set git proxies

git_proxy.sh

# Set a git proxy for the SSH a git protocols in the current shell.
#
# Note that for SSH you can also set the Proxycommand in the ~/.config/ssh
# file, which might be more convenient than setting that in each shell 
#
# Host gh
#     User git
#     Hostname github.com
#     Port 22
#     IdentityFile ~/.ssh/my_key
#     Proxycommand socat - PROXY:myproxy:%h:%p,proxyport=8000,
#
# References:
#
# http://gitolite.com/git-over-proxy.html
# https://stackoverflow.com/a/28527476/1836144


set_git_proxy() {
    # usage:
    #
    #   set_git_proxy <yourproxy>
    #
    local proxy=${1}
    local git_proxy_wrapper=/tmp/git_proxy_wrapper.sh
    local git_ssh_proxy_wrapper=/tmp/git_ssh_proxy_wrapper.sh

    # Proxy  the git protocol
    rm -f ${git_proxy_wrapper}
    cat > ${git_proxy_wrapper} << EOF
#!/bin/sh
set -x
socat - PROXY:${proxy%:*}:\$1:\$2,proxyport=${proxy#*:}
EOF
    chmod u+x ${git_proxy_wrapper}
    export GIT_PROXY_COMMAND=${git_proxy_wrapper}

    # Proxy for the SSH protocol
    rm -f ${git_ssh_proxy_wrapper}
    cat > ${git_ssh_proxy_wrapper} << EOF
#!/bin/sh
set -x
ssh -o ProxyCommand='socat - PROXY:${proxy%:*}:%h:%p,proxyport=${proxy#*:}' "\$@"
EOF
    chmod u+x ${git_ssh_proxy_wrapper}
    export GIT_SSH=${git_proxy_wrapper}

    # Since git 2.3 we can use the GIT_SSH_COMMAND instead. It takes precedence over GIT_SSH.
    # shellcheck disable=SC2089
    GIT_SSH_COMMAND="ssh -o Proxycommand='socat - PROXY:${proxy%:*}:%h:%p,proxyport=${proxy#*:}'"
    # shellcheck disable=SC2090
    export GIT_SSH_COMMAND
}

unset_git_proxy() {
    unset GIT_SSH
    unset GIT_SSH_COMMAND
    unset GIT_PROXY_COMMAND
    rm -f /tmp/git_proxy_wrapper.sh /tmp/git_ssh_proxy_wrapper.sh
}