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: 2025-06-22

Project overview: libhtp

High level conclusions

Reachability and coverage overview

Functions statically reachable by fuzzers
31.0%
138 / 443
Cyclomatic complexity statically reachable by fuzzers
28.0%
963 / 3443
Runtime code coverage of functions
56.0%
246 / 443

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 2366 1011 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 0 102 24.6%
gold [1:9] 1 0.24%
yellow [10:29] 3 0.72%
greenyellow [30:49] 0 0.0%
lawngreen 50+ 308 74.3%
All colors 414 100

Fuzz blockers

The followings are the branches where fuzzer fails to bypass.

Unique non-covered Complexity Unique Reachable Complexities Unique Reachable Functions All non-covered Complexity All Reachable Complexity Function Name Function Callsite Blocked Branch
177 177 4 :

['htp_parse_authorization_basic', 'htp_parse_authorization_bearer', 'bstr_begins_with_c_nocase', 'htp_parse_authorization_digest']

177 177 htp_parse_authorization call site: 00000 /src/libhtp/htp/htp_parsers.c:189
167 631 14 :

['bstr_index_of_c_nocasenorzero', 'bstr_free', 'htp_is_space', 'bstr_cmp_c_nocase', 'htp_table_size', 'free', 'htp_table_clear', 'bstr_index_of_c_nocase', 'htp_log', 'htp_table_get_index', 'bstr_adjust_len', 'htp_parse_content_length', 'bstr_dup_lower', 'htp_table_get_c']

167 801 htp_connp_RES_BODY_DETERMINE call site: 00000 /src/libhtp/htp/htp_response.c:607
150 189 2 :

['htp_log', 'htp_parse_content_length']

150 195 htp_process_request_header_generic call site: 00000 /src/libhtp/htp/htp_request_generic.c:92
150 189 2 :

['htp_log', 'htp_parse_content_length']

150 195 htp_process_response_header_generic call site: 00000 /src/libhtp/htp/htp_response_generic.c:289
100 110 3 :

['htp_parse_single_cookie_v0', 'htp_table_create', '__ctype_b_loc']

100 110 htp_parse_cookies_v0 call site: 00000 /src/libhtp/htp/htp_cookies.c:90
95 107 7 :

['bstr_builder_destroy', 'htp_list_array_size', 'bstr_free', 'free', 'htp_list_array_get', 'htp_list_array_destroy', 'htp_mpart_part_destroy']

95 107 htp_mpartp_destroy call site: 00305 /src/libhtp/htp/htp_multipart.c:945
17 63 6 :

['bstr_builder_destroy', 'bstr_free', 'htp_table_size', 'htp_table_destroy', 'free', 'htp_table_get_index']

17 63 htp_urlenp_destroy call site: 00293 /src/libhtp/htp/htp_urlencoded.c:208
2 2 1 :

['calloc']

12 120 htp_parse_uri call site: 00000 /src/libhtp/htp/htp_util.c:722
2 2 1 :

['__snprintf_chk']

6 28 htp_log call site: 00167 /src/libhtp/htp/htp_util.c:428
0 107 1 :

['htp_tx_destroy_incomplete']

0 107 htp_tx_create call site: 00000 /src/libhtp/htp/htp_transaction.c:101
0 39 1 :

['htp_log']

0 45 htp_process_request_header_generic call site: 00000 /src/libhtp/htp/htp_request_generic.c:123
0 39 1 :

['htp_log']

0 45 htp_process_response_header_generic call site: 00000 /src/libhtp/htp/htp_response_generic.c:324

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 0 407 75 30 89 0 599 513
htp_connp_REQ_LINE /src/libhtp/htp/htp_request.c 1 ['N/A'] 7 0 65 12 5 58 0 510 287
htp_config_register_multipart_parser /src/libhtp/htp/htp_config.c 1 ['N/A'] 8 0 23 6 3 67 0 408 253
htp_mpartp_handle_data /src/libhtp/htp/htp_multipart.c 4 ['N/A', 'N/A', 'size_t', 'int'] 7 0 69 14 6 63 0 379 190
htp_connp_RES_BODY_DETERMINE /src/libhtp/htp/htp_response.c 1 ['N/A'] 6 0 642 130 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 13 3 2 21 0 179 110
htp_config_register_urlencoded_parser /src/libhtp/htp/htp_config.c 1 ['N/A'] 8 0 24 6 3 56 0 289 76
htp_connp_RES_HEADERS /src/libhtp/htp/htp_response.c 1 ['N/A'] 5 0 736 134 56 31 0 186 68
htp_connp_RES_BODY_CHUNKED_LENGTH /src/libhtp/htp/htp_response.c 1 ['N/A'] 6 0 224 38 16 48 0 549 57
test_run /src/libhtp/test/test.c 4 ['N/A', 'N/A', 'N/A', 'N/A'] 10 0 28 3 2 114 0 849 55

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

Functions statically reachable by fuzzers
68.0%
302 / 443
Cyclomatic complexity statically reachable by fuzzers
77.0%
2646 / 3443

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

Directories in report

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

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-0-9ffeNe9NCW.data fuzzerLogFile-0-9ffeNe9NCW.data.yaml fuzz_htp_c.covreport