When downloading a keytab to a file that already exists, merge the new

keytab keys into that file rather than moving aside the old keytab and
creating a new keytab with only the new keys.

Also fix get handling in the client for all types other than keytabs.
This isn't visible yet since the server doesn't yet support other types
of objects.

5 files changed, 140 insertions, 27 deletions

diff --git a/client/error.c b/client/error.c
index e95b284..22e7e5b 100644
--- a/client/error.c
+++ b/client/error.c
@@ -85,7 +85,7 @@ free_error(krb5_context ctx, const char *msg)
 **  Report a Kerberos error and exit.
 */
 void
-die_krb5(krb5_context ctx,  krb5_error_code code, const char *format, ...)
+die_krb5(krb5_context ctx, krb5_error_code code, const char *format, ...)
 {
     const char *k5_msg = NULL;
     char *message;
@@ -93,10 +93,10 @@ die_krb5(krb5_context ctx,  krb5_error_code code, const char *format, ...)
 
     k5_msg = get_error(ctx, code);
     va_start(args, format);
-    if (xasprintf(&message, format, args) < 0)
+    if (xvasprintf(&message, format, args) < 0)
         die("internal error: unable to format error message");
     va_end(args);
-    die("%s: %s\n", message, k5_msg);
+    die("%s: %s", message, k5_msg);
 }
 
 
@@ -104,7 +104,7 @@ die_krb5(krb5_context ctx,  krb5_error_code code, const char *format, ...)
 **  Report a Kerberos error.
 */
 void
-warn_krb5(krb5_context ctx,  krb5_error_code code, const char *format, ...)
+warn_krb5(krb5_context ctx, krb5_error_code code, const char *format, ...)
 {
     const char *k5_msg = NULL;
     char *message;
@@ -112,10 +112,10 @@ warn_krb5(krb5_context ctx,  krb5_error_code code, const char *format, ...)
 
     k5_msg = get_error(ctx, code);
     va_start(args, format);
-    if (xasprintf(&message, format, args) < 0)
+    if (xvasprintf(&message, format, args) < 0)
         die("internal error: unable to format error message");
     va_end(args);
-    warn("%s: %s\n", message, k5_msg);
+    warn("%s: %s", message, k5_msg);
     free(message);
     free_error(ctx, k5_msg);
 }
diff --git a/client/file.c b/client/file.c
index 8e16103..ce25ab5 100644
--- a/client/file.c
+++ b/client/file.c
@@ -3,7 +3,7 @@
 **  File handling for the wallet client.
 **
 **  Written by Russ Allbery <rra@stanford.edu>
-**  Copyright 2007 Board of Trustees, Leland Stanford Jr. University
+**  Copyright 2007, 2008 Board of Trustees, Leland Stanford Jr. University
 **
 **  See LICENSE for licensing terms.
 */
@@ -18,28 +18,40 @@
 
 /*
 **  Given a filename, some data, and a length, write that data to the given
-**  file safely and atomically by creating file.new, writing the data, linking
-**  file to file.bak, and then renaming file.new to file.
+**  file safely, but overwrite any existing file by that name.
 */
 void
-write_file(const char *name, const void *data, size_t length)
+overwrite_file(const char *name, const void *data, size_t length)
 {
     int fd;
     ssize_t status;
-    char *temp, *backup;
 
-    temp = concat(name, ".new", (char *) 0);
-    backup = concat(name, ".bak", (char *) 0);
-    fd = open(temp, O_WRONLY | O_CREAT | O_TRUNC, 0600);
+    fd = open(name, O_WRONLY | O_CREAT | O_TRUNC, 0600);
     if (fd < 0)
-        sysdie("open of %s failed", temp);
+        sysdie("open of %s failed", name);
     status = write(fd, data, length);
     if (status < 0)
-        sysdie("write to %s failed", temp);
+        sysdie("write to %s failed", name);
     else if (status != (ssize_t) length)
-        die("write to %s truncated", temp);
+        die("write to %s truncated", name);
     if (close(fd) < 0)
-        sysdie("close of %s failed (file probably truncated)", temp);
+        sysdie("close of %s failed (file probably truncated)", name);
+}
+
+
+/*
+**  Given a filename, some data, and a length, write that data to the given
+**  file safely and atomically by creating file.new, writing the data, linking
+**  file to file.bak, and then renaming file.new to file.
+*/
+void
+write_file(const char *name, const void *data, size_t length)
+{
+    char *temp, *backup;
+
+    temp = concat(name, ".new", (char *) 0);
+    backup = concat(name, ".bak", (char *) 0);
+    overwrite_file(temp, data, length);
     if (access(name, F_OK) == 0) {
         if (access(backup, F_OK) == 0)
             if (unlink(backup) < 0)
@@ -52,3 +64,41 @@ write_file(const char *name, const void *data, size_t length)
     free(temp);
     free(backup);
 }
+
+
+/*
+**  Given a remctl object, the command prefix, object type, and object name,
+**  and a file (which may be NULL), send a wallet get command and write the
+**  results to the provided file.  If the file is NULL, write the results to
+**  standard output instead.  Returns 0 on success and an exit status on
+**  failure.
+*/
+int
+get_file(struct remctl *r, const char *prefix, const char *type,
+         const char *name, const char *file)
+{
+    const char *command[5];
+    char *data = NULL;
+    size_t length = 0;
+    int status;
+
+    command[0] = prefix;
+    command[1] = "get";
+    command[2] = type;
+    command[3] = name;
+    command[4] = NULL;
+    status = run_command(r, command, &data, &length);
+    if (status != 0)
+        return status;
+    if (data == NULL) {
+        warn("no data returned by wallet server");
+        return 255;
+    }
+    if (file != NULL)
+        write_file(file, data, length);
+    else {
+        if (fwrite(data, length, 1, stdout) != 1)
+            sysdie("cannot write to standard output");
+    }
+    return 0;
+}
diff --git a/client/internal.h b/client/internal.h
index 1dcb608..8595412 100644
--- a/client/internal.h
+++ b/client/internal.h
@@ -37,6 +37,14 @@ BEGIN_DECLS
 int run_command(struct remctl *, const char **command, char **data,
                 size_t *length);
 
+/* Given a remctl object, the type for the wallet interface, object type,
+   object name, and a file (which may be NULL), send a wallet get command and
+   write the results to the provided file.  If the file is NULL, write the
+   results to standard output instead.  Returns 0 on success and an exit
+   status on failure. */
+int get_file(struct remctl *, const char *prefix, const char *type,
+             const char *name, const char *file);
+
 /* Given a remctl object, the Kerberos context, the type for the wallet
    interface, the name of a keytab object, and a file name, call the correct
    wallet commands to download a keytab and write it to that file.  If srvtab
@@ -46,6 +54,10 @@ int get_keytab(struct remctl *, krb5_context, const char *type,
                const char *name, const char *file, const char *srvtab);
 
 /* Given a filename, some data, and a length, write that data to the given
+   file with error checking, overwriting any existing contents. */
+void overwrite_file(const char *name, const void *data, size_t length);
+
+/* Given a filename, some data, and a length, write that data to the given
    file safely and atomically by creating file.new, writing the data, linking
    file to file.bak, and then renaming file.new to file. */
 void write_file(const char *name, const void *data, size_t length);
diff --git a/client/keytab.c b/client/keytab.c
index 7554f50..a3e35ed 100644
--- a/client/keytab.c
+++ b/client/keytab.c
@@ -18,6 +18,55 @@
 
 
 /*
+**  Given keytab data as a pointer to memory and a length and the path of a
+**  second keytab, merge the keys in the memory keytab into the file keytab.
+**  Currently, this doesn't do any cleanup of old kvnos and doesn't handle
+**  duplicate kvnos correctly.  Dies on any error.
+*/
+static void
+merge_keytab(krb5_context ctx, const char *name, const char *data,
+             size_t length)
+{
+    char *tempfile, *oldfile;
+    krb5_keytab old = NULL, temp = NULL;
+    krb5_kt_cursor cursor;
+    krb5_keytab_entry entry;
+    krb5_error_code status;
+
+    tempfile = concat(name, ".new", (char *) 0);
+    oldfile = concat("WRFILE:", name, (char *) 0);
+    overwrite_file(tempfile, data, length);
+    memset(&entry, 0, sizeof(entry));
+    status = krb5_kt_resolve(ctx, oldfile, &old);
+    if (status != 0)
+        die_krb5(ctx, status, "cannot open keytab %s", name);
+    free(oldfile);
+    status = krb5_kt_resolve(ctx, tempfile, &temp);
+    if (status != 0)
+        die_krb5(ctx, status, "cannot open temporary keytab %s", tempfile);
+    status = krb5_kt_start_seq_get(ctx, temp, &cursor);
+    if (status != 0)
+        die_krb5(ctx, status, "cannot read temporary keytab %s", tempfile);
+    while ((status = krb5_kt_next_entry(ctx, temp, &entry, &cursor)) == 0) {
+        status = krb5_kt_add_entry(ctx, old, &entry);
+        if (status != 0)
+            die_krb5(ctx, status, "cannot write to keytab %s", name);
+        krb5_free_keytab_entry_contents(ctx, &entry);
+    }
+    if (status != KRB5_KT_END)
+        die_krb5(ctx, status, "error reading temporary keytab %s", tempfile);
+    krb5_kt_end_seq_get(ctx, temp, &cursor);
+    if (unlink(tempfile) < 0)
+        sysdie("unlink of temporary keytab file %s failed", tempfile);
+    free(tempfile);
+    if (old != NULL)
+        krb5_kt_close(ctx, old);
+    if (temp != NULL)
+        krb5_kt_close(ctx, temp);
+}
+
+
+/*
 **  Configure a given keytab to be synchronized with an AFS kaserver if it
 **  isn't already.  Returns true on success, false on failure.
 */
@@ -79,12 +128,10 @@ get_keytab(struct remctl *r, krb5_context ctx, const char *type,
         warn("no data returned by wallet server");
         return 255;
     }
-    if (file != NULL)
+    if (access(file, F_OK) == 0)
+        merge_keytab(ctx, file, data, length);
+    else
         write_file(file, data, length);
-    else {
-        if (fwrite(data, length, 1, stdout) != 1)
-            sysdie("write to standard output failed");
-    }
     if (srvtab != NULL)
         write_srvtab(ctx, srvtab, name, file);
     return 0;
diff --git a/client/wallet.c b/client/wallet.c
index d48a52c..9dc97c2 100644
--- a/client/wallet.c
+++ b/client/wallet.c
@@ -207,12 +207,16 @@ main(int argc, char *argv[])
     if (!remctl_open(r, options.server, options.port, options.principal))
         die("%s", remctl_error(r));
 
-    /* Most commands, we handle ourselves, but keytab get commands with -f are
-       special. */
-    if (strcmp(argv[0], "get") == 0 && strcmp(argv[1], "keytab") == 0) {
+    /* Most commands, we handle ourselves, but get commands are special and
+       keytab get commands with -f are doubly special. */
+    if (strcmp(argv[0], "get") == 0) {
         if (argc > 3)
             die("too many arguments");
-        status = get_keytab(r, ctx, options.type, argv[2], file, srvtab);
+        if (strcmp(argv[1], "keytab") == 0 && file != NULL) {
+            status = get_keytab(r, ctx, options.type, argv[2], file, srvtab);
+        } else {
+            status = get_file(r, options.type, argv[1], argv[2], file);
+        }
     } else {
         command = xmalloc(sizeof(char *) * (argc + 2));
         command[0] = options.type;