IP:\u5206\u7247\u4e0e\u91cd\u7ec4<\/p>\n
\t1. \u5f15\u8a00
\n\t\u4e3a\u4e86\u4e0e\u4e92\u8054\u7f51\u4e0a\u7684\u4efb\u610f\u8ba1\u7b97\u673a\u901a\u4fe1,\u6bcf\u4e2a\u5e94\u7528TCP\/IP\u7684\u8ba1\u7b97\u673a\u5fc5\u987b\u5177\u6709\u5206\u7247\u548c\u91cd\u7ec4\u7684\u4ee3\u7801,\u4e00\u4e2a\u8bbe\u8ba1\u826f\u597d\u7684\u5e94\u7528\u8f6f\u4ef6,\u4f1a\u751f\u6210\u8db3\u591f\u5c0f\u7684\u6570\u636e\u62a5,
\n\t\u56e0\u6b64\u4e3b\u673a\u5e76\u4e0d\u9700\u8981\u7ecf\u5e38\u6267\u884c\u5206\u7247\u4efb\u52a1. <\/p>\n
\t2. \u6570\u636e\u62a5\u7684\u5206\u7247
\n\t\u5206\u7247\u53d1\u751f\u5728\u9009\u62e9\u8def\u7531\u4e4b\u540e,\u4ee5\u53ca\u653e\u5165\u63a5\u53e3\u961f\u5217\u4e4b\u524d.IP\u628a\u6570\u636e\u62a5\u957f\u5ea6\u4e0eMTU\u8fdb\u884c\u6bd4\u8f83,\u786e\u5b9a\u662f\u5426\u9700\u8981\u5206\u7247.
\n\t\u5982\u9700\u5206\u7247,IP\u9996\u5148\u751f\u6210\u591a\u4e2a\u6570\u636e\u62a5,\u5e76\u5c06\u6bcf\u4e2a\u6570\u636e\u62a5\u4e2d\u7684\u5206\u7247\u4f4d\u7f6e1,\u5c06\u6e90\u6570\u636e\u62a5\u4e2d\u7684\u6570\u636e\u6309\u987a\u5e8f\u5206\u7247,\u5e76\u5c06\u5b83\u4eec\u88c5\u5165\u8fd9\u4e9b\u6570\u636e\u62a5\u4e2d.
\n\t\u5b83\u8fd8\u5728\u540c\u4e00\u6e90\u6570\u636e\u62a5\u4ea7\u751f\u7684\u6240\u6709\u6570\u636e\u62a5\u7247\u4e2d\u5c06MF\u4f4d\u7f6e\u4e3a1,\u672b\u5c3e\u7247\u9664\u5916.IP\u4e00\u8fb9\u5206\u7247,\u4e00\u8fb9\u5c06\u5b83\u4eec\u4f20\u9012\u7ed9\u7f51\u7edc\u63a5\u53e3\u53d1\u9001\u51fa\u53bb.<\/p>\n
\t2.1 \u4e3a\u4e00\u4e2a\u6570\u636e\u62a5\u7247\u518d\u6b21\u5206\u7247
\n\t\u5bf9\u4e8eMF\u672a\u7f6e1\u7684\u7247,\u548c\u4e0a\u8fb9\u8bf4\u7684\u6ca1\u533a\u522b,\u9664\u4e86\u6700\u540e\u4e00\u4e2a\u7247\u5916,\u5176\u5b83\u5168\u7f6e1.\u4f46\u5bf9\u4e8eMF\u4e3a1\u7684\u6e90\u7247,\u518d\u6b21\u5206\u7247\u540e\u7684\u6240\u6709\u5206\u7247MF\u5168\u7f6e1<\/p>\n
\t3. \u5206\u7247\u7684\u5b9e\u73b0<\/p>\n
\t\/* ipputp.c – ipputp *\/<\/p>\n
\t#include <conf.h>
\n\t#include <kernel.h>
\n\t#include <network.h><\/p>\n
\t\/*————————————————————————
\n\t * ipputp – \u53d1\u9001\u4e00\u4e2a\u6570\u636e\u5305\u5230\u4e00\u4e2a\u63a5\u53e3\u7684\u8f93\u51fa\u961f\u5217
\n\t *————————————————————————
\n\t *\/
\n\tint
\n\tipputp(unsigned ifn, IPaddr nh, struct ep *pep)
\n\t{
\n\t struct netif *pni = &nif[ifn]; \/* \u63a5\u53e3\u6307\u9488*\/
\n\t struct ip *pip; \/* IP\u62a5\u6307\u9488*\/
\n\t int hlen, maxdlen, tosend, offset, offindg;<\/p>\n
\t if (pni->ni_state == NIS_DOWN) { \/* \u63a5\u53e3\u5173\u95ed\u5219\u8fd4\u56de*\/
\n\t freebuf(pep);
\n\t return SYSERR;
\n\t }
\n\t pip = (struct ip *)pep->ep_data; \/* IP\u62a5\u6307\u5411*\/
\n\t if (pip->ip_len <= pni->ni_mtu) { \/* IP\u62a5\u957f\u5ea6\u5c0f\u4e8e\u7b49\u4e8e\u63a5\u53e3MTU,\u5219\u76f4\u63a5\u53d1\u9001\u6570\u636e\u62a5*\/
\n\t pep->ep_nexthop = nh;
\n\t pip->ip_cksum = 0;
\n\t iph2net(pip);
\n\t pep->ep_order &= ~EPO_IP;
\n\t pip->ip_cksum = cksum((WORD *)pip, IP_HLEN(pip));
\n\t return netwrite(pni, pep, EP_HLEN+net2hs(pip->ip_len));
\n\t }
\n\t \/* \u5426\u5219\uff0c\u6211\u4eec\u5fc5\u987b\u5206\u7247 *\/<\/p>\n
\t if (pip->ip_fragoff & IP_DF) { \/* \u80fd\u5426\u5206\u7247,\u4e0d\u80fd\u5206\u7247\u5219\u62a5\u9519\u5e76\u8fd4\u56de*\/
\n\t IpFragFails++;
\n\t icmp(ICT_DESTUR, ICC_FNADF, pip->ip_src, pep, 0);
\n\t return OK;
\n\t }
\n\t maxdlen = (pni->ni_mtu – IP_HLEN(pip)) &~ 7; \/* \u6700\u5927\u957f\u5ea6\u4e3aMTU\u51cf\u53bbIP\u5934\u957f\u5ea6,\u5e76\u589e\u52a0\u52308\u7684\u500d\u6570*\/
\n\t offset = 0; \/* \u504f\u79fb\u91cf*\/
\n\t offindg = (pip->ip_fragoff & IP_FRAGOFF)<<3; \/* \u504f\u79fb\u91cf,\u4fdd\u5b58\u63a7\u5236\u4f4d*\/
\n\t tosend = pip->ip_len – IP_HLEN(pip); \/* \u8981\u53d1\u9001\u7684IP\u62a5\u957f\u5ea6,\u4e0d\u5305\u62ecIP\u62a5\u5934*\/<\/p>\n
\t while (tosend > maxdlen) { \/* \u4ec5\u5f53\u5269\u4f59\u7684\u6570\u636e\u5927\u4e8e\u53ef\u53d1\u9001\u7684\u6700\u5927\u6570\u636e\u91cf\u65f6\u624d\u53d1\u9001*\/
\n\t if (ipfsend(pni,nh,pep,offset,maxdlen,offindg) != OK) { \/* \u751f\u6210\u5e76\u53d1\u9001\u5206\u7247*\/
\n\t IpOutDiscards++;
\n\t freebuf(pep);
\n\t return SYSERR;
\n\t }
\n\t IpFragCreates++;
\n\t tosend -= maxdlen;
\n\t offset += maxdlen;
\n\t offindg += maxdlen; \/* *\/
\n\t }
\n\t IpFragOKs++;
\n\t IpFragCreates++;
\n\t hlen = ipfhcopy(pep, pep, offindg); \/* \u9996\u90e8\u62f7\u8d1d\u5904\u7406\uff0c\u8fd4\u56de\u9996\u90e8\u957f\u5ea6*\/
\n\t pip = (struct ip *)pep->ep_data; \/* \u53d6IP\u6570\u636e\u62a5*\/
\n\t \/*\u5904\u7406\u6700\u540e\u4e00\u4e2a\u5206\u7247,\u5f53\u6700\u540e\u5269\u4f59\u7684\u6570\u636e\u5c0f\u4e8e\u7b49\u4e8e\u53ef\u53d1\u9001\u7684\u6700\u5927\u6570\u636e\u91cf *\/
\n\t memcpy(&pep->ep_data[hlen], &pep->ep_data[IP_HLEN(pip)+offset],
\n\t tosend); \/* \u4fee\u6539\u6e90\u62a5,\u4f7f\u4e4b\u53d8\u4e3a\u6700\u540e\u4e00\u4e2a\u62a5\u7247*\/
\n\t \/*\u975e\u672b\u5c3e\u7684\u6570\u636e\u62a5\u7247\u518d\u6b21\u5206\u7247\u65f6\uff0c\u4fdd\u8bc1MF\u5168\u4e3a1 *\/
\n\t pip->ip_fragoff = (pip->ip_fragoff & IP_MF)|(offindg>>3);
\n\t pip->ip_len = tosend + hlen;
\n\t pip->ip_cksum = 0;
\n\t iph2net(pip);
\n\t pep->ep_order &= ~EPO_IP;
\n\t pip->ip_cksum = cksum((WORD *)pip, hlen);
\n\t pep->ep_nexthop = nh;
\n\t return netwrite(pni, pep, EP_HLEN+net2hs(pip->ip_len));
\n\t}<\/p>\n
\t3.1 \u53d1\u9001\u4e00\u4e2a\u6570\u636e\u62a5\u7247<\/p>\n
\t\/* ipfsend.c – ipfsend *\/<\/p>\n
\t#include <conf.h>
\n\t#include <kernel.h>
\n\t#include <network.h><\/p>\n
\tint ipfhcopy(struct ep *, struct ep *, unsigned);<\/p>\n
\t\/*————————————————————————
\n\t * ipfsend – \u53d1\u9001\u4e00\u4e2aIP\u6570\u636e\u62a5\u7684\u5206\u7247
\n\t *————————————————————————
\n\t *\/
\n\tint
\n\tipfsend(struct netif *pni, IPaddr nexthop, struct ep *pep,
\n\t unsigned offset, unsigned maxdlen, unsigned offindg)
\n\t{
\n\t struct ep *pepnew;
\n\t struct ip *pip, *pipnew;
\n\t int hlen, len;<\/p>\n
\t pepnew = (struct ep *)getbuf(Net.netpool); \/* \u7533\u8bf7\u4e00\u4e2a\u65b0\u5e27\u7684\u7f13\u51b2\u533a*\/
\n\t if (pepnew == (struct ep *)SYSERR)
\n\t return SYSERR;
\n\t pepnew->ep_order = ~0;
\n\t hlen = ipfhcopy(pepnew, pep, offindg); \/* \u590d\u5236\u5934 *\/<\/p>\n
\t pip = (struct ip *)pep->ep_data; \/* \u6e90IP\u62a5\u7684\u6307\u5411*\/
\n\t pipnew = (struct ip *)pepnew->ep_data; \/* \u65b0\u751f\u6210\u7684IP\u62a5*\/
\n\t pipnew->ip_fragoff = IP_MF | (offindg>>3);
\n\t pipnew->ip_len = len = maxdlen + hlen;
\n\t pipnew->ip_cksum = 0;<\/p>\n
\t iph2net(pipnew);
\n\t pepnew->ep_order &= ~EPO_IP; \/* \u6e05\u9664\u5b57\u8282\u987a\u5e8f*\/
\n\t pipnew->ip_cksum = cksum((WORD *)pipnew, hlen);<\/p>\n
\t memcpy(&pepnew->ep_data[hlen], \/* \u590d\u5236\u6570\u636e*\/
\n\t &pep->ep_data[IP_HLEN(pip)+offset], maxdlen);
\n\t pepnew->ep_nexthop = nexthop;<\/p>\n
\t return netwrite(pni, pepnew, EP_HLEN+len); \/* \u53d1\u9001\u5e76\u8fd4\u56de *\/
\n\t}<\/p>\n
\t3.2 \u590d\u5236\u6570\u636e\u62a5\u9996\u90e8<\/p>\n
\t\/* ipfhcopy.c – ipfhcopy *\/<\/p>\n
\t#include <conf.h>
\n\t#include <kernel.h>
\n\t#include <network.h><\/p>\n
\t\/*————————————————————————
\n\t * ipfhcopy – copy the hardware, IP header, and options for a fragment
\n\t *————————————————————————
\n\t *\/
\n\tint
\n\tipfhcopy(struct ep *pepto, struct ep *pepfrom, unsigned offindg)
\n\t{
\n\t struct ip *pipfrom = (struct ip *)pepfrom->ep_data; \/* \u65e7IP\u62a5*\/
\n\t unsigned i, maxhlen, olen, otype;
\n\t unsigned hlen = (IP_MINHLEN<<2); \/* IP\u5934\u6700\u5c0f\u957f\u5ea6*4 ,\u5c31\u662f\u4ee5\u5b57\u8282\u4e3a\u5355\u4f4d\u4e86*\/<\/p>\n
\t if (offindg == 0) { \/* \u504f\u79fb\u4e3a0,\u8bf4\u660e\u662f\u7b2c\u4e00\u4e2a\u5206\u7247,\u590d\u5236\u5e27\u7684\u5934\u548cIP\u5934\u5230\u65b0\u7684\u5e27*\/
\n\t memcpy(pepto, pepfrom, EP_HLEN+IP_HLEN(pipfrom));
\n\t return IP_HLEN(pipfrom);
\n\t }
\n\t \/* \u4ee5\u4e0b\u5c31\u8bf4\u660e\u4e0d\u662f\u7b2c\u4e00\u4e2aIP\u5206\u7247\u4e86*\/
\n\t memcpy(pepto, pepfrom, EP_HLEN+hlen); \/* \u590d\u5236\u5e27\u7684\u5934\u548c\u9664\u4e86IP\u9009\u9879\u5916\u7684\u62a5\u5934*\/<\/p>\n
\t \/*\u590d\u5236\u9009\u9879 *\/<\/p>\n
\t maxhlen = IP_HLEN(pipfrom); \/* \u5305\u62ec\u9009\u9879\u7684IP\u5934\u7684\u957f\u5ea6*\/
\n\t i = hlen; \/* \u4e0d\u5305\u62ec\u9009\u9879\u7684IP\u5934\u957f\u5ea6*\/
\n\t while (i < maxhlen) { \/* \u6700\u5c0f\u5934\u6bd4\u6700\u5927\u5934\u5c0f,\u8bf4\u660e\u6709IP\u9009\u9879*\/
\n\t otype = pepfrom->ep_data[i]; \/* IP\u9009\u9879*\/
\n\t olen = pepfrom->ep_data[++i]; \/* \u9009\u9879\u957f\u5ea6*\/
\n\t if (otype & IPO_COPY) { \/* \u5982\u679c\u590d\u5236\u4f4d\u4e3a1*\/
\n\t memcpy(&pepto->ep_data[hlen],
\n\t &pepfrom->ep_data[i-1], olen); \/* \u590d\u5236\u8fd9\u4e2a\u9009\u9879\u5230\u6240\u6709\u65b0\u7684\u5e27*\/
\n\t hlen += olen;
\n\t } else if (otype == IPO_NOP || otype == IPO_EOOP) { \/* \u9009\u9879\u7ed3\u675f\u6216\u6ca1\u6709\u64cd\u4f5c*\/
\n\t pepto->ep_data[hlen++] = otype;
\n\t olen = 1;
\n\t }
\n\t i += olen-1;
\n\t
\n\t if (otype == IPO_EOOP)
\n\t break;
\n\t }
\n\t \/* pad to a multiple of 4 octets *\/
\n\t while (hlen % 4) \/* \u586b\u5145\u52304\u5b57\u8282\u7684\u6574\u6570\u500d*\/
\n\t pepto->ep_data[hlen++] = IPO_NOP;
\n\t return hlen;
\n\t}<\/p>\n
\t4. \u6570\u636e\u62a5\u7684\u91cd\u7ec4<\/p>\n
\t4.1 \u6570\u636e\u7ed3\u6784<\/p>\n
\t\/* ipreass.h *\/<\/p>\n
\t\/* Internet Protocol (IP) reassembly support *\/<\/p>\n
\t#define IP_FQSIZE 10 \/* \u5206\u7247\u961f\u5217\u7684\u6570\u5927\u6570\u91cf *\/
\n\t#define IP_MAXNF 10 \/* \u5206\u7247\/\u6570\u636e\u62a5 \u7684\u6700\u5927\u6570\u91cf *\/
\n\t#define IP_FTTL 60 \/* \u751f\u5b58\u65f6\u95f4\uff08\u79d2\uff09*\/<\/p>\n
\t\/* ipf_state flags *\/<\/p>\n
\t#define IPFF_VALID 1 \/* \u5185\u5bb9\u662f\u6709\u6548\u7684 *\/
\n\t#define IPFF_BOGUS 2 \/* \u4e22\u5f03 *\/
\n\t#define IPFF_FREE 3 \/* \u8fd9\u4e2a\u961f\u5217\u53ef\u4ee5\u81ea\u7531\u5206\u914d *\/<\/p>\n
\tstruct ipfq {
\n\t char ipf_state; \/* \u961f\u5217\u72b6\u6001,\u503c\u4e3a\u4e0a\u8fb9 3\u79cd *\/
\n\t IPaddr ipf_src; \/* \u6e90IP\u5730\u5740 *\/
\n\t short ipf_id; \/* \u6570\u636e\u62a5ID *\/
\n\t int ipf_ttl; \/* \u6570\u636e\u62a5\u91cd\u7ec4\u7684\u751f\u5b58\u65f6\u95f4 *\/
\n\t int ipf_q; \/* \u5206\u7247\u5b58\u50a8\u7684\u94fe\u8868 *\/
\n\t};<\/p>\n
\textern int ipfmutex; \/* \u4e92\u65a5 mutex for ipfqt[] *\/
\n\textern struct ipfq ipfqt[]; \/* IP\u5206\u7247\u961f\u5217\u8868 *\/<\/p>\n
\tint ipfsend(struct netif *, IPaddr, struct ep *, unsigned, unsigned,
\n\t unsigned);
\n\tint ipfhcopy(struct ep *, struct ep *, unsigned);<\/p>\n
\n\t4.2 \u4e92\u65a5\u64cd\u4f5c<\/p>\n
\t\u4e3a\u4e86\u4f55\u8bc1\u8fdb\u7a0b\u5728\u6570\u636e\u62a5\u7247\u7684\u94fe\u8868\u65f6\u4e0d\u4f1a\u4e92\u76f8\u5e72\u6270,\u91cd\u7ec4\u7a0b\u5e8f\u4ee3\u7801\u4f7f\u7528\u4e86\u4e00\u4e2a\u4e92\u65a5\u4fe1\u53f7\u91cfipfmutex.\u5728ipreass.h\u4e2d<\/p>\n
\t4.3 \u5728\u94fe\u8868\u4e2d\u52a0\u5165\u4e00\u4e2a\u6570\u636e\u62a5\u7247<\/p>\n
\t\/* ipreass.c – ipreass *\/<\/p>\n
\t#include <conf.h>
\n\t#include <kernel.h>
\n\t#include <network.h><\/p>\n
\tint ipfadd(struct ipfq *, struct ep *);
\n\tstruct ep *ipfjoin(struct ipfq *);<\/p>\n
\t\/*————————————————————————
\n\t * ipreass – reassemble an IP datagram, if necessary
\n\t * returns packet, if complete; 0 otherwise
\n\t * IP\u6570\u636e\u62a5\u91cd\u7ec4,\u5982\u679c\u62a5\u7247\u5230\u9f50\u5219\u91cd\u7ec4\u8be5\u5305,\u5e76\u8fd4\u56de\u5b8c\u6574\u7684\u6570\u636e\u62a5,\u5426\u5219\u8fd4\u56de0
\n\t *————————————————————————
\n\t *\/
\n\tstruct ep *
\n\tipreass(struct ep *pep)
\n\t{
\n\t struct ep *pep2;
\n\t struct ip *pip;
\n\t int firstfree;
\n\t int i;<\/p>\n
\t pip = (struct ip *)pep->ep_data; \/* \u5f97\u5230IP\u6570\u636e\u62a5\u7684*\/<\/p>\n
\t wait(ipfmutex); \/* \u4e92\u65a5*\/<\/p>\n
\t if ((pip->ip_fragoff & (IP_FRAGOFF|IP_MF)) == 0) { \/*\u5982\u679c\u4e0d\u662f\u5206\u7247,\u8fd4\u56de\u5f53\u524d\u5e27*\/
\n\t signal(ipfmutex);
\n\t return pep;
\n\t }
\n\t IpReasmReqds++;
\n\t firstfree = -1;
\n\t \/* \u4ee5\u4e0b\u60c5\u51b5\u4e3a\u662f\u5206\u7247 *\/
\n\t for (i=0; i<IP_FQSIZE; ++i) {
\n\t struct ipfq *piq = &ipfqt[i];<\/p>\n
\t if (piq->ipf_state == IPFF_FREE) { \/* \u961f\u5217\u672a\u4f7f\u7528,\u5219\u7ee7\u7eed*\/
\n\t if (firstfree == -1)
\n\t firstfree = i;
\n\t continue;
\n\t }
\n\t if (piq->ipf_id != pip->ip_id) \/* \u961f\u5217ID\u4e0d\u7b49\u4e8e\u5206\u7247ID,\u5219\u7ee7\u7eed*\/
\n\t continue;
\n\t if (piq->ipf_src != pip->ip_src) \/* \u6e90\u5730\u5740\u4e0d\u540c,\u5219\u7ee7\u7eed*\/
\n\t continue;
\n\t \/* \u627e\u5230\u5339\u914d *\/
\n\t if (ipfadd(piq, pep) == 0) { \/* \u628a\u8be5\u5206\u7247\u52a0\u5165\u5339\u914d\u7684\u961f\u5217*\/
\n\t signal(ipfmutex);
\n\t return 0;
\n\t }
\n\t pep2 = ipfjoin(piq); \/* \u68c0\u67e5\u662f\u5426\u53ef\u4ee5\u91cd\u7ec4\u6570\u636e\u62a5*\/
\n\t signal(ipfmutex);
\n\t return pep2;
\n\t
\n\t }
\n\t \/* \u6ca1\u6709\u5339\u914d *\/<\/p>\n
\t if (firstfree < 0) { \/* \u68c0\u67e5\u662f\u5426\u6709\u7a7a\u95f2\u961f\u5217*\/
\n\t \/* no room– drop *\/ \/* \u6ca1\u6709\u7a7a\u95f2\u5219\u4e22\u5f03*\/
\n\t freebuf(pep);
\n\t signal(ipfmutex);
\n\t return 0;
\n\t }
\n\t ipfqt[firstfree].ipf_q = newq(IP_FQSIZE, QF_WAIT); \/* \u5206\u914d\u4e00\u4e2a\u7a7a\u95f2\u8868\u9879*\/
\n\t if (ipfqt[firstfree].ipf_q < 0) {
\n\t freebuf(pep);
\n\t signal(ipfmutex);
\n\t return 0;
\n\t }
\n\t ipfqt[firstfree].ipf_src = pip->ip_src; \/* \u586b\u5145*\/
\n\t ipfqt[firstfree].ipf_id = pip->ip_id;
\n\t ipfqt[firstfree].ipf_ttl = IP_FTTL;
\n\t ipfqt[firstfree].ipf_state = IPFF_VALID;
\n\t ipfadd(&ipfqt[firstfree], pep);
\n\t signal(ipfmutex);
\n\t return 0;
\n\t}<\/p>\n
\tint ipfmutex;
\n\tstruct ipfq ipfqt[IP_FQSIZE];<\/p>\n
\n\t4.4 \u6ea2\u51fa\u65f6\u7684\u4e22\u5f03<\/p>\n
\t\/* ipfadd.c – ipfadd *\/<\/p>\n
\t#include <conf.h>
\n\t#include <kernel.h>
\n\t#include <proc.h>
\n\t#include <network.h><\/p>\n
\t\/*————————————————————————
\n\t * ipfadd – \u589e\u52a0\u4e00\u4e2a\u5206\u7247\u5230\u4e00\u4e2aIP\u788e\u7247\u961f\u5217
\n\t *————————————————————————
\n\t *\/
\n\tBool
\n\tipfadd(struct ipfq *iq, struct ep *pep)
\n\t{
\n\t struct ip *pip;
\n\t int fragoff;<\/p>\n
\t if (iq->ipf_state != IPFF_VALID) { \/* \u5206\u7247\u961f\u5217\u65e0\u6548,\u5219\u4e22\u5f03*\/
\n\t freebuf(pep);
\n\t return FALSE;
\n\t }
\n\t pip = (struct ip *)pep->ep_data; \/* \u5f97\u5230IP\u6570\u636e\u62a5\u7684*\/
\n\t fragoff = pip->ip_fragoff & IP_FRAGOFF; \/* \u5f97\u5230\u504f\u79fb\u91cf*\/
\n\t \/* -fragoff\u7528\u4f5c\u5173\u952e\u503c\uff0c\u8d8a\u5927\u8d8a\u9760\u524d *\/
\n\t if (enq(iq->ipf_q, pep, -fragoff) < 0) { \/* \u4e3e\u51fa\u4e22\u5f03\u5e76\u91ca\u653e\u5185\u5b58*\/
\n\t \/* overflow– free all frags and drop *\/
\n\t freebuf(pep);
\n\t IpReasmFails++;
\n\t while (pep = (struct ep *)deq(iq->ipf_q)) { \/* \u4ece\u961f\u5217\u5220\u9664\u5e27\u5e76\u91ca\u653e\u5e27*\/
\n\t freebuf(pep);
\n\t IpReasmFails++;
\n\t }
\n\t freeq(iq->ipf_q); \/* \u91ca\u653e\u961f\u5217*\/
\n\t iq->ipf_state = IPFF_BOGUS;
\n\t return FALSE;
\n\t }
\n\t iq->ipf_ttl = IP_FTTL; \/* \u91cd\u7f6e\u751f\u5b58\u65f6\u95f4 *\/
\n\t return TRUE;
\n\t}<\/p>\n
\n\t4.5 \u6d4b\u8bd5\u4e00\u4e2a\u5b8c\u6574\u7684\u6570\u636e\u636e\u62a5<\/p>\n
\t\/* ipfjoin.c – ipfjoin *\/<\/p>\n
\t#include <conf.h>
\n\t#include <kernel.h>
\n\t#include <proc.h>
\n\t#include <network.h><\/p>\n
\tstruct ep *ipfcons(struct ipfq *);<\/p>\n
\t\/*————————————————————————
\n\t * ipfjoin – join fragments, if all collected
\n\t *————————————————————————
\n\t *\/
\n\tstruct ep *
\n\tipfjoin(struct ipfq *iq)
\n\t{
\n\t struct ep *pep;
\n\t struct ip *pip = 0;
\n\t int off, packoff;<\/p>\n
\t if (iq->ipf_state == IPFF_BOGUS)
\n\t return 0;
\n\t \/* see if we have the whole datagram *\/
\n\t \/* \u770b\u6211\u4eec\u662f\u5426\u6709\u6574\u4e2a\u7684\u6570\u636e\u5305 *\/<\/p>\n
\t off = 0;
\n\t while (pep=(struct ep *)seeq(iq->ipf_q)) { \/* \u53d6\u51fa\u5e27*\/
\n\t pip = (struct ip *)pep->ep_data; \/* \u53d6\u51faIP\u62a5*\/
\n\t packoff = (pip->ip_fragoff & IP_FRAGOFF)<<3;
\n\t if (off < packoff) { \/* \u504f\u79fb\u5927\u4e8e0*\/
\n\t while(seeq(iq->ipf_q)) \/* \u4e00\u4e2a\u4e0d\u6ee1\u8db3,\u8bf4\u6ca1\u6ca1\u5168\u5230*\/
\n\t \/*empty*\/;
\n\t return 0;
\n\t }
\n\t off = packoff + pip->ip_len – IP_HLEN(pip); \/*\u8ba1\u7b97\u603b\u957f\u5ea6,\u4e0d\u542b\u5934*\/
\n\t }
\n\t \/* \u8fd9\u91cc\u5229\u7528off\u6765\u6d4b\u8bd5\uff0c\u9996\u5148ipfjoin\u67e5\u770b\u5f53\u524d\u6570\u636e\u62a5\u7247\u7684\u504f\u79fb\u91cf\u662f\u5426\u4e0eoff\u503c\u76f8\u7b26\u3002
\n\t \u5982\u679c\u5f53\u524d\u6570\u636e\u62a5\u7247\u7684\u504f\u79fb\u91cf\u8d85\u8fc7\u4e86off\u7684\u503c\uff0c\u90a3\u4e48\u5fc5\u5b9a\u6709\u5c1a\u672a\u5230\u8fbe\u7684\u6570\u636e\u62a5\u7247\uff0c
\n\t \u56e0\u6b64ipfjoin\u8fd4\u56de0\u3002\u5982\u679c\u504f\u79fb\u91cf\u4e0eoff\u503c\u4e00\u81f4\uff0c\u90a3\u4e48ipfjoin\u901a\u8fc7\u5c06off\u503c\u52a0\u4e0a\u5f53\u524d
\n\t \u6570\u636e\u62a5\u7247\u957f\u5ea6\u51cf\u53bb\u9996\u90e8\u8ba1\u7b97\u51fa\u4e0b\u4e00\u4e2a\u6570\u636e\u62a5\u7247\u7684\u504f\u79fb\u91cf\u3002*\/
\n\t if (off > MAXLRGBUF) { \/* \u8d85\u8fc7\u7f13\u51b2\u533a\u5219\u4e22\u5f03 – too big for us to handle *\/
\n\t while (pep = (struct ep *)deq(iq->ipf_q))
\n\t freebuf(pep);
\n\t freeq(iq->ipf_q);
\n\t iq->ipf_state = IPFF_FREE;
\n\t return 0;
\n\t }
\n\t if (pip == 0 || (pip->ip_fragoff & IP_MF) == 0) \/* \u6ca1\u6709IP\u62a5\u6216\u6ca1\u6709\u66f4\u591a\u7684\u5206\u7247*\/
\n\t return ipfcons(iq); \/* \u6536\u96c6\u6570\u636e\u62a5\u7247\u5e76\u91cd\u5efa\u5b8c\u6574\u7684\u6570\u636e\u62a5 *\/<\/p>\n
\t return 0;
\n\t}<\/p>\n
\n\t4.6 \u5c06\u6570\u636e\u62a5\u7247\u7ec4\u88c5\u6210\u5b8c\u6574\u7684\u6570\u636e\u62a5<\/p>\n
\t\/* ipfcons.c – ipfcons *\/<\/p>\n
\t#include <conf.h>
\n\t#include <kernel.h>
\n\t#include <network.h><\/p>\n
\t\/*————————————————————————
\n\t * ipfcons – \u4eceIP\u788e\u7247\u961f\u5217\u6784\u5efa\u4e00\u4e2a\u5206\u7ec4
\n\t *————————————————————————
\n\t *\/
\n\tstruct ep *
\n\tipfcons(struct ipfq *iq)
\n\t{
\n\t struct ep *pep, *peptmp;
\n\t struct ip *pip;
\n\t int off, seq;<\/p>\n
\t pep = (struct ep *)getbuf(Net.lrgpool); \/* \u7533\u8bf7\u7f13\u5b58\u7a7a\u95f4*\/
\n\t if (pep == (struct ep *)SYSERR) { \/* \u7533\u8bf7\u5931\u8d25\u5219\u4e22\u5f03\u8be5\u62a5*\/
\n\t while (peptmp = (struct ep *)deq(iq->ipf_q)) {
\n\t IpReasmFails++;
\n\t freebuf(peptmp);
\n\t }
\n\t freeq(iq->ipf_q); \/* \u91ca\u653e\u961f\u5217*\/
\n\t iq->ipf_state = IPFF_FREE;
\n\t return 0;
\n\t }
\n\t \/* \u590d\u5236\u5e27\u548cIP\u62a5\u5934 *\/<\/p>\n
\t peptmp = (struct ep *)deq(iq->ipf_q); \/* \u53d6\u51fa\u4e00\u4e2a\u5206\u7247*\/
\n\t pip = (struct ip *)peptmp->ep_data; \/* \u5f97\u5230IP\u62a5*\/
\n\t off = IP_HLEN(pip); \/* \u5f97\u5230IP\u5934\u957f\u5ea6*\/
\n\t seq = 0;
\n\t memcpy(pep, peptmp, EP_HLEN+off); \/* \u590d\u5236IP\u62a5\u5934\u5230pep*\/<\/p>\n
\t \/* \u590d\u5236\u6570\u636e\u90e8\u5206 *\/
\n\t while (peptmp != 0) {
\n\t int dlen, doff;<\/p>\n
\t pip = (struct ip *)peptmp->ep_data; \/* \u53d6IP\u62a5*\/
\n\t doff = IP_HLEN(pip) + seq
\n\t – ((pip->ip_fragoff&IP_FRAGOFF)<<3);
\n\t dlen = pip->ip_len – doff;
\n\t memcpy(pep->ep_data+off, peptmp->ep_data+doff, dlen);
\n\t off += dlen;
\n\t seq += dlen;
\n\t freebuf(peptmp);
\n\t peptmp = (struct ep *)deq(iq->ipf_q);
\n\t }<\/p>\n
\t \/* \u4fee\u590d\u5206\u7ec4\u7684\u5934 *\/
\n\t pip = (struct ip *)pep->ep_data; \/* \u53d6\u51faIP\u62a5*\/
\n\t pip->ip_len = off; \/* \u4fee\u590d\u957f\u5ea6*\/
\n\t pip->ip_fragoff = 0; \/* \u4fee\u590d\u504f\u79fb\u91cf*\/<\/p>\n
\t \/* \u91ca\u653e\u8d44\u6e90 *\/
\n\t freeq(iq->ipf_q);
\n\t iq->ipf_state = IPFF_FREE;
\n\t IpReasmOKs++;
\n\t return pep;
\n\t}<\/p>\n
\t5. \u6570\u636e\u62a5\u7247\u94fe\u8868\u7684\u7ef4\u62a4\u7ba1\u7406<\/p>\n
\t\/* ipftimer.c – ipftimer *\/<\/p>\n
\t#include <conf.h>
\n\t#include <kernel.h>
\n\t#include <network.h><\/p>\n
\t\/*————————————————————————
\n\t * ipftimer – \u66f4\u65b0\u751f\u5b58\u5468\u671f\u5e76\u5220\u9664\u8fc7\u671f\u7684\u788e\u7247
\n\t *————————————————————————
\n\t *\/
\n\tvoid
\n\tipftimer(int gran)
\n\t{
\n\t struct ep *pep;
\n\t struct ip *pip;
\n\t int i;<\/p>\n
\t wait(ipfmutex); \/* \u7533\u8bf7\u4e92\u65a5\u91cf *\/
\n\t for (i=0; i<IP_FQSIZE; ++i) { \/* \u904d\u5386\u961f\u5217*\/
\n\t struct ipfq *iq = &ipfqt[i];<\/p>\n
\t if (iq->ipf_state == IPFF_FREE) \/* \u7a7a\u95f2\u5219\u7ee7\u7eed*\/
\n\t continue;
\n\t iq->ipf_ttl -= gran; \/* \u975e\u7a7a\u95f2\u5219ttl-1*\/
\n\t if (iq->ipf_ttl <= 0) { \/* \u751f\u5b58\u5468\u671f\u5230\u8fbe\u5219*\/
\n\t if (iq->ipf_state == IPFF_BOGUS) { \/* \u5982\u679c\u4e3a\u4e22\u5f03\u72b6\u6001,\u5219\u7ee7\u7eed*\/
\n\t \/* resources already gone *\/
\n\t iq->ipf_state = IPFF_FREE;
\n\t continue;
\n\t }
\n\t if (pep = (struct ep *)deq(iq->ipf_q)) { \/* \u53d6\u5206\u7247*\/
\n\t IpReasmFails++;
\n\t pip = (struct ip *)pep->ep_data; \/* \u53d6IP\u62a5*\/
\n\t icmp(ICT_TIMEX, ICC_FTIMEX, \/* \u5411\u6e90\u7ad9\u62a5\u9519*\/
\n\t pip->ip_src, pep, 0);
\n\t }
\n\t while (pep = (struct ep *)deq(iq->ipf_q)) { \/* \u91ca\u653e\u8d44\u6e90*\/
\n\t IpReasmFails++;
\n\t freebuf(pep);
\n\t }
\n\t freeq(iq->ipf_q); \/* \u91ca\u653e\u961f\u5217*\/
\n\t iq->ipf_state = IPFF_FREE;
\n\t }
\n\t }
\n\t signal(ipfmutex); \/* \u4e92\u65a5\u89e3\u9501*\/
\n\t}<\/p>\n
\t6. \u521d\u59cb\u5316<\/p>\n
\t\/* ipfinit.c – ipfinit *\/<\/p>\n
\t#include <conf.h>
\n\t#include <kernel.h>
\n\t#include <network.h><\/p>\n
\t\/*————————————————————————
\n\t * ipfinit – initialize IP fragment queue data structures
\n\t *————————————————————————
\n\t *\/
\n\tvoid
\n\tipfinit(void)
\n\t{
\n\t int i;<\/p>\n
\t ipfmutex = screate(1); \/* \u4e0d\u591a\u8bf4\u4e86,\u7b80\u5355,\u592a~~~,\u8fd9\u4e2a\u770b\u4e0d\u660e\u767d\u5c31\u4e0d\u7528\u770b\u4e86. \ud83d\ude42 *\/
\n\t for (i=0; i<IP_FQSIZE; ++i)
\n\t ipfqt[i].ipf_state = IPFF_FREE;
\n\t}
\n\t <\/p>\n","protected":false},"excerpt":{"rendered":"
IP:\u5206\u7247\u4e0e\u91cd\u7ec4 1. \u5f15\u8a00 \u4e3a\u4e86\u4e0e\u4e92\u8054\u7f51\u4e0a\u7684\u4efb\u610f\u8ba1\u7b97\u673a\u901a\u4fe1,\u6bcf\u4e2a\u5e94\u7528TCP\/IP\u7684\u8ba1\u7b97\u673a\u5fc5\u987b\u5177\u6709\u5206\u7247\u548c\u91cd\u7ec4\u7684 […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5,14],"tags":[],"class_list":["post-619","post","type-post","status-publish","format-standard","hentry","category-linux-c","category-14"],"_links":{"self":[{"href":"https:\/\/www.kumouse.com\/index.php?rest_route=\/wp\/v2\/posts\/619","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.kumouse.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.kumouse.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.kumouse.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.kumouse.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=619"}],"version-history":[{"count":0,"href":"https:\/\/www.kumouse.com\/index.php?rest_route=\/wp\/v2\/posts\/619\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.kumouse.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=619"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.kumouse.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=619"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.kumouse.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=619"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}