header, uint8_t* buf, size_t length);
-    bool write(uint8_t header, uint8_t* buf, size_t length);
-    size_t writeString(const char* string, uint8_t* buf, size_t pos, size_t size);
-    size_t writeNextMsgId(uint8_t* buf, size_t pos, size_t size);
+    uint8_t buildHeader(uint8_t header, size_t length);
+    bool writeControlPacket(uint8_t header, size_t length);
+    size_t writeBuffer(size_t pos, size_t size);
+    size_t writeStringImpl(bool progmem, const char* string, size_t pos);
+    size_t writeString(const char* string, size_t pos);
+    size_t writeNextMsgId(size_t pos);
 
+    bool beginPublishImpl(bool progmem, const char* topic, size_t plength, uint8_t qos, bool retained);
+    bool subscribeImpl(bool progmem, const char* topic, uint8_t qos);
+    bool unsubscribeImpl(bool progmem, const char* topic);
 
-    // Add to buffer and flush if full (only to be used with beginPublish/endPublish)Add commentMore actions
+    // Add to buffer and flush if full (only to be used with beginPublish/endPublish)
     size_t appendBuffer(uint8_t data);
-    size_t appendBuffer(const uint8_t *data, size_t size);
     size_t flushBuffer();
 
    public:
@@ -428,7 +431,9 @@ class PubSubClient : public Print {
      * @return true If client succeeded in establishing a connection to the broker.
      * false If client failed to establish a connection to the broker.
      */
-    bool connect(const char* id);
+    inline bool connect(const char* id) {
+        return connect(id, nullptr, nullptr, nullptr, MQTT_QOS0, false, nullptr, true);
+    }
 
     /**
      * @brief Connects the client using a clean session with username and password.
@@ -440,7 +445,9 @@ class PubSubClient : public Print {
      * @return true If client succeeded in establishing a connection to the broker.
      * false If client failed to establish a connection to the broker.
      */
-    bool connect(const char* id, const char* user, const char* pass);
+    inline bool connect(const char* id, const char* user, const char* pass) {
+        return connect(id, user, pass, nullptr, MQTT_QOS0, false, nullptr, true);
+    }
 
     /**
      * @brief Connects the client using a clean session and will.
@@ -453,7 +460,9 @@ class PubSubClient : public Print {
      * @return true If client succeeded in establishing a connection to the broker.
      * false If client failed to establish a connection to the broker.
      */
-    bool connect(const char* id, const char* willTopic, uint8_t willQos, bool willRetain, const char* willMessage);
+    inline bool connect(const char* id, const char* willTopic, uint8_t willQos, bool willRetain, const char* willMessage) {
+        return connect(id, nullptr, nullptr, willTopic, willQos, willRetain, willMessage, true);
+    }
 
     /**
      * @brief Connects the client using a clean session with username, password and will.
@@ -470,7 +479,10 @@ class PubSubClient : public Print {
      * @return true If client succeeded in establishing a connection to the broker.
      * false If client failed to establish a connection to the broker.
      */
-    bool connect(const char* id, const char* user, const char* pass, const char* willTopic, uint8_t willQos, bool willRetain, const char* willMessage);
+    inline bool connect(const char* id, const char* user, const char* pass, const char* willTopic, uint8_t willQos, bool willRetain,
+                        const char* willMessage) {
+        return connect(id, user, pass, willTopic, willQos, willRetain, willMessage, true);
+    }
 
     /**
      * @brief Connects the client with all possible parameters (user, password, will and session).
@@ -503,7 +515,9 @@ class PubSubClient : public Print {
      * @return true If the publish succeeded.
      * false If the publish failed, either connection lost or message too large.
      */
-    bool publish(const char* topic, const char* payload);
+    inline bool publish(const char* topic, const char* payload) {
+        return publish(topic, payload, MQTT_QOS0, false);
+    }
 
     /**
      * @brief Publishes a message to the specified topic using QoS 0.
@@ -513,7 +527,9 @@ class PubSubClient : public Print {
      * @return true If the publish succeeded.
      * false If the publish failed, either connection lost or message too large.
      */
-    bool publish(const char* topic, const char* payload, bool retained);
+    inline bool publish(const char* topic, const char* payload, bool retained) {
+        return publish(topic, payload, MQTT_QOS0, retained);
+    }
 
     /**
      * @brief Publishes a message to the specified topic.
@@ -524,7 +540,35 @@ class PubSubClient : public Print {
      * @return true If the publish succeeded.
      * false If the publish failed, either connection lost or message too large.
      */
-    bool publish(const char* topic, const char* payload, uint8_t qos, bool retained);
+    inline bool publish(const char* topic, const char* payload, uint8_t qos, bool retained) {
+        return publish(topic, reinterpret_cast<const uint8_t*>(payload), payload ? strlen(payload) : 0, qos, retained);
+    }
+
+    /**
+     * @brief Publishes a message to the specified topic.
+     * @param topic The topic from __FlashStringHelper to publish to.
+     * @param payload The message to publish.
+     * @param qos The quality of service (\ref group_qos) to publish at. [0, 1, 2].
+     * @param retained Publish the message with the retain flag.
+     * @return true If the publish succeeded.
+     * false If the publish failed, either connection lost or message too large.
+     */
+    inline bool publish(const __FlashStringHelper* topic, const char* payload, uint8_t qos, bool retained) {
+        return publish(topic, reinterpret_cast<const uint8_t*>(payload), payload ? strlen(payload) : 0, qos, retained);
+    }
+
+    /**
+     * @brief Publishes a message from __FlashStringHelper to the specified topic from __FlashStringHelper.
+     * @param topic The topic to publish to.
+     * @param payload The message to publish.
+     * @param qos The quality of service (\ref group_qos) to publish at. [0, 1, 2].
+     * @param retained Publish the message with the retain flag.
+     * @return true If the publish succeeded.
+     * false If the publish failed, either connection lost or message too large.
+     */
+    inline bool publish(const __FlashStringHelper* topic, const __FlashStringHelper* payload, uint8_t qos, bool retained) {
+        return publish_P(topic, reinterpret_cast<const uint8_t*>(payload), payload ? strlen_P(reinterpret_cast<const char*>(payload)) : 0, qos, retained);
+    }
 
     /**
      * @brief Publishes a non retained message to the specified topic using QoS 0.
@@ -534,7 +578,9 @@ class PubSubClient : public Print {
      * @return true If the publish succeeded.
      * false If the publish failed, either connection lost or message too large.
      */
-    bool publish(const char* topic, const uint8_t* payload, size_t plength);
+    inline bool publish(const char* topic, const uint8_t* payload, size_t plength) {
+        return publish(topic, payload, plength, MQTT_QOS0, false);
+    }
 
     /**
      * @brief Publishes a message to the specified topic using QoS 0.
@@ -545,7 +591,9 @@ class PubSubClient : public Print {
      * @return true If the publish succeeded.
      * false If the publish failed, either connection lost or message too large.
      */
-    bool publish(const char* topic, const uint8_t* payload, size_t plength, bool retained);
+    inline bool publish(const char* topic, const uint8_t* payload, size_t plength, bool retained) {
+        return publish(topic, payload, plength, MQTT_QOS0, retained);
+    }
 
     /**
      * @brief Publishes a message to the specified topic.
@@ -559,6 +607,18 @@ class PubSubClient : public Print {
      */
     bool publish(const char* topic, const uint8_t* payload, size_t plength, uint8_t qos, bool retained);
 
+    /**
+     * @brief Publishes a message to the specified topic.
+     * @param topic The topic from __FlashStringHelper to publish to.
+     * @param payload The message to publish.
+     * @param plength The length of the payload.
+     * @param qos The quality of service (\ref group_qos) to publish at. [0, 1, 2].
+     * @param retained Publish the message with the retain flag.
+     * @return true If the publish succeeded.
+     * false If the publish failed, either connection lost or message too large.
+     */
+    bool publish(const __FlashStringHelper* topic, const uint8_t* payload, size_t plength, uint8_t qos, bool retained);
+
     /**
      * @brief Publishes a message stored in PROGMEM to the specified topic using QoS 0.
      * @param topic The topic to publish to.
@@ -567,7 +627,9 @@ class PubSubClient : public Print {
      * @return true If the publish succeeded.
      * false If the publish failed, either connection lost or message too large.
      */
-    bool publish_P(const char* topic, const char* payload, bool retained);
+    inline bool publish_P(const char* topic, PGM_P payload, bool retained) {
+        return publish_P(topic, payload, MQTT_QOS0, retained);
+    }
 
     /**
      * @brief Publishes a message stored in PROGMEM to the specified topic.
@@ -578,7 +640,22 @@ class PubSubClient : public Print {
      * @return true If the publish succeeded.
      * false If the publish failed, either connection lost or message too large.
      */
-    bool publish_P(const char* topic, const char* payload, uint8_t qos, bool retained);
+    inline bool publish_P(const char* topic, PGM_P payload, uint8_t qos, bool retained) {
+        return publish_P(topic, reinterpret_cast<const uint8_t*>(payload), payload ? strlen_P(payload) : 0, qos, retained);
+    }
+
+    /**
+     * @brief Publishes a message stored in PROGMEM to the specified topic.
+     * @param topic The topic from __FlashStringHelper to publish to.
+     * @param payload The message to publish.
+     * @param qos The quality of service (\ref group_qos) to publish at. [0, 1, 2].
+     * @param retained Publish the message with the retain flag.
+     * @return true If the publish succeeded.
+     * false If the publish failed, either connection lost or message too large.
+     */
+    bool publish_P(const __FlashStringHelper* topic, PGM_P payload, uint8_t qos, bool retained) {
+        return publish_P(topic, reinterpret_cast<const uint8_t*>(payload), payload ? strlen_P(payload) : 0, qos, retained);
+    }
 
     /**
      * @brief Publishes a message stored in PROGMEM to the specified topic using QoS 0.
@@ -589,7 +666,9 @@ class PubSubClient : public Print {
      * @return true If the publish succeeded.
      * false If the publish failed, either connection lost or message too large.
      */
-    bool publish_P(const char* topic, const uint8_t* payload, size_t plength, bool retained);
+    inline bool publish_P(const char* topic, const uint8_t* payload, size_t plength, bool retained) {
+        return publish_P(topic, payload, plength, MQTT_QOS0, retained);
+    }
 
     /**
      * @brief Publishes a message stored in PROGMEM to the specified topic.
@@ -603,6 +682,18 @@ class PubSubClient : public Print {
      */
     bool publish_P(const char* topic, const uint8_t* payload, size_t plength, uint8_t qos, bool retained);
 
+    /**
+     * @brief Publishes a message stored in PROGMEM to the specified topic.
+     * @param topic The topic from __FlashStringHelper to publish to.
+     * @param payload The message from PROGMEM to publish.
+     * @param plength The length of the payload.
+     * @param qos The quality of service (\ref group_qos) to publish at. [0, 1, 2].
+     * @param retained Publish the message with the retain flag.
+     * @return true If the publish succeeded.
+     * false If the publish failed, either connection lost or message too large.
+     */
+    bool publish_P(const __FlashStringHelper* topic, const uint8_t* payload, size_t plength, uint8_t qos, bool retained);
+
     /**
      * @brief Start to publish a message using QoS 0.
      * This API:
@@ -617,7 +708,9 @@ class PubSubClient : public Print {
      * @return true If the publish succeeded.
      * false If the publish failed, either connection lost or message too large.
      */
-    bool beginPublish(const char* topic, size_t plength, bool retained);
+    inline bool beginPublish(const char* topic, size_t plength, bool retained) {
+        return beginPublishImpl(false, topic, plength, MQTT_QOS0, retained);
+    }
 
     /**
      * @brief Start to publish a message.
@@ -634,7 +727,48 @@ class PubSubClient : public Print {
      * @return true If the publish succeeded.
      * false If the publish failed, either connection lost or message too large.
      */
-    bool beginPublish(const char* topic, size_t plength, uint8_t qos, bool retained);
+    inline bool beginPublish(const char* topic, size_t plength, uint8_t qos, bool retained) {
+        return beginPublishImpl(false, topic, plength, qos, retained);
+    }
+
+    /**
+     * @brief Start to publish a message using a topic from __FlashStringHelper F().
+     * This API:
+     *   beginPublish(...)
+     *   one or more calls to write(...)
+     *   endPublish()
+     * Allows for arbitrarily large payloads to be sent without them having to be copied into
+     * a new buffer and held in memory at one time.
+     * @param topic The topic from __FlashStringHelper to publish to.
+     * @param plength The length of the payload.
+     * @param qos The quality of service (\ref group_qos) to publish at. [0, 1, 2].
+     * @param retained Publish the message with the retain flag.
+     * @return true If the publish succeeded.
+     * false If the publish failed, either connection lost or message too large.
+     */
+    inline bool beginPublish(const __FlashStringHelper* topic, size_t plength, uint8_t qos, bool retained) {
+        // convert FlashStringHelper in PROGMEM-pointer
+        return beginPublishImpl(true, reinterpret_cast<const char*>(topic), plength, qos, retained);
+    }
+
+    /**
+     * @brief Start to publish a message using a topic in PROGMEM.
+     * This API:
+     *   beginPublish_P(...)
+     *   one or more calls to write(...)
+     *   endPublish()
+     * Allows for arbitrarily large payloads to be sent without them having to be copied into
+     * a new buffer and held in memory at one time.
+     * @param topic The topic in PROGMEM to publish to.
+     * @param plength The length of the payload.
+     * @param qos The quality of service (\ref group_qos) to publish at. [0, 1, 2].
+     * @param retained Publish the message with the retain flag.
+     * @return true If the publish succeeded.
+     * false If the publish failed, either connection lost or message too large.
+     */
+    inline bool beginPublish_P(PGM_P topic, size_t plength, uint8_t qos, bool retained) {
+        return beginPublishImpl(true, reinterpret_cast<const char*>(topic), plength, qos, retained);
+    }
 
     /**
      * @brief Finish sending a message that was started with a call to beginPublish.
@@ -645,21 +779,43 @@ class PubSubClient : public Print {
 
     /**
      * @brief Writes a single byte as a component of a publish started with a call to beginPublish.
-     *        For performance reasons, this will be appended to the internal buffer, 
+     *        For performance reasons, this will be appended to the internal buffer,
      *        which will be flushed when full or on a call to endPublish().
      * @param data A byte to write to the publish payload.
-     * @return The number of bytes written.
+     * @return The number of bytes written (0 or 1). If 0 is returned a write error occurred.
      */
     virtual size_t write(uint8_t data);
 
     /**
      * @brief Writes an array of bytes as a component of a publish started with a call to beginPublish.
-     *        For performance reasons, this will be appended to the internal buffer, 
-     *        which will be flushed when full or on a call to endPublish().     * @param buffer The bytes to write.
+     *        For performance reasons, this will be appended to the internal buffer,
+     *        which will be flushed when full or on a call to endPublish().
+     * @param buf The bytes to write.
      * @param size The length of the payload to be sent.
-     * @return The number of bytes written.
+     * @return The number of bytes written. If return value is != size a write error occurred.
      */
-    virtual size_t write(const uint8_t* buffer, size_t size);
+    virtual size_t write(const uint8_t* buf, size_t size);
+
+    /**
+     * @brief Writes a string in PROGMEM as a component of a publish started with a call to beginPublish.
+     *        For performance reasons, this will be appended to the internal buffer,
+     *        which will be flushed when full or on a call to endPublish().
+     * @param string The message to write.
+     * @return The number of bytes written. If return value is != string length a write error occurred.
+     */
+    inline size_t write_P(PGM_P string) {
+        return write_P(reinterpret_cast<const uint8_t*>(string), strlen_P(string));
+    }
+
+    /**
+     * @brief Writes an array of progmem bytes as a component of a publish started with a call to beginPublish.
+     *        For performance reasons, this will be appended to the internal buffer,
+     *        which will be flushed when full or on a call to endPublish().
+     * @param buf The bytes to write.
+     * @param size The length of the payload to be sent.
+     * @return The number of bytes written. If return value is != size a write error occurred.
+     */
+    size_t write_P(const uint8_t* buf, size_t size);
 
     /**
      * @brief Subscribes to messages published to the specified topic using QoS 0.
@@ -667,7 +823,30 @@ class PubSubClient : public Print {
      * @return true If sending the subscribe succeeded.
      * false If sending the subscribe failed, either connection lost or message too large.
      */
-    bool subscribe(const char* topic);
+    inline bool subscribe(const char* topic) {
+        return subscribeImpl(false, topic, MQTT_QOS0);
+    }
+
+    /**
+     * @brief Subscribes to messages published to the specified topic from __FlashStringHelper using QoS 0.
+     * @param topic The topic from __FlashStringHelper to subscribe to.
+     * @return true If sending the subscribe succeeded.
+     * false If sending the subscribe failed, either connection lost or message too large.
+     */
+    inline bool subscribe(const __FlashStringHelper* topic) {
+        // convert FlashStringHelper in PROGMEM-pointer
+        return subscribeImpl(true, reinterpret_cast<const char*>(topic), MQTT_QOS0);
+    }
+
+    /**
+     * @brief Subscribes to messages published to the specified topic in PROGMEM using QoS 0.
+     * @param topic The topic in PROGMEM to subscribe to.
+     * @return true If sending the subscribe succeeded.
+     * false If sending the subscribe failed, either connection lost or message too large.
+     */
+    inline bool subscribe_P(PGM_P topic) {
+        return subscribeImpl(true, reinterpret_cast<const char*>(topic), MQTT_QOS0);
+    }
 
     /**
      * @brief Subscribes to messages published to the specified topic.
@@ -676,7 +855,32 @@ class PubSubClient : public Print {
      * @return true If sending the subscribe succeeded.
      * false If sending the subscribe failed, either connection lost or message too large.
      */
-    bool subscribe(const char* topic, uint8_t qos);
+    inline bool subscribe(const char* topic, uint8_t qos) {
+        return subscribeImpl(false, topic, qos);
+    }
+
+    /**
+     * @brief Subscribes to messages published to the specified topic from __FlashStringHelper.
+     * @param topic The topic from __FlashStringHelper to subscribe to.
+     * @param qos The qos to subscribe at. [0, 1].
+     * @return true If sending the subscribe succeeded.
+     * false If sending the subscribe failed, either connection lost or message too large.
+     */
+    inline bool subscribe(const __FlashStringHelper* topic, uint8_t qos) {
+        // convert FlashStringHelper in PROGMEM-pointer
+        return subscribeImpl(true, reinterpret_cast<const char*>(topic), qos);
+    }
+
+    /**
+     * @brief Subscribes to messages published to the specified topic in PROGMEM.
+     * @param topic The topic in PROGMEM to subscribe to.
+     * @param qos The qos to subscribe at. [0, 1].
+     * @return true If sending the subscribe succeeded.
+     * false If sending the subscribe failed, either connection lost or message too large.
+     */
+    inline bool subscribe_P(PGM_P topic, uint8_t qos) {
+        return subscribeImpl(true, reinterpret_cast<const char*>(topic), qos);
+    }
 
     /**
      * @brief Unsubscribes from the specified topic.
@@ -684,7 +888,30 @@ class PubSubClient : public Print {
      * @return true If sending the unsubscribe succeeded.
      * false If sending the unsubscribe failed, either connection lost or message too large.
      */
-    bool unsubscribe(const char* topic);
+    inline bool unsubscribe(const char* topic) {
+        return unsubscribeImpl(false, topic);
+    }
+
+    /**
+     * @brief Unsubscribes from the specified topic from __FlashStringHelper.
+     * @param topic The topic from __FlashStringHelper to unsubscribe from.
+     * @return true If sending the unsubscribe succeeded.
+     * false If sending the unsubscribe failed, either connection lost or message too large.
+     */
+    inline bool unsubscribe(const __FlashStringHelper* topic) {
+        // convert FlashStringHelper in PROGMEM-pointer
+        return unsubscribeImpl(true, reinterpret_cast<const char*>(topic));
+    }
+
+    /**
+     * @brief Unsubscribes from the specified topic in PROGMEM.
+     * @param topic The topic in PROGMEM to unsubscribe from.
+     * @return true If sending the unsubscribe succeeded.
+     * false If sending the unsubscribe failed, either connection lost or message too large.
+     */
+    inline bool unsubscribe_P(PGM_P topic) {
+        return unsubscribeImpl(true, reinterpret_cast<const char*>(topic));
+    }
 
     /**
      * @brief This should be called regularly to allow the client to process incoming messages and maintain its connection to the server.

lib/pubsubclient3/tests/src/lib/Arduino.h

@@ -20,9 +20,14 @@ extern void loop(void);
 unsigned long millis(void);
 }
 
+class __FlashStringHelper;
 #define PROGMEM
+#define PGM_P  const char*
+#define memcpy_P memcpy
+#define strlen_P strlen
 #define strnlen_P strnlen
 #define pgm_read_byte_near(x) *(x)
+#define F(x) (reinterpret_cast<const __FlashStringHelper*>(x))
 
 #define yield(x) {}
 

lib/pubsubclient3/tests/src/publish_spec.cpp

@@ -13,6 +13,7 @@ int test_publish_bytes();
 int test_publish_retained();
 int test_publish_retained_2();
 int test_publish_not_connected();
+int test_publish_long();
 int test_publish_too_long();
 int test_publish_P();
 int test_publish_P_too_long();
@@ -22,6 +23,10 @@ int test_publish_qos1();
 int test_publish_qos2();
 int test_publish_P_qos1();
 int test_publish_P_qos2();
+int test_publish_FlashStringHelper();
+int test_publish_FlashStringHelper2();
+int test_publish_P_FlashStringHelper();
+int test_publish_P_P();
 
 void callback(_UNUSED_ char* topic, _UNUSED_ uint8_t* payload, _UNUSED_ size_t plength) {
     // handle message arrived
@@ -139,6 +144,49 @@ int test_publish_not_connected() {
     END_IT
 }
 
+int test_publish_long() {
+    IT("publishes with long payload message (> buffer size)");
+    ShimClient shimClient;
+    shimClient.setAllowConnect(true);
+
+    // buffer size 64 bytes - 5 bytes header - 2 bytes topic length = max. 57 bytes topic
+    //              0        1         2         3         4         5         6         7         8         9         0         1         2
+    char topic[] = "123456789012345678901234567890123456789012345678901234567";
+
+    //                0        1         2         3         4         5         6         7         8         9         0         1         2
+    char payload[] = "123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890";
+    size_t plength = strlen(payload);
+
+    byte connack[] = {0x20, 0x02, 0x00, 0x00};
+    shimClient.respond(connack, 4);
+
+    PubSubClient client(server, 1883, callback, shimClient);
+    client.setBufferSize(64);
+    bool rc = client.connect("client_test1");
+    IS_TRUE(rc);
+
+    byte publish[256];
+    publish[0] = 0x30;  // PUBLISH, QoS 0, no retain
+    publish[1] = 0xb3;  // Remaining length byte 1: 2 + 57 + 120 bytes (topic length bytes + topic length + payload length = 179)
+    publish[2] = 0x01;  // Remaining length byte 2
+    publish[3] = 0x00;  // Topic length MSB
+    publish[4] = 0x39;  // Topic length LSB (57 bytes)
+    memcpy(&publish[5], topic, sizeof(topic) - 1);
+    memcpy(&publish[5 + sizeof(topic) - 1], payload, sizeof(payload) - 1);
+    shimClient.expect(publish, 5 + sizeof(topic) - 1 + sizeof(payload) - 1);
+
+    rc = client.beginPublish(topic, plength, 0, false);
+    IS_TRUE(rc);
+    plength = client.write((uint8_t*)payload, plength);
+    IS_EQUAL(plength, strlen(payload));
+    rc = client.endPublish();
+    IS_TRUE(rc);
+
+    IS_FALSE(shimClient.error());
+
+    END_IT
+}
+
 int test_publish_too_long() {
     IT("publish fails when topic/payload are too long");
     ShimClient shimClient;
@@ -167,7 +215,7 @@ int test_publish_too_long() {
 }
 
 int test_publish_P() {
-    IT("publishes using PROGMEM");
+    IT("publishes using PROGMEM payload");
     ShimClient shimClient;
     shimClient.setAllowConnect(true);
 
@@ -193,7 +241,7 @@ int test_publish_P() {
 }
 
 int test_publish_P_too_long() {
-    IT("publish using PROGMEM fails when topic is too long");
+    IT("publish using PROGMEM payload fails when topic is too long");
     ShimClient shimClient;
     shimClient.setAllowConnect(true);
 
@@ -219,6 +267,112 @@ int test_publish_P_too_long() {
     END_IT
 }
 
+int test_publish_FlashStringHelper() {
+    IT("publishes using FlashStringHelper topic");
+    ShimClient shimClient;
+    shimClient.setAllowConnect(true);
+
+    char payload[] = "12345";
+
+    byte connack[] = {0x20, 0x02, 0x00, 0x00};
+    shimClient.respond(connack, sizeof(connack));
+
+    PubSubClient client(server, 1883, callback, shimClient);
+    bool rc = client.connect("client_test1");
+    IS_TRUE(rc);
+
+    byte publish[] = {0x31, 0x0c, 0x00, 0x05, 't', 'o', 'p', 'i', 'c', '1', '2', '3', '4', '5'};
+    shimClient.expect(publish, sizeof(publish));
+
+    rc = client.publish(F("topic"), payload, MQTT_QOS0, true);
+    IS_TRUE(rc);
+
+    IS_FALSE(shimClient.error());
+
+    END_IT
+}
+
+int test_publish_FlashStringHelper2() {
+    IT("publishes using FlashStringHelper topic and payload");
+    ShimClient shimClient;
+    shimClient.setAllowConnect(true);
+
+    char payload[] = "12345";
+
+    byte connack[] = {0x20, 0x02, 0x00, 0x00};
+    shimClient.respond(connack, sizeof(connack));
+
+    PubSubClient client(server, 1883, callback, shimClient);
+    bool rc = client.connect("client_test1");
+    IS_TRUE(rc);
+
+    byte publish[] = {0x31, 0x0c, 0x00, 0x05, 't', 'o', 'p', 'i', 'c', '1', '2', '3', '4', '5'};
+    shimClient.expect(publish, sizeof(publish));
+
+    rc = client.publish(F("topic"), F(payload), MQTT_QOS0, true);
+    IS_TRUE(rc);
+
+    IS_FALSE(shimClient.error());
+
+    END_IT
+}
+
+int test_publish_P_FlashStringHelper() {
+    IT("publishes using FlashStringHelper topic and PROGMEM payload");
+    ShimClient shimClient;
+    shimClient.setAllowConnect(true);
+
+    char payload[] PROGMEM = "12345";
+
+    byte connack[] = {0x20, 0x02, 0x00, 0x00};
+    shimClient.respond(connack, sizeof(connack));
+
+    PubSubClient client(server, 1883, callback, shimClient);
+    bool rc = client.connect("client_test1");
+    IS_TRUE(rc);
+
+    byte publish[] = {0x31, 0x0c, 0x00, 0x05, 't', 'o', 'p', 'i', 'c', '1', '2', '3', '4', '5'};
+    shimClient.expect(publish, sizeof(publish));
+
+    rc = client.publish_P(F("topic"), payload, MQTT_QOS0, true);
+    IS_TRUE(rc);
+
+    IS_FALSE(shimClient.error());
+
+    END_IT
+}
+
+int test_publish_P_P() {
+    IT("publishes using PROGMEM topic and PROGMEM payload");
+    ShimClient shimClient;
+    shimClient.setAllowConnect(true);
+
+    char topic[] PROGMEM = "topic";
+    char payload[] PROGMEM = "12345";
+    size_t length = strlen_P(payload);
+
+    byte connack[] = {0x20, 0x02, 0x00, 0x00};
+    shimClient.respond(connack, sizeof(connack));
+
+    PubSubClient client(server, 1883, callback, shimClient);
+    bool rc = client.connect("client_test1");
+    IS_TRUE(rc);
+
+    byte publish[] = {0x31, 0x0c, 0x00, 0x05, 't', 'o', 'p', 'i', 'c', '1', '2', '3', '4', '5'};
+    shimClient.expect(publish, sizeof(publish));
+
+    rc = client.beginPublish_P(topic, length, MQTT_QOS0, true);
+    IS_TRUE(rc);
+    length = client.write_P(payload);
+    IS_EQUAL(length, strlen_P(payload));
+    rc = client.endPublish();
+    IS_TRUE(rc);
+
+    IS_FALSE(shimClient.error());
+
+    END_IT
+}
+
 int test_publish_empty_topic() {
     IT("publish fails when topic is empty");
     ShimClient shimClient;
@@ -275,7 +429,7 @@ int test_publish_qos1() {
     IS_TRUE(rc);
 
     // Example publish packet for QoS 1 (0x32)
-    byte publish[] = {0x32, 0x10, 0x00, 0x05, 't', 'o', 'p', 'i', 'c', 'p', 'a', 'y', 'l', 'o', 'a', 'd', 0x00, 0x02};
+    byte publish[] = {0x32, 0x10, 0x00, 0x05, 't', 'o', 'p', 'i', 'c', 0x00, 0x02, 'p', 'a', 'y', 'l', 'o', 'a', 'd'};
     shimClient.expect(publish, sizeof(publish));
 
     rc = client.publish("topic", "payload", MQTT_QOS1, false);
@@ -299,7 +453,7 @@ int test_publish_qos2() {
     IS_TRUE(rc);
 
     // Example publish packet for QoS 2 (0x34)
-    byte publish[] = {0x34, 0x10, 0x00, 0x05, 't', 'o', 'p', 'i', 'c', 'p', 'a', 'y', 'l', 'o', 'a', 'd', 0x00, 0x02};
+    byte publish[] = {0x34, 0x10, 0x00, 0x05, 't', 'o', 'p', 'i', 'c', 0x00, 0x02, 'p', 'a', 'y', 'l', 'o', 'a', 'd'};
     shimClient.expect(publish, sizeof(publish));
 
     rc = client.publish("topic", "payload", MQTT_QOS2, false);
@@ -311,7 +465,7 @@ int test_publish_qos2() {
 }
 
 int test_publish_P_qos1() {
-    IT("publishes using PROGMEM with QoS 1 retained");
+    IT("publishes using PROGMEM payload with QoS 1 retained");
     ShimClient shimClient;
     shimClient.setAllowConnect(true);
 
@@ -325,7 +479,7 @@ int test_publish_P_qos1() {
     bool rc = client.connect("client_test1");
     IS_TRUE(rc);
 
-    byte publish[] = {0x33, 0x0e, 0x00, 0x05, 't', 'o', 'p', 'i', 'c', 0x01, 0x02, 0x03, 0x04, 0x05, 0x00, 0x02};
+    byte publish[] = {0x33, 0x0e, 0x00, 0x05, 't', 'o', 'p', 'i', 'c', 0x00, 0x02, 0x01, 0x02, 0x03, 0x04, 0x05};
     shimClient.expect(publish, sizeof(publish));
 
     rc = client.publish_P("topic", payload, length, MQTT_QOS1, true);
@@ -337,7 +491,7 @@ int test_publish_P_qos1() {
 }
 
 int test_publish_P_qos2() {
-    IT("publishes using PROGMEM with QoS 2 retained");
+    IT("publishes using PROGMEM payload with QoS 2 retained");
     ShimClient shimClient;
     shimClient.setAllowConnect(true);
 
@@ -351,7 +505,7 @@ int test_publish_P_qos2() {
     bool rc = client.connect("client_test1");
     IS_TRUE(rc);
 
-    byte publish[] = {0x35, 0x0e, 0x00, 0x05, 't', 'o', 'p', 'i', 'c', 0x01, 0x02, 0x03, 0x04, 0x05, 0x00, 0x02};
+    byte publish[] = {0x35, 0x0e, 0x00, 0x05, 't', 'o', 'p', 'i', 'c', 0x00, 0x02, 0x01, 0x02, 0x03, 0x04, 0x05};
     shimClient.expect(publish, sizeof(publish));
 
     rc = client.publish_P("topic", payload, length, MQTT_QOS2, true);
@@ -371,6 +525,7 @@ int main() {
     test_publish_qos1();
     test_publish_qos2();
     test_publish_null_payload();
+    test_publish_long();
     test_publish_not_connected();
     test_publish_empty_topic();
     test_publish_too_long();
@@ -378,6 +533,10 @@ int main() {
     test_publish_P_qos1();
     test_publish_P_qos2();
     test_publish_P_too_long();
+    test_publish_FlashStringHelper();
+    test_publish_FlashStringHelper2();
+    test_publish_P_FlashStringHelper();
+    test_publish_P_P();
 
     FINISH
 }

lib/pubsubclient3/tests/src/receive_spec.cpp

@@ -28,6 +28,7 @@ int test_receive_oversized_message();
 int test_resize_buffer();
 int test_receive_oversized_stream_message();
 int test_receive_qos1();
+int test_receive_qos2();
 
 void reset_callback() {
     callback_called = false;
@@ -330,6 +331,57 @@ int test_receive_qos1() {
     END_IT
 }
 
+int test_receive_qos2() {
+    IT("receives a qos2 message - responds PUBREC then PUBCOMP");
+    reset_callback();
+
+    ShimClient shimClient;
+    shimClient.setAllowConnect(true);
+
+    byte connack[] = {0x20, 0x02, 0x00, 0x00};
+    shimClient.respond(connack, 4);
+
+    PubSubClient client(server, 1883, callback, shimClient);
+    bool rc = client.connect("client_test1");
+    IS_TRUE(rc);
+
+    // QoS 2 PUBLISH from broker (0x34 = MQTTPUBLISH | QoS2 bits)
+    // Fixed header 0x34, remaining length 0x10 (16), topic len 0x0005, topic "topic",
+    // msgId 0x1234, payload "payload"
+    byte publish[] = {0x34, 0x10, 0x0, 0x5, 0x74, 0x6f, 0x70, 0x69, 0x63, 0x12, 0x34, 0x70, 0x61, 0x79, 0x6c, 0x6f, 0x61, 0x64};
+    shimClient.respond(publish, 18);
+
+    // Client must respond with PUBREC (0x50), remaining length 2, msgId 0x1234
+    byte pubrec[] = {0x50, 0x02, 0x12, 0x34};
+    shimClient.expect(pubrec, 4);
+
+    rc = client.loop();
+    IS_TRUE(rc);
+    IS_TRUE(callback_called);
+    IS_TRUE(strcmp(lastTopic, "topic") == 0);
+    IS_TRUE(memcmp(lastPayload, "payload", 7) == 0);
+    IS_TRUE(lastLength == 7);
+    IS_FALSE(shimClient.error());
+
+    reset_callback();
+
+    // Broker sends PUBREL (0x62 = MQTTPUBREL | bit1), remaining length 2, msgId 0x1234
+    byte pubrel[] = {0x62, 0x02, 0x12, 0x34};
+    shimClient.respond(pubrel, 4);
+
+    // Client must respond with PUBCOMP (0x70), remaining length 2, msgId 0x1234
+    byte pubcomp[] = {0x70, 0x02, 0x12, 0x34};
+    shimClient.expect(pubcomp, 4);
+
+    rc = client.loop();
+    IS_TRUE(rc);
+    IS_FALSE(callback_called);  // callback must NOT fire again on PUBREL
+
+    IS_FALSE(shimClient.error());
+
+    END_IT
+}
+
 int main() {
     SUITE("Receive");
     test_receive_callback();
@@ -340,6 +392,7 @@ int main() {
     test_resize_buffer();
     test_receive_oversized_stream_message();
     test_receive_qos1();
+    test_receive_qos2();
 
     FINISH
 }

lib/pubsubclient3/tests/src/subscribe_spec.cpp

@@ -10,6 +10,10 @@ byte server[] = {172, 16, 0, 2};
 void callback(char* topic, uint8_t* payload, size_t plength);
 int test_subscribe_no_qos();
 int test_subscribe_qos_1();
+int test_subscribe_P();
+int test_subscribe_P_qos_1();
+int test_subscribe_FlashStringHelper();
+int test_subscribe_FlashStringHelper_qos_1();
 int test_subscribe_not_connected();
 int test_subscribe_invalid_qos();
 int test_subscribe_too_long();
@@ -70,6 +74,108 @@ int test_subscribe_qos_1() {
     END_IT
 }
 
+int test_subscribe_P() {
+    IT("subscribe using PROGMEM");
+    ShimClient shimClient;
+    shimClient.setAllowConnect(true);
+
+    byte connack[] = {0x20, 0x02, 0x00, 0x00};
+    shimClient.respond(connack, 4);
+
+    PubSubClient client(server, 1883, callback, shimClient);
+    bool rc = client.connect("client_test1");
+    IS_TRUE(rc);
+
+    byte subscribe[] = {0x82, 0xa, 0x0, 0x2, 0x0, 0x5, 0x74, 0x6f, 0x70, 0x69, 0x63, 0x0};
+    shimClient.expect(subscribe, 12);
+    byte suback[] = {0x90, 0x3, 0x0, 0x2, 0x0};
+    shimClient.respond(suback, 5);
+
+    char topic[] PROGMEM = "topic";
+    rc = client.subscribe_P(topic);
+    IS_TRUE(rc);
+
+    IS_FALSE(shimClient.error());
+
+    END_IT
+}
+
+int test_subscribe_P_qos_1() {
+    IT("subscribe using PROGMEM with QoS 1");
+    ShimClient shimClient;
+    shimClient.setAllowConnect(true);
+
+    byte connack[] = {0x20, 0x02, 0x00, 0x00};
+    shimClient.respond(connack, 4);
+
+    PubSubClient client(server, 1883, callback, shimClient);
+    bool rc = client.connect("client_test1");
+    IS_TRUE(rc);
+
+    byte subscribe[] = {0x82, 0xa, 0x0, 0x2, 0x0, 0x5, 0x74, 0x6f, 0x70, 0x69, 0x63, 0x1};
+    shimClient.expect(subscribe, 12);
+    byte suback[] = {0x90, 0x3, 0x0, 0x2, 0x1};
+    shimClient.respond(suback, 5);
+
+    char topic[] PROGMEM = "topic";
+    rc = client.subscribe_P(topic, MQTT_QOS1);
+    IS_TRUE(rc);
+
+    IS_FALSE(shimClient.error());
+
+    END_IT
+}
+
+int test_subscribe_FlashStringHelper() {
+    IT("subscribe using FlashStringHelper");
+    ShimClient shimClient;
+    shimClient.setAllowConnect(true);
+
+    byte connack[] = {0x20, 0x02, 0x00, 0x00};
+    shimClient.respond(connack, 4);
+
+    PubSubClient client(server, 1883, callback, shimClient);
+    bool rc = client.connect("client_test1");
+    IS_TRUE(rc);
+
+    byte subscribe[] = {0x82, 0xa, 0x0, 0x2, 0x0, 0x5, 0x74, 0x6f, 0x70, 0x69, 0x63, 0x0};
+    shimClient.expect(subscribe, 12);
+    byte suback[] = {0x90, 0x3, 0x0, 0x2, 0x0};
+    shimClient.respond(suback, 5);
+
+    rc = client.subscribe(F("topic"));
+    IS_TRUE(rc);
+
+    IS_FALSE(shimClient.error());
+
+    END_IT
+}
+
+int test_subscribe_FlashStringHelper_qos_1() {
+    IT("subscribe using FlashStringHelper with QoS 1");
+    ShimClient shimClient;
+    shimClient.setAllowConnect(true);
+
+    byte connack[] = {0x20, 0x02, 0x00, 0x00};
+    shimClient.respond(connack, 4);
+
+    PubSubClient client(server, 1883, callback, shimClient);
+    bool rc = client.connect("client_test1");
+    IS_TRUE(rc);
+
+    byte subscribe[] = {0x82, 0xa, 0x0, 0x2, 0x0, 0x5, 0x74, 0x6f, 0x70, 0x69, 0x63, 0x1};
+    shimClient.expect(subscribe, 12);
+    byte suback[] = {0x90, 0x3, 0x0, 0x2, 0x1};
+    shimClient.respond(suback, 5);
+
+    rc = client.subscribe(F("topic"), MQTT_QOS1);
+    IS_TRUE(rc);
+
+    IS_FALSE(shimClient.error());
+
+    END_IT
+}
+
 int test_subscribe_not_connected() {
     IT("subscribe fails when not connected");
     ShimClient shimClient;
@@ -176,6 +282,10 @@ int main() {
     SUITE("Subscribe");
     test_subscribe_no_qos();
     test_subscribe_qos_1();
+    test_subscribe_P();
+    test_subscribe_P_qos_1();
+    test_subscribe_FlashStringHelper();
+    test_subscribe_FlashStringHelper_qos_1();
     test_subscribe_not_connected();
     test_subscribe_invalid_qos();
     test_subscribe_too_long();