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Accept UUID.local hostnames #4

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Accept UUID.local hostnames #4

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37 changes: 31 additions & 6 deletions ssh-uuid.sh
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Original file line number Diff line number Diff line change
Expand Up @@ -169,6 +169,7 @@ function parse_args {
local args=("$@")
local nargs=${#args[@]}
local i
SSUU_PROXY=1
SSUU_USER=''
SSUU_OPT_ARGS=()
SSUU_POS_ARGS=()
Expand All @@ -184,20 +185,28 @@ function parse_args {
# Is arg a UUID.balena hostname specification?
# For ssh:
# '[user@]UUID.balena'
# '[user@]UUID.local'
# 'ssh://[user@]UUID.balena[:port]'
# 'ssh://[user@]UUID.local[:port]'
# For scp:
# '[user@]UUID.balena:'
# '[user@]UUID.local:'
# 'scp://[user@]UUID.balena[:port][/path]'
# 'scp://[user@]UUID.local[:port][/path]'
# where UUID is a hexadecimal number with exactly 32 or 62 characters,
# where 62 is not typo meant to read 64, it really is 62.
# where 62 is not typo meant to read 64, it really is 62. 7-character
# abbreviated UUIDs are also accepted for local-mode devices.
if [[ "${SSUU_SCP}" = 0 &&
"${arg}" =~ ^(ssh://)?((.+)@)?([[:xdigit:]]{32}|[[:xdigit:]]{62})\.balena(:[0-9]+)?$
"${arg}" =~ ^(ssh://)?((.+)@)?([[:xdigit:]]{7}|[[:xdigit:]]{32}|[[:xdigit:]]{62})\.(balena|local)(:[0-9]+)?$
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@pdcastro pdcastro Jun 14, 2024

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In a previous comment, I asked you to update the README file to clarify that 7-character UUIDs can be used with .local hostnames. However, hang on — I’ve thought of something. For a remote device reachable through the Balena cloud proxy server, the UUID has a special meaning as the identifier of the device in the cloud. Therefore, a regex ensuring a hexadecimal string of a certain length makes sense. However, for a .local hostname like abc1234.local (7-char UUID), the UUID is merely the device’s hostname discoverable through mDNS / Ahavi and configurable through the device’s config.json file. In this case, abc1234.local (7-char hex) is just as good as foo.local (if config.json specified "hostname": "foo"), and a regex requiring a 7-char hex string would be unnecessarily restrictive.

Does that make sense? So the code could / should be changed to simply check for a .local hostname suffix, in which case any string should be allowed as the hostname prefix. Then the README could be updated along the following lines:

Before:

The device's ssh/scp hostname has the format '<device-UUID>.balena', using the device's
-full UUID (not a shortened form).

After:

The device’s ssh/scp hostname should have one of the following formats:

  • '<device-UUID>.balena' - Remote devices reachable through Balena’s cloud proxy server.
  • '<hostname>.local' - Devices on the same local network as the client.

For remote devices, <device-UUID> must be the device’s “full” UUID (32 or 62 characters long). For local devices, <hostname> is the device’s hostname configured in its config.json file — by default, it is the device’s 7-character short UUID.

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@pdcastro pdcastro Jun 14, 2024

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Also, in this PR’s initial approach, abc1234.balena would not fail the regex check, but it should fail the regex check in order to alert the user of a hostname problem.

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@spinda spinda Jun 15, 2024

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Sure thing! That sounds like a very reasonable approach.

]]; then
SSUU_USER="${BASH_REMATCH[3]}"
SSUU_POS_ARGS=("${args[@]:i}")
if [[ "${BASH_REMATCH[5]}" == "local" ]]; then
SSUU_PROXY=0
fi
break
elif [[ "${SSUU_SCP}" = 1 &&
"${arg}" =~ ^scp://((.+)@)?([[:xdigit:]]{32}|[[:xdigit:]]{62})\.balena(:[0-9]+)?(/.*)?$
"${arg}" =~ ^scp://((.+)@)?([[:xdigit:]]{7}|[[:xdigit:]]{32}|[[:xdigit:]]{62})\.(balena|local)(:[0-9]+)?(/.*)?$
]]; then
SSUU_USER="${BASH_REMATCH[2]}"
if [ -z "${SSUU_USER}" ] && [ -n "${BALENA_USERNAME}" ]; then
Expand All @@ -206,9 +215,12 @@ function parse_args {
args[i]="${arg}"
fi
SSUU_POS_ARGS=("${args[@]:i}")
if [[ "${BASH_REMATCH[4]}" == "local" ]]; then
SSUU_PROXY=0
fi
break
elif [[ "${SSUU_SCP}" = 1 &&
"${arg}" =~ ^((.+)@)?([[:xdigit:]]{32}|[[:xdigit:]]{62})\.balena:.*$
"${arg}" =~ ^((.+)@)?([[:xdigit:]]{7}|[[:xdigit:]]{32}|[[:xdigit:]]{62})\.(balena|local):.*$
]]; then
SSUU_USER="${BASH_REMATCH[2]}"
if [ -z "${SSUU_USER}" ] && [ -n "${BALENA_USERNAME}" ]; then
Expand All @@ -217,6 +229,9 @@ function parse_args {
args[i]="${arg}"
fi
SSUU_POS_ARGS=("${args[@]:i}")
if [[ "${BASH_REMATCH[4]}" == "local" ]]; then
SSUU_PROXY=0
fi
break
fi
if [ "${arg:0:1}" = '-' ] && [ "${arg:1:1}" != '-' ]; then
Expand Down Expand Up @@ -264,12 +279,17 @@ function run_ssh {
l_arg=('-l' "${BALENA_USERNAME}")
fi
opt_args=(
-o "ProxyCommand='$0' do_proxy %h %p"
-p 22222
"${l_arg[@]}"
"${t_arg[@]}"
"${opt_args[@]}"
)
if [[ "${SSUU_PROXY}" == 1 ]]; then
opt_args=(
-o "ProxyCommand='$0' do_proxy %h %p"
"${opt_args[@]}"
)
fi
set +e
[ -n "${DEBUG}" ] && set -x
# shellcheck disable=SC2029
Expand Down Expand Up @@ -341,10 +361,15 @@ function run_scp {
fi
args=(
-P 22222
-o "ProxyCommand='$0' do_proxy %h %p"
"${SSUU_OPT_ARGS[@]}"
"${SSUU_POS_ARGS[@]}"
)
if [[ "${SSUU_PROXY}" == 1 ]]; then
args=(
-o "ProxyCommand='$0' do_proxy %h %p"
"${args[@]}"
)
fi
set +e
[ -n "${DEBUG}" ] && set -x
scp "${args[@]}"
Expand Down