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继续this question我问以下问题。反汇编HTTP响应（C）
我已经设法阅读和理解D.Shawley推荐的内容，并且我已经完成了大量工作。但是我又遇到了一个问题。我设法从HTTP响应中获取页面的Content-Length，但现在我遇到了获取HTTP响应头长度的一些问题。正如我从RFC 2616文档中所理解的那样，响应头可以在几个CRLF之前，并且必须跟一个或多个CRLF。现在，我在确定响应头的末尾时遇到了麻烦。
我已经与以下文件上来：
IEFDowner.h
/*
* IEFDowner.h
* Downer
*
* Created by ief2 on 2/08/10.
* Copyright 2010 ief2. All rights reserved.
*
* http://developerief2.site11.com
*
*/
#include <stdio.h> /* snprintf() */
#include <sys/socket.h> /* SOCKET */
#include <netdb.h> /* struct addrinfo */
#include <stdlib.h> /* exit() */
#include <string.h> /* memset(), strlen(), strcpy(), strstr() */
#include <errno.h> /* errno */
#include <unistd.h> /* close() */
enum _IEFDownerErrorType {
IEFNoError,
IEFGAIError, /* Use gai_strerror() to get the error message */
IEFConnectError, /* Failed to connect with the socket */
IEFSendError, /* Use strerror() to get the error message */
IEFReceiveError /* Error with recv() */
};
typedef enum _IEFDownerErrorType IEFDownerErrorType;
/*
Requests the data from the host at the given path thru the given protocol.
PAREMTERS
- host
The host to connect to.
- filepath
The path to the file which to download from the host.
- buffer
A buffer to fill with the received data
- maxSize
The maximum size of the buffer
- receivedBytes
The amount of received bytes
- errorType
The type of error received. See the header file for more info (enum _IEFDownerErrorType)
RETURN VALUE
The function returns 0 if it succeeded or another code if it failed.
*/
int
IEFDownerHTTPDownload(const char *host,
const char *filepath,
void *buffer,
unsigned long maxSize,
long *receivedBytes,
IEFDownerErrorType *errorType);
/*
Returns a pointer to a structure containing the IP4 or IP6 addresss.
PARAMETERS
- sa
A pointer to a structure of sockaddr.
RETURN VALUE
Returns a pointer to a structure of the type sockaddr_in or the type sockaddr_in6.
*/
void *
IEFDownerGetInAddr(struct sockaddr *sa);
/*
Gets the content-length information out of an HTTP response header.
PARAMETERS
- httpHeader
The null terminated response.
- contentLength
Upon return it contains the content length.
RETURN VALUE
The function returns 0 if it succeeded or -1 if it did not.
*/
int
IEFDownerGetContentLengthOfPage(const char *httpHeader,
int *contentLength);
/*
Gets the string lenth of the header information
PARAMETERS
- received
The received header
- headerSize
Upon return contains the header length
RETURN VALUE
The function returns 0 if it succeeded. If there was no header information found, it returns -1.
DISCUSSION
The header size includes the trailing CRLF's behind the header data.
All empty CRLF's are included until a non-empty line is met.
If there're zero empty lines after the first non empty line, the header information was not found.
*/
int
IEFDownerGetSizeOfHeader(const char *received,
int *headerSize);
IEFDowner.c
/*
* IEFDowner.c
* Downer
*
* Created by ief2 on 2/08/10.
* Copyright 2010 ief2. All rights reserved.
*
* http://developerief2.site11.com
*
*/
#include "IEFDowner.h"
int
IEFDownerHTTPDownload(const char *host, const char *filepath, void *buffer, unsigned long maxSize, long *rB, IEFDownerErrorType *errorType) {
int status; // contains returned statuses
int sockfd; // the socket file descriptor
struct addrinfo *infos; // linked list
struct addrinfo hints; // hints to getaddrinfo()
struct addrinfo *p; // used in the loop to get valid addrinfo
long receivedBytes; // the received bytes
unsigned requestLength; // the length of the request
char *request; // the http request
// GET ADDRESS INFO
// fill hints
memset(&hints, 0, sizeof(hints));
hints.ai_socktype = SOCK_STREAM;
hints.ai_flags = AI_PASSIVE;
hints.ai_family = AF_UNSPEC;
// getaddrinfo
status = getaddrinfo(host,
"80",
&hints,
&infos);
if(status != 0) {
if(errorType) *errorType = IEFGAIError;
return status;
}
// FIND FIRST VALID SOCKET
for(p = infos; p != NULL; p = p->ai_next) {
// create
sockfd = socket(p->ai_family,
p->ai_socktype,
p->ai_protocol);
if(sockfd == -1)
continue;
// try to connect
status = connect(sockfd,
p->ai_addr,
p->ai_addrlen);
if(status == -1) {
close(sockfd);
continue;
}
break;
}
// no valid socket found
if(p == NULL) {
if(errorType) *errorType = IEFConnectError;
return status;
}
// GET RID OF INFOS
freeaddrinfo(infos);
// SEND HTTP REQUEST
// calculate request length and make
requestLength = strlen("GET ") + strlen(filepath) + strlen(" HTTP\1.0\n") + strlen("Host: ") + strlen(host) + strlen(":80\n\n") + 1;
request = malloc(sizeof(char) * requestLength);
snprintf(request, requestLength, "GET %s HTTP\1.0\nHost: %s:80\n\n", filepath, host);
// send
status = send(sockfd,
request,
requestLength - 1,
0);
if(status == -1) {
if(errorType) *errorType = IEFSendError;
close(sockfd);
return errno;
}
// RECEIVE DATA
receivedBytes = recv(sockfd,
buffer,
maxSize,
0);
if(receivedBytes == -1 || receivedBytes == 0) {
if(errorType) *errorType = IEFReceiveError;
close(sockfd);
return receivedBytes;
}
// SET POINTERS
if(errorType) *errorType = IEFNoError;
if(rB) *rB = receivedBytes;
return 0;
}
void *
IEFDownerGetInAddr(struct sockaddr *sa) {
// IP4
if(sa->sa_family == AF_INET)
return &(((struct sockaddr_in *) sa)->sin_addr);
// IP6
return &(((struct sockaddr_in6 *) sa)->sin6_addr);
}
int
IEFDownerGetContentLengthOfPage(const char *httpHeader, int *contentLength) {
register int i;
int length;
char *next;
char *completeHeader;
char *header;
char *fieldName;
// MAKE HEADER MUTABLE
completeHeader = malloc(sizeof(char) * (strlen(httpHeader) + 1));
strcpy(completeHeader, httpHeader);
header = completeHeader;
// SEARCH FOR LINE
// loop for all lines
next = header;
do {
header = next;
// replace newline
next = strstr(header, "\n");
if(next == NULL) {
free(header);
return -1;
}
*next = '\0';
for(i = 0; i != strlen("\n"); i++)
next++;
} while (strcasestr(header, "Content-Length:") == NULL);
// SCAN INTEGER
fieldName = strcasestr(header, "Content-Length:");
for(i = 0; i != strlen("Content-Length:"); i++)
fieldName++;
sscanf(fieldName, "%d", &length);
if(contentLength) *contentLength = length;
free(completeHeader);
return 0;
}
int
IEFDownerGetSizeOfHeader(const char *received, int *headerSize) {
int length;
int receivedLength;
char *next;
char *completeHeader;
char *header;
char *checkChar;
int firstNonEmptyLineFound;
int emptiesFound;
// MAKE HEADER MUTABLE
completeHeader = malloc(sizeof(char) * (strlen(received) + 1));
strcpy(completeHeader, received);
header = completeHeader;
// SEARCH FOR FIRST NON EMPTY LINE
receivedLength = strlen(header);
firstNonEmptyLineFound = 0;
for(next = header; *next != (char)NULL; next++) {
printf("%c",*next);
if(*next != '\n' && *next != '\r') {
firstNonEmptyLineFound = 1;
printf("\nFirst Non Empty Found\n\n");
next++;
break;
}
}
if(firstNonEmptyLineFound == 0) {
free(completeHeader);
return -1;
}
// SEARCH FOR FIRST EMPTY LINE
emptiesFound = 0;
for(; *next != (char)NULL; next++) {
checkChar = next;
printf("%c", *checkChar);
if(*checkChar == '\n' || *checkChar == '\r') {
checkChar++;
printf("%c", *checkChar);
if(*checkChar == '\n' || *checkChar == '\r') {
emptiesFound = 1;
printf("Empty Line Found\n\n");
break;
}
}
}
if(emptiesFound == 0) {
free(completeHeader);
return -1;
}
// GET END OF HEADER
for(; *next != (char)NULL; next++) {
printf("%c", *next);
if(*next != '\n' && *next != '\r') {
printf("End of header found");
break;
}
}
// INSERT NULL
*next == '\0';
length = strlen(header);
if(headerSize) *headerSize = length;
free(completeHeader);
return 0;
}
的main.c
#include <stdio.h>
#include <stdarg.h>
#include "IEFDowner.h"
#define SERVERNAME "developerief2.site11.com"
#define PROTOCOL "80"
#define FILENAME "http://developerief2.site11.com/welcome/welcome.php"
#define MAXHEADERSIZE (1024*1024)
#define DESTFILE "/Users/ief2/Desktop/file.png"
void errorOut(int status, const char *format, ...);
int main (int argc, const char * argv[]) {
int status; // return status
void *headerData; // header data
int headerSize; // size of header
long rB; // received bytes
int pageSize; // size of bytes of page
// GET PAGE SIZE
// get data
headerData = malloc(1024);
status = IEFDownerHTTPDownload(SERVERNAME,
FILENAME,
(void *)headerData,
1024 - 1,
&rB, NULL);
if(status != 0)
errorOut(status, "An error occured while downloading header info\n");
// null terminate data
((char *)headerData)[rB] = '\0';
// get size
status = IEFDownerGetContentLengthOfPage((const char *)headerData, &pageSize);
if(status != 0)
errorOut(status, "An error occured while retreiving page size\n");
printf("Page Size: %d\n", pageSize);
printf("---------------------\n%s\n---------------------\n", headerData);
// CALCULATE HEADER SIZE
status = IEFDownerGetSizeOfHeader(headerData, &headerSize);
if(status != 0)
errorOut(status, "An error occured while getting the header size\n");
printf("Header Size: %d\n", headerSize);
return 0;
}
void errorOut(int status, const char *format, ...) {
va_list args;
va_start(args, format);
vfprintf(stderr, format, args);
va_end(args);
exit(status);
}
我得到的结果是不正确的。我得到了响应的结束已经是第一个行后：
[Session started at 2010-08-03 21:32:47 +0000.]
Page Size: 3600
---------------------
HTTP/1.1 200 OK
Date: Tue, 03 Aug 2010 19:32:44 GMT
Server: Apache
X-Powered-By: PHP/5.2.11
Content-Length: 3600
Connection: close
Content-Type: text/html
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xml:lang="en">
<!-- HEAD -->
<head>
<meta http-equiv="Content-type" content="text/html; charset=utf-16" />
<meta name="description" content="A site containing quality freeware for Mac OS X Tiger and newer. All applications are made by a 14 year old developer who masters AppleScript Studio, Objective-C, HTML, PHP, CSS and JavaScript." />
<meta name="keywords" content="free, freeware, mac os x, 10, tiger, leopard, mac os x, young, developer, freeware, AppleScript, Studio, Xcode, Objective-C, Cocoa" />
<title>Free OSX Software :: Welcome</title>
<!-- Shared Styles -->
<link rel="stylesheet" href="../site-style/styles.css" type="text/css" media="screen" title="no title" charset="utf-8" />
</head>
<!-- PAGE CONTENTS -->
<body>
---------------------
H
First Non Empty Found
TTP/1.1 200 OK
Empty Line Found
DEnd of header foundHeader Size: 1023
The Debugger has exited with status 0.
我希望有人能帮助我， ief2