Alternative location for liboprf

[v-p-b]

Currently the Makefile allows specifying the location of the headers of OPRF dependency:

https://github.com/stef/libopaque/blob/a4209e3319718d1c72b9d1c2147ecd03a5e2ff97/src/makefile#L24-L27

However, no logic is implemented to locate the corresponding library files - I would assume that if headers are not in system default directories, neither will be the libs.

Solving static linking seems to be an easy extension of LIBS, but somehow dynamic linking gets involved (looking for liboprf.so) and I couldn't resolve this one yet:

gcc -march=native -Wall -O2 -g -fstack-protector-strong -D_FORTIFY_SOURCE=2 -fasynchronous-unwind-tables -fpic -fstack-clash-protection -fcf-protection=full -Werror=format-security -Werror=implicit-function-declaration -Warray-bounds -fsanitize=bounds -fsanitize-undefined-trap-on-error -fsanitize=bounds -fsanitize-undefined-trap-on-error -Wl,-z,defs -Wl,-z,relro -ftrapv -Wl,-z,noexecstack -std=c99  -Iaux_ -I. -o utils/opaque utils/main.c -L. -lopaque -lsodium
/usr/bin/ld: warning: liboprf.so, needed by ./libopaque.so, not found (try using -rpath or -rpath-link)
/usr/bin/ld: ./libopaque.so: undefined reference to `oprf_Unblind'
/usr/bin/ld: ./libopaque.so: undefined reference to `expand_message_xmd'
/usr/bin/ld: ./libopaque.so: undefined reference to `oprf_KeyGen'
/usr/bin/ld: ./libopaque.so: undefined reference to `oprf_Blind'
/usr/bin/ld: ./libopaque.so: undefined reference to `oprf_Finalize'
/usr/bin/ld: ./libopaque.so: undefined reference to `voprf_hash_to_group'
/usr/bin/ld: ./libopaque.so: undefined reference to `oprf_Evaluate'
collect2: error: ld returned 1 exit status
make: *** [makefile:86: utils/opaque] Error 1

[stef]

-L$(OPRFHOME) should work. no? or OPRFLIBS?=$(OPRFHOME) or so

[stef]

if you agree that this change does this fix the problem please close the issue!

thank you very much!

[stef]

fixing the fix: https://github.com/stef/libopaque/commit/65b15eaf4114f75c2d55b54cdbb6de85a314fd5e

[v-p-b]

same error unfortunately

[stef]

is that on a glibc system or on a musl system? if it is glibc, then we need to call ldconfig.

[stef]

ah, i get it, it's not linked directly, but only as a dep to libopaque. hmmmm

[stef]

i solved the wrong problem. /o\

[stef]

let's see if this one gets through CI and you...

[v-p-b]

The latest commit had a syntax issue, but showed me the way to fix, so I created a PR.