有哪位大神用过uIP中的WEB Client？给讲解一下过程，看不懂呀
有哪位大神用过uIP中的WEB Client？给讲解一下过程，看不懂呀下面是源码：
/**
* \addtogroup apps
* @{
*/
/**
* \defgroup webclient Web client
* @{
*
* This example shows a HTTP client that is able to download web pages
* and files from web servers. It requires a number of callback
* functions to be implemented by the module that utilizes the code:
* webclient_datahandler(), webclient_connected(),
* webclient_timedout(), webclient_aborted(), webclient_closed().
*/
/**
* \file
* Implementation of the HTTP client.
* \author Adam Dunkels <adam@dunkels.com>
*/
/*
* Copyright (c) 2002, Adam Dunkels.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials provided
* with the distribution.
* 3. The name of the author may not be used to endorse or promote
* products derived from this software without specific prior
* written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
* OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED.IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
* GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* This file is part of the uIP TCP/IP stack.
*
* $Id: webclient.c,v 1.2 2006/06/11 21:46:37 adam Exp $
*
*/
#include "uip.h"
#include "uiplib.h"
#include "webclient.h"
#include "resolv.h"
#include "usart.h"
#include <string.h>
#define WEBCLIENT_TIMEOUT 100
#define WEBCLIENT_STATE_STATUSLINE 0
#define WEBCLIENT_STATE_HEADERS 1
#define WEBCLIENT_STATE_DATA 2
#define WEBCLIENT_STATE_CLOSE 3
#define HTTPFLAG_NONE 0
#define HTTPFLAG_OK 1
#define HTTPFLAG_MOVED2
#define HTTPFLAG_ERROR3
#define ISO_nl 0x0a
#define ISO_cr 0x0d
#define ISO_space 0x20
static struct webclient_state s;
/*-----------------------------------------------------------------------------------*/
char *
webclient_mimetype(void)
{
return s.mimetype;
}
/*-----------------------------------------------------------------------------------*/
char *
webclient_filename(void)
{
return s.file;
}
/*-----------------------------------------------------------------------------------*/
char *
webclient_hostname(void)
{
return s.host;
}
/*-----------------------------------------------------------------------------------*/
unsigned short
webclient_port(void)
{
return s.port;
}
/*-----------------------------------------------------------------------------------*/
void
webclient_init(void)
{
}
/*-----------------------------------------------------------------------------------*/
static void
init_connection(void)
{
s.state = WEBCLIENT_STATE_STATUSLINE;
s.getrequestleft = sizeof(http_get) - 1 + 1 +
sizeof(http_10) - 1 +
sizeof(http_crnl) - 1 +
sizeof(http_host) - 1 +
sizeof(http_crnl) - 1 +
strlen(http_user_agent_fields) +
strlen(s.file) + strlen(s.host);
s.getrequestptr = 0;
s.httpheaderlineptr = 0;
}
/*-----------------------------------------------------------------------------------*/
void
webclient_close(void)
{
s.state = WEBCLIENT_STATE_CLOSE;
}
/*-----------------------------------------------------------------------------------*/
unsigned char
webclient_get(char *host, u16_t port, char *file)
{
struct uip_conn *conn;
uip_ipaddr_t *ipaddr;
static uip_ipaddr_t addr;
/* First check if the host is an IP address. */
ipaddr = &addr;
if(uiplib_ipaddrconv(host, (unsigned char *)addr) == 0) {
ipaddr = (uip_ipaddr_t *)resolv_lookup(host);
if(ipaddr == NULL) {
return 0;
}
}
conn = uip_connect(ipaddr, htons(port));
if(conn == NULL) {
return 0;
}
s.port = port;
strncpy(s.file, file, sizeof(s.file));
strncpy(s.host, host, sizeof(s.host));
init_connection();
return 1;
}
/*-----------------------------------------------------------------------------------*/
static unsigned char *
copy_string(unsigned char *dest,
const unsigned char *src, unsigned char len)
{
strncpy(dest, src, len);
return dest + len;
}
/*-----------------------------------------------------------------------------------*/
static void
senddata(void)
{
u16_t len;
char *getrequest;
char *cptr;
if(s.getrequestleft > 0) {
cptr = getrequest = (char *)uip_appdata;
cptr = copy_string(cptr, http_get, sizeof(http_get) - 1);
cptr = copy_string(cptr, s.file, strlen(s.file));
*cptr++ = ISO_space;
cptr = copy_string(cptr, http_10, sizeof(http_10) - 1);
cptr = copy_string(cptr, http_crnl, sizeof(http_crnl) - 1);
cptr = copy_string(cptr, http_host, sizeof(http_host) - 1);
cptr = copy_string(cptr, s.host, strlen(s.host));
cptr = copy_string(cptr, http_crnl, sizeof(http_crnl) - 1);
cptr = copy_string(cptr, http_user_agent_fields,
strlen(http_user_agent_fields));
len = s.getrequestleft > uip_mss()?
uip_mss():
s.getrequestleft;
uip_send(&(getrequest), len);
}
}
/*-----------------------------------------------------------------------------------*/
static void
acked(void)
{
u16_t len;
if(s.getrequestleft > 0) {
len = s.getrequestleft > uip_mss()?
uip_mss():
s.getrequestleft;
s.getrequestleft -= len;
s.getrequestptr += len;
}
}
/*-----------------------------------------------------------------------------------*/
static u16_t
parse_statusline(u16_t len)
{
char *cptr;
while(len > 0 && s.httpheaderlineptr < sizeof(s.httpheaderline)) {
s.httpheaderline = *(char *)uip_appdata;
++((char *)uip_appdata);
--len;
if(s.httpheaderline == ISO_nl) {
if((strncmp(s.httpheaderline, http_10,
sizeof(http_10) - 1) == 0) ||
(strncmp(s.httpheaderline, http_11,
sizeof(http_11) - 1) == 0)) {
cptr = &(s.httpheaderline);
s.httpflag = HTTPFLAG_NONE;
if(strncmp(cptr, http_200, sizeof(http_200) - 1) == 0) {
/* 200 OK */
s.httpflag = HTTPFLAG_OK;
} else if(strncmp(cptr, http_301, sizeof(http_301) - 1) == 0 ||
strncmp(cptr, http_302, sizeof(http_302) - 1) == 0) {
/* 301 Moved permanently or 302 Found. Location: header line
will contain thw new location. */
s.httpflag = HTTPFLAG_MOVED;
} else {
s.httpheaderline = 0;
}
} else {
uip_abort();
webclient_aborted();
return 0;
}
/* We're done parsing the status line, so we reset the pointer
and start parsing the HTTP headers.*/
s.httpheaderlineptr = 0;
s.state = WEBCLIENT_STATE_HEADERS;
break;
} else {
++s.httpheaderlineptr;
}
}
return len;
}
/*-----------------------------------------------------------------------------------*/
static char
casecmp(char *str1, const char *str2, char len)
{
static char c;
while(len > 0) {
c = *str1;
/* Force lower-case characters. */
if(c & 0x40) {
c |= 0x20;
}
if(*str2 != c) {
return 1;
}
++str1;
++str2;
--len;
}
return 0;
}
/*-----------------------------------------------------------------------------------*/
static u16_t
parse_headers(u16_t len)
{
char *cptr;
static unsigned char i;
while(len > 0 && s.httpheaderlineptr < sizeof(s.httpheaderline)) {
s.httpheaderline = *(char *)uip_appdata;
++((char *)uip_appdata);
--len;
if(s.httpheaderline == ISO_nl) {
/* We have an entire HTTP header line in s.httpheaderline, so
we parse it. */
if(s.httpheaderline == ISO_cr) {
/* This was the last header line (i.e., and empty "\r\n"), so
we are done with the headers and proceed with the actual
data. */
s.state = WEBCLIENT_STATE_DATA;
return len;
}
s.httpheaderline = 0;
/* Check for specific HTTP header fields. */
if(casecmp(s.httpheaderline, http_content_type,
sizeof(http_content_type) - 1) == 0) {
/* Found Content-type field. */
cptr = strchr(s.httpheaderline, ';');
if(cptr != NULL) {
*cptr = 0;
}
strncpy(s.mimetype, s.httpheaderline +
sizeof(http_content_type) - 1, sizeof(s.mimetype));
} else if(casecmp(s.httpheaderline, http_location,
sizeof(http_location) - 1) == 0) {
cptr = s.httpheaderline +
sizeof(http_location) - 1;
if(strncmp(cptr, http_http, 7) == 0) {
cptr += 7;
for(i = 0; i < s.httpheaderlineptr - 7; ++i) {
if(*cptr == 0 ||
*cptr == '/' ||
*cptr == ' ' ||
*cptr == ':') {
s.host = 0;
break;
}
s.host = *cptr;
++cptr;
}
}
strncpy(s.file, cptr, sizeof(s.file));
/* s.file = 0;*/
}
/* We're done parsing, so we reset the pointer and start the
next line. */
s.httpheaderlineptr = 0;
} else {
++s.httpheaderlineptr;
}
}
return len;
}
/*-----------------------------------------------------------------------------------*/
static void
newdata(void)
{
u16_t len;
len = uip_datalen();
if(s.state == WEBCLIENT_STATE_STATUSLINE) {
len = parse_statusline(len);
}
if(s.state == WEBCLIENT_STATE_HEADERS && len > 0) {
len = parse_headers(len);
}
if(len > 0 && s.state == WEBCLIENT_STATE_DATA &&
s.httpflag != HTTPFLAG_MOVED) {
webclient_datahandler((char *)uip_appdata, len);
}
}
/*-----------------------------------------------------------------------------------*/
void
webclient_appcall(void)
{
if(uip_connected()) {
s.timer = 0;
s.state = WEBCLIENT_STATE_STATUSLINE;
senddata();
webclient_connected();
return;
}
if(s.state == WEBCLIENT_STATE_CLOSE) {
webclient_closed();
uip_abort();
return;
}
if(uip_aborted()) {
webclient_aborted();
}
if(uip_timedout()) {
webclient_timedout();
}
if(uip_acked()) {
s.timer = 0;
acked();
}
if(uip_newdata()) {
s.timer = 0;
newdata();
}
if(uip_rexmit() ||
uip_newdata() ||
uip_acked()) {
senddata();
} else if(uip_poll()) {
++s.timer;
if(s.timer == WEBCLIENT_TIMEOUT) {
webclient_timedout();
uip_abort();
return;
}
/* senddata();*/
}
if(uip_closed()) {
if(s.httpflag != HTTPFLAG_MOVED) {
/* Send NULL data to signal EOF. */
webclient_datahandler(NULL, 0);
} else {
if(resolv_lookup(s.host) == NULL) {
resolv_query(s.host);
}
webclient_get(s.host, s.port, s.file);
}
}
}
void webclient_datahandler(char *data, u16_t len)
{
}
void webclient_connected(void)
{
}
void webclient_timedout(void)
{
}
void webclient_aborted(void)
{
}
void webclient_closed(void)
{
}
/*-----------------------------------------------------------------------------------*/
/** @} */
/** @} */
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