Compatibility issues with musl on Alpine

[christian-simmen]

Hi Jerry,

I just tried to compile dsc on a Docker Alpine image. It seems to run into an compatibility issue in ip_proto_index.c where getprotobynumber_r is explicitly linked. Unfortunately musl does not support getprotobynumber_r.

Here's a Dockerfile to reproduce:

FROM alpine:3.13
RUN echo 'https://dl-cdn.alpinelinux.org/alpine/edge/testing' >> /etc/apk/repositories \
    && apk add --no-cache --update-cache \
    make \
    musl-dev \
    alpine-sdk \
    libcap libcap-dev \
    libpcap libpcap-dev \
    wget \
    autoconf \
    automake \
    git \
    && apk upgrade

RUN git clone --branch master https://github.com/DNS-OARC/dsc.git dsc \
  && cd dsc \
  && git submodule update --init \
  && ./autogen.sh \
  && ./configure \
  && make \
  && make install

which results in

ip_proto_index.c: In function 'ip_proto_iterator':
ip_proto_index.c:78:5: warning: implicit declaration of function 'getprotobynumber_r'; did you mean 'getprotobynumber'? [-Wimplicit-function-declaration]
   78 |     getprotobynumber_r(next_iter, &proto, buf, sizeof(buf), &p);
      |     ^~~~~~~~~~~~~~~~~~
      |     getprotobynumber

/usr/lib/gcc/x86_64-alpine-linux-musl/10.2.1/../../../../x86_64-alpine-linux-musl/bin/ld: ip_proto_index.o: in function `ip_proto_iterator':
/dsc/src/ip_proto_index.c:78: undefined reference to `getprotobynumber_r'
collect2: error: ld returned 1 exit status
make[3]: *** [Makefile:582: dsc] Error 1

Best,
Christian

[jelu]

This isn't really an issue with Alpine, more an issue with musl which we do not support. If you want support for this then please provide a patch that changes calls only when musl is used.