httpd: simplify insane conf file parser

function                                             old     new   delta
bb_simplify_abs_path_inplace                           -      98     +98
parse_expr                                           824     832      +8
passwd_main                                         1025    1027      +2
evalvar                                             1374    1376      +2
parse_command                                       1463    1460      -3
bb_simplify_path                                     137      55     -82
parse_conf                                          1572    1422    -150
------------------------------------------------------------------------------
(add/remove: 3/2 grow/shrink: 3/3 up/down: 126/-251)         Total: -125 bytes

3 files changed, 194 insertions, 188 deletions

diff --git a/include/libbb.h b/include/libbb.h
index 4de3e7915..3a94a0070 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -1093,6 +1093,8 @@ const char *get_signame(int number) FAST_FUNC;
 void print_signames(void) FAST_FUNC;
 
 char *bb_simplify_path(const char *path) FAST_FUNC;
+/* Returns ptr to NUL */
+char *bb_simplify_abs_path_inplace(char *path) FAST_FUNC;
 
 #define FAIL_DELAY 3
 extern void bb_do_delay(int seconds) FAST_FUNC;
diff --git a/libbb/simplify_path.c b/libbb/simplify_path.c
index 367f1f04d..f80e3e8a5 100644
--- a/libbb/simplify_path.c
+++ b/libbb/simplify_path.c
@@ -6,22 +6,13 @@
  *
  * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
  */
-
 #include "libbb.h"
 
-char* FAST_FUNC bb_simplify_path(const char *path)
+char* FAST_FUNC bb_simplify_abs_path_inplace(char *start)
 {
-        char *s, *start, *p;
+        char *s, *p;
 
-        if (path[0] == '/')
-                start = xstrdup(path);
-        else {
-                s = xrealloc_getcwd_or_warn(NULL);
-                start = concat_path_file(s, path);
-                free(s);
-        }
         p = s = start;
-
         do {
                 if (*p == '/') {
                         if (*s == '/') {        /* skip duplicate (or initial) slash */
@@ -47,7 +38,22 @@ char* FAST_FUNC bb_simplify_path(const char *path)
         if ((p == start) || (*p != '/')) {      /* not a trailing slash */
                 ++p;                                    /* so keep last character */
         }
-        *p = 0;
+        *p = '\0';
+        return p;
+}
+
+char* FAST_FUNC bb_simplify_path(const char *path)
+{
+        char *s, *p;
+
+        if (path[0] == '/')
+                s = xstrdup(path);
+        else {
+                p = xrealloc_getcwd_or_warn(NULL);
+                s = concat_path_file(p, path);
+                free(p);
+        }
 
-        return start;
+        bb_simplify_abs_path_inplace(s);
+        return s;
 }
diff --git a/networking/httpd.c b/networking/httpd.c
index 803a98b46..243d76f94 100644
--- a/networking/httpd.c
+++ b/networking/httpd.c
@@ -54,7 +54,7 @@
  * /adm:admin:setup  # Require user admin, pwd setup on urls starting with /adm/
  * /adm:toor:PaSsWd  # or user toor, pwd PaSsWd on urls starting with /adm/
  * .au:audio/basic   # additional mime type for audio.au files
- * *.php:/path/php   # running cgi.php scripts through an interpreter
+ * *.php:/path/php   # run xxx.php through an interpreter
  *
  * A/D may be as a/d or allow/deny - only first char matters.
  * Deny/Allow IP logic:
@@ -115,8 +115,8 @@
 
 #define HEADER_READ_TIMEOUT 60
 
-static const char default_path_httpd_conf[] ALIGN1 = "/etc";
-static const char httpd_conf[] ALIGN1 = "httpd.conf";
+static const char DEFAULT_PATH_HTTPD_CONF[] ALIGN1 = "/etc";
+static const char HTTPD_CONF[] ALIGN1 = "httpd.conf";
 static const char HTTP_200[] ALIGN1 = "HTTP/1.0 200 OK\r\n";
 
 typedef struct has_next_ptr {
@@ -242,7 +242,7 @@ struct globals {
         const char *bind_addr_or_port;
 
         const char *g_query;
-        const char *configFile;
+        const char *opt_c_configFile;
         const char *home_httpd;
         const char *index_page;
 
@@ -289,7 +289,7 @@ struct globals {
 #define rmt_ip            (G.rmt_ip           )
 #define bind_addr_or_port (G.bind_addr_or_port)
 #define g_query           (G.g_query          )
-#define configFile        (G.configFile       )
+#define opt_c_configFile  (G.opt_c_configFile )
 #define home_httpd        (G.home_httpd       )
 #define index_page        (G.index_page       )
 #define found_mime_type   (G.found_mime_type  )
@@ -452,14 +452,6 @@ static int scan_ip_mask(const char *str, unsigned *ipp, unsigned *maskp)
 /*
  * Parse configuration file into in-memory linked list.
  *
- * The first non-white character is examined to determine if the config line
- * is one of the following:
- *    .ext:mime/type   # new mime type not compiled into httpd
- *    [adAD]:from      # ip address allow/deny, * for wildcard
- *    /path:user:pass  # username/password
- *    Ennn:error.html  # error page for status nnn
- *    P:/url:[http://]hostname[:port]/new/path # reverse proxy
- *
  * Any previous IP rules are discarded.
  * If the flag argument is not SUBDIR_PARSE then all /path and mime rules
  * are also discarded.  That is, previous settings are retained if flag is
@@ -469,99 +461,136 @@ static int scan_ip_mask(const char *str, unsigned *ipp, unsigned *maskp)
  * path   Path where to look for httpd.conf (without filename).
  * flag   Type of the parse request.
  */
-/* flag */
-#define FIRST_PARSE          0
-#define SUBDIR_PARSE         1
-#define SIGNALED_PARSE       2
-#define FIND_FROM_HTTPD_ROOT 3
+/* flag param: */
+enum {
+        FIRST_PARSE    = 0, /* path will be "/etc" */
+        SIGNALED_PARSE = 1, /* path will be "/etc" */
+        SUBDIR_PARSE   = 2, /* path will be derived from URL */
+};
 static void parse_conf(const char *path, int flag)
 {
+        /* internally used extra flag state */
+        enum { TRY_CURDIR_PARSE = 3 };
+
         FILE *f;
-#if ENABLE_FEATURE_HTTPD_BASIC_AUTH
-        Htaccess *prev;
-#endif
-        Htaccess *cur;
-        const char *filename = configFile;
+        const char *filename;
         char buf[160];
-        char *p, *p0;
-        char *after_colon;
-        Htaccess_IP *pip;
 
         /* discard old rules */
         free_Htaccess_IP_list(&ip_a_d);
         flg_deny_all = 0;
         /* retain previous auth and mime config only for subdir parse */
         if (flag != SUBDIR_PARSE) {
+                free_Htaccess_list(&mime_a);
 #if ENABLE_FEATURE_HTTPD_BASIC_AUTH
                 free_Htaccess_list(&g_auth);
 #endif
-                free_Htaccess_list(&mime_a);
 #if ENABLE_FEATURE_HTTPD_CONFIG_WITH_SCRIPT_INTERPR
                 free_Htaccess_list(&script_i);
 #endif
         }
 
+        filename = opt_c_configFile;
         if (flag == SUBDIR_PARSE || filename == NULL) {
-                filename = alloca(strlen(path) + sizeof(httpd_conf) + 2);
-                sprintf((char *)filename, "%s/%s", path, httpd_conf);
+                filename = alloca(strlen(path) + sizeof(HTTPD_CONF) + 2);
+                sprintf((char *)filename, "%s/%s", path, HTTPD_CONF);
         }
 
         while ((f = fopen_for_read(filename)) == NULL) {
-                if (flag == SUBDIR_PARSE || flag == FIND_FROM_HTTPD_ROOT) {
+                if (flag >= SUBDIR_PARSE) { /* SUBDIR or TRY_CURDIR */
                         /* config file not found, no changes to config */
                         return;
                 }
-                if (configFile && flag == FIRST_PARSE) /* if -c option given */
-                        bb_simple_perror_msg_and_die(filename);
-                flag = FIND_FROM_HTTPD_ROOT;
-                filename = httpd_conf;
+                if (flag == FIRST_PARSE) {
+                        /* -c CONFFILE given, but CONFFILE doesn't exist? */
+                        if (opt_c_configFile)
+                                bb_simple_perror_msg_and_die(opt_c_configFile);
+                        /* else: no -c, thus we looked at /etc/httpd.conf,
+                         * and it's not there. try ./httpd.conf: */
+                }
+                flag = TRY_CURDIR_PARSE;
+                filename = HTTPD_CONF;
         }
 
 #if ENABLE_FEATURE_HTTPD_BASIC_AUTH
-        prev = g_auth;
-#endif
-        /* This could stand some work */
-        while ((p0 = fgets(buf, sizeof(buf), f)) != NULL) {
-                after_colon = NULL;
-                for (p = p0; *p0 != '\0' && *p0 != '#'; p0++) {
-                        if (!isspace(*p0)) {
-                                *p++ = *p0;
-                                if (*p0 == ':' && after_colon == NULL)
-                                        after_colon = p;
+        /* in "/file:user:pass" lines, we prepend path in subdirs */
+        if (flag != SUBDIR_PARSE)
+                path = "";
+#endif
+        /* The lines can be:
+         *
+         * I:default_index_file
+         * H:http_home
+         * [AD]:IP[/mask]   # allow/deny, * for wildcard
+         * Ennn:error.html  # error page for status nnn
+         * P:/url:[http://]hostname[:port]/new/path # reverse proxy
+         * .ext:mime/type   # mime type
+         * *.php:/path/php  # run xxx.php through an interpreter
+         * /file:user:pass  # username and password
+         */
+        while (fgets(buf, sizeof(buf), f) != NULL) {
+                unsigned strlen_buf;
+                unsigned char ch;
+                char *after_colon = NULL;
+
+                { /* remove all whitespace, and # comments */
+                        char *p, *p0;
+
+                        p = p0 = buf;
+                        while ((ch = *p0++) != '\0' && ch != '#') {
+                                if (!isspace(ch)) {
+                                        *p++ = ch;
+                                        if (ch == ':' && after_colon == NULL)
+                                                after_colon = p;
+                                }
                         }
+                        *p = '\0';
+                        strlen_buf = p - buf;
                 }
-                *p = '\0';
 
-                /* test for empty or strange line */
+                /* empty or strange line? */
                 if (after_colon == NULL || *after_colon == '\0')
+                        goto config_error;
+
+                ch = (buf[0] & ~0x20); /* toupper if it's a letter */
+
+                if (ch == 'I') {
+                        index_page = xstrdup(after_colon);
                         continue;
-                p0 = buf;
-                if (*p0 == 'd' || *p0 == 'a')
-                        *p0 -= 0x20; /* a/d -> A/D */
-                if (*after_colon == '*') {
-                        if (*p0 == 'D') {
-                                /* memorize "deny all" */
-                                flg_deny_all = 1;
-                        }
-                        /* skip assumed "A:*", it is a default anyway */
+                }
+
+                /* do not allow jumping around using H in subdir's configs */
+                if (flag == FIRST_PARSE && ch == 'H') {
+                        home_httpd = xstrdup(after_colon);
+                        xchdir(home_httpd);
                         continue;
                 }
 
-                if (*p0 == 'A' || *p0 == 'D') {
-                        /* storing current config IP line */
-                        pip = xzalloc(sizeof(Htaccess_IP));
-                        if (scan_ip_mask(after_colon, &(pip->ip), &(pip->mask))) {
+                if (ch == 'A' || ch == 'D') {
+                        Htaccess_IP *pip;
+
+                        if (*after_colon == '*') {
+                                if (ch == 'D') {
+                                        /* memorize "deny all" */
+                                        flg_deny_all = 1;
+                                }
+                                /* skip assumed "A:*", it is a default anyway */
+                                continue;
+                        }
+                        /* store "allow/deny IP/mask" line */
+                        pip = xzalloc(sizeof(*pip));
+                        if (scan_ip_mask(after_colon, &pip->ip, &pip->mask)) {
                                 /* IP{/mask} syntax error detected, protect all */
-                                *p0 = 'D';
+                                ch = 'D';
                                 pip->mask = 0;
                         }
-                        pip->allow_deny = *p0;
-                        if (*p0 == 'D') {
+                        pip->allow_deny = ch;
+                        if (ch == 'D') {
                                 /* Deny:from_IP - prepend */
                                 pip->next = ip_a_d;
                                 ip_a_d = pip;
                         } else {
-                                /* A:from_IP - append (thus D precedes A) */
+                                /* A:from_IP - append (thus all D's precedes A's) */
                                 Htaccess_IP *prev_IP = ip_a_d;
                                 if (prev_IP == NULL) {
                                         ip_a_d = pip;
@@ -575,12 +604,12 @@ static void parse_conf(const char *path, int flag)
                 }
 
 #if ENABLE_FEATURE_HTTPD_ERROR_PAGES
-                if (flag == FIRST_PARSE && *p0 == 'E') {
+                if (flag == FIRST_PARSE && ch == 'E') {
                         unsigned i;
-                        int status = atoi(++p0); /* error status code */
+                        int status = atoi(buf + 1); /* error status code */
+
                         if (status < HTTP_CONTINUE) {
-                                bb_error_msg("config error '%s' in '%s'", buf, filename);
-                                continue;
+                                goto config_error;
                         }
                         /* then error page; find matching status */
                         for (i = 0; i < ARRAY_SIZE(http_response_type); i++) {
@@ -597,7 +626,7 @@ static void parse_conf(const char *path, int flag)
 #endif
 
 #if ENABLE_FEATURE_HTTPD_PROXY
-                if (flag == FIRST_PARSE && *p0 == 'P') {
+                if (flag == FIRST_PARSE && ch == 'P') {
                         /* P:/url:[http://]hostname[:port]/new/path */
                         char *url_from, *host_port, *url_to;
                         Htaccess_Proxy *proxy_entry;
@@ -605,23 +634,20 @@ static void parse_conf(const char *path, int flag)
                         url_from = after_colon;
                         host_port = strchr(after_colon, ':');
                         if (host_port == NULL) {
-                                bb_error_msg("config error '%s' in '%s'", buf, filename);
-                                continue;
+                                goto config_error;
                         }
                         *host_port++ = '\0';
                         if (strncmp(host_port, "http://", 7) == 0)
                                 host_port += 7;
                         if (*host_port == '\0') {
-                                bb_error_msg("config error '%s' in '%s'", buf, filename);
-                                continue;
+                                goto config_error;
                         }
                         url_to = strchr(host_port, '/');
                         if (url_to == NULL) {
-                                bb_error_msg("config error '%s' in '%s'", buf, filename);
-                                continue;
+                                goto config_error;
                         }
                         *url_to = '\0';
-                        proxy_entry = xzalloc(sizeof(Htaccess_Proxy));
+                        proxy_entry = xzalloc(sizeof(*proxy_entry));
                         proxy_entry->url_from = xstrdup(url_from);
                         proxy_entry->host_port = xstrdup(host_port);
                         *url_to = '/';
@@ -631,115 +657,87 @@ static void parse_conf(const char *path, int flag)
                         continue;
                 }
 #endif
+                /* the rest of directives are non-alphabetic,
+                 * must avoid using "toupper'ed" ch */
+                ch = buf[0];
 
-#if ENABLE_FEATURE_HTTPD_BASIC_AUTH
-                if (*p0 == '/') {
-                        /* make full path from httpd root / current_path / config_line_path */
-                        const char *tp = (flag == SUBDIR_PARSE ? path : "");
-                        p0 = xmalloc(strlen(tp) + (after_colon - buf) + 2 + strlen(after_colon));
-                        after_colon[-1] = '\0';
-                        sprintf(p0, "/%s%s", tp, buf);
-
-                        /* looks like bb_simplify_path... */
-                        tp = p = p0;
-                        do {
-                                if (*p == '/') {
-                                        if (*tp == '/') {    /* skip duplicate (or initial) slash */
-                                                continue;
-                                        }
-                                        if (*tp == '.') {
-                                                if (tp[1] == '/' || tp[1] == '\0') { /* remove extra '.' */
-                                                        continue;
-                                                }
-                                                if ((tp[1] == '.') && (tp[2] == '/' || tp[2] == '\0')) {
-                                                        ++tp;
-                                                        if (p > p0) {
-                                                                while (*--p != '/') /* omit previous dir */
-                                                                        continue;
-                                                        }
-                                                        continue;
-                                                }
-                                        }
-                                }
-                                *++p = *tp;
-                        } while (*++tp);
+                if (ch == '.' /* ".ext:mime/type" */
+#if ENABLE_FEATURE_HTTPD_CONFIG_WITH_SCRIPT_INTERPR
+                 || (ch == '*' && buf[1] == '.') /* "*.php:/path/php" */
+#endif
+                ) {
+                        char *p;
+                        Htaccess *cur;
 
-                        if ((p == p0) || (*p != '/')) { /* not a trailing slash */
-                                ++p;                    /* so keep last character */
+                        cur = xzalloc(sizeof(*cur) /* includes space for NUL */ + strlen_buf);
+                        strcpy(cur->before_colon, buf);
+                        p = cur->before_colon + (after_colon - buf);
+                        p[-1] = '\0';
+                        cur->after_colon = p;
+                        if (ch == '.') {
+                                /* .mime line: prepend to mime_a list */
+                                cur->next = mime_a;
+                                mime_a = cur;
+                        }
+#if ENABLE_FEATURE_HTTPD_CONFIG_WITH_SCRIPT_INTERPR
+                        else {
+                                /* script interpreter line: prepend to script_i list */
+                                cur->next = script_i;
+                                script_i = cur;
                         }
-                        *p = ':';
-                        strcpy(p + 1, after_colon);
-                }
 #endif
-                if (*p0 == 'I') {
-                        index_page = xstrdup(after_colon);
-                        continue;
-                }
-
-                /* Do not allow jumping around using H in subdir's configs */
-                if (flag == FIRST_PARSE && *p0 == 'H') {
-                        home_httpd = xstrdup(after_colon);
-                        xchdir(home_httpd);
                         continue;
                 }
 
-                /* storing current config line */
-                cur = xzalloc(sizeof(Htaccess) + strlen(p0));
-                strcpy(cur->before_colon, p0);
 #if ENABLE_FEATURE_HTTPD_BASIC_AUTH
-                if (*p0 == '/') /* was malloced - see above */
-                        free(p0);
-#endif
-                cur->after_colon = strchr(cur->before_colon, ':');
-                *cur->after_colon++ = '\0';
-                if (cur->before_colon[0] == '.') {
-                        /* .mime line: prepend to mime_a list */
-                        cur->next = mime_a;
-                        mime_a = cur;
-                        continue;
-                }
-#if ENABLE_FEATURE_HTTPD_CONFIG_WITH_SCRIPT_INTERPR
-                if (cur->before_colon[0] == '*' && cur->before_colon[1] == '.') {
-                        /* script interpreter line: prepend to script_i list */
-                        cur->next = script_i;
-                        script_i = cur;
-                        continue;
-                }
-#endif
-#if ENABLE_FEATURE_HTTPD_BASIC_AUTH
-//TODO: we do not test for leading "/"??
-//also, do we leak cur if BASIC_AUTH is off?
-                if (prev == NULL) {
-                        /* first line */
-                        g_auth = prev = cur;
-                } else {
-                        /* sort path, if current length eq or bigger then move up */
-                        Htaccess *prev_hti = g_auth;
-                        size_t l = strlen(cur->before_colon);
-                        Htaccess *hti;
-
-                        for (hti = prev_hti; hti; hti = hti->next) {
-                                if (l >= strlen(hti->before_colon)) {
-                                        /* insert before hti */
-                                        cur->next = hti;
-                                        if (prev_hti != hti) {
-                                                prev_hti->next = cur;
-                                        } else {
-                                                /* insert as top */
-                                                g_auth = cur;
+                if (ch == '/') { /* "/file:user:pass" */
+                        char *p;
+                        Htaccess *cur;
+                        unsigned file_len;
+
+                        /* note: path is "" unless we are in SUBDIR parse,
+                         * otherwise it always starts with "/" */
+                        cur = xzalloc(sizeof(*cur) /* includes space for NUL */
+                                + strlen(path)
+                                + strlen_buf
+                                );
+                        /* form "/path/file" */
+                        sprintf(cur->before_colon, "%s%.*s",
+                                path,
+                                after_colon - buf - 1, /* includes "/", but not ":" */
+                                buf);
+                        /* canonicalize it */
+                        p = bb_simplify_abs_path_inplace(cur->before_colon);
+                        file_len = p - cur->before_colon;
+                        /* add "user:pass" after NUL */
+                        strcpy(++p, after_colon);
+                        cur->after_colon = p;
+
+                        /* insert cur into g_auth */
+                        /* g_auth is sorted by decreased filename length */
+                        {
+                                Htaccess *auth, **authp;
+
+                                authp = &g_auth;
+                                while ((auth = *authp) != NULL) {
+                                        if (file_len >= strlen(auth->before_colon)) {
+                                                /* insert cur before auth */
+                                                cur->next = auth;
+                                                break;
                                         }
-                                        break;
+                                        authp = &auth->next;
                                 }
-                                if (prev_hti != hti)
-                                        prev_hti = prev_hti->next;
-                        }
-                        if (!hti) {       /* not inserted, add to bottom */
-                                prev->next = cur;
-                                prev = cur;
+                                *authp = cur;
                         }
+                        continue;
                 }
 #endif /* BASIC_AUTH */
+
+                /* the line is not recognized */
+ config_error:
+                bb_error_msg("config error '%s' in '%s'", buf, filename);
          } /* while (fgets) */
+
          fclose(f);
 }
 
@@ -2031,8 +2029,8 @@ static void handle_incoming_and_exit(const len_and_sockaddr *fromAddr)
         /* We are done reading headers, disable peer timeout */
         alarm(0);
 
-        if (strcmp(bb_basename(urlcopy), httpd_conf) == 0 || !ip_allowed) {
-                /* protect listing [/path]/httpd_conf or IP deny */
+        if (strcmp(bb_basename(urlcopy), HTTPD_CONF) == 0 || !ip_allowed) {
+                /* protect listing [/path]/httpd.conf or IP deny */
                 send_headers_and_exit(HTTP_FORBIDDEN);
         }
 
@@ -2245,7 +2243,7 @@ static void mini_httpd_inetd(void)
 
 static void sighup_handler(int sig UNUSED_PARAM)
 {
-        parse_conf(default_path_httpd_conf, SIGNALED_PARSE);
+        parse_conf(DEFAULT_PATH_HTTPD_CONF, SIGNALED_PARSE);
 }
 
 enum {
@@ -2304,7 +2302,7 @@ int httpd_main(int argc UNUSED_PARAM, char **argv)
                         IF_FEATURE_HTTPD_AUTH_MD5("m:")
                         IF_FEATURE_HTTPD_SETUID("u:")
                         "p:ifv",
-                        &configFile, &url_for_decode, &home_httpd
+                        &opt_c_configFile, &url_for_decode, &home_httpd
                         IF_FEATURE_HTTPD_ENCODE_URL_STR(, &url_for_encode)
                         IF_FEATURE_HTTPD_BASIC_AUTH(, &g_realm)
                         IF_FEATURE_HTTPD_AUTH_MD5(, &pass)
@@ -2375,7 +2373,7 @@ int httpd_main(int argc UNUSED_PARAM, char **argv)
         }
 #endif
 
-        parse_conf(default_path_httpd_conf, FIRST_PARSE);
+        parse_conf(DEFAULT_PATH_HTTPD_CONF, FIRST_PARSE);
         if (!(opt & OPT_INETD))
                 signal(SIGHUP, sighup_handler);