Fuzz introspector
For issues and ideas: https://github.com/ossf/fuzz-introspector/issues
Project coverage
Per-fuzzer coverage

Table of contents

Project overview: unit
High level conclusions
Reachability and coverage overview
Fuzzers overview
Project functions overview
Fuzzer details
Fuzzer: fuzz_http_h1p
Call tree
Fuzzer: fuzz_http_h1p_peer
Call tree
Fuzzer: fuzz_http_controller
Call tree
Fuzzer: fuzz_json
Call tree
Fuzzer: fuzz_basic
Call tree
Analyses and suggestions
Optimal target analysis
Remaining optimal interesting functions
All functions overview
Fuzz engine guidance
fuzzing/nxt_http_h1p_fuzz.c
Dictionary
Fuzzer function priority
fuzzing/nxt_http_h1p_peer_fuzz.c
Dictionary
Fuzzer function priority
fuzzing/nxt_http_controller_fuzz.c
Dictionary
Fuzzer function priority
fuzzing/nxt_json_fuzz.c
Dictionary
Fuzzer function priority
fuzzing/nxt_basic_fuzz.c
Dictionary
Fuzzer function priority
Runtime coverage analysis
Files and Directories in report
Files in report
Directories in report
Metadata section
Report generation date: 2025-07-02

Project overview: unit

High level conclusions

Reachability and coverage overview

Functions statically reachable by fuzzers
11.0%
140 / 1293
Cyclomatic complexity statically reachable by fuzzers
12.0%
973 / 7835
Runtime code coverage of functions
0.0%
0 / 1293

Fuzzers overview

Fuzzer Fuzzer filename Functions Reached Functions unreached Fuzzer depth Files reached Basic blocks reached Cyclomatic complexity Details
fuzz_http_h1p fuzzing/nxt_http_h1p_fuzz.c 40 1408 9 12 449 186 nxt_http_h1p_fuzz.c
fuzz_http_h1p_peer fuzzing/nxt_http_h1p_peer_fuzz.c 43 1405 9 12 487 200 nxt_http_h1p_peer_fuzz.c
fuzz_http_controller fuzzing/nxt_http_controller_fuzz.c 40 1408 9 12 445 184 nxt_http_controller_fuzz.c
fuzz_json fuzzing/nxt_json_fuzz.c 108 1340 14 22 1908 750 nxt_json_fuzz.c
fuzz_basic fuzzing/nxt_basic_fuzz.c 60 1402 9 17 802 331 nxt_basic_fuzz.c

Project functions overview

The following table shows data about each function in the project. The functions included in this table correspond to all functions that exist in the executables of the fuzzers. As such, there may be functions that are from third-party libraries.

For further technical details on the meaning of columns in the below table, please see the Glossary .

Func name Functions filename Args Function call depth Reached by Fuzzers Runtime reached by Fuzzers Combined reached by Fuzzers Fuzzers runtime hit Func lines hit % I Count BB Count Cyclomatic complexity Functions reached Reached by functions Accumulated cyclomatic complexity Undiscovered complexity

Fuzzer details

Fuzzer: fuzz_http_h1p

Call tree

The calltree shows the control flow of the fuzzer. This is overlaid with coverage information to display how much of the potential code a fuzzer can reach is in fact covered at runtime. In the following there is a link to a detailed calltree visualisation as well as a bitmap showing a high-level view of the calltree. For further information about these topics please see the glossary for full calltree and calltree overview

Full calltree

Call tree overview bitmap:

The project has no code coverage. Will not display blockers as blockers depend on code coverage.

Fuzzer: fuzz_http_h1p_peer

Call tree

The calltree shows the control flow of the fuzzer. This is overlaid with coverage information to display how much of the potential code a fuzzer can reach is in fact covered at runtime. In the following there is a link to a detailed calltree visualisation as well as a bitmap showing a high-level view of the calltree. For further information about these topics please see the glossary for full calltree and calltree overview

Full calltree

Call tree overview bitmap:

The project has no code coverage. Will not display blockers as blockers depend on code coverage.

Fuzzer: fuzz_http_controller

Call tree

The calltree shows the control flow of the fuzzer. This is overlaid with coverage information to display how much of the potential code a fuzzer can reach is in fact covered at runtime. In the following there is a link to a detailed calltree visualisation as well as a bitmap showing a high-level view of the calltree. For further information about these topics please see the glossary for full calltree and calltree overview

Full calltree

Call tree overview bitmap:

The project has no code coverage. Will not display blockers as blockers depend on code coverage.

Fuzzer: fuzz_json

Call tree

The calltree shows the control flow of the fuzzer. This is overlaid with coverage information to display how much of the potential code a fuzzer can reach is in fact covered at runtime. In the following there is a link to a detailed calltree visualisation as well as a bitmap showing a high-level view of the calltree. For further information about these topics please see the glossary for full calltree and calltree overview

Full calltree

Call tree overview bitmap:

The project has no code coverage. Will not display blockers as blockers depend on code coverage.

Fuzzer: fuzz_basic

Call tree

The calltree shows the control flow of the fuzzer. This is overlaid with coverage information to display how much of the potential code a fuzzer can reach is in fact covered at runtime. In the following there is a link to a detailed calltree visualisation as well as a bitmap showing a high-level view of the calltree. For further information about these topics please see the glossary for full calltree and calltree overview

Full calltree

Call tree overview bitmap:

The project has no code coverage. Will not display blockers as blockers depend on code coverage.

Analyses and suggestions

Optimal target analysis

Remaining optimal interesting functions

The following table shows a list of functions that are optimal targets. Optimal targets are identified by finding the functions that in combination, yield a high code coverage.

Func name Functions filename Arg count Args Function depth hitcount instr count bb count cyclomatic complexity Reachable functions Incoming references total cyclomatic complexity Unreached complexity
nxt_router_conf_data_handler /src/unit/src/nxt_router.c 2 ['N/A', 'N/A'] 33 0 345 33 11 426 0 2470 1746
nxt_http_application_handler /src/unit/src/nxt_http_request.c 3 ['N/A', 'N/A', 'N/A'] 26 0 57 8 3 242 0 1409 532
nxt_runtime_create /src/unit/src/nxt_runtime.c 1 ['N/A'] 22 0 285 35 17 331 0 1665 478
nxt_controller_process_new_port_handler /src/unit/src/nxt_controller.c 2 ['N/A', 'N/A'] 29 0 47 9 4 275 0 1587 271
nxt_main_port_modules_handler /src/unit/src/nxt_main_process.c 2 ['N/A', 'N/A'] 30 0 490 63 23 328 0 1652 230
nxt_http_parse_request_line /src/unit/src/nxt_http_parse.c 3 ['N/A', 'N/A', 'N/A'] 16 0 1862 248 88 36 0 334 193
nxt_isolation_main_prefork /src/unit/src/nxt_isolation.c 3 ['N/A', 'N/A', 'N/A'] 17 0 395 51 18 73 0 449 166
nxt_http_route_handler /src/unit/src/nxt_http_route.c 3 ['N/A', 'N/A', 'N/A'] 22 0 213 29 9 109 0 674 150
nxt_http_static_send /src/unit/src/nxt_http_static.c 3 ['N/A', 'N/A', 'N/A'] 26 0 1107 119 38 130 4 826 149
nxt_proto_setup /src/unit/src/nxt_application.c 2 ['N/A', 'N/A'] 10 0 329 46 16 58 0 289 127

Implementing fuzzers that target the above functions will improve reachability such that it becomes:

Functions statically reachable by fuzzers
53.0%
691 / 1293
Cyclomatic complexity statically reachable by fuzzers
61.0%
4761 / 7835

All functions overview

If you implement fuzzers for these functions, the status of all functions in the project will be:

Func name Functions filename Args Function call depth Reached by Fuzzers Runtime reached by Fuzzers Combined reached by Fuzzers Fuzzers runtime hit Func lines hit % I Count BB Count Cyclomatic complexity Functions reached Reached by functions Accumulated cyclomatic complexity Undiscovered complexity

Fuzz engine guidance

This sections provides heuristics that can be used as input to a fuzz engine when running a given fuzz target. The current focus is on providing input that is usable by libFuzzer.

fuzzing/nxt_http_h1p_fuzz.c

Dictionary

Use this with the libFuzzer -dict=DICT.file flag


fuzzing/nxt_http_h1p_peer_fuzz.c

Dictionary

Use this with the libFuzzer -dict=DICT.file flag


fuzzing/nxt_http_controller_fuzz.c

Dictionary

Use this with the libFuzzer -dict=DICT.file flag


fuzzing/nxt_json_fuzz.c

Dictionary

Use this with the libFuzzer -dict=DICT.file flag


fuzzing/nxt_basic_fuzz.c

Dictionary

Use this with the libFuzzer -dict=DICT.file flag


Runtime coverage analysis

No runtime coverage data was found

Files and Directories in report

This section shows which files and directories are considered in this report. The main reason for showing this is fuzz introspector may include more code in the reasoning than is desired. This section helps identify if too many files/directories are included, e.g. third party code, which may be irrelevant for the threat model. In the event too much is included, fuzz introspector supports a configuration file that can exclude data from the report. See the following link for more information on how to create a config file: link

Files in report

Source file Reached by Covered by
[] []
/src/unit/fuzzing/nxt_http_h1p_peer_fuzz.c ['fuzz_http_h1p_peer'] []
/src/unit/src/nxt_utf8.c ['fuzz_json', 'fuzz_basic'] []
/src/unit/src/nxt_app_nncq.h [] []
/src/unit/src/nxt_port_socket.c [] []
/src/unit/src/nxt_linux_sendfile.c [] []
/src/unit/src/nxt_conf_validation.c ['fuzz_json'] []
/src/unit/src/nxt_murmur_hash.c ['fuzz_basic'] []
/src/unit/src/nxt_mem_map.c [] []
/src/unit/src/nxt_http_request.c ['fuzz_json'] []
/src/unit/src/nxt_time.c ['fuzz_http_h1p', 'fuzz_http_h1p_peer', 'fuzz_http_controller', 'fuzz_json', 'fuzz_basic'] []
/src/unit/src/nxt_http_response.c [] []
/src/unit/src/nxt_port_rpc.c [] []
/src/unit/src/nxt_lib.c [] []
/src/unit/src/nxt_djb_hash.c ['fuzz_json', 'fuzz_basic'] []
/src/unit/src/nxt_http_route_addr.c [] []
/src/unit/src/nxt_router.c [] []
/src/unit/src/nxt_recvbuf.c [] []
/src/unit/src/nxt_socket_msg.c [] []
/src/unit/src/nxt_signal.c [] []
/src/unit/src/nxt_conn_accept.c [] []
/src/unit/src/nxt_spinlock.c ['fuzz_http_h1p', 'fuzz_http_h1p_peer', 'fuzz_http_controller', 'fuzz_json', 'fuzz_basic'] []
/src/unit/src/nxt_http_set_headers.c [] []
/src/unit/src/nxt_capability.c [] []
/src/unit/src/nxt_h1proto.c [] []
/src/unit/src/nxt_conf.c ['fuzz_json'] []
/src/unit/src/nxt_select_engine.c [] []
/src/unit/src/nxt_timer.c ['fuzz_http_h1p', 'fuzz_http_h1p_peer', 'fuzz_http_controller', 'fuzz_json', 'fuzz_basic'] []
/src/unit/src/nxt_router_access_log.c [] []
/src/unit/src/nxt_thread_mutex.c [] []
/src/unit/src/nxt_sendbuf.c [] []
/src/unit/src/nxt_http_compression.c [] []
/src/unit/src/nxt_h1proto_websocket.c [] []
/src/unit/src/nxt_lvlhsh.c ['fuzz_http_h1p', 'fuzz_http_h1p_peer', 'fuzz_http_controller', 'fuzz_json'] []
/src/unit/src/nxt_errno.c [] []
/src/unit/src/nxt_websocket.c ['fuzz_basic'] []
/src/unit/src/nxt_application.c [] []
/src/unit/src/nxt_service.c [] []
/src/unit/src/nxt_sha1.c ['fuzz_basic'] []
/src/unit/src/nxt_log_moderation.c ['fuzz_http_h1p', 'fuzz_http_h1p_peer', 'fuzz_http_controller', 'fuzz_json', 'fuzz_basic'] []
/src/unit/src/nxt_conn_close.c [] []
/src/unit/src/nxt_parse.c ['fuzz_basic'] []
/src/unit/src/nxt_http_proxy.c [] []
/src/unit/src/nxt_rbtree.c ['fuzz_http_h1p', 'fuzz_http_h1p_peer', 'fuzz_http_controller', 'fuzz_json', 'fuzz_basic'] []
/src/unit/src/nxt_port_hash.c [] []
/src/unit/src/nxt_buf.h [] []
/src/unit/src/nxt_port_memory.c [] []
/src/unit/src/nxt_sockaddr.c [] []
/src/unit/src/nxt_port.c [] []
/src/unit/src/nxt_thread_pool.c [] []
/src/unit/src/nxt_process_title.c [] []
/src/unit/src/nxt_http_static.c [] []
/src/unit/src/nxt_semaphore.c [] []
/src/unit/src/nxt_signal_handlers.c [] []
/src/unit/src/nxt_clone.c [] []
/src/unit/src/nxt_unit_sptr.h [] []
/src/unit/src/nxt_epoll_engine.c [] []
/src/unit/src/nxt_gmtime.c [] []
/src/unit/src/nxt_socket.c [] []
/src/unit/src/nxt_main_process.c [] []
/src/unit/src/nxt_work_queue.c [] []
/src/unit/src/nxt_nncq.h [] []
/src/unit/src/nxt_controller.c [] []
/src/unit/src/nxt_list.c ['fuzz_http_h1p', 'fuzz_http_h1p_peer', 'fuzz_http_controller', 'fuzz_json'] []
/src/unit/src/nxt_event_engine.c [] []
/src/unit/src/nxt_fs.c [] []
/src/unit/src/nxt_listen_socket.c [] []
/src/unit/src/nxt_tstr.c ['fuzz_json'] []
/src/unit/src/nxt_http_websocket.c [] []
/src/unit/src/nxt_malloc.c ['fuzz_http_h1p', 'fuzz_http_h1p_peer', 'fuzz_http_controller', 'fuzz_json', 'fuzz_basic'] []
/src/unit/src/nxt_websocket_accept.c ['fuzz_basic'] []
/src/unit/src/nxt_file.c [] []
/src/unit/src/nxt_isolation.c [] []
/src/unit/src/nxt_conn.c [] []
/src/unit/src/nxt_string.c ['fuzz_json', 'fuzz_basic'] []
/src/unit/src/nxt_process.c [] []
/src/unit/fuzzing/nxt_http_h1p_fuzz.c ['fuzz_http_h1p'] []
/src/unit/fuzzing/nxt_http_controller_fuzz.c ['fuzz_http_controller'] []
/src/unit/src/nxt_http_route.c [] []
/src/unit/src/nxt_var.c ['fuzz_json'] []
/src/unit/src/nxt_file_name.c [] []
/src/unit/src/nxt_sprintf.c ['fuzz_json'] []
/src/unit/src/nxt_random.c [] []
/src/unit/src/nxt_thread_time.c ['fuzz_http_h1p', 'fuzz_http_h1p_peer', 'fuzz_http_controller', 'fuzz_json', 'fuzz_basic'] []
/src/unit/src/nxt_poll_engine.c [] []
/src/unit/src/nxt_time_parse.c ['fuzz_basic'] []
/src/unit/src/nxt_external.c [] []
/src/unit/src/nxt_upstream_round_robin.c [] []
/src/unit/src/nxt_mp.c ['fuzz_http_h1p', 'fuzz_http_h1p_peer', 'fuzz_http_controller', 'fuzz_json'] []
/src/unit/src/nxt_thread.c [] []
/src/unit/src/nxt_conn_read.c [] []
/src/unit/fuzzing/nxt_basic_fuzz.c ['fuzz_basic'] []
/src/unit/src/nxt_http_return.c [] []
/src/unit/src/nxt_upstream.c [] []
/src/unit/src/nxt_log.c [] []
/src/unit/src/nxt_socketpair.c [] []
/src/unit/src/nxt_credential.c [] []
/src/unit/src/nxt_array.c ['fuzz_json'] []
/src/unit/src/nxt_http_variables.c ['fuzz_json'] []
/src/unit/src/nxt_conn_write.c [] []
/src/unit/src/nxt_buf.c [] []
/src/unit/src/nxt_http_error.c [] []
/src/unit/src/nxt_http_rewrite.c [] []
/src/unit/src/nxt_http_chunk_parse.c [] []
/src/unit/src/nxt_runtime.c [] []
/src/unit/src/nxt_fs_mount.c [] []
/src/unit/src/nxt_http_parse.c ['fuzz_http_h1p', 'fuzz_http_h1p_peer', 'fuzz_http_controller'] []
/src/unit/fuzzing/nxt_json_fuzz.c ['fuzz_json'] []
/src/unit/src/nxt_conn_connect.c [] []
/src/unit/src/nxt_status.c [] []

Directories in report

Directory
/src/unit/src/
/src/unit/fuzzing/

Metadata section

This sections shows the raw data that is used to produce this report. This is mainly used for further processing and developer debugging.

Fuzzer Calltree file Program data file Coverage file
fuzz_http_h1p fuzzerLogFile-0-wyoVrgtN0h.data fuzzerLogFile-0-wyoVrgtN0h.data.yaml
fuzz_http_h1p_peer fuzzerLogFile-0-WlkmPAXw97.data fuzzerLogFile-0-WlkmPAXw97.data.yaml
fuzz_http_controller fuzzerLogFile-0-wr9kbxg3yW.data fuzzerLogFile-0-wr9kbxg3yW.data.yaml
fuzz_json fuzzerLogFile-0-con9q0e40R.data fuzzerLogFile-0-con9q0e40R.data.yaml
fuzz_basic fuzzerLogFile-0-p1OO9aKfZ7.data fuzzerLogFile-0-p1OO9aKfZ7.data.yaml