参考文档
https://en.wikipedia.org/wiki/Iproute2
https://en.wikipedia.org/wiki/Netlink
查看Makefile
IPOBJ=ip.o ipaddress.o ipaddrlabel.o iproute.o iprule.o ipnetns.o \
rtm_map.o iptunnel.o ip6tunnel.o tunnel.o ipneigh.o ipntable.o iplink.o \
ipmaddr.o ipmonitor.o ipmroute.o ipprefix.o iptuntap.o iptoken.o \
ipxfrm.o xfrm_state.o xfrm_policy.o xfrm_monitor.o \
iplink_vlan.o link_veth.o link_gre.o iplink_can.o \
iplink_macvlan.o ipl2tp.o link_vti.o link_vti6.o \
iplink_vxlan.o tcp_metrics.o iplink_ipoib.o ipnetconf.o link_ip6tnl.o \
link_iptnl.o link_gre6.o iplink_bond.o iplink_bond_slave.o iplink_hsr.o \
iplink_bridge.o iplink_bridge_slave.o ipfou.o iplink_ipvlan.o \
iplink_geneve.o iplink_vrf.o iproute_lwtunnel.o ipmacsec.o ipila.o
RTMONOBJ=rtmon.o
make后输出
ip
CC ip.o
CC ipaddress.o
CC ipaddrlabel.o
CC iproute.o
CC iprule.o
CC ipnetns.o
CC rtm_map.o
CC iptunnel.o
CC ip6tunnel.o
CC tunnel.o
CC ipneigh.o
CC ipntable.o
CC iplink.o
CC ipmaddr.o
CC ipmonitor.o
CC ipmroute.o
CC ipprefix.o
CC iptuntap.o
CC iptoken.o
CC ipxfrm.o
CC xfrm_state.o
CC xfrm_policy.o
CC xfrm_monitor.o
CC iplink_vlan.o
CC link_veth.o
CC link_gre.o
CC iplink_can.o
CC iplink_macvlan.o
CC ipl2tp.o
CC link_vti.o
CC link_vti6.o
CC iplink_vxlan.o
CC tcp_metrics.o
CC iplink_ipoib.o
CC ipnetconf.o
CC link_ip6tnl.o
CC link_iptnl.o
CC link_gre6.o
CC iplink_bond.o
CC iplink_bond_slave.o
CC iplink_hsr.o
CC iplink_bridge.o
CC iplink_bridge_slave.o
CC ipfou.o
CC iplink_ipvlan.o
CC iplink_geneve.o
CC iplink_vrf.o
CC iproute_lwtunnel.o
CC ipmacsec.o
CC ipila.o
LINK ip
CC rtmon.o
LINK rtmon
ip.c 文件主要流程
// ip route add 127.0.0/8 via 172.16.17.2
int main(int argc, char **argv) { char *basename; // 声明数组指针 char *batch_file = NULL; basename = strrchr(argv[0], \'/\'); // strrchr函数从后向前解析第一个输入参数 if (basename == NULL) basename = argv[0]; else basename++; // basename 为第一个参数的值ip
argc = 6
**argv=[
"ip"
"route"
"add"
"127.0.0/8"
"via"
"172.16.17.2"
]
while 参数个数 > 1
将第2个参数赋值给opt 判断是否是可可选项
如果opt的值 -- ， argc = 5, argv = 1, 结束循环
如果opt != - , 结束循环
如果opt[1] == - ， opt指针+1
如果是 -loops 选项，调用 atoi函数
或如果是 family 选项，preferred_family = readfamily函数读协议栈
或如果是 4 选项， preferred_family = AF_INET
或如果是 6 选项 preferred_family = AF_INET6
或如果是 0 选项 preferred_family = AF_PACKET;
或如果是 I 选项 preferred_family = AF_IPX;
或如果是 D 选项 preferred_family = AF_DECnet;
或如果是 M 选项 preferred_family = AF_MPLS;
或如果是 B 选项 preferred_family = AF_BRIDGE
或如果是 human 选项 ++human_readable ？？
或如果是 iec 选项 ++use_iec; ？？
或如果是 stats 选项 ++show_stats ？？
或如果是 details 选项 ++show_details ??
或如果是 resolve 选项 ++resolve_hosts
或如果是 oneline 选项 ++oneline ？？
或如果是 timestamp 选项 ++timestamp ？？
或如果是 tshort 选项 timestamp 与 timestamp_short 都+1
或如果是 -Version 选项 打印SNAPSHOT 变量
或如果是 force 选项 ++force
或如果是 batch 选项 将参数1的值赋值给 数组batch_file
或如果是 brief 选项 ++brief
或如果是 json 选项 ++json
或如果是 rcvbuf 选项 调用 get_unsigned(&size, argv[1], 0) 获得bufsize的大小
或如果是 color 选项 调用 enable_color() 函数
或如果是 help 选项 调用 usage() 函数
或如果是 netns
或如果是 all 选项 do_all = true
或者 打印错误信息
argc参数个数减1， argv的值的+1
判断循环while循环参数个数是否大于1
执行 rtnl_open(&rth, 0) 函数 初始化信息
如果 argc 的参数 > 1时
do_cmd(argv[1], argc-1, argv+1)
while (argc > 1) { char *opt = argv[1]; if (strcmp(opt, "--") == 0) { argc--; argv++; break; } if (opt[0] != \'-\') break; if (opt[1] == \'-\') opt++; if (matches(opt, "-loops") == 0) { argc--; argv++; if (argc <= 1) usage(); max_flush_loops = atoi(argv[1]); } else if (matches(opt, "-family") == 0) { argc--; argv++; if (argc <= 1) usage(); if (strcmp(argv[1], "help") == 0) usage(); else preferred_family = read_family(argv[1]); if (preferred_family == AF_UNSPEC) invarg("invalid protocol family", argv[1]); } else if (strcmp(opt, "-4") == 0) { preferred_family = AF_INET; } else if (strcmp(opt, "-6") == 0) { preferred_family = AF_INET6; } else if (strcmp(opt, "-0") == 0) { preferred_family = AF_PACKET; } else if (strcmp(opt, "-I") == 0) { preferred_family = AF_IPX; } else if (strcmp(opt, "-D") == 0) { preferred_family = AF_DECnet; } else if (strcmp(opt, "-M") == 0) { preferred_family = AF_MPLS; } else if (strcmp(opt, "-B") == 0) { preferred_family = AF_BRIDGE; } else if (matches(opt, "-human") == 0 || matches(opt, "-human-readable") == 0) { ++human_readable; } else if (matches(opt, "-iec") == 0) { ++use_iec; } else if (matches(opt, "-stats") == 0 || matches(opt, "-statistics") == 0) { ++show_stats; } else if (matches(opt, "-details") == 0) { ++show_details; } else if (matches(opt, "-resolve") == 0) { ++resolve_hosts; } else if (matches(opt, "-oneline") == 0) { ++oneline; } else if (matches(opt, "-timestamp") == 0) { ++timestamp; } else if (matches(opt, "-tshort") == 0) { ++timestamp; ++timestamp_short; #if 0 } else if (matches(opt, "-numeric") == 0) { rtnl_names_numeric++; #endif } else if (matches(opt, "-Version") == 0) { printf("ip utility, iproute2-ss%s\n", SNAPSHOT); exit(0); } else if (matches(opt, "-force") == 0) { ++force; } else if (matches(opt, "-batch") == 0) { argc--; argv++; if (argc <= 1) usage(); batch_file = argv[1]; } else if (matches(opt, "-brief") == 0) { ++brief; } else if (matches(opt, "-json") == 0) { ++json; } else if (matches(opt, "-rcvbuf") == 0) { unsigned int size; argc--; argv++; if (argc <= 1) usage(); if (get_unsigned(&size, argv[1], 0)) { fprintf(stderr, "Invalid rcvbuf size \'%s\'\n", argv[1]); exit(-1); } rcvbuf = size; } else if (matches(opt, "-color") == 0) { enable_color(); } else if (matches(opt, "-help") == 0) { usage(); } else if (matches(opt, "-netns") == 0) { NEXT_ARG(); if (netns_switch(argv[1])) exit(-1); } else if (matches(opt, "-all") == 0) { do_all = true; } else { fprintf(stderr, "Option \"%s\" is unknown, try \"ip -help\".\n", opt); exit(-1); } argc--; argv++; } _SL_ = oneline ? "\\" : "\n"; if (json) check_if_color_enabled(); if (batch_file) return batch(batch_file); if (rtnl_open(&rth, 0) < 0) exit(1); if (strlen(basename) > 2) return do_cmd(basename+2, argc, argv); if (argc > 1) return do_cmd(argv[1], argc-1, argv+1); rtnl_close(&rth); usage(); }
初始化函数 rtnl_open(&rth, 0)
第一个参数 rth 的地址， rth 是 rtnl_handle 结构，定义在 include/libnetlink.h 头文件中
struct rtnl_handle { int fd; // fd是socket 打开的值 struct sockaddr_nl local; // local 是本地地址 struct sockaddr_nl peer; // peer 是邻居地址 __u32 seq; // seq 是32位序列号 __u32 dump; // dump 是32位 int proto; // proto 是协议号 FILE *dump_fp; // dump_fp 是文件名 int flags; // flags 是 标志字段 };
rtnl_open 函数是libnetlink函数库中的函数 man 3 libnetlink
#include <asm/types.h> #include <libnetlink.h> #include <linux/netlink.h> #include <linux/rtnetlink.h> /* 打开一个rtnetlink socket接口，并且将状态信息保存到rtnl_handle数据结构中 */ int rtnl_open(struct rtnl_handle *rth, unsigned subscriptions)
第一个参数： rtnl_handle 是即将要保存的状态信息
第二个参数： subscription是组播号
成功返回0， 失败返回负整数
调用do_cmd函数
do_cmd(argv[1], argc-1, argv+1)
第一个参数 argv[1] 是 对象
第二个参数 argv+1 是指针后移
static int do_cmd(const char *argv0, int argc, char **argv) { const struct cmd *c; for (c = cmds; c->cmd; ++c) { if (matches(argv0, c->cmd) == 0) return -(c->func(argc-1, argv+1)); } fprintf(stderr, "Object \"%s\" is unknown, try \"ip help\".\n", argv0); return EXIT_FAILURE; }
结构cmd命令
static const struct cmd { const char *cmd; int (*func)(int argc, char **argv); } cmds[] = { { "address", do_ipaddr }, { "addrlabel", do_ipaddrlabel }, { "maddress", do_multiaddr }, { "route", do_iproute }, { "rule", do_iprule }, { "neighbor", do_ipneigh }, { "neighbour", do_ipneigh }, { "ntable", do_ipntable }, { "ntbl", do_ipntable }, { "link", do_iplink }, { "l2tp", do_ipl2tp }, { "fou", do_ipfou }, { "ila", do_ipila }, { "macsec", do_ipmacsec }, { "tunnel", do_iptunnel }, { "tunl", do_iptunnel }, { "tuntap", do_iptuntap }, { "tap", do_iptuntap }, { "token", do_iptoken }, { "tcpmetrics", do_tcp_metrics }, { "tcp_metrics", do_tcp_metrics }, { "monitor", do_ipmonitor }, { "xfrm", do_xfrm }, { "mroute", do_multiroute }, { "mrule", do_multirule }, { "netns", do_netns }, { "netconf", do_ipnetconf }, { "vrf", do_ipvrf}, { "sr", do_seg6 }, { "help", do_help }, { 0 } };
命令行一般格式
ip [ OPTIONS ] OBJECT { COMMAND [ ARGUMENTS ] }
一、OPTIONS 选项
说明：option 以 - 或 -- 开头
-V, -Version 打印版本信息且退出， 在SNAPSHOT.h头文件中定义
二、OBJECT 对象
OBJECT := { link | address | addrlabel | route | rule | neigh |
ntable | tunnel | tuntap | maddress | mroute | mrule |
monitor | xfrm | netns | l2tp | tcp_metrics | token | macsec }
link 对象表示网络设备
rotue 对象 表示对路由表进行操作
路由表选路流程：
1. 根据前缀最长匹配
2. 根据TOS字段匹配
3. 根据优先级来匹配
4. 如果还有，则第一条匹配
添加路由
ip route add 10.0.0./24 via 193.233.7.65 ip ro chg 10.0.0/24 via 193.233.7.65 dev dummy ip route add nat 192.203.80.142 via 193.233.7.83
ipaddress.c 地址模块解析
函数一：
参数：
argc是整形变量，参数个数
**argv是参数列表
flush 是整形变量
全局变量
static struct
{
int ifindex; // 接口序列
int family; // 协议簇
int oneline; // 一行
int showqueue; // 显示队列
inet_prefix pfx;
int scope, scopemask;
int flags, flagmask;
int up; // 接口状态
char *label;
int flushed;
char *flushb;
int flushp;
int flushe;
int group;
} filter;
extern struct rtnl_handle rth;
rtnl_handle 定义在库文件中
struct rtnl_handle
{
int fd; // 打开文件指针
struct sockaddr_nl local; // 本地地址
struct sockaddr_nl peer; // 邻居地址
__u32 seq; // 序列号
__u32 dump;
};
调用方法
ipaddr_list_or_flush(0, NULL, 0);
static int ipaddr_list_or_flush(int argc, char **argv, int flush) { struct nlmsg_list *linfo = NULL; struct nlmsg_list *ainfo = NULL; struct nlmsg_list *l, *n; char *filter_dev = NULL; int no_link = 0;
// 第一步： 将filter结构初始化 ipaddr_reset_filter(oneline); filter.showqueue = 1; if (filter.family == AF_UNSPEC) filter.family = preferred_family;
// filter.group = INIT_NETDEV_GROUP; if (flush) { if (argc <= 0) { fprintf(stderr, "Flush requires arguments.\n"); return -1; } if (filter.family == AF_PACKET) { fprintf(stderr, "Cannot flush link addresses.\n"); return -1; } } while (argc > 0) { if (strcmp(*argv, "to") == 0) { NEXT_ARG(); get_prefix(&filter.pfx, *argv, filter.family); if (filter.family == AF_UNSPEC) filter.family = filter.pfx.family; } else if (strcmp(*argv, "scope") == 0) { unsigned scope = 0; NEXT_ARG(); filter.scopemask = -1; if (rtnl_rtscope_a2n(&scope, *argv)) { if (strcmp(*argv, "all") != 0) invarg("invalid \"scope\"\n", *argv); scope = RT_SCOPE_NOWHERE; filter.scopemask = 0; } filter.scope = scope; } else if (strcmp(*argv, "up") == 0) { filter.up = 1; } else if (strcmp(*argv, "dynamic") == 0) { filter.flags &= ~IFA_F_PERMANENT; filter.flagmask |= IFA_F_PERMANENT; } else if (strcmp(*argv, "permanent") == 0) { filter.flags |= IFA_F_PERMANENT; filter.flagmask |= IFA_F_PERMANENT; } else if (strcmp(*argv, "secondary") == 0 || strcmp(*argv, "temporary") == 0) { filter.flags |= IFA_F_SECONDARY; filter.flagmask |= IFA_F_SECONDARY; } else if (strcmp(*argv, "primary") == 0) { filter.flags &= ~IFA_F_SECONDARY; filter.flagmask |= IFA_F_SECONDARY; } else if (strcmp(*argv, "tentative") == 0) { filter.flags |= IFA_F_TENTATIVE; filter.flagmask |= IFA_F_TENTATIVE; } else if (strcmp(*argv, "deprecated") == 0) { filter.flags |= IFA_F_DEPRECATED; filter.flagmask |= IFA_F_DEPRECATED; } else if (strcmp(*argv, "home") == 0) { filter.flags |= IFA_F_HOMEADDRESS; filter.flagmask |= IFA_F_HOMEADDRESS; } else if (strcmp(*argv, "nodad") == 0) { filter.flags |= IFA_F_NODAD; filter.flagmask |= IFA_F_NODAD; } else if (strcmp(*argv, "dadfailed") == 0) { filter.flags |= IFA_F_DADFAILED; filter.flagmask |= IFA_F_DADFAILED; } else if (strcmp(*argv, "label") == 0) { NEXT_ARG(); filter.label = *argv; } else if (strcmp(*argv, "group") == 0) { NEXT_ARG(); if (rtnl_group_a2n(&filter.group, *argv)) invarg("Invalid \"group\" value\n", *argv); } else { if (strcmp(*argv, "dev") == 0) { NEXT_ARG(); } if (matches(*argv, "help") == 0) usage(); if (filter_dev) duparg2("dev", *argv); filter_dev = *argv; } argv++; argc--; } if (rtnl_wilddump_request(&rth, preferred_family, RTM_GETLINK) < 0) { perror("Cannot send dump request"); exit(1); } if (rtnl_dump_filter(&rth, store_nlmsg, &linfo, NULL, NULL) < 0) { fprintf(stderr, "Dump terminated\n"); exit(1); } if (filter_dev) { filter.ifindex = ll_name_to_index(filter_dev); if (filter.ifindex <= 0) { fprintf(stderr, "Device \"%s\" does not exist.\n", filter_dev); return -1; } } if (flush) { int round = 0; char flushb[4096-512]; filter.flushb = flushb; filter.flushp = 0; filter.flushe = sizeof(flushb); while ((max_flush_loops == 0) || (round < max_flush_loops)) { const struct rtnl_dump_filter_arg a[3] = { { .filter = print_addrinfo_secondary, .arg1 = stdout, .junk = NULL, .arg2 = NULL }, { .filter = print_addrinfo_primary, .arg1 = stdout, .junk = NULL, .arg2 = NULL }, { .filter = NULL, .arg1 = NULL, .junk = NULL, .arg2 = NULL }, }; if (rtnl_wilddump_request(&rth, filter.family, RTM_GETADDR) < 0) { perror("Cannot send dump request"); exit(1); } filter.flushed = 0; if (rtnl_dump_filter_l(&rth, a) < 0) { fprintf(stderr, "Flush terminated\n"); exit(1); } if (filter.flushed == 0) { flush_done: if (show_stats) { if (round == 0) printf("Nothing to flush.\n"); else printf("*** Flush is complete after %d round%s ***\n", round, round>1?"s":""); } fflush(stdout); return 0; } round++; if (flush_update() < 0) return 1; if (show_stats) { printf("\n*** Round %d, deleting %d addresses ***\n", round, filter.flushed); fflush(stdout); } /* If we are flushing, and specifying primary, then we * want to flush only a single round. Otherwise, we\'ll * start flushing secondaries that were promoted to * primaries. */ if (!(filter.flags & IFA_F_SECONDARY) && (filter.flagmask & IFA_F_SECONDARY)) goto flush_done; } fprintf(stderr, "*** Flush remains incomplete after %d rounds. ***\n", max_flush_loops); fflush(stderr); return 1; } if (filter.family != AF_PACKET) { if (rtnl_wilddump_request(&rth, filter.family, RTM_GETADDR) < 0) { perror("Cannot send dump request"); exit(1); } if (rtnl_dump_filter(&rth, store_nlmsg, &ainfo, NULL, NULL) < 0) { fprintf(stderr, "Dump terminated\n"); exit(1); } } if (filter.family && filter.family != AF_PACKET) { struct nlmsg_list **lp; lp=&linfo; if (filter.oneline) no_link = 1; while ((l=*lp)!=NULL) { int ok = 0; struct ifinfomsg *ifi = NLMSG_DATA(&l->h); struct nlmsg_list *a; for (a=ainfo; a; a=a->next) { struct nlmsghdr *n = &a->h; struct ifaddrmsg *ifa = NLMSG_DATA(n); if (ifa->ifa_index != ifi->ifi_index || (filter.family && filter.family != ifa->ifa_family)) continue; if ((filter.scope^ifa->ifa_scope)&filter.scopemask) continue; if ((filter.flags^ifa->ifa_flags)&filter.flagmask) continue; if (filter.pfx.family || filter.label) { struct rtattr *tb[IFA_MAX+1]; parse_rtattr(tb, IFA_MAX, IFA_RTA(ifa), IFA_PAYLOAD(n)); if (!tb[IFA_LOCAL]) tb[IFA_LOCAL] = tb[IFA_ADDRESS]; if (filter.pfx.family && tb[IFA_LOCAL]) { inet_prefix dst; memset(&dst, 0, sizeof(dst)); dst.family = ifa->ifa_family; memcpy(&dst.data, RTA_DATA(tb[IFA_LOCAL]), RTA_PAYLOAD(tb[IFA_LOCAL])); if (inet_addr_match(&dst, &filter.pfx, filter.pfx.bitlen)) continue; } if (filter.label) { SPRINT_BUF(b1); const char *label; if (tb[IFA_LABEL]) label = RTA_DATA(tb[IFA_LABEL]); else label = ll_idx_n2a(ifa->ifa_index, b1); if (fnmatch(filter.label, label, 0) != 0) continue; } } ok = 1; break; } if (!ok) *lp = l->next; else lp = &l->next; } } for (l=linfo; l; l = n) { n = l->next; if (no_link || print_linkinfo(NULL, &l->h, stdout) == 0) { struct ifinfomsg *ifi = NLMSG_DATA(&l->h); if (filter.family != AF_PACKET) print_selected_addrinfo(ifi->ifi_index, ainfo, stdout); } fflush(stdout); free(l); } return 0; }