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

Table of contents

Project overview: coturn
High level conclusions
Reachability and coverage overview
Fuzzers overview
Project functions overview
Fuzzer details
Fuzzer: FuzzStun
Call tree
Fuzz blockers
Runtime coverage analysis
Files reached
Fuzzer: FuzzStunClient
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
/src/coturn/fuzzing/FuzzStun.c
Dictionary
Fuzzer function priority
/src/coturn/fuzzing/FuzzStunClient.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: 2025-07-02

Project overview: coturn

High level conclusions

Reachability and coverage overview

Functions statically reachable by fuzzers
14.0%
27 / 187
Cyclomatic complexity statically reachable by fuzzers
14.0%
130 / 925
Runtime code coverage of functions
6.0%
11 / 187

Fuzzers overview

Fuzzer Fuzzer filename Functions Reached Functions unreached Fuzzer depth Files reached Basic blocks reached Cyclomatic complexity Details
FuzzStun /src/coturn/fuzzing/FuzzStun.c 40 161 6 2 240 144 FuzzStun.c
FuzzStunClient /src/coturn/fuzzing/FuzzStunClient.c 14 226 4 3 120 58 FuzzStunClient.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: FuzzStun

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 86 100.%
gold [1:9] 0 0.0%
yellow [10:29] 0 0.0%
greenyellow [30:49] 0 0.0%
lawngreen 50+ 0 0.0%
All colors 86 100

Fuzz blockers

The following nodes represent call sites where fuzz blockers occur.

Amount of callsites blocked Calltree index Parent function Callsite Largest blocked function
85 0 EP call site: 00000 stun_check_message_integrity_str

Runtime coverage analysis

Covered functions
0
Functions that are reachable but not covered
40
Reachable functions
40
Percentage of reachable functions covered
0.0%
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.
Function name source code lines source lines hit percentage hit

Files reached

filename functions hit
/src/coturn/fuzzing/FuzzStun.c 1
client/ns_turn_msg.c 18

Fuzzer: FuzzStunClient

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 0 0.0%
gold [1:9] 0 0.0%
yellow [10:29] 2 8.69%
greenyellow [30:49] 5 21.7%
lawngreen 50+ 16 69.5%
All colors 23 100

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
0 0 None 0 0 stun_is_command_message call site: 00001 /src/coturn/src/apps/common/stun_buffer.c:81
0 0 None 0 0 stun_get_method_str call site: 00020 /src/coturn/src/client/ns_turn_msg.c:374
0 0 None 0 0 stun_get_msg_type_str call site: 00010 /src/coturn/src/client/ns_turn_msg.c:384
0 0 None 0 0 stun_is_success_response_str call site: 00015 /src/coturn/src/client/ns_turn_msg.c:471
0 0 None 0 0 stun_is_response_str call site: 00008 /src/coturn/src/client/ns_turn_msg.c:562

Runtime coverage analysis

Covered functions
12
Functions that are reachable but not covered
2
Reachable functions
14
Percentage of reachable functions covered
85.71%
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.
Function name source code lines source lines hit percentage hit

Files reached

filename functions hit
/src/coturn/fuzzing/FuzzStunClient.c 1
apps/common/stun_buffer.c 4
client/ns_turn_msg.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
stun_set_binding_response /src/coturn/src/apps/common/stun_buffer.c 5 ['N/A', 'N/A', 'N/A', 'int', 'N/A'] 8 0 36 3 2 39 0 159 142
encode_oauth_token /src/coturn/src/client/ns_turn_msg.c 5 ['N/A', 'N/A', 'N/A', 'N/A', 'N/A'] 4 0 94 20 5 22 0 75 62
stun_get_message_len_str /src/coturn/src/client/ns_turn_msg.c 4 ['N/A', 'size_t', 'int', 'N/A'] 4 0 284 51 20 9 0 60 54
convert_oauth_key_data /src/coturn/src/client/ns_turn_msg.c 4 ['N/A', 'N/A', 'N/A', 'size_t'] 1 0 352 47 17 10 0 57 51
make_ioa_addr_from_full_string /src/coturn/src/client/ns_turn_ioaddr.c 3 ['N/A', 'int', 'N/A'] 2 0 78 12 5 13 0 57 47
stun_attr_get_first_addr /src/coturn/src/apps/common/stun_buffer.c 4 ['N/A', 'short', 'N/A', 'N/A'] 5 0 33 3 2 23 0 107 47

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

Functions statically reachable by fuzzers
45.0%
84 / 187
Cyclomatic complexity statically reachable by fuzzers
52.0%
483 / 925

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.

/src/coturn/fuzzing/FuzzStun.c

Dictionary

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


/src/coturn/fuzzing/FuzzStunClient.c

Dictionary

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


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

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/coturn/fuzzing/FuzzStunClient.c ['FuzzStunClient'] ['FuzzStunClient']
/src/coturn/src/client/ns_turn_msg_addr.c [] []
/src/coturn/src/ns_turn_defs.h [] []
/src/coturn/src/client/ns_turn_msg.c ['FuzzStun', 'FuzzStunClient'] ['FuzzStunClient']
/src/coturn/src/client/ns_turn_ioaddr.c [] []
/src/coturn/fuzzing/FuzzStun.c ['FuzzStun'] []
/src/coturn/src/apps/common/stun_buffer.c ['FuzzStunClient'] ['FuzzStunClient']

Directories in report

Directory
/src/coturn/fuzzing/
/src/coturn/src/
/src/coturn/src/client/
/src/coturn/src/apps/common/

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
FuzzStun fuzzerLogFile-0-RXCuNKZb45.data fuzzerLogFile-0-RXCuNKZb45.data.yaml FuzzStun.covreport
FuzzStunClient fuzzerLogFile-0-tZz2JAnNuA.data fuzzerLogFile-0-tZz2JAnNuA.data.yaml FuzzStunClient.covreport