#define MAXLINELEN 512 
 typedef enum {
    Subject,
    Title,
    Expires,
    Sender,
    From,
    Newsgroups,
    Content_Type,
    Content_Length,
    Reply_To,
    References,
    Date,
    Lines,
    Base,
    Author,
    Mailing_List,
    Boundary,
    Location,
    EndOfHeaderTp,
} HeaderTp;
 typedef struct {
    char *head[EndOfHeaderTp];
    MIME_encoding content_transfer_encoding;
    ISO_charset charset;
} MIME_header;
 void free_header(MIME_header header);