libbb: shrink obscure()

function                                             old     new   delta
string_checker_helper                                 59      45     -14
string_checker                                       116      98     -18
obscure                                              367     204    -163
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 0/3 up/down: 0/-195)           Total: -195 bytes

Signed-off-by: Bob Dunlop <bob.dunlop@xyzzy.org.uk>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 45 insertions, 33 deletions

diff --git a/libbb/obscure.c b/libbb/obscure.c
index 22bcb9dec..06f00281a 100644
--- a/libbb/obscure.c
+++ b/libbb/obscure.c
@@ -45,53 +45,59 @@ static int string_checker_helper(const char *p1, const char *p2) __attribute__ (
 
 static int string_checker_helper(const char *p1, const char *p2)
 {
-        /* as-is or capitalized */
-        if (strcasecmp(p1, p2) == 0
         /* as sub-string */
-        || strcasestr(p2, p1) != NULL
+        if (strcasestr(p2, p1) != NULL
         /* invert in case haystack is shorter than needle */
-        || strcasestr(p1, p2) != NULL)
+         || strcasestr(p1, p2) != NULL
+        /* as-is or capitalized */
+        /* || strcasecmp(p1, p2) == 0 - 1st strcasestr should catch this too */
+        ) {
                 return 1;
+        }
         return 0;
 }
 
 static int string_checker(const char *p1, const char *p2)
 {
-        int size;
+        int size, i;
         /* check string */
         int ret = string_checker_helper(p1, p2);
-        /* Make our own copy */
+        /* make our own copy */
         char *p = xstrdup(p1);
-        /* reverse string */
-        size = strlen(p);
 
-        while (size--) {
-                *p = p1[size];
-                p++;
+        /* reverse string */
+        i = size = strlen(p1);
+        while (--i >= 0) {
+                *p++ = p1[i];
         }
-        /* restore pointer */
-        p -= strlen(p1);
+        p -= size; /* restore pointer */
+
         /* check reversed string */
         ret |= string_checker_helper(p, p2);
+
         /* clean up */
-        memset(p, 0, strlen(p1));
+        memset(p, 0, size);
         free(p);
+
         return ret;
 }
 
-#define LOWERCASE          1
-#define UPPERCASE          2
-#define NUMBERS            4
-#define SPECIAL            8
+#define CATEGORIES  4
+
+#define LOWERCASE   1
+#define UPPERCASE   2
+#define NUMBERS     4
+#define SPECIAL     8
+
+#define LAST_CAT    8
 
 static const char *obscure_msg(const char *old_p, const char *new_p, const struct passwd *pw)
 {
-        int i;
-        int c;
-        int length;
-        int mixed = 0;
-        /* Add 2 for each type of characters to the minlen of password */
-        int size = CONFIG_PASSWORD_MINLEN + 8;
+        unsigned length;
+        unsigned size;
+        unsigned mixed;
+        unsigned c;
+        unsigned i;
         const char *p;
         char *hostname;
 
@@ -104,7 +110,7 @@ static const char *obscure_msg(const char *old_p, const char *new_p, const struc
                 return "similar to username";
         }
         /* no gecos as-is, as sub-string, reversed, capitalized, doubled */
-        if (*pw->pw_gecos && string_checker(new_p, pw->pw_gecos)) {
+        if (pw->pw_gecos[0] && string_checker(new_p, pw->pw_gecos)) {
                 return "similar to gecos";
         }
         /* hostname as-is, as sub-string, reversed, capitalized, doubled */
@@ -115,6 +121,7 @@ static const char *obscure_msg(const char *old_p, const char *new_p, const struc
                 return "similar to hostname";
 
         /* Should / Must contain a mix of: */
+        mixed = 0;
         for (i = 0; i < length; i++) {
                 if (islower(new_p[i])) {        /* a-z */
                         mixed |= LOWERCASE;
@@ -125,7 +132,7 @@ static const char *obscure_msg(const char *old_p, const char *new_p, const struc
                 } else  {                       /* special characters */
                         mixed |= SPECIAL;
                 }
-                /* More than 50% similar characters ? */
+                /* Count i'th char */
                 c = 0;
                 p = new_p;
                 while (1) {
@@ -134,26 +141,31 @@ static const char *obscure_msg(const char *old_p, const char *new_p, const struc
                                 break;
                         }
                         c++;
-                        if (!++p) {
-                                break; /* move past the matched char if possible */
+                        p++;
+                        if (!*p) {
+                                break;
                         }
                 }
-
-                if (c >= (length / 2)) {
+                /* More than 50% similar characters ? */
+                if (c*2 >= length) {
                         return "too many similar characters";
                 }
         }
-        for (i=0; i<4; i++)
-                if (mixed & (1<<i)) size -= 2;
+
+        size = CONFIG_PASSWORD_MINLEN + 2*CATEGORIES;
+        for (i = 0; i <= LAST_CAT; i <<= 1)
+                if (mixed & i)
+                        size -= 2;
         if (length < size)
                 return "too weak";
 
-        if (old_p && old_p[0] != '\0') {
+        if (old_p && old_p[0]) {
                 /* check vs. old password */
                 if (string_checker(new_p, old_p)) {
                         return "similar to old password";
                 }
         }
+
         return NULL;
 }