[src/trunk]: src/distrib/utils/sysinst Make url_decode() return a pointer to ...

[dsl <dsl%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/a2697d9f1c8f
branches:  trunk
changeset: 571154:a2697d9f1c8f
user:      dsl <dsl%NetBSD.org@localhost>
date:      Thu Nov 11 21:36:23 2004 +0000

description:
Make url_decode() return a pointer to the end of the string, and take a
char * limit (not a length) to simplify buffer overrun avoidance.

diffstat:

 distrib/utils/sysinst/net.c |  49 +++++++++++++++++++++-----------------------
 1 files changed, 23 insertions(+), 26 deletions(-)

diffs (104 lines):

diff -r 4e4400e85f96 -r a2697d9f1c8f distrib/utils/sysinst/net.c
--- a/distrib/utils/sysinst/net.c       Thu Nov 11 21:24:40 2004 +0000
+++ b/distrib/utils/sysinst/net.c       Thu Nov 11 21:36:23 2004 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: net.c,v 1.103 2004/11/11 21:24:41 dsl Exp $    */
+/*     $NetBSD: net.c,v 1.104 2004/11/11 21:36:23 dsl Exp $    */
 
 /*
  * Copyright 1997 Piermont Information Systems Inc.
@@ -86,7 +86,7 @@
 
 /* URL encode unsafe characters.  */
 
-static char *url_encode (char *dst, const char *src, size_t len,
+static char *url_encode (char *dst, const char *src, const char *ep,
                                const char *safe_chars,
                                int encode_leading_slash);
 
@@ -172,35 +172,35 @@
 #define RFC1738_SAFE_LESS_SHELL_PLUS_SLASH     "-_.+!,/"
 
 static char *
-url_encode(char *dst, const char *src, size_t len,
+url_encode(char *dst, const char *src, const char *ep,
        const char *safe_chars, int encode_leading_slash)
 {
-       char *p = dst;
-       char *ep = dst + len;
        int ch;
 
-       for (; ep - p > 1; src++) {
+       ep--;
+
+       for (; dst < ep; src++) {
                ch = *src & 0xff;
                if (ch == 0)
                        break;
                if (safe_chars != NULL &&
                    (ch != '/' || !encode_leading_slash) &&
                    (isalnum(ch) || strchr(safe_chars, ch))) {
-                       *p++ = ch;
+                       *dst++ = ch;
                } else {
                        /* encode this char */
-                       if (ep - p < 3)
+                       if (ep - dst < 3)
                                break;
-                       snprintf(p, ep - p, "%%%02X", ch);
-                       p += 3;
+                       snprintf(dst, ep - dst, "%%%02X", ch);
+                       dst += 3;
                }
                encode_leading_slash = 0;
        }
-done:
-       *p = '\0';
+       *dst = '\0';
        return dst;
 }
 
+
 static const char *ignored_if_names[] = {
        "eon",                  /* netiso */
        "gre",                  /* net */
@@ -804,28 +804,25 @@
                        ftp_user_encoded[0] = 0;
                } else {
                        ftp_opt = "";
-                       url_encode(ftp_user_encoded, ftp_user,
-                                   sizeof ftp_user_encoded / 2 - 1,
-                                   RFC1738_SAFE_LESS_SHELL, 0),
-                       cp = strchr(ftp_user_encoded, 0);
+                       cp = url_encode(ftp_user_encoded, ftp_user,
+                               ftp_user_encoded + sizeof ftp_user_encoded - 1,
+                               RFC1738_SAFE_LESS_SHELL, 0);
                        *cp++ = ':';
-                       url_encode(cp, ftp_pass,
-                                   sizeof ftp_user_encoded / 2 - 1,
-                                   NULL, 0),
-                       cp = strchr(cp, 0);
+                       cp = url_encode(cp, ftp_pass,
+                               ftp_user_encoded + sizeof ftp_user_encoded - 1,
+                               NULL, 0);
                        *cp++ = '@';
                        *cp = 0;
                }
 
-               url_encode(ftp_dir_encoded, ftp_dir,
-                           sizeof ftp_dir_encoded - 1,
-                           RFC1738_SAFE_LESS_SHELL_PLUS_SLASH, 1),
-               cp = strchr(ftp_dir_encoded, 0);
+               cp = url_encode(ftp_dir_encoded, ftp_dir,
+                               ftp_dir_encoded + sizeof ftp_dir_encoded - 1,
+                               RFC1738_SAFE_LESS_SHELL_PLUS_SLASH, 1);
                if (set_dir[0] != '/')
                        *cp++ = '/';
                url_encode(cp, set_dir,
-                           ftp_dir_encoded + sizeof ftp_dir_encoded - cp,
-                           RFC1738_SAFE_LESS_SHELL_PLUS_SLASH, 0),
+                               ftp_dir_encoded + sizeof ftp_dir_encoded,
+                               RFC1738_SAFE_LESS_SHELL_PLUS_SLASH, 0);
 
                ret = run_program(RUN_DISPLAY | RUN_PROGRESS, 
                            "/usr/bin/ftp %s%s://%s%s/%s/%s%s",