[Debian-iot-maintainers] Bug#1138432: mosquitto: FTBFS with openssl 4.0

[Sebastian Andrzej Siewior]

Package: mosquitto
Version: 2.0.22-5
Severity: normal
Tags: sid
control: affects -1 src:openssl
User: pkg-openssl-devel at lists.alioth.debian.org
Usertags: openssl-4.0

OpenSSL 4.0 is in experimental. This package fails to build against it:

| cd /build/reproducible-path/mosquitto-2.0.22/obj-x86_64-linux-gnu/lib && /usr/bin/cc -DCMAKE -DOPENSSL_API_COMPAT=0x10100000L -DVERSION=\"2.0.22\" -DWITH_DLT -DWITH_EC -DWITH_SOCKS -DWITH_THREADING -DWITH_TLS -DWITH_TLS_PSK -DWITH_UNIX_SOCKETS -Dlibmosquitto_EXPORTS -I/build/reproducible-path/mosquitto-2.0.22 -I/build/reproducible-path/mosquitto-2.0.22/lib -I/build/reproducible-path/mosquitto-2.0.22/include -g -O2 -Werror=implicit-function-declaration -ffile-prefix-map=/build/reproducible-path/mosquitto-2.0.22=. -fstack-protector-strong -fstack-clash-protection -Wformat -Werror=format-security -fcf-protection -Wdate-time -D_FORTIFY_SOURCE=2 -fPIC -MD -MT lib/CMakeFiles/libmosquitto.dir/tls_mosq.c.o -MF CMakeFiles/libmosquitto.dir/tls_mosq.c.o.d -o CMakeFiles/libmosquitto.dir/tls_mosq.c.o -c /build/reproducible-path/mosquitto-2.0.22/lib/tls_mosq.c
| /build/reproducible-path/mosquitto-2.0.22/lib/tls_mosq.c: In function ‘mosquitto__verify_certificate_hostname’:
| /build/reproducible-path/mosquitto-2.0.22/lib/tls_mosq.c:171:53: error: invalid use of incomplete typedef ‘ASN1_OCTET_STRING’ {aka ‘struct asn1_string_st’}
|   171 |                                 if(nval->d.iPAddress->length == 4 && ipv4_ok){
|       |                                                     ^~
| /build/reproducible-path/mosquitto-2.0.22/lib/tls_mosq.c:176:59: error: invalid use of incomplete typedef ‘ASN1_OCTET_STRING’ {aka ‘struct asn1_string_st’}
|   176 |                                 }else if(nval->d.iPAddress->length == 16 && ipv6_ok){
|       |                                                           ^~
| /build/reproducible-path/mosquitto-2.0.22/lib/tls_mosq.c:191:14: warning: assignment discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]
|   191 |         subj = X509_get_subject_name(cert);
|       |              ^
| make[3]: *** [lib/CMakeFiles/libmosquitto.dir/build.make:614: lib/CMakeFiles/libmosquitto.dir/tls_mosq.c.o] Error 1

Full buildlog
 	https://breakpoint.cc/openssl-rebuild/logs-4/attempted/mosquitto_2.0.22-5_amd64-2026-04-19T13:50:17Z

Sebastian