parse.c

parse.c

bool parse(const char* line, char* abs_path, char* query)
{
    /* method SP request-target SP HTTP-version CRLF
    * GET /path/to/file.extension?query  HTTP/1.1\r\n
    * very likely inputs
    * GET /path/to/file.extension  HTTP/1.1\r\n
    * GET path/to/file.extension?query  HTTP/1.1\r\n
    * GET "/path/to/file.extension?query"  HTTP/1.1\r\n
    * GET /path/to/file.extension?query  HTTP/1.0\r\n
    */
    
    // makes sure method is GET
    // create a buffer in which to hold line
    char buffer[strlen(line)];
    
    // copy the line into the buffer for further parsing
    strcpy(buffer, line);
    
    // parse up until the first space which should be the method
    char* method = strtok(buffer, " ");
    
    // if the method is GET (the only supported method), continue, otherwise
    if(strcmp(method, "GET") != 0)
    {
        // error
        error(405);
        return false;
    }
    
    // makes sure request target begins with /
    // store the next token into target
    // this token should end by the next space
    char* target = strtok(NULL, " ");
    
    // if first character isn't /
    if(target[0] != '/')
    {
        // error
        error(501);
        return false;
    }
    
    // otherwise, continue
    
    // makes sure the target doesn't contain any ""
    // iterate over every character
    for(int  i = 0, len = strlen(target); i < len; i++)
    {
        // if current character is a '
        if(target[i] == '"')
        {
            error(400);
            return false;
        }
    }
    
    // make sure version is HTTP/1.1 and \r\n
    // The next token should be the version
    // store the next token into a variable called version
    char* version = strtok(NULL, " ");
    
    // compare HTTP/1.1 supported version vs whatever version the user
    // may be using
    if(strcmp(version, "HTTP/1.1\r\n") != 0)
    {
        // error if not supported
        error(505);
        return false;
    }
    
    // else we continue
    // store target up until ? in the abs_path if it exists
    // else there's nothing to do
    
    // to do this, let's iterate over all the chars in target
    // break in case we find an ? or an space, whatever comes first
    int i;
    for(i = 0; target[i] != '?' && target[i] != ' ' && target[i] != '\0'; i++)
    {
        abs_path[i] = target[i];
    }
     
    // store the query substring in target in query 
    // it comes after ? and before an space
    // if there's space after ? return ""
    // else the substring before the space
    
    if(target[i] == '?' && target[i + 1] != ' ')
    {
        i++;
        for(int z = 0; target[i] != ' ' && target[i] != '\0'; i++, z++)
        {
            query[z] = target[i];
        }   
    }
    else if(target[i] == '?' && target[i + 1] == ' ')
    {
        query[0] = '\0';   
    }
    else if(target[i] == ' ')
    {
        query[0] = '\0';
    }
    return true;
}