blobserver/sftp: add SFTP storage target

Fixes perkeep#1111

Change-Id: I4bedfa44241c1e6cc607658c991179ee04f9eb31

Gopkg.toml

@@ -231,7 +231,7 @@ ignored = [
 
 [[constraint]]
   name = "golang.org/x/crypto"
-  revision = "13931e22f9e72ea58bb73048bc752b48c6d4d4ac"
+  revision = "master"
 
 [[constraint]]
   name = "golang.org/x/image"

pkg/blobserver/sftp/Dockerfile.sftp-server

@@ -0,0 +1,36 @@
+# For debugging sftp-server crashes.
+# https://twitter.com/bradfitz/status/994307991712104448
+# https://twitter.com/bradfitz/status/994317057381449728
+
+# docker build -f Dockerfile.sftp-server  -t openssh .
+# docker run -p 1150:115 openssh
+# Then an integration JSON file like:
+#    {"user": "RAWSFTPNOSSH", "dir": ".", "addr": "localhost:1150"}
+
+
+FROM debian:jessie
+
+ENV DEBIAN_FRONTEND noninteractive
+
+RUN apt-get update && apt-get install --no-install-recommends --yes autoconf automake gcc libc6-dev \
+    curl ca-certificates zlib1g-dev libssl-dev make
+RUN apt-get install --no-install-recommends --yes make
+
+# Synology NAS's crashing version; https://twitter.com/bradfitz/status/994317057381449728
+ARG opensshver=6.8p1
+
+WORKDIR /root
+RUN curl -O https://cloudflare.cdn.openbsd.org/pub/OpenBSD/OpenSSH/portable/openssh-$opensshver.tar.gz
+RUN tar -zxvf openssh-$opensshver.tar.gz
+
+WORKDIR openssh-$opensshver
+
+RUN ./configure --without-openssl-header-check
+RUN make
+RUN make install
+
+RUN apt-get install --no-install-recommends --yes inetutils-inetd
+
+RUN mkdir /tmp/sftp-root
+RUN echo "sftp stream tcp nowait  root /usr/local/libexec/sftp-server -e -l DEBUG3 -d /tmp/sftp-root" >> /etc/inetd.conf
+CMD ["/usr/sbin/inetutils-inetd", "-d"]