Refactor basic command parsing

Make more bullet proof and efficient

diff --git a/gatchat/gatserver.c b/gatchat/gatserver.c
index 71e366d..711bf78 100644 (file)
--- a/gatchat/gatserver.c
+++ b/gatchat/gatserver.c
@@ -308,68 +308,58 @@ next:
        return i + 1;
 }
 
-static gboolean get_basic_prefix(const char *buf, char *out_prefix)
+static int get_basic_prefix_size(const char *buf)
 {
-       char c = *buf;
-       char prefix[4];
-
-       if (g_ascii_isalpha(c)) {
-               c = g_ascii_toupper(c);
-
-               if (c == 'S') {
-                       int i;
-
-                       prefix[0] = 'S';
+       if (g_ascii_isalpha(buf[0])) {
+               if (g_ascii_toupper(buf[0]) == 'S') {
+                       int size;
 
                        /* V.250 5.3.2 'S' command follows with a parameter
-                        * number. Limited to two digits since 100
-                        * S-registers should be enough.
+                        * number.
                         */
-                       for (i = 1; i < 3 && g_ascii_isdigit(buf[i]); i++)
-                               prefix[i] = buf[i];
-
-                       prefix[i] = '\0';
+                       for (size = 1; g_ascii_isdigit(buf[size]); size++)
+                               ;
 
                        /*
                         * Do some basic sanity checking, don't accept 00, 01,
                         * etc or empty S values
                         */
-                       if (prefix[1] == '\0')
-                               return FALSE;
-
-                       if (prefix[1] == '0' && prefix[2] != '\0')
-                               return FALSE;
-               } else {
-                       prefix[0] = c;
-                       prefix[1] = '\0';
-               }
-       } else if (c == '&') {
-               prefix[0] = '&';
+                       if (size == 1)
+                               return 0;
 
-               if (g_ascii_isalpha(buf[1] == FALSE))
-                       return FALSE;
+                       if (size > 2 && buf[1] == '0')
+                               return 0;
 
-               prefix[1] = g_ascii_toupper(buf[1]);
-               prefix[2] = '\0';
+                       return size;
+               }
+
+               /* All other cases it is a simple 1 character prefix */
+               return 1;
        }
+       
+       if (buf[0] == '&') {
+               if (g_ascii_isalpha(buf[0] == FALSE))
+                       return 0;
 
-       memcpy(out_prefix, prefix, sizeof(prefix));
+               return 2;
+       }
 
-       return TRUE;
+       return 0;
 }
 
 static unsigned int parse_basic_command(GAtServer *server, char *buf)
 {
-       char *command;
-       char prefix[4];
-       unsigned int i;
-       GAtServerRequestType type;
        gboolean seen_equals = FALSE;
+       char prefix[4], tmp;
+       unsigned int i, prefix_size;
+       GAtServerRequestType type;
 
-       if (!get_basic_prefix(buf, prefix))
+       prefix_size = get_basic_prefix_size(buf);
+       if (prefix_size == 0)
                return 0;
 
-       i = strlen(prefix);
+       i = prefix_size;
+       prefix[0] = g_ascii_toupper(buf[0]);
 
        if (prefix[0] == 'D') {
                type = G_AT_SERVER_REQUEST_TYPE_SET;
@@ -384,18 +374,7 @@ static unsigned int parse_basic_command(GAtServer *server, char *buf)
                goto done;
        }
 
-       if (buf[i] == '\0' || buf[i] == ';') {
-               type = G_AT_SERVER_REQUEST_TYPE_COMMAND_ONLY;
-               goto done;
-       }
-
-       /* Additional commands may follow a command without any character
-        * required for separation.
-        */
-       if (is_basic_command_prefix(&buf[i])) {
-               type = G_AT_SERVER_REQUEST_TYPE_COMMAND_ONLY;
-               goto done;
-       }
+       type = G_AT_SERVER_REQUEST_TYPE_COMMAND_ONLY;
 
        /* Match '?', '=',  '=?' and '=xxx' */
        if (buf[i] == '=') {
@@ -411,19 +390,27 @@ static unsigned int parse_basic_command(GAtServer *server, char *buf)
                else
                        type = G_AT_SERVER_REQUEST_TYPE_QUERY;
        } else {
+               int before = i;
+
                /* V.250 5.3.1 The subparameter (if any) are all digits */
                while (g_ascii_isdigit(buf[i]))
                        i++;
 
-               type = G_AT_SERVER_REQUEST_TYPE_SET;
+               if (i - before > 0)
+                       type = G_AT_SERVER_REQUEST_TYPE_SET;
        }
 
 done:
-       command = g_strndup(buf, i);
-
-       at_command_notify(server, command, prefix, type);
-
-       g_free(command);
+       if (prefix_size <= 3) {
+               memcpy(prefix + 1, buf + 1, prefix_size - 1);
+               prefix[prefix_size] = '\0';
+
+               tmp = buf[i];
+               buf[i] = '\0';
+               at_command_notify(server, buf, prefix, type);
+               buf[i] = tmp;
+       } else /* Handle S-parameter with 100+ */
+               g_at_server_send_final(server, G_AT_SERVER_RESULT_ERROR);
 
        /* Commands like ATA, ATZ cause the remainder line
         * to be ignored.
@@ -431,7 +418,7 @@ done:
        if (prefix[0] == 'A' || prefix[0] == 'Z')
                return strlen(buf);
 
-       /* Consumed the seperator ';' */
+       /* Consume the seperator ';' */
        if (buf[i] == ';')
                i += 1;