/*
?*?proxy.c?-?CS:APP?Web?proxy
?*
?*?TEAM?MEMBERS:
?*?????Andrew?Carnegie?ac00@cs.cmu.edu?
?*?????Harry?Q.?Bovik?bovik@cs.cmu.edu
?*?
?*?A?simple?web?proxy?implement.
?*?No?cache.?No?thread?pool.?No?post?method.
?*?
?*/?

#include?“csapp.h“
#include?

#define?_DEBUG

#define?DEFPORT?8888

typedef?struct?client_info
{
??int?connfd;
??struct?sockaddr_in?sockaddr;
}?client_info_t;

/*
?*?Gloval?vars
?*/
sem_t?sem_log;
sem_t?sem_dns;
FILE?*log_file;

/*
?*?Function?prototypes
?*/
int?parse_uri（char?*uri?char?*target_addr?char?*path?int?*port）;
void?format_log_entry（char?*logstring?struct?sockaddr_in?*sockaddr?char?*uri?int?size）;
void?*work_init（void?*arg）;
void?do_work（int?connfd?struct?sockaddr_in?*sockaddr）;
void?my_clienterror（int?fd?int?errnum?char?*errmsg?char?*longmsg）;
int?open_clientfd_ts（char?*hostname?int?port）;
int?Open_clientfd_ts（char?*hostname?int?port）?;
void?dbg_printf（char?*format?...）;



/*
?*?dbg_printf?-?only?print?msg?in?debug?mode
?*/
void?dbg_printf（char?*format?...）
{
#ifdef?_DEBUG
????va_list?va;
????va_start（va?format）;
????vprintf（format?va）;
????va_end（va）;
#endif
}

/*
?*?wrapper?of?three?rio?functions
?*/
ssize_t?Rio_readnb_w（rio_t?*rp?void?*usrbuf?size_t?n）?
{
????ssize_t?rc;

????if?（（rc?=?rio_readnb（rp?usrbuf?n））?????{
??????fprintf（stderr?“Rio_readnb?error:?%s\n“?strerror（errno））;
??????return?0;
????}
????return?rc;
}

ssize_t?Rio_readlineb_w（rio_t?*rp?void?*usrbuf?size_t?maxlen）?
{
????ssize_t?rc;

????if?（（rc?=?rio_readlineb（rp?usrbuf?maxlen））?????{
??????fprintf（stderr?“Rio_readlineb?error:?%s\n“?strerror（errno））;
??????return?0;
????}
????return?rc;
}?

void?Rio_writen_w（int?fd?void?*usrbuf?size_t?n）?
{
????if?（rio_writen（fd?usrbuf?n）?!=?n）
??????fprintf（stderr?“Rio_writen?error:?%s\n“?strerror（errno））;
}

/*
?*?Open_clientfd_ts?-?wrapper?of?open_clientfd_s
?*/
int?Open_clientfd_ts（char?*hostname?int?port）?
{
????int?rc?=?open_clientfd_ts（hostname?port）;
????if?（rc?==?-1）
??????unix_error（“Open_clientfd_s?Unix?error“）;
????else?if（rc?==?-2）????????
	????dns_error（“Open_clientfd_s?DNS?error“）;
????return?rc;
}

/*
?*?open_clientfd_s?-?thread-safe?version?for?open_clientfd
?*/
int?open_clientfd_ts（char?*hostname?int?port）?
{
????int?clientfd;
????struct?hostent?*hp;
????struct?sockaddr_in?serveraddr;

????if?（（clientfd?=?socket（AF_INET?SOCK_STREAM?0））???????return?-1;?/*?check?errno?for?cause?of?error?*/

????/*?Fill?in?the?server‘s?IP?address?and?port?*/
????P（&sem_dns）;
????if?（（hp?=?gethostbyname（hostname））?==?NULL）
????{
??????V（&sem_dns）;
??????return?-2;?/*?check?h_errno?for?cause?of?error?*/
????}?
????bzero（（char?*）?&serveraddr?sizeof（serveraddr））;
????serveraddr.sin_family?=?AF_INET;
????bcopy（（char?*）hp->h_addr_list[0]?
	??（char?*）&serveraddr.sin_addr.s_addr?hp->h_length）;
????V（&sem_dns）;
????serveraddr.sin_port?=?htons（port）;

????/*?Establish?a?connection?with?the?server?*/
????if?（connect（clientfd?（SA?*）?&serveraddr?sizeof（ser