Backport reimplementation of known_hosts completion (bug #848125)

Upstream commit:

commit 71ac42b98c0eba39819fb8478d6443032c6ef6f1
Author: Ville Skyttä <ville.skytta@iki.fi>
Date:   Mon Mar 19 18:58:09 2018 +0200

    _known_hosts_real: Reimplement known hosts file parsing in pure bash

reimplements completion of hostnames from ssh/known_hosts files.  As a
side-effect, it also fixes Debian bug #848125.

Thanks to Vincent Danjean for reporting and to Ville Skyttä for
suggesting the backport.

3 files changed, 105 insertions, 0 deletions

diff --git a/debian/changelog b/debian/changelog
index 168dd1f7..523d5171 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,5 +1,7 @@
 bash-completion (1:2.8-4) UNRELEASED; urgency=medium
 
+  * Allow `+' in (ssh/know_hosts) hostnames.  (Closes: #848125)
+
  -- Gabriel F. T. Gomes <gabriel@inconstante.eti.br>  Sat, 10 Nov 2018 18:07:37 -0200
 
 bash-completion (1:2.8-3) unstable; urgency=medium
diff --git a/debian/patches/10-reimplement-known-hosts-file-parsing.patch b/debian/patches/10-reimplement-known-hosts-file-parsing.patch
new file mode 100644
index 00000000..f7db7ee7
--- /dev/null
+++ b/debian/patches/10-reimplement-known-hosts-file-parsing.patch
@@ -0,0 +1,102 @@
+commit 71ac42b98c0eba39819fb8478d6443032c6ef6f1
+Author: Ville Skyttä <ville.skytta@iki.fi>
+Date:   Mon Mar 19 18:58:09 2018 +0200
+
+    _known_hosts_real: Reimplement known hosts file parsing in pure bash
+
+diff --git a/bash_completion b/bash_completion
+index ca84b01d..98d277bd 100644
+--- a/bash_completion
++++ b/bash_completion
+@@ -1482,9 +1482,9 @@ _included_ssh_config_files()
+ # Return: Completions, starting with CWORD, are added to COMPREPLY[]
+ _known_hosts_real()
+ {
+-    local configfile flag prefix
+-    local cur curd awkcur user suffix aliases i host ipv4 ipv6
+-    local -a kh khd config
++    local configfile flag prefix OIFS=$IFS
++    local cur user suffix aliases i host ipv4 ipv6
++    local -a kh tmpkh khd config
+ 
+     # TODO remove trailing %foo from entries
+ 
+@@ -1523,8 +1523,7 @@ _known_hosts_real()
+ 
+     # Known hosts files from configs
+     if [[ ${#config[@]} -gt 0 ]]; then
+-        local OIFS=$IFS IFS=$'\n' j
+-        local -a tmpkh
++        local IFS=$'\n' j
+         # expand paths (if present) to global and user known hosts files
+         # TODO(?): try to make known hosts files with more than one consecutive
+         #          spaces in their name work (watch out for ~ expansion
+@@ -1561,35 +1560,31 @@ _known_hosts_real()
+ 
+     # If we have known_hosts files to use
+     if [[ ${#kh[@]} -gt 0 || ${#khd[@]} -gt 0 ]]; then
+-        # Escape slashes and dots in paths for awk
+-        awkcur=${cur//\//\\\/}
+-        awkcur=${awkcur//\./\\\.}
+-        curd=$awkcur
+-
+-        if [[ "$awkcur" == [0-9]*[.:]* ]]; then
+-            # Digits followed by a dot or a colon - just search for that
+-            awkcur="^$awkcur[.:]*"
+-        elif [[ "$awkcur" == [0-9]* ]]; then
+-            # Digits followed by no dot or colon - search for digits followed
+-            # by a dot or a colon
+-            awkcur="^$awkcur.*[.:]"
+-        elif [[ -z $awkcur ]]; then
+-            # A blank - search for a dot, a colon, or an alpha character
+-            awkcur="[a-z.:]"
+-        else
+-            awkcur="^$awkcur"
+-        fi
+-
+         if [[ ${#kh[@]} -gt 0 ]]; then
+-            # FS needs to look for a comma separated list
+-            COMPREPLY+=( $( awk 'BEGIN {FS=","}
+-            /^\s*[^|\#]/ {
+-            sub("^@[^ ]+ +", ""); \
+-            sub(" .*$", ""); \
+-            for (i=1; i<=NF; ++i) { \
+-            sub("^\\[", "", $i); sub("\\](:[0-9]+)?$", "", $i); \
+-            if ($i !~ /[*?]/ && $i ~ /'"$awkcur"'/) {print $i} \
+-            }}' "${kh[@]}" 2>/dev/null ) )
++            # https://man.openbsd.org/sshd.8#SSH_KNOWN_HOSTS_FILE_FORMAT
++            for i in "${kh[@]}"; do
++                while read -ra tmpkh; do
++                    set -- "${tmpkh[@]}"
++                    # Skip entries starting with | (hashed) and # (comment)
++                    [[ $1 == [\|\#]* ]] && continue
++                    # Ignore leading @foo (markers)
++                    [[ $1 == @* ]] && shift
++                    # Split entry on commas
++                    local IFS=,
++                    for host in $1; do
++                        # Skip hosts containing wildcards
++                        [[ $host == *[*?]* ]] && continue
++                        # Remove leading [
++                        host="${host#[}"
++                        # Remove trailing ] + optional :port
++                        host="${host%]?(:+([0-9]))}"
++                        # Add host to candidates
++                        COMPREPLY+=( $host )
++                    done
++                    IFS=$OIFS
++                done < "$i"
++            done
++            COMPREPLY=( $( compgen -W '${COMPREPLY[@]}' -- "$cur" ) )
+         fi
+         if [[ ${#khd[@]} -gt 0 ]]; then
+             # Needs to look for files called
+@@ -1597,7 +1592,7 @@ _known_hosts_real()
+             # dont fork any processes, because in a cluster environment,
+             # there can be hundreds of hostkeys
+             for i in "${khd[@]}" ; do
+-                if [[ "$i" == *key_22_$curd*.pub && -r "$i" ]]; then
++                if [[ "$i" == *key_22_$cur*.pub && -r "$i" ]]; then
+                     host=${i/#*key_22_/}
+                     host=${host/%.pub/}
+                     COMPREPLY+=( $host )
diff --git a/debian/patches/series b/debian/patches/series
index c5cebc15..badbeee3 100644
--- a/debian/patches/series
+++ b/debian/patches/series
@@ -8,4 +8,5 @@
 07-dpkg_support_raw-extract_vextract.patch
 08-completion-for-cvs-log.patch
 09-backport-to-fix-wildcard-completion.patch
+10-reimplement-known-hosts-file-parsing.patch
 99-use-install-data-hook.patch