httpd: explain IP/mask parsing, and simplify it a bit.

parse_conf                                          1258    1247     -11
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-11)             Total: -11 bytes
   text    data     bss     dec     hex filename
 772602    1058   11092  784752   bf970 busybox_old
 772594    1058   11092  784744   bf968 busybox_unstripped

diff --git a/networking/httpd.c b/networking/httpd.c
index a7473ed..0b4e305 100644 (file)
--- a/networking/httpd.c
+++ b/networking/httpd.c
@@ -289,17 +289,26 @@ static ALWAYS_INLINE void free_Htaccess_IP_list(Htaccess_IP **pptr)
        free_llist((has_next_ptr**)pptr);
 }
 
-static int scan_ip(const char **ep, unsigned *ip, unsigned char endc)
+//#undef isdigit
+//#define isdigit(a) ((unsigned)((a) - '0') <= 9)
+//#define notdigit(a) ((unsigned)((a) - '0') > 9)
+
+/* Returns presumed mask width in bits or < 0 on error.
+ * Updates strp, stores IP at provided pointer */
+static int scan_ip(const char **strp, unsigned *ipp, unsigned char endc)
 {
-       const char *p = *ep;
+       const char *p = *strp;
        int auto_mask = 8;
+       unsigned ip = 0;
        int j;
 
-       *ip = 0;
+       if (*p == '/')
+               return -auto_mask;
+
        for (j = 0; j < 4; j++) {
                unsigned octet;
 
-               if ((*p < '0' || *p > '9') && (*p != '/' || j == 0) && *p != '\0')
+               if ((*p < '0' || *p > '9') && *p != '/' && *p)
                        return -auto_mask;
                octet = 0;
                while (*p >= '0' && *p <= '9') {
@@ -311,55 +320,61 @@ static int scan_ip(const char **ep, unsigned *ip, unsigned char endc)
                }
                if (*p == '.')
                        p++;
-               if (*p != '/' && *p != '\0')
+               if (*p != '/' && *p)
                        auto_mask += 8;
-               *ip = ((*ip) << 8) | octet;
+               ip = (ip << 8) | octet;
        }
-       if (*p != '\0') {
+       if (*p) {
                if (*p != endc)
                        return -auto_mask;
                p++;
                if (*p == '\0')
                        return -auto_mask;
        }
-       *ep = p;
+       *ipp = ip;
+       *strp = p;
        return auto_mask;
 }
 
-static int scan_ip_mask(const char *ipm, unsigned *ip, unsigned *mask)
+/* Returns 0 on success. Stores IP and mask at provided pointers */
+static int scan_ip_mask(const char *str, unsigned *ipp, unsigned *maskp)
 {
        int i;
-       unsigned msk;
+       unsigned mask;
+       char *p;
 
-       i = scan_ip(&ipm, ip, '/');
+       i = scan_ip(&str, ipp, '/');
        if (i < 0)
                return i;
-       if (*ipm) {
-               const char *p = ipm;
-
-               i = 0;
-               while (*p) {
-                       if (*p < '0' || *p > '9') {
-                               if (*p == '.') {
-                                       i = scan_ip(&ipm, mask, 0);
-                                       return i != 32;
-                               }
-                               return -1;
-                       }
-                       i *= 10;
-                       i += *p - '0';
-                       p++;
+
+       if (*str) {
+               /* there is /xxx after dotted-IP address */
+               i = bb_strtou(str, &p, 10);
+               if (*p == '.') {
+                       /* 'xxx' itself is dotted-IP mask, parse it */
+                       /* (return 0 (success) only if it has N.N.N.N form) */
+                       return scan_ip(&str, maskp, '\0') - 32;
                }
+               if (*p)
+                       return -1;
        }
-       if (i > 32 || i < 0)
+
+       if (i > 32)
                return -1;
-       msk = 0x80000000;
-       *mask = 0;
-       while (i > 0) {
-               *mask |= msk;
-               msk >>= 1;
-               i--;
+
+       if (sizeof(unsigned) == 4 && i == 32) {
+               /* mask >>= 32 below may not work */
+               mask = 0;
+       } else {
+               mask = 0xffffffff;
+               mask >>= i;
        }
+       /* i == 0 -> *maskp = 0x00000000
+        * i == 1 -> *maskp = 0x80000000
+        * i == 4 -> *maskp = 0xf0000000
+        * i == 31 -> *maskp = 0xfffffffe
+        * i == 32 -> *maskp = 0xffffffff */
+       *maskp = (uint32_t)(~mask);
        return 0;
 }