Generate a Repository ID and verify it in the manifest (REPO FORMAT CHANGE)

This is a simplification and defends at someone maliciously switching
around different sign+encrypted manifest files of the same user. This
way we verify the repository we read is the repository we want.

Repo ID is not secret. Only requirement is that the same user does not
generate the same repo id more than onece.

diff --git a/git-remote-gcrypt b/git-remote-gcrypt
index cb78ca3e919a92efa2ce2ad4d1dd36f027164391..7ab505e985fb5dcbe65c23459044931c60489596 100755 (executable)
--- a/git-remote-gcrypt
+++ b/git-remote-gcrypt
@@ -13,7 +13,7 @@ DID_FIND_REPO=  # yes for connected, no for no repo
 LOCALDIR="${GIT_DIR:-.git}/remote-gcrypt"
 export GITCEPTION="$GITCEPTION+" # Reuse $GREF except when stacked
 GREF="refs/gcrypt/gitception$GITCEPTION"
-MANIFESTFILE=5e4a937219be20f8a9a16ae7b35a83db0c16ce501d27b231dbad6586
+REPOID=
 PACKPFX="pack :SHA224:"
 
 isurl() { test -z "${2%%$1://*}" ; }
@@ -200,6 +200,7 @@ xgrep() { command grep "$@" || : ; }
 sort_C() { LC_ALL=C command sort "$@"; }
 tac() { sed '1!G;h;$!d'; }
 echo_info() { echo "gcrypt:" "$@" >&2; }
+echo_die() { echo_info "$@" ; exit 1; }
 
 check_recipients()
 {
@@ -219,10 +220,25 @@ check_recipients()
 
 make_new_repo()
 {
+       local URLID=
+       local FIXCONFIG=
        echo_info "Setting up new repository at $URL"
        PUTREPO "$URL"
-       echo_info "Generating master key"
        MASTERKEY="$(genkey)"
+
+       # We need a relatively short ID for URL+REPO
+       # The manifest will be stored at SHA224(URLID)
+       # Needed assumption: the same user should have no duplicate URLID
+       # For now, we use 20 random hex digits (80 bits), can be increased
+       URLID=$(printf "%.20s" "$(genkey | pack_hash)")
+       REPOID=$(printf "%s" "$URLID" | pack_hash)
+       echo_info "Repository ID is" "$URLID"
+       [ "${NAME#gcrypt::}" != "$URL" ] && {
+               git config "remote.$NAME.url" "gcrypt::$URL/G/$URLID"
+               FIXCONFIG=1
+       } || :
+       echo_info "Repository URL is" "gcrypt::$URL/G/$URLID"
+       [ -n "$FIXCONFIG" ] && echo_info "(configuration for $NAME updated)" ||:
 }
 
 
@@ -234,6 +250,8 @@ read_config()
 ensure_connected()
 {
        local MANIFEST
+       local RCVREPOID
+       local URLID
 
        if [ -n "$DID_FIND_REPO" ]
        then
@@ -242,9 +260,17 @@ ensure_connected()
        DID_FIND_REPO=no
        read_config
 
+       # split out REPOID from URL
+       URLID=${URL##*/G/}
+       [ "$URLID" = "$URL" ] && URLID= && return 0 || :
+
+       URL=${URL%/G/"$URLID"}
+       REPOID=$(printf "%s" "$URLID" | pack_hash)
+
        TMPMANIFEST_ENC="$LOCALDIR/manifest.$$"
        trap 'rm -f "$TMPMANIFEST_ENC"' EXIT
-       GET "$URL" "$MANIFESTFILE" 2>/dev/null > "$TMPMANIFEST_ENC" || return 0
+       GET "$URL" "$REPOID" 2>/dev/null > "$TMPMANIFEST_ENC" ||
+               echo_die "Repository not found: $URLID at $URL"
 
        DID_FIND_REPO=yes
        echo_info "Decrypting manifest"
@@ -261,6 +287,8 @@ ensure_connected()
        MASTERKEY=$(printf "%s\n" "$MANIFEST" | head -n 1)
        BRANCHLIST=$(printf "%s\n" "$MANIFEST" | xgrep -E '^[0-9a-f]{40} ')
        PACKLIST=$(printf "%s\n" "$MANIFEST" | xgrep "^$PACKPFX")
+       RCVREPOID=$(printf "%s\n" "$MANIFEST" | xgrep "^repo ")
+       [ "repo $REPOID" = "$RCVREPOID" ] || echo_die "Repository id mismatch!"
 }
 
 do_capabilities()
@@ -325,8 +353,7 @@ do_fetch()
                RCVID="$(GET "$URL" "$PACK" | tee "$TMPPACK_ENCRYPTED" | pack_hash)"
                if [ "$RCVID" != "$PACK" ]
                then
-                       echo_info "Packfile $PACK does not match digest!"
-                       exit 1
+                       echo_die "Packfile $PACK does not match digest!"
                fi
                DECRYPT < "$TMPPACK_ENCRYPTED" |
                        git index-pack -v --stdin >/dev/null
@@ -410,9 +437,9 @@ do_push()
        TMPMANIFEST_ENC="$LOCALDIR/manifest.$$"
        trap 'rm -f "$TMPMANIFEST_ENC"' EXIT
 
-       printf "%s\n%s\n%s\n" "$MASTERKEY" "$BRANCHLIST" "$PACKLIST" |
-               PRIVENCRYPT "$RECIPIENTS" > "$TMPMANIFEST_ENC"
-       PUT "$URL" "$MANIFESTFILE" < "$TMPMANIFEST_ENC"
+       printf "%s\n%s\n%s\n%s\n" "$MASTERKEY" "$BRANCHLIST" "$PACKLIST" \
+               "repo $REPOID" | PRIVENCRYPT "$RECIPIENTS" > "$TMPMANIFEST_ENC"
+       PUT "$URL" "$REPOID" < "$TMPMANIFEST_ENC"
 
        PUT_FINAL "$URL"
 
@@ -439,8 +466,8 @@ do_push()
 NAME=$1
 URL=$2
 ( isurl ssh "$URL" || isurl sftp "$URL" ||
-       isurl gitception "$URL" || test -z ${URL##/*} ) || {
-       echo_info "Supported URLs: gitception://<giturl>, Absolute path, sftp://, ssh://" && exit 1 ; }
+       isurl gitception "$URL" || test -z ${URL##/*} ) ||
+       echo_die "Supported URLs: gitception://<giturl>, Absolute path, sftp://, ssh://"
 
 mkdir -p "$LOCALDIR"
 
@@ -486,8 +513,7 @@ do
                do_push "$PUSH_ARGS"
                ;;
        ?*)
-               echo_info "Unknown input!"
-               exit 1
+               echo_die "Unknown input!"
                ;;
        *)
                #echo_info "Blank line, we are done"