Fuzz introspector
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Project coverage
Per-fuzzer coverage

Table of contents

Project overview: libhtp
High level conclusions
Reachability and coverage overview
Fuzzers overview
Project functions overview
Fuzzer details
Fuzzer: fuzz_htp_c
Call tree
Fuzz blockers
Runtime coverage analysis
Files reached
Analyses and suggestions
Optimal target analysis
Remaining optimal interesting functions
All functions overview
Fuzz engine guidance
test/fuzz/fuzz_htp.c
Dictionary
Fuzzer function priority
Runtime coverage analysis
Complex functions with low coverage
Files and Directories in report
Files in report
Directories in report
Metadata section
Report generation date: 2025-10-10

Project overview: libhtp

High level conclusions

Reachability and coverage overview

Functions statically reachable by fuzzers
31.0%
138 / 442
Cyclomatic complexity statically reachable by fuzzers
28.0%
964 / 3442
Runtime code coverage of functions
56.0%
246 / 442

Warning: The number of runtime covered functions are larger than the number of reachable functions. This means that Fuzz Introspector found there are more functions covered at runtime than what is considered reachable based on the static analysis. This is a limitation in the analysis as anything covered at runtime is by definition reachable by the fuzzers.
This is likely due to a limitation in the static analysis. In this case, the count of functions covered at runtime is the true value, which means this is what should be considered "achieved" by the fuzzer.

Use the project functions table below to query all functions that were not covered at runtime.

Fuzzers overview

Fuzzer Fuzzer filename Functions Reached Functions unreached Fuzzer depth Files reached Basic blocks reached Cyclomatic complexity Details
fuzz_htp_c test/fuzz/fuzz_htp.c 153 331 11 18 2369 1012 fuzz_htp.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_htp_c

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 distribution of callsites in terms of coloring is
Color Runtime hitcount Callsite count Percentage
red 0 103 24.8%
gold [1:9] 1 0.24%
yellow [10:29] 2 0.48%
greenyellow [30:49] 2 0.48%
lawngreen 50+ 307 73.9%
All colors 415 100

Fuzz blockers

The following nodes represent call sites where fuzz blockers occur.

Amount of callsites blocked Calltree index Parent function Callsite Largest blocked function
31 31 htp_config_set_server_personality call site: 00031 htp_config_set_backslash_convert_slashes
18 306 htp_tx_destroy_incomplete call site: 00306 htp_mpart_part_destroy
10 294 htp_tx_destroy_incomplete call site: 00294 htp_table_destroy
7 326 htp_tx_destroy_incomplete call site: 00326 htp_table_destroy
3 194 htp_req_run_hook_body_data call site: 00194 htp_gzip_decompressor_decompress
3 240 htp_gzip_decompressor_restart call site: 00240 htp_tx_req_destroy_decompressors
3 253 htp_tx_finalize call site: 00253 htp_tx_destroy
2 184 htp_connp_req_data call site: 00184 htp_log
2 357 htp_connp_res_data call site: 00357 htp_log
1 1 LLVMFuzzerTestOneInput call site: 00001 abort
1 16 htp_config_create call site: 00016 htp_config_set_backslash_convert_slashes
1 18 htp_config_set_backslash_convert_slashes call site: 00018 htp_config_set_path_separators_decode

Runtime coverage analysis

Covered functions
247
Functions that are reachable but not covered
20
Reachable functions
153
Percentage of reachable functions covered
86.93%
NB: The sum of covered functions and functions that are reachable but not covered need not be equal to Reachable functions . This is because the reachability analysis is an approximation and thus at runtime some functions may be covered that are not included in the reachability analysis. This is a limitation of our static analysis capabilities.
Warning: The number of covered functions are larger than the number of reachable functions. This means that there are more functions covered at runtime than are extracted using static analysis. This is likely a result of the static analysis component failing to extract the right call graph or the coverage runtime being compiled with sanitizers in code that the static analysis has not analysed. This can happen if lto/gold is not used in all places that coverage instrumentation is used.
Function name source code lines source lines hit percentage hit

Files reached

filename functions hit
test/fuzz/fuzz_htp.c 13
htp/htp_config.c 35
htp/htp_hooks.c 4
htp/htp_list.c 9
htp/bstr.c 3
htp/htp_connection_parser.c 7
htp/htp_connection.c 7
htp/htp_util.c 4
test/test.c 2
htp/htp_request.c 7
htp/htp_transaction.c 14
htp/htp_decompressors.c 5
htp/lzma/LzmaDec.c 14
htp/htp_table.c 4
htp/htp_urlencoded.c 1
htp/bstr_builder.c 1
htp/htp_multipart.c 2
htp/htp_response.c 7

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
htp_connp_REQ_HEADERS /src/libhtp/htp/htp_request.c 1 ['N/A'] 8 0 384 75 30 89 0 597 511
htp_connp_REQ_LINE /src/libhtp/htp/htp_request.c 1 ['N/A'] 7 0 64 12 5 58 0 510 288
htp_config_register_multipart_parser /src/libhtp/htp/htp_config.c 1 ['N/A'] 8 0 22 6 3 67 0 407 252
htp_mpartp_handle_data /src/libhtp/htp/htp_multipart.c 4 ['N/A', 'N/A', 'size_t', 'int'] 7 0 65 14 6 63 0 378 189
htp_connp_RES_BODY_DETERMINE /src/libhtp/htp/htp_response.c 1 ['N/A'] 6 0 621 130 52 53 0 340 122
htp_parse_request_line_apache_2_2 /src/libhtp/htp/htp_request_apache_2_2.c 1 ['N/A'] 4 0 12 3 2 21 0 178 109
htp_config_register_urlencoded_parser /src/libhtp/htp/htp_config.c 1 ['N/A'] 8 0 23 6 3 56 0 289 76
htp_connp_RES_HEADERS /src/libhtp/htp/htp_response.c 1 ['N/A'] 5 0 685 135 56 31 0 186 68
htp_connp_RES_BODY_CHUNKED_LENGTH /src/libhtp/htp/htp_response.c 1 ['N/A'] 6 0 213 38 16 48 0 550 57
test_run /src/libhtp/test/test.c 4 ['N/A', 'N/A', 'N/A', 'N/A'] 10 0 24 3 2 114 0 850 55

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

Functions statically reachable by fuzzers
68.0%
301 / 442
Cyclomatic complexity statically reachable by fuzzers
77.0%
2641 / 3442

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.

test/fuzz/fuzz_htp.c

Dictionary

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


Fuzzer function priority

Use one of these functions as input to libfuzzer with flag: -focus_function name 

-focus_function=['htp_config_set_server_personality', 'htp_tx_destroy_incomplete', 'htp_req_run_hook_body_data', 'htp_gzip_decompressor_restart', 'htp_tx_finalize', 'htp_connp_req_data', 'htp_connp_res_data', 'LLVMFuzzerTestOneInput']

Runtime coverage analysis

This section shows analysis of runtime coverage data.

For futher technical details on how this section is generated, please see the Glossary .

Complex functions with low coverage

Func name Function total lines Lines covered at runtime percentage covered Reached by fuzzers
htp_config_set_server_personality 93 26 27.95% ['fuzz_htp_c']
htp_tx_req_process_body_data_ex 35 18 51.42% ['fuzz_htp_c']
htp_tx_process_request_headers 133 73 54.88% ['fuzz_htp_c']

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/libhtp/htp/htp_transaction.c ['fuzz_htp_c'] ['fuzz_htp_c']
/src/libhtp/htp/htp_request_generic.c [] []
/src/libhtp/htp/htp_parsers.c [] []
/src/libhtp/htp/bstr.c ['fuzz_htp_c'] ['fuzz_htp_c']
/src/libhtp/htp/htp_base64.c [] []
/src/libhtp/test/test.c ['fuzz_htp_c'] ['fuzz_htp_c']
/src/libhtp/htp/htp_multipart.c ['fuzz_htp_c'] ['fuzz_htp_c']
/src/libhtp/htp/htp_utf8_decoder.c [] []
/src/libhtp/htp/htp_connection_parser.c ['fuzz_htp_c'] ['fuzz_htp_c']
/src/libhtp/htp/htp_request.c ['fuzz_htp_c'] ['fuzz_htp_c']
/src/libhtp/htp/htp_response_generic.c [] []
/src/libhtp/htp/htp_list.c ['fuzz_htp_c'] ['fuzz_htp_c']
/src/libhtp/htp/htp_request_apache_2_2.c [] []
/src/libhtp/htp/htp_table.c ['fuzz_htp_c'] ['fuzz_htp_c']
/src/libhtp/htp/htp_connection.c ['fuzz_htp_c'] ['fuzz_htp_c']
/src/libhtp/htp/htp_response.c ['fuzz_htp_c'] ['fuzz_htp_c']
/src/libhtp/htp/lzma/LzmaDec.c ['fuzz_htp_c'] ['fuzz_htp_c']
/src/libhtp/htp/strlcat.c [] []
/src/libhtp/htp/htp_util.c ['fuzz_htp_c'] ['fuzz_htp_c']
/src/libhtp/test/fuzz/fuzz_htp.c ['fuzz_htp_c'] ['fuzz_htp_c']
/src/libhtp/htp/bstr_builder.c ['fuzz_htp_c'] []
/src/libhtp/htp/htp_content_handlers.c [] []
/src/libhtp/htp/htp_hooks.c ['fuzz_htp_c'] ['fuzz_htp_c']
/src/libhtp/htp/htp_decompressors.c ['fuzz_htp_c'] ['fuzz_htp_c']
/src/libhtp/htp/htp_cookies.c [] []
/src/libhtp/htp/htp_urlencoded.c ['fuzz_htp_c'] ['fuzz_htp_c']
/src/libhtp/htp/htp_config.c ['fuzz_htp_c'] ['fuzz_htp_c']

Directories in report

Directory
/src/libhtp/test/
/src/libhtp/htp/lzma/
/src/libhtp/htp/
/src/libhtp/test/fuzz/

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_htp_c fuzzerLogFile-0-iExUoRpXrj.data fuzzerLogFile-0-iExUoRpXrj.data.yaml fuzz_htp_c.covreport