在你的应用程序中使用 WinPcap
[WinPcap用户指南]
创建一个使用 wpcap.dll的应用程序
用 Microsoft Visual C++ 创建一个使用 wpcap.dll 的应用程序，需要按一下步骤
- 在每一个使用了库的源程序中，将 pcap.h 头文件包含(include)进来。
- 如果你在程序中使用了WinPcap中提供给Win32平台的特有的函数， 记得在预处理中加入 WPCAP 的定义。
- 如果你的程序使用了WinPcap的远程捕获功能，那么在预处理定义中加入HAVE_REMOTE。不要直接把remote-ext.h直接加入到你的源文件中去。
- 置VC++的链接器(Linker)，把 wpcap.lib 库文件包含进来。 wpcap.lib 可以在WinPcap中找到。
- 设置VC++的链接器(Linker)，把 ws2_32.lib 库文件包含进来。这个文件分布于C的编译器，并且包含了Windows的一些socket函数。本教程中的一些范例程序，会需要它
记住以下几点:
- 要添加一个预处理定义，你需要打开Project菜单，选择Settings，然后选择C/C++选项卡，在General类下，你必须在Preprocessor Definitions下的文本框中添加定义。
- 要在一个VC++6.0工程中，添加一，个新的库，你必须打开Project菜单，选择Settings，然后选择Link选项卡，然后把新库的名字添加到Object/Library modules下的文本框中
- 要向VC++6.0中添加一个新的库所在的路径，你必须打开Tool菜单，选择Options，然后选择Directories选项卡，在Show directories下拉框中选择Library files，并且将新的路径添加到Directories中去
- 要向VC++6.0中添加一个新的包含文件所在的路径，你必须打开Tool菜单，选择Options，然后选择Directories选项卡，在Show directories下拉框中选择Include files，并且将新的路径添加到Directories中去
范例程序
我们一共了一些范例程序来显示WinPcap API的用法。这些程序的源代码，以及编译运行这些代码所需的所有文件，都可以在 Developer's Pack找到。作为教程，在这里，我们提供了浏览器式的代码：这样，在每个函数和变量之间的跳转会比较方便。更多完整的范例程序，请参阅 WinPcap 教程.
Packet Dump
这个程序会依据命令行参数，从网络适配器，或是从文件来读取数据包。如果没有提供源，那么程序会显示出所有可用的适配器，你可以选其中一个。当捕获过程开始，程序会打印数据包的时间戳，长度，原始内容。一旦被编译了，那么它将能运行于所有的Win32平台，当然，它也可以被编译成Unix平台的程序。
/* * Copyright (c) 1999 - 2005 NetGroup, Politecnico di Torino (Italy) * Copyright (c) 2005 - 2006 CACE Technologies, Davis (California) * 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. Neither the name of the Politecnico di Torino, CACE Technologies * nor the names of its contributors may be used to endorse or promote * products derived from this software without specific prior written * permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "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 COPYRIGHT * OWNER OR CONTRIBUTORS 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. * */ #include <stdlib.h> #include <stdio.h> // // NOTE: remember to include WPCAP and HAVE_REMOTE among your // preprocessor definitions. // #include <pcap.h> #define LINE_LEN 16 int main(int argc, char **argv) { pcap_if_t *alldevs, *d; pcap_t *fp; u_int inum, i=0; char errbuf[PCAP_ERRBUF_SIZE]; int res; struct pcap_pkthdr *header; const u_char *pkt_data; printf("pktdump_ex: prints the packets of the network using WinPcap.\n"); printf(" Usage: pktdump_ex [-s source]\n\n" " Examples:\n" " pktdump_ex -s file://c:/temp/file.acp\n" " pktdump_ex -s rpcap://\\Device\\NPF_{C8736017-F3C3-4373-94AC-9A34B7DAD998}\n\n"); if(argc < 3) { printf("\nNo adapter selected: printing the device list:\n"); /* The user didn't provide a packet source: Retrieve the local device list */ if (pcap_findalldevs_ex(PCAP_SRC_IF_STRING, NULL, &alldevs, errbuf) == -1) { fprintf(stderr,"Error in pcap_findalldevs_ex: %s\n", errbuf); return -1; } /* Print the list */ for(d=alldevs; d; d=d->next) { printf("%d. %s\n ", ++i, d->name); if (d->description) printf(" (%s)\n", d->description); else printf(" (No description available)\n"); } if (i==0) { fprintf(stderr,"No interfaces found! Exiting.\n"); return -1; } printf("Enter the interface number (1-%d):",i); scanf_s("%d", &inum); if (inum < 1 || inum > i) { printf("\nInterface number out of range.\n"); /* Free the device list */ pcap_freealldevs(alldevs); return -1; } /* Jump to the selected adapter */ for (d=alldevs, i=0; i< inum-1 ;d=d->next, i++); /* Open the device */ if ( (fp= pcap_open(d->name, 100 /*snaplen*/, PCAP_OPENFLAG_PROMISCUOUS /*flags*/, 20 /*read timeout*/, NULL /* remote authentication */, errbuf) ) == NULL) { fprintf(stderr,"\nError opening adapter\n"); return -1; } } else { // Do not check for the switch type ('-s') if ( (fp= pcap_open(argv[2], 100 /*snaplen*/, PCAP_OPENFLAG_PROMISCUOUS /*flags*/, 20 /*read timeout*/, NULL /* remote authentication */, errbuf) ) == NULL) { fprintf(stderr,"\nError opening source: %s\n", errbuf); return -1; } } /* Read the packets */ while((res = pcap_next_ex( fp, &header, &pkt_data)) >= 0) { if(res == 0) /* Timeout elapsed */ continue; /* print pkt timestamp and pkt len */ printf("%ld:%ld (%ld)\n", header->ts.tv_sec, header->ts.tv_usec, header->len); /* Print the packet */ for (i=1; (i < header->caplen + 1 ) ; i++) { printf("%.2x ", pkt_data[i-1]); if ( (i % LINE_LEN) == 0) printf("\n"); } printf("\n\n"); } if(res == -1) { fprintf(stderr, "Error reading the packets: %s\n", pcap_geterr(fp)); return -1; } return 0; }
数据包过滤器
这是一个更加完整的使用libpcap的范例程序，它显示了如何创建和设置过滤器，如何把捕获保存到磁盘。这个程序在Win32和Unix平台下都能编译。Pcap_filter(pf.exe)是一个通用的数据包过滤程序：它的输入参数有数据包的源(可以是物理接口，或是一个文件)，过滤器和一个输出文件。它会从源获取数据包，并对它们进行过滤，如果它们符合过滤器的要求，就把它们保存到输出文件，直到按下Ctrl+C，或者整个文件处理完毕。Pcap_filter不但可以根据一个特定的过滤器，来堆处理网络中的数据，而且可以从已经保存过的文件中提取数据包。输入和输出文件的格式都是libpcap兼容的格式，比如，WinDump,tcpdump和其他许多网络工具。
/* * Copyright (c) 1999 - 2005 NetGroup, Politecnico di Torino (Italy) * Copyright (c) 2005 - 2006 CACE Technologies, Davis (California) * 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. Neither the name of the Politecnico di Torino, CACE Technologies * nor the names of its contributors may be used to endorse or promote * products derived from this software without specific prior written * permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "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 COPYRIGHT * OWNER OR CONTRIBUTORS 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. * */ #include <stdlib.h> #include <stdio.h> #include <pcap.h> #define MAX_PRINT 80 #define MAX_LINE 16 void usage(); void main(int argc, char **argv) { pcap_t *fp; char errbuf[PCAP_ERRBUF_SIZE]; char *source=NULL; char *ofilename=NULL; char *filter=NULL; int i; pcap_dumper_t *dumpfile; struct bpf_program fcode; bpf_u_int32 NetMask; int res; struct pcap_pkthdr *header; const u_char *pkt_data; if (argc == 1) { usage(); return; } for(i=1;i < argc; i+= 2) { switch (argv[i] [1]) { case 's': { source=argv[i+1]; }; break; case 'o': { ofilename=argv[i+1]; }; break; case 'f': { filter=argv[i+1]; }; break; } } // open a capture from the network if (source != NULL) { if ( (fp= pcap_open(source, 1514 /*snaplen*/, PCAP_OPENFLAG_PROMISCUOUS /*flags*/, 20 /*read timeout*/, NULL /* remote authentication */, errbuf) ) == NULL) { fprintf(stderr,"\nUnable to open the adapter.\n"); return; } } else usage(); if (filter != NULL) { // We should loop through the adapters returned by the pcap_findalldevs_ex() // in order to locate the correct one. // // Let's do things simpler: we suppose to be in a C class network ;-) NetMask=0xffffff; //compile the filter if(pcap_compile(fp, &fcode, filter, 1, NetMask) < 0) { fprintf(stderr,"\nError compiling filter: wrong syntax.\n"); return; } //set the filter if(pcap_setfilter(fp, &fcode)<0) { fprintf(stderr,"\nError setting the filter\n"); return; } } //open the dump file if (ofilename != NULL) { dumpfile= pcap_dump_open(fp, ofilename); if (dumpfile == NULL) { fprintf(stderr,"\nError opening output file\n"); return; } } else usage(); //start the capture while((res = pcap_next_ex( fp, &header, &pkt_data)) >= 0) { if(res == 0) /* Timeout elapsed */ continue; //save the packet on the dump file pcap_dump((unsigned char *) dumpfile, header, pkt_data); } } void usage() { printf("\npf - Generic Packet Filter.\n"); printf("\nUsage:\npf -s source -o output_file_name [-f filter_string]\n\n"); exit(0); }