ftplib源码剖析
ftplib是一组例程实现FTP协议。他们允许应用程序创建和访问远程文件通过函数调用,而不是需要叉和执行一个交互式的ftp客户端程序。
ftplib已经在Linux上构建和测试(X86)、Mac os x和OpenVMS(AXP)。
很快:我正在使用autotools版本。这应该是释放不久。
以上是ftplib官网上的说明文字。。(FTP官网链接，可以下载代码：http://www.nbpfaus.net/~pfau/ftplib/)
ftplib是一个小巧的实现FTP协议的一组例程，里面包含了关于FTP各种操作的函数。阅读代码，不仅可以了解一下FTP的具体工作原理，还可以看一下FTP网络编程相关的知识，可谓一举两得。OK，闲话少说，还是直接上代码比较实在
关于FTP的原理说明及FTP的应代码的介绍请参考：计算机网络中关于FTP的介绍和 FTP应答码
我用的是ftplib-4.0的版本，下载链接：http://download.csdn.net/detail/u012796139/8877857
代码结构说明
ftplib代码量比较小(总共也就1500行左右代码)，主要有2个函数构成，ftplib.c和ftplib.h文件，还有一个测试程序qftp.c文件。
其中，ftplib最主要的一个结构就是NetBuf结构体了，它是ftplib的整个操作核心，包括了一下FTP相关的操作成员等，如下：
struct NetBuf {
char *cput,*cget; /* cput和cget指向该buf的接收缓冲区 */
int handle; /* 待处理的文件描述符(比如在handle上设置的select I/O复用) */
int cavail,cleft; /* cavail 可用的字节数，*/
char *buf; /* 读写缓冲区 */
int dir; /* 表明执行的操作，比如write操作时，dir为FTPLIB_WRITE，read操作时，dir为FTPLIB_READ*/
netbuf *ctrl; /* 指向控制连接的netbuf */
netbuf *data; /* 指向数据连接的netbuf */
int cmode; /* connection mode 连接模式 可选值：FTPLIB_PASSIVE(被动传输模式) FTPLIB_PORT(主动传输模式) */
struct timeval idletime; /* IO复用函数的超时时间，暂时看到select用到了 */
FtpCallback idlecb; /* 回调函数，用于IO复用函数的等待 */
void *idlearg; /* 传递给idlecb回调函数的参数 */
unsigned long int xfered;
unsigned long int cbbytes; /* 回调函数传输的字节数 */
unsigned long int xfered1;
char response[RESPONSE_BUFSIZ]; /* 存放服务器的应答数据*/
};FTP的控制操作有两个连接，一个是控制连接，负责命令的传输；另一个是数据连接，负责数据的收发等，比如上传下载等就是走的数据连接。
源代码分析
下面是ftplib.h头文件
/***************************************************************************/
/* */
/* ftplib.h - header file for callable ftp access routines */
/* Copyright (C) 1996-2001, 2013 Thomas Pfau, [email protected] */
/* 1407 Thomas Ave, North Brunswick, NJ, 08902 */
/* */
/* This library is free software. You can redistribute it and/or */
/* modify it under the terms of the Artistic License 2.0. */
/* */
/* This library is distributed in the hope that it will be useful, */
/* but WITHOUT ANY WARRANTY; without even the implied warranty of */
/* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the */
/* Artistic License 2.0 for more details. */
/* */
/* See the file LICENSE or */
/* http://www.perlfoundation.org/artistic_license_2_0 */
/* */
/***************************************************************************/
#if !defined(__FTPLIB_H)
#define __FTPLIB_H
#if defined(__unix__) || defined(VMS)
#define GLOBALDEF
#define GLOBALREF extern
#elif defined(_WIN32)
#if defined BUILDING_LIBRARY
#define GLOBALDEF __declspec(dllexport)
#define GLOBALREF __declspec(dllexport)
#else
#define GLOBALREF __declspec(dllimport)
#endif
#endif
#include
#include
/* FtpAccess() type codes */
#define FTPLIB_DIR 1
#define FTPLIB_DIR_VERBOSE 2
#define FTPLIB_FILE_READ 3
#define FTPLIB_FILE_WRITE 4
/* FtpAccess() mode codes */
#define FTPLIB_ASCII 'A'
#define FTPLIB_IMAGE 'I'
#define FTPLIB_TEXT FTPLIB_ASCII
#define FTPLIB_BINARY FTPLIB_IMAGE
/* connection modes */
#define FTPLIB_PASSIVE 1
#define FTPLIB_PORT 2
/* connection option names */
#define FTPLIB_CONNMODE 1
#define FTPLIB_CALLBACK 2
#define FTPLIB_IDLETIME 3
#define FTPLIB_CALLBACKARG 4
#define FTPLIB_CALLBACKBYTES 5
#ifdef __cplusplus
extern "C" {
#endif
#if defined(__UINT64_MAX)
typedef uint64_t fsz_t;
#else
typedef uint32_t fsz_t;
#endif
typedef struct NetBuf netbuf;
typedef int (*FtpCallback)(netbuf *nControl, fsz_t xfered, void *arg);
typedef struct FtpCallbackOptions {
FtpCallback cbFunc; /* function to call */
void *cbArg; /* argument to pass to function */
unsigned int bytesXferred; /* callback if this number of bytes transferred */
unsigned int idleTime; /* callback if this many milliseconds have elapsed */
} FtpCallbackOptions;
GLOBALREF int ftplib_debug;
GLOBALREF void FtpInit(void);
GLOBALREF char *FtpLastResponse(netbuf *nControl);
GLOBALREF int FtpConnect(const char *host, netbuf **nControl);
GLOBALREF int FtpOptions(int opt, long val, netbuf *nControl);
GLOBALREF int FtpSetCallback(const FtpCallbackOptions *opt, netbuf *nControl);
GLOBALREF int FtpClearCallback(netbuf *nControl);
GLOBALREF int FtpLogin(const char *user, const char *pass, netbuf *nControl);
GLOBALREF int FtpAccess(const char *path, int typ, int mode, netbuf *nControl,
netbuf **nData);
GLOBALREF int FtpRead(void *buf, int max, netbuf *nData);
GLOBALREF int FtpWrite(const void *buf, int len, netbuf *nData);
GLOBALREF int FtpClose(netbuf *nData);
GLOBALREF int FtpSite(const char *cmd, netbuf *nControl);
GLOBALREF int FtpSysType(char *buf, int max, netbuf *nControl);
GLOBALREF int FtpMkdir(const char *path, netbuf *nControl);
GLOBALREF int FtpChdir(const char *path, netbuf *nControl);
GLOBALREF int FtpCDUp(netbuf *nControl);
GLOBALREF int FtpRmdir(const char *path, netbuf *nControl);
GLOBALREF int FtpPwd(char *path, int max, netbuf *nControl);
GLOBALREF int FtpNlst(const char *output, const char *path, netbuf *nControl);
GLOBALREF int FtpDir(const char *output, const char *path, netbuf *nControl);
GLOBALREF int FtpSize(const char *path, unsigned int *size, char mode, netbuf *nControl);
#if defined(__UINT64_MAX)
GLOBALREF int FtpSizeLong(const char *path, fsz_t *size, char mode, netbuf *nControl);
#endif
GLOBALREF int FtpModDate(const char *path, char *dt, int max, netbuf *nControl);
GLOBALREF int FtpGet(const char *output, const char *path, char mode,
netbuf *nControl);
GLOBALREF int FtpPut(const char *input, const char *path, char mode,
netbuf *nControl);
GLOBALREF int FtpRename(const char *src, const char *dst, netbuf *nControl);
GLOBALREF int FtpDelete(const char *fnm, netbuf *nControl);
GLOBALREF void FtpQuit(netbuf *nControl);
#ifdef __cplusplus
};
#endif
#endif /* __FTPLIB_H */
下面是ftplib.c文件
/***************************************************************************/
/* */
/* ftplib.c - callable ftp access routines */
/* Copyright (C) 1996-2001, 2013 Thomas Pfau, [email protected] */
/* 1407 Thomas Ave, North Brunswick, NJ, 08902 */
/* */
/* This library is free software. You can redistribute it and/or */
/* modify it under the terms of the Artistic License 2.0. */
/* */
/* This library is distributed in the hope that it will be useful, */
/* but WITHOUT ANY WARRANTY; without even the implied warranty of */
/* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the */
/* Artistic License 2.0 for more details. */
/* */
/* See the file LICENSE or */
/* http://www.perlfoundation.org/artistic_license_2_0 */
/* */
/***************************************************************************/
#if defined(__unix__) || defined(__VMS)
#include
#endif
#if defined(_WIN32)
#include
#endif
#include
#include
#include
#include
#include
#if defined(__unix__)
#include
#include
#include
#include
#include
#include
#elif defined(VMS)
#include
#include
#include
#include
#include
#elif defined(_WIN32)
#include
#endif
#if defined(__APPLE__)
#undef _REENTRANT
#endif
#define BUILDING_LIBRARY
#include "ftplib.h"
#if defined(__UINT64_MAX) && !defined(PRIu64)
#if ULONG_MAX == __UINT32_MAX
#define PRIu64 "llu"
#else
#define PRIu64 "lu"
#endif
#endif
#if defined(_WIN32)
#define SETSOCKOPT_OPTVAL_TYPE (const char *)
#else
#define SETSOCKOPT_OPTVAL_TYPE (void *)
#endif
#define FTPLIB_BUFSIZ 8192
#define RESPONSE_BUFSIZ 1024
#define TMP_BUFSIZ 1024
#define ACCEPT_TIMEOUT 30
#define FTPLIB_CONTROL 0
#define FTPLIB_READ 1
#define FTPLIB_WRITE 2
#if !defined FTPLIB_DEFMODE
#define FTPLIB_DEFMODE FTPLIB_PASSIVE
#endif
struct NetBuf {
char *cput,*cget; /* cput和cget指向该buf的接收缓冲区 */
int handle; /* 待处理的文件描述符(比如在handle上设置的select I/O复用) */
int cavail,cleft; /* cavail 可用的字节数，*/
char *buf; /* 读写缓冲区 */
int dir; /* 表明执行的操作，比如write操作时，dir为FTPLIB_WRITE，read操作时，dir为FTPLIB_READ*/
netbuf *ctrl; /* 指向控制连接的netbuf */
netbuf *data; /* 指向数据连接的netbuf */
int cmode; /* connection mode 连接模式 可选值：FTPLIB_PASSIVE(被动传输模式) FTPLIB_PORT(主动传输模式) */
struct timeval idletime; /* IO复用函数的超时时间，暂时看到select用到了 */
FtpCallback idlecb; /* 回调函数，用于IO复用函数的等待 */
void *idlearg; /* 传递给idlecb回调函数的参数 */
unsigned long int xfered;
unsigned long int cbbytes; /* 回调函数传输的字节数 */
unsigned long int xfered1;
char response[RESPONSE_BUFSIZ]; /* 存放服务器的应答数据*/
};
static char *version =
"ftplib Release 4.0 07-Jun-2013, copyright 1996-2003, 2013 Thomas Pfau";
GLOBALDEF int ftplib_debug = 0;
#if defined(__unix__) || defined(VMS)
int net_read(int fd, char *buf, size_t len)
{
while ( 1 )
{
int c = read(fd, buf, len);
if ( c == -1 )
{
if ( errno != EINTR && errno != EAGAIN )
return -1;
}
else
{
return c;
}
}
}
int net_write(int fd, const char *buf, size_t len)
{
int done = 0;
while ( len > 0 )
{
int c = write( fd, buf, len );
if ( c == -1 )
{
if ( errno != EINTR && errno != EAGAIN )
return -1;
}
else if ( c == 0 )
{
return done;
}
else
{
buf += c;
done += c;
len -= c;
}
}
return done;
}
#define net_close close
#elif defined(_WIN32)
#define net_read(x,y,z) recv(x,y,z,0)
#define net_write(x,y,z) send(x,y,z,0)
#define net_close closesocket
#endif
#if defined(NEED_MEMCCPY)
/*
* VAX C does not supply a memccpy routine so I provide my own
* 从src中赋值以c结尾的字符串，赋值的最大字节数为n
*/
void *memccpy(void *dest, const void *src, int c, size_t n)
{
int i=0;
const unsigned char *ip=src;
unsigned char *op=dest;
while (i < n)
{
if ((*op++ = *ip++) == c)
break;
i++;
}
if (i == n)
return NULL; /* 此时src的前n个字符中没有字符c */
return op;
}
#endif
#if defined(NEED_STRDUP)
/*
* strdup - return a malloc'ed copy of a string
*/
char *strdup(const char *src)
{
int l = strlen(src) + 1;
char *dst = malloc(l);
if (dst)
strcpy(dst,src);
return dst;
}
#endif
/*
* socket_wait - wait for socket to receive or flush data
*
* return 1 if no user callback, otherwise, return value returned by
* user callback
* 等待socket就绪，就绪时返回1，否则返回0
*/
static int socket_wait(netbuf *ctl)
{
fd_set fd,*rfd = NULL,*wfd = NULL;
struct timeval tv;
int rv = 0;
if ((ctl->dir == FTPLIB_CONTROL) || (ctl->idlecb == NULL))
return 1;
if (ctl->dir == FTPLIB_WRITE)
wfd = &fd;
else
rfd = &fd;
FD_ZERO(&fd);
do
{
FD_SET(ctl->handle,&fd);
tv = ctl->idletime; /* 设定select的超时时间 */
rv = select(ctl->handle+1, rfd, wfd, NULL, &tv);
if (rv == -1)
{
rv = 0;
strncpy(ctl->ctrl->response, strerror(errno),
sizeof(ctl->ctrl->response)); /* 这个地方问什么把错误信息复制到了ctl->ctrl->response中?*/
break;
}
else if (rv > 0)
{
rv = 1; /* 为什么再把rv赋值为1呢，因为fd中只有一个文件描述符被监听，所以select最大也就返回1 */
break;
}
}while ((rv = ctl->idlecb(ctl, ctl->xfered, ctl->idlearg))); /* 设置的idlecb回调函数 */
return rv;
}
/*
* read a line of text
* return -1 on error or bytecount
* ctl->handle存放的是文件描述符
* 当ctrl->buf中的数据够读时，直接复制到buf中，否则调用net_read进行读取操作
*/
static int readline(char *buf,int max,netbuf *ctl)
{
int x,retval = 0;
char *end,*bp=buf;
int eof = 0;
if ((ctl->dir != FTPLIB_CONTROL) && (ctl->dir != FTPLIB_READ))
return -1;
if (max == 0)
return 0;
do
{
if (ctl->cavail > 0)
{
x = (max >= ctl->cavail) ? ctl->cavail : max-1;
end = memccpy(bp,ctl->cget,'\n',x);
if (end != NULL)
x = end - bp;
retval += x;
bp += x;
*bp = '\0';
max -= x;
ctl->cget += x; /* 已经读取了x字节数据 */
ctl->cavail -= x;
if (end != NULL)
{
bp -= 2;
if (strcmp(bp,"\r\n") == 0) /* 把buf中最后两个字节为\r\n，改为 \n\0 */
{
*bp++ = '\n';
*bp++ = '\0';
--retval;
}
break;
}
}
if (max == 1) /* max=1说明buf中已容不下输入缓冲区中的一行数据，直接返回，buf数组中最后一位必须存'\0' */
{
*buf = '\0';
break;
}
if (ctl->cput == ctl->cget) /* 该条件什么时候成立，参考FtpConnect函数中的ctrl = calloc(1,sizeof(netbuf));*/
{
ctl->cput = ctl->cget = ctl->buf;
ctl->cavail = 0;
ctl->cleft = FTPLIB_BUFSIZ;
}
if (eof)
{
if (retval == 0)
retval = -1;
break;
}
if (!socket_wait(ctl))
return retval;
if ((x = net_read(ctl->handle,ctl->cput,ctl->cleft)) == -1)
{
if (ftplib_debug)
perror("read");
retval = -1;
break;
}
if (x == 0) /* net_read返回为0 */
eof = 1;
ctl->cleft -= x;
ctl->cavail += x;
ctl->cput += x;
}
while (1);
return retval;
}
/*
* write lines of text
* return -1 on error or bytecount
* 写一行数据到dData->handler(文件描述符)
*/
static int writeline(const char *buf, int len, netbuf *nData)
{
int x, nb=0, w;
const char *ubp = buf;
char *nbp;
char lc=0;
if (nData->dir != FTPLIB_WRITE)
return -1;
nbp = nData->buf;
for (x=0; x < len; x++)
{
if ((*ubp == '\n') && (lc != '\r'))
{
if (nb == FTPLIB_BUFSIZ)
{
if (!socket_wait(nData))
return x;
w = net_write(nData->handle, nbp, FTPLIB_BUFSIZ);
if (w != FTPLIB_BUFSIZ)
{
if (ftplib_debug)
printf("net_write(1) returned %d, errno = %d\n", w, errno);
return(-1);
}
nb = 0;
}
nbp[nb++] = '\r';
}
if (nb == FTPLIB_BUFSIZ) /* 如果nData->buf已满，则发送出去 */
{
if (!socket_wait(nData))
return x;
w = net_write(nData->handle, nbp, FTPLIB_BUFSIZ);
if (w != FTPLIB_BUFSIZ)
{
if (ftplib_debug)
printf("net_write(2) returned %d, errno = %d\n", w, errno);
return(-1);
}
nb = 0;
}
nbp[nb++] = lc = *ubp++;
}
if (nb)
{
if (!socket_wait(nData))
return x;
w = net_write(nData->handle, nbp, nb);
if (w != nb)
{
if (ftplib_debug)
printf("net_write(3) returned %d, errno = %d\n", w, errno);
return(-1);
}
}
return len;
}
/*
* read a response from the server
* return 0 if first char doesn't match
* return 1 if first char matches
* 如果应答数据的第一个字符是c的话，返回1，否则返回0
*/
static int readresp(char c, netbuf *nControl)
{
char match[5];
if (readline(nControl->response,RESPONSE_BUFSIZ,nControl) == -1)
{
if (ftplib_debug)
perror("Control socket read failed");
return 0;
}
if (ftplib_debug > 1)
fprintf(stderr,"%s",nControl->response);
if (nControl->response[3] == '-') /* 这个条件很少达到 */
{
strncpy(match,nControl->response,3);
match[3] = ' ';
match[4] = '\0';
do
{
if (readline(nControl->response,RESPONSE_BUFSIZ,nControl) == -1)
{
if (ftplib_debug)
perror("Control socket read failed");
return 0;
}
if (ftplib_debug > 1)
fprintf(stderr,"%s",nControl->response);
}
while (strncmp(nControl->response,match,4));
}
if (nControl->response[0] == c)
return 1;
return 0;
}
/*
* FtpInit for stupid operating systems that require it (Windows NT)
* 该函数只有在windows NT中需要首先调用
*/
GLOBALDEF void FtpInit(void)
{
#if defined(_WIN32)
WORD wVersionRequested;
WSADATA wsadata;
int err;
wVersionRequested = MAKEWORD(1,1);
if ((err = WSAStartup(wVersionRequested,&wsadata)) != 0)
fprintf(stderr,"Network failed to start: %d\n",err);
#endif
}
/*
* FtpLastResponse - return a pointer to the last response received
* 返回最后一次接收到的服务器应答数据，数据存放在nControl->response中
*/
GLOBALDEF char *FtpLastResponse(netbuf *nControl)
{
if ((nControl) && (nControl->dir == FTPLIB_CONTROL))
return nControl->response;
return NULL;
}
/*
* FtpConnect - connect to remote server
* return 1 if connected, 0 if not
* 与ftp server进行连接，host存放主机名
*/
GLOBALDEF int FtpConnect(const char *host, netbuf **nControl)
{
int sControl;
struct sockaddr_in sin;
int on=1;
netbuf *ctrl;
char *lhost;
char *pnum;
memset(&sin,0,sizeof(sin));
sin.sin_family = AF_INET;
lhost = strdup(host);
pnum = strchr(lhost,':');
if (pnum == NULL) /* lhost中不包含':' */
pnum = "ftp";
else
*pnum++ = '\0';
if (isdigit(*pnum))
sin.sin_port = htons(atoi(pnum));
else
{
/* 未输入端口号时，获取主机信息，然后 */
struct servent *pse;
#if _REENTRANT /* 如果是可重入函数 */
struct servent se;
char tmpbuf[TMP_BUFSIZ];
int i;
if ( ( i = getservbyname_r(pnum,"tcp",&se,tmpbuf,TMP_BUFSIZ,&pse) ) != 0 )
{
errno = i;
if ( ftplib_debug )
perror("getservbyname_r");
free(lhost);
return 0;
}
#else
if ((pse = getservbyname(pnum,"tcp") ) == NULL )
{
if ( ftplib_debug )
perror("getservbyname");
free(lhost); /* 释放strdup申请的内存空间 */
return 0;
}
#endif
sin.sin_port = pse->s_port; /* 该端口号默认为21，里面存放的为21的网络序 */
}
if ((sin.sin_addr.s_addr = inet_addr(lhost)) == INADDR_NONE)
{
struct hostent *phe;
#ifdef _REENTRANT
struct hostent he;
char tmpbuf[TMP_BUFSIZ];
int i, herr;
if ( ( i = gethostbyname_r( lhost, &he, tmpbuf, TMP_BUFSIZ, &phe, &herr ) ) != 0 )
{
if ( ftplib_debug )
fprintf(stderr, "gethostbyname: %s\n", hstrerror(herr));
free(lhost);
return 0;
}
#else
if ((phe = gethostbyname(lhost)) == NULL) /* 获取server主机信息 */
{
if (ftplib_debug)
fprintf(stderr, "gethostbyname: %s\n", hstrerror(h_errno));
free(lhost);
return 0;
}
#endif
memcpy((char *)&sin.sin_addr, phe->h_addr, phe->h_length);
}
free(lhost);
sControl = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
if (sControl == -1)
{
if (ftplib_debug)
perror("socket");
return 0;
}
/* 端口可重用 */
if (setsockopt(sControl,SOL_SOCKET,SO_REUSEADDR,
SETSOCKOPT_OPTVAL_TYPE &on, sizeof(on)) == -1)
{
if (ftplib_debug)
perror("setsockopt");
net_close(sControl);
return 0;
}
if (connect(sControl, (struct sockaddr *)&sin, sizeof(sin)) == -1)
{
if (ftplib_debug)
perror("connect");
net_close(sControl);
return 0;
}
ctrl = calloc(1,sizeof(netbuf)); /* 分配内存并初始化为0，*/
if (ctrl == NULL)
{
if (ftplib_debug)
perror("calloc");
net_close(sControl);
return 0;
}
ctrl->buf = malloc(FTPLIB_BUFSIZ);
if (ctrl->buf == NULL)
{
if (ftplib_debug)
perror("calloc");
net_close(sControl);
free(ctrl);
return 0;
}
ctrl->handle = sControl;
ctrl->dir = FTPLIB_CONTROL;
ctrl->ctrl = NULL;
ctrl->cmode = FTPLIB_DEFMODE;
ctrl->idlecb = NULL;
ctrl->idletime.tv_sec = ctrl->idletime.tv_usec = 0;
ctrl->idlearg = NULL;
ctrl->xfered = 0;
ctrl->xfered1 = 0;
ctrl->cbbytes = 0; /* ctrl中的其余变量都已经初始化为0了，ctrl执行的内存使用calloc分配的 */
/* 如果应答开头是'2'，表示命令成功
* FTP应答码: http://t175010415.blog.163.com/blog/static/1317066342012111914836972/
*/
if (readresp('2', ctrl) == 0)
{
net_close(sControl);
free(ctrl->buf);
free(ctrl);
return 0;
}
*nControl = ctrl;
return 1;
}
/*
* 创建和清除回调函数
*/
GLOBALDEF int FtpSetCallback(const FtpCallbackOptions *opt, netbuf *nControl)
{
nControl->idlecb = opt->cbFunc;
nControl->idlearg = opt->cbArg;
nControl->idletime.tv_sec = opt->idleTime / 1000;
nControl->idletime.tv_usec = (opt->idleTime % 1000) * 1000;
nControl->cbbytes = opt->bytesXferred;
return 1;
}
GLOBALDEF int FtpClearCallback(netbuf *nControl)
{
nControl->idlecb = NULL;
nControl->idlearg = NULL;
nControl->idletime.tv_sec = 0;
nControl->idletime.tv_usec = 0;
nControl->cbbytes = 0;
return 1;
}
/*
* FtpOptions - change connection options
* returns 1 if successful, 0 on error
*/
GLOBALDEF int FtpOptions(int opt, long val, netbuf *nControl)
{
int v,rv=0;
/* 根据opt的不同更改netbuf中不同的成员变量 */
switch (opt)
{
case FTPLIB_CONNMODE:
v = (int) val;
if ((v == FTPLIB_PASSIVE) || (v == FTPLIB_PORT))
{
nControl->cmode = v;
rv = 1;
}
break;
case FTPLIB_CALLBACK: /* 以下几个选项不建议修改 */
nControl->idlecb = (FtpCallback) val;
rv = 1;
break;
case FTPLIB_IDLETIME:
v = (int) val;
rv = 1;
nControl->idletime.tv_sec = v / 1000;
nControl->idletime.tv_usec = (v % 1000) * 1000;
break;
case FTPLIB_CALLBACKARG: /* 更改回调函数参数 */
rv = 1;
nControl->idlearg = (void *) val;
break;
case FTPLIB_CALLBACKBYTES:
rv = 1;
nControl->cbbytes = (int) val;
break;
}
return rv;
}
/*
* FtpSendCmd - send a command and wait for expected response
* return 1 if proper response received, 0 otherwise
* 发送命令 FTP应答码: http://t175010415.blog.163.com/blog/static/1317066342012111914836972/
*/
static int FtpSendCmd(const char *cmd, char expresp, netbuf *nControl)
{
char buf[TMP_BUFSIZ];
if (nControl->dir != FTPLIB_CONTROL)
return 0;
if (ftplib_debug > 2)
fprintf(stderr,"%s\n",cmd);
if ((strlen(cmd) + 3) > sizeof(buf))
return 0;
sprintf(buf,"%s\r\n",cmd);
if (net_write(nControl->handle,buf,strlen(buf)) <= 0)
{
if (ftplib_debug)
perror("write");
return 0;
}
return readresp(expresp, nControl);
}
/*
* FtpLogin - log in to remote server
* return 1 if logged in, 0 otherwise
* ftp登陆函数，需要输入用户名和密码
*/
GLOBALDEF int FtpLogin(const char *user, const char *pass, netbuf *nControl)
{
char tempbuf[64];
if (((strlen(user) + 7) > sizeof(tempbuf)) ||
((strlen(pass) + 7) > sizeof(tempbuf)))
return 0;
sprintf(tempbuf,"USER %s",user);
if (!FtpSendCmd(tempbuf,'3',nControl)) /* 应答码第一位不是3的话，表示不需要密码 */
{
if (nControl->response[0] == '2')
return 1;
return 0;
}
sprintf(tempbuf,"PASS %s",pass);
return FtpSendCmd(tempbuf,'2',nControl);
}
/*
* FtpOpenPort - set up data connection
* return 1 if successful, 0 otherwise
* 打开一个端口，在passive模式下与ftp server进行connect
* 在主动模式下等待ftp server的connect
*/
static int FtpOpenPort(netbuf *nControl, netbuf **nData, int mode, int dir)
{
int sData;
union {
struct sockaddr sa;
struct sockaddr_in in;
} sin;
struct linger lng = { 0, 0 };
unsigned int l;
int on=1;
netbuf *ctrl;
char *cp;
unsigned int v[6];
char buf[TMP_BUFSIZ];
if (nControl->dir != FTPLIB_CONTROL)
return -1;
if ((dir != FTPLIB_READ) && (dir != FTPLIB_WRITE))
{
sprintf(nControl->response, "Invalid direction %d\n", dir);
return -1;
}
if ((mode != FTPLIB_ASCII) && (mode != FTPLIB_IMAGE))
{
sprintf(nControl->response, "Invalid mode %c\n", mode);
return -1;
}
l = sizeof(sin);
if (nControl->cmode == FTPLIB_PASSIVE) /* 使用被动模式进行数据传输 */
{
memset(&sin, 0, l);
sin.in.sin_family = AF_INET;
if (!FtpSendCmd("PASV",'2',nControl)) /* 进入被动模式，FTP服务器在指定的端口进行监听 */
return -1;
cp = strchr(nControl->response,'(');
if (cp == NULL)
return -1;
cp++;
sscanf(cp,"%u,%u,%u,%u,%u,%u",&v[2],&v[3],&v[4],&v[5],&v[0],&v[1]);
sin.sa.sa_data[2] = v[2];
sin.sa.sa_data[3] = v[3];
sin.sa.sa_data[4] = v[4];
sin.sa.sa_data[5] = v[5]; /* 以上4个存放的是IP地址 */
sin.sa.sa_data[0] = v[0];
sin.sa.sa_data[1] = v[1]; /* 以上2个存放的是端口号 */
}
else
{
if (getsockname(nControl->handle, &sin.sa, &l) < 0) /* 获取sockfd对应的本端socket地址 */
{
if (ftplib_debug)
perror("getsockname");
return -1;
}
}
sData = socket(PF_INET,SOCK_STREAM,IPPROTO_TCP);
if (sData == -1)
{
if (ftplib_debug)
perror("socket");
return -1;
}
/* 设置socket可重用 */
if (setsockopt(sData,SOL_SOCKET,SO_REUSEADDR,
SETSOCKOPT_OPTVAL_TYPE &on,sizeof(on)) == -1)
{
if (ftplib_debug)
perror("setsockopt");
net_close(sData);
return -1;
}
/* SO_LINGER若有数据发送，则延迟关闭 */
if (setsockopt(sData,SOL_SOCKET,SO_LINGER,
SETSOCKOPT_OPTVAL_TYPE &lng,sizeof(lng)) == -1)
{
if (ftplib_debug)
perror("setsockopt");
net_close(sData);
return -1;
}
if (nControl->cmode == FTPLIB_PASSIVE) /* 被动模式，client主动连接FTP server */
{
if (connect(sData, &sin.sa, sizeof(sin.sa)) == -1)
{
if (ftplib_debug)
perror("connect");
net_close(sData);
return -1;
}
}
else /* 主动模式 */
{
sin.in.sin_port = 0;
if (bind(sData, &sin.sa, sizeof(sin)) == -1)
{
if (ftplib_debug)
perror("bind");
net_close(sData);
return -1;
}
if (listen(sData, 1) < 0)
{
if (ftplib_debug)
perror("listen");
net_close(sData);
return -1;
}
if (getsockname(sData, &sin.sa, &l) < 0)
return -1;
sprintf(buf, "PORT %d,%d,%d,%d,%d,%d",
(unsigned char) sin.sa.sa_data[2],
(unsigned char) sin.sa.sa_data[3],
(unsigned char) sin.sa.sa_data[4],
(unsigned char) sin.sa.sa_data[5],
(unsigned char) sin.sa.sa_data[0],
(unsigned char) sin.sa.sa_data[1]);
if (!FtpSendCmd(buf,'2',nControl))
{
net_close(sData);
return -1;
}
}
ctrl = calloc(1,sizeof(netbuf));
if (ctrl == NULL)
{
if (ftplib_debug)
perror("calloc");
net_close(sData);
return -1;
}
if ((mode == 'A') && ((ctrl->buf = malloc(FTPLIB_BUFSIZ)) == NULL))
{
if (ftplib_debug)
perror("calloc");
net_close(sData);
free(ctrl);
return -1;
}
ctrl->handle = sData; /* sData 是监听描述符 */
ctrl->dir = dir;
ctrl->idletime = nControl->idletime;
ctrl->idlearg = nControl->idlearg;
ctrl->xfered = 0;
ctrl->xfered1 = 0;
ctrl->cbbytes = nControl->cbbytes;
if (ctrl->idletime.tv_sec || ctrl->idletime.tv_usec || ctrl->cbbytes)
ctrl->idlecb = nControl->idlecb;
else
ctrl->idlecb = NULL;
*nData = ctrl;
return 1;
}
/*
* FtpAcceptConnection - accept connection from server
* return 1 if successful, 0 otherwise
* 此函数是在被动模式下调用的
*/
static int FtpAcceptConnection(netbuf *nData, netbuf *nControl)
{
int sData;
struct sockaddr addr;
unsigned int l;
int i;
struct timeval tv;
fd_set mask;
int rv;
FD_ZERO(&mask);
FD_SET(nControl->handle, &mask);
FD_SET(nData->handle, &mask);
tv.tv_usec = 0;
tv.tv_sec = ACCEPT_TIMEOUT;
i = nControl->handle;
if (i < nData->handle)
i = nData->handle;
i = select(i+1, &mask, NULL, NULL, &tv);
if (i == -1)
{
strncpy(nControl->response, strerror(errno),
sizeof(nControl->response));
net_close(nData->handle);
nData->handle = 0;
rv = 0;
}
else if (i == 0)
{
strcpy(nControl->response, "timed out waiting for connection");
net_close(nData->handle);
nData->handle = 0;
rv = 0;
}
else
{
if (FD_ISSET(nData->handle, &mask))
{
l = sizeof(addr);
sData = accept(nData->handle, &addr, &l);
i = errno;
net_close(nData->handle);
if (sData > 0)
{
rv = 1;
nData->handle = sData;
}
else
{
strncpy(nControl->response, strerror(i),
sizeof(nControl->response));
nData->handle = 0;
rv = 0;
}
}
else if (FD_ISSET(nControl->handle, &mask))
{
net_close(nData->handle);
nData->handle = 0;
readresp('2', nControl);
rv = 0;
}
}
return rv;
}
/*
* FtpAccess - return a handle for a data stream
* return 1 if successful, 0 otherwise
* mode: 设置传输的文件类型 'A'/'I'
*/
GLOBALDEF int FtpAccess(const char *path, int typ, int mode, netbuf *nControl,
netbuf **nData)
{
char buf[TMP_BUFSIZ];
int dir;
if ((path == NULL) &&
((typ == FTPLIB_FILE_WRITE) || (typ == FTPLIB_FILE_READ)))
{
sprintf(nControl->response,
"Missing path argument for file transfer\n");
return 0;
}
sprintf(buf, "TYPE %c", mode);
if (!FtpSendCmd(buf, '2', nControl))
return 0;
switch (typ)
{
case FTPLIB_DIR:
strcpy(buf,"NLST");
dir = FTPLIB_READ;
break;
case FTPLIB_DIR_VERBOSE:
strcpy(buf,"LIST");
dir = FTPLIB_READ;
break;
case FTPLIB_FILE_READ:
strcpy(buf,"RETR");
dir = FTPLIB_READ;
break;
case FTPLIB_FILE_WRITE:
strcpy(buf,"STOR");
dir = FTPLIB_WRITE;
break;
default:
sprintf(nControl->response, "Invalid open type %d\n", typ);
return 0;
}
if (path != NULL)
{
int i = strlen(buf);
buf[i++] = ' ';
if ((strlen(path) + i + 1) >= sizeof(buf))
return 0;
strcpy(&buf[i],path);
}
if (FtpOpenPort(nControl, nData, mode, dir) == -1)
return 0;
if (!FtpSendCmd(buf, '1', nControl))
{
FtpClose(*nData);
*nData = NULL;
return 0;
}
(*nData)->ctrl = nControl;
nControl->data = *nData;
if (nControl->cmode == FTPLIB_PORT)
{
if (!FtpAcceptConnection(*nData,nControl))
{
FtpClose(*nData);
*nData = NULL;
nControl->data = NULL;
return 0;
}
}
return 1;
}
/*
* FtpRead - read from a data connection
* 读取数据
*/
GLOBALDEF int FtpRead(void *buf, int max, netbuf *nData)
{
int i;
if (nData->dir != FTPLIB_READ)
return 0;
if (nData->buf) /* 如果nData有缓冲区，则读取到dData的缓冲区中 */
i = readline(buf, max, nData);
else
{
i = socket_wait(nData);
if (i != 1)
return 0;
i = net_read(nData->handle, buf, max);
}
if (i == -1)
return 0;
nData->xfered += i;
if (nData->idlecb && nData->cbbytes)
{
nData->xfered1 += i;
if (nData->xfered1 > nData->cbbytes)
{
if (nData->idlecb(nData, nData->xfered, nData->idlearg) == 0)
return 0;
nData->xfered1 = 0;
}
}
return i;
}
/*
* FtpWrite - write to a data connection
* 写数据
*/
GLOBALDEF int FtpWrite(const void *buf, int len, netbuf *nData)
{
int i;
if (nData->dir != FTPLIB_WRITE)
return 0;
if (nData->buf)
i = writeline(buf, len, nData);
else
{
socket_wait(nData);
i = net_write(nData->handle, buf, len);
}
if (i == -1)
return 0;
nData->xfered += i;
if (nData->idlecb && nData->cbbytes)
{
nData->xfered1 += i;
if (nData->xfered1 > nData->cbbytes)
{
nData->idlecb(nData, nData->xfered, nData->idlearg);
nData->xfered1 = 0;
}
}
return i;
}
/*
* FtpClose - close a data connection
* 关闭数据连接
*/
GLOBALDEF int FtpClose(netbuf *nData)
{
netbuf *ctrl;
switch (nData->dir)
{
case FTPLIB_WRITE:
/* potential problem - if buffer flush fails, how to notify user? */
if (nData->buf != NULL)
writeline(NULL, 0, nData);
case FTPLIB_READ:
if (nData->buf)
free(nData->buf);
shutdown(nData->handle,2);
net_close(nData->handle);
ctrl = nData->ctrl;
free(nData);
ctrl->data = NULL;
if (ctrl && ctrl->response[0] != '4' && ctrl->response[0] != 5)
{
return(readresp('2', ctrl));
}
return 1;
case FTPLIB_CONTROL:
if (nData->data)
{
nData->ctrl = NULL;
FtpClose(nData->data);
}
net_close(nData->handle);
free(nData);
return 0;
}
return 1;
}
/*
* FtpSite - send a SITE command
* return 1 if command successful, 0 otherwise
* site不知道什么意思
*/
GLOBALDEF int FtpSite(const char *cmd, netbuf *nControl)
{
char buf[TMP_BUFSIZ];
if ((strlen(cmd) + 7) > sizeof(buf))
return 0;
sprintf(buf,"SITE %s",cmd);
if (!FtpSendCmd(buf,'2',nControl))
return 0;
return 1;
}
/*
* FtpSysType - send a SYST command
* Fills in the user buffer with the remote system type. If more
* information from the response is required, the user can parse
* it out of the response buffer returned by FtpLastResponse().
* return 1 if command successful, 0 otherwise
* 获取FTP服务器的操作系统,复制到buf中，比如WINDOWS
*/
GLOBALDEF int FtpSysType(char *buf, int max, netbuf *nControl)
{
int l = max;
char *b = buf;
char *s;
if (!FtpSendCmd("SYST",'2',nControl))
return 0;
s = &nControl->response[4];
while ((--l) && (*s != ' '))
*b++ = *s++;
*b++ = '\0';
return 1;
}
/*
* FtpMkdir - create a directory at server
* return 1 if successful, 0 otherwise
* 创建文件夹
*/
GLOBALDEF int FtpMkdir(const char *path, netbuf *nControl)
{
char buf[TMP_BUFSIZ];
if ((strlen(path) + 6) > sizeof(buf))
return 0;
sprintf(buf,"MKD %s",path);
if (!FtpSendCmd(buf,'2', nControl))
return 0;
return 1;
}
/*
* FtpChdir - change path at remote
* return 1 if successful, 0 otherwise
* 切换文件夹
*/
GLOBALDEF int FtpChdir(const char *path, netbuf *nControl)
{
char buf[TMP_BUFSIZ];
if ((strlen(path) + 6) > sizeof(buf))
return 0;
sprintf(buf,"CWD %s",path);
if (!FtpSendCmd(buf,'2',nControl))
return 0;
return 1;
}
/*
* FtpCDUp - move to parent directory at remote
* return 1 if successful, 0 otherwise
* 跳到..文件夹，当在最顶层的文件夹时，就不要在跳了，否则可能错粗呦
*/
GLOBALDEF int FtpCDUp(netbuf *nControl)
{
if (!FtpSendCmd("CDUP",'2',nControl))
return 0;
return 1;
}
/*
* FtpRmdir - remove directory at remote
* return 1 if successful, 0 otherwise
* 删除文件夹
*/
GLOBALDEF int FtpRmdir(const char *path, netbuf *nControl)
{
char buf[TMP_BUFSIZ];
if ((strlen(path) + 6) > sizeof(buf))
return 0;
sprintf(buf,"RMD %s",path);
if (!FtpSendCmd(buf,'2',nControl))
return 0;
return 1;
}
/*
* FtpPwd - get working directory at remote
* return 1 if successful, 0 otherwise
* 获取当前文件夹
*/
GLOBALDEF int FtpPwd(char *path, int max, netbuf *nControl)
{
int l = max;
char *b = path;
char *s;
if (!FtpSendCmd("PWD",'2',nControl))
return 0;
s = strchr(nControl->response, '"');
if (s == NULL)
return 0;
s++;
while ((--l) && (*s) && (*s != '"'))
*b++ = *s++;
*b++ = '\0';
return 1;
}
/*
* FtpXfer - issue a command and transfer data
* return 1 if successful, 0 otherwise
* typ: read/write, mode: IMAGE/ASCII
*/
static int FtpXfer(const char *localfile, const char *path,
netbuf *nControl, int typ, int mode)
{
int l,c;
char *dbuf;
FILE *local = NULL;
netbuf *nData;
int rv=1;
if (localfile != NULL)
{
char ac[4];
memset( ac, 0, sizeof(ac) );
if (typ == FTPLIB_FILE_WRITE)
ac[0] = 'r';
else
ac[0] = 'w';
if (mode == FTPLIB_IMAGE)
ac[1] = 'b';
local = fopen(localfile, ac);
if (local == NULL)
{
strncpy(nControl->response, strerror(errno),
sizeof(nControl->response));
return 0;
}
}
/* when localfile is NULL, local point to stdin/stdout */
if (local == NULL)
local = (typ == FTPLIB_FILE_WRITE) ? stdin : stdout;
if (!FtpAccess(path, typ, mode, nControl, &nData)) /* open the remote file error */
{
if (localfile)
{
fclose(local);
if ( typ == FTPLIB_FILE_WRITE )
unlink(localfile);
}
return 0;
}
dbuf = malloc(FTPLIB_BUFSIZ);
if (typ == FTPLIB_FILE_WRITE)
{
while ((l = fread(dbuf, 1, FTPLIB_BUFSIZ, local)) > 0)
{
if ((c = FtpWrite(dbuf, l, nData)) < l)
{
printf("short write: passed %d, wrote %d\n", l, c);
rv = 0;
break;
}
}
}
else
{
while ((l = FtpRead(dbuf, FTPLIB_BUFSIZ, nData)) > 0)
{
if (fwrite(dbuf, 1, l, local) == 0)
{
if (ftplib_debug)
perror("localfile write");
rv = 0;
break;
}
}
}
free(dbuf);
fflush(local);
if (localfile != NULL)
fclose(local);
FtpClose(nData);
return rv;
}
/*
* FtpNlst - issue an NLST command and write response to output
* return 1 if successful, 0 otherwise
* 返回指定路径下的目录列表
*/
GLOBALDEF int FtpNlst(const char *outputfile, const char *path,
netbuf *nControl)
{
return FtpXfer(outputfile, path, nControl, FTPLIB_DIR, FTPLIB_ASCII);
}
/*
* FtpDir - issue a LIST command and write response to output
* return 1 if successful, 0 otherwise
* 返回指定路径下的目录列表
*/
GLOBALDEF int FtpDir(const char *outputfile, const char *path, netbuf *nControl)
{
return FtpXfer(outputfile, path, nControl, FTPLIB_DIR_VERBOSE, FTPLIB_ASCII);
}
/*
* FtpSize - determine the size of a remote file
* return 1 if successful, 0 otherwise
*/
GLOBALDEF int FtpSize(const char *path, unsigned int *size, char mode, netbuf *nControl)
{
char cmd[TMP_BUFSIZ];
int resp,rv=1;
unsigned int sz;
if ((strlen(path) + 7) > sizeof(cmd))
return 0;
sprintf(cmd, "TYPE %c", mode);
if (!FtpSendCmd(cmd, '2', nControl))
return 0;
sprintf(cmd,"SIZE %s",path);
if (!FtpSendCmd(cmd,'2',nControl))
rv = 0;
else
{
if (sscanf(nControl->response, "%d %u", &resp, &sz) == 2)
*size = sz;
else
rv = 0;
}
return rv;
}
#if defined(__UINT64_MAX)
/*
* FtpSizeLong - determine the size of a remote file
* return 1 if successful, 0 otherwise
*/
GLOBALDEF int FtpSizeLong(const char *path, fsz_t *size, char mode, netbuf *nControl)
{
char cmd[TMP_BUFSIZ];
int resp,rv=1;
fsz_t sz;
if ((strlen(path) + 7) > sizeof(cmd))
return 0;
sprintf(cmd, "TYPE %c", mode);
if (!FtpSendCmd(cmd, '2', nControl))
return 0;
sprintf(cmd,"SIZE %s",path);
if (!FtpSendCmd(cmd,'2',nControl))
rv = 0;
else
{
if (sscanf(nControl->response, "%d %" PRIu64 "", &resp, &sz) == 2)
*size = sz;
else
rv = 0;
}
return rv;
}
#endif
/*
* FtpModDate - determine the modification date of a remote file
* return 1 if successful, 0 otherwise
*/
GLOBALDEF int FtpModDate(const char *path, char *dt, int max, netbuf *nControl)
{
char buf[TMP_BUFSIZ];
int rv = 1;
if ((strlen(path) + 7) > sizeof(buf))
return 0;
sprintf(buf,"MDTM %s",path);
if (!FtpSendCmd(buf,'2',nControl))
rv = 0;
else
strncpy(dt, &nControl->response[4], max);
return rv;
}
/*
* FtpGet - issue a GET command and write received data to output
* return 1 if successful, 0 otherwise
* 下载文件
*/
GLOBALDEF int FtpGet(const char *outputfile, const char *path,
char mode, netbuf *nControl)
{
return FtpXfer(outputfile, path, nControl, FTPLIB_FILE_READ, mode);
}
/*
* FtpPut - issue a PUT command and send data from input
* return 1 if successful, 0 otherwise
* 上传文件
*/
GLOBALDEF int FtpPut(const char *inputfile, const char *path, char mode,
netbuf *nControl)
{
return FtpXfer(inputfile, path, nControl, FTPLIB_FILE_WRITE, mode);
}
/*
* FtpRename - rename a file at remote
* return 1 if successful, 0 otherwise
* 更改文件名称
*/
GLOBALDEF int FtpRename(const char *src, const char *dst, netbuf *nControl)
{
char cmd[TMP_BUFSIZ];
if (((strlen(src) + 7) > sizeof(cmd)) ||
((strlen(dst) + 7) > sizeof(cmd)))
return 0;
sprintf(cmd,"RNFR %s",src);
if (!FtpSendCmd(cmd,'3',nControl))
return 0;
sprintf(cmd,"RNTO %s",dst);
if (!FtpSendCmd(cmd,'2',nControl))
return 0;
return 1;
}
/*
* FtpDelete - delete a file at remote
* return 1 if successful, 0 otherwise
* 删除文件
*/
GLOBALDEF int FtpDelete(const char *fnm, netbuf *nControl)
{
char cmd[TMP_BUFSIZ];
if ((strlen(fnm) + 7) > sizeof(cmd))
return 0;
sprintf(cmd,"DELE %s",fnm);
if (!FtpSendCmd(cmd,'2', nControl))
return 0;
return 1;
}
/*
* FtpQuit - disconnect from remote
* return 1 if successful, 0 otherwise
* 退出ftp登录
*/
GLOBALDEF void FtpQuit(netbuf *nControl)
{
if (nControl->dir != FTPLIB_CONTROL)
return;
FtpSendCmd("QUIT",'2',nControl);
net_close(nControl->handle);
free(nControl->buf);
free(nControl);
}
参考：
1、《计算机网络》 第6版 FTP相关章节
2、《UNIX网络编程》 第3版 相关章节