您的位置: 旅游网 > 生活

UTL_INADDR包获取ip地址的内部原理

发布时间:2019-09-13 19:52:44

今天有朋友在MSN上问我如何获得已经连接用户的IP地址。

我们知道,通过SYS_CONTEXT函数可以获得这部分信息,当前用户的ip等信息可以通过如下命令轻易获取:

SQL> select sys_context('userenv','host') from dual; SYS_CONTEXT('USERENV','HOST')

--------------------------------------------------------------------------------

WORKGROUPGQGAI

SQL> select sys_context('userenv','ip_address') from dual;

SYS_CONTEXT('USERENV','IP_ADDR

--------------------------------------------------------------------------------

172.16.34.20

可是如果我们希望获取其它session的地址信息等,通过SYS_CONTEXT函数就只能通过LOGON触发器来完成。

而如果没有触发器记录,则我们可以通过UTL_INADDR Package来实现。

我们看一下UTL_INADDR包获取ip等信息的实现原理。

我们在数据库中进行如下查询:

[oracle@jumper oracle]$ sqlplus "/ as sysdba" SQL*Plus: Release 9.2.0.4.0 - Production on Wed Oct 25 11:24:22 2006

Copyright (c) 1982, 2002, Oracle Corporation. All rights reserved.

Connected to:

Oracle9i Enterprise Edition Release 9.2.0.4.0 - Production

With the Partitioning option

JServer Release 9.2.0.4.0 - Production

SQL> !

[oracle@jumper oracle]$ ps -ef|grep sql

oracle 14700 14663 1 11:24 pts/0 00:00:00 sqlplus

oracle 14732 14702 0 11:24 pts/0 00:00:00 grep sql

[oracle@jumper oracle]$ ps -ef|grep LO

oracle 14701 14700 0 11:24 ? 00:00:00 oracleeygle (DESCRIPTION=(LOCAL=YES)(ADDRESS=(PROTOCOL=beq)))

oracle 14734 14702 0 11:24 pts/0 00:00:00 grep LO

[oracle@jumper oracle]$ exit

exit

SQL> SELECT UTL_INADDR.get_host_address('www.anysql.net') from dual;

UTL_INADDR.GET_HOST_ADDRESS('WWW.ANYSQL.NET')

---------------------------------------------------------------------

208.113.151.109

在Linux中我们通过strace跟踪这个进程,可以得到以下堆栈信息:

[oracle@jumper oracle]$ strace -p 14701

Process 14701 attached - interrupt to quit

read(7, "3^a0@2"..., 2064) = 203

gettimeofday({1161746697, 269895}, NULL) = 0

getrusage(RUSAGE_SELF, {ru_utime={0, 30000}, ru_stime={0, 10000}, ...}) = 0

getrusage(RUSAGE_SELF, {ru_utime={0, 40000}, ru_stime={0, 10000}, ...}) = 0

gettimeofday({1161746697, 270542}, NULL) = 0

gettimeofday({1161746697, 270670}, NULL) = 0

getrusage(RUSAGE_SELF, {ru_utime={0, 40000}, ru_stime={0, 10000}, ...}) = 0

getrusage(RUSAGE_SELF, {ru_utime={0, 40000}, ru_stime={0, 10000}, ...}) = 0

gettimeofday({1161746697, 271614}, NULL) = 0

gettimeofday({1161746697, 271748}, NULL) = 0

getrusage(RUSAGE_SELF, {ru_utime={0, 40000}, ru_stime={0, 10000}, ...}) = 0

getrusage(RUSAGE_SELF, {ru_utime={0, 40000}, ru_stime={0, 10000}, ...}) = 0

gettimeofday({1161746697, 272347}, NULL) = 0

gettimeofday({1161746697, 272699}, NULL) = 0

getrusage(RUSAGE_SELF, {ru_utime={0, 40000}, ru_stime={0, 10000}, ...}) = 0

gettimeofday({1161746697, 272989}, NULL) = 0

gettimeofday({1161746697, 273140}, NULL) = 0

gettimeofday({1161746697, 273273}, NULL) = 0

getrusage(RUSAGE_SELF, {ru_utime={0, 40000}, ru_stime={0, 10000}, ...}) = 0

gettimeofday({1161746697, 273771}, NULL) = 0

gettimeofday({1161746697, 275526}, NULL) = 0

getpid() = 14701

open("/etc/resolv.conf", O_RDONLY) = 12

fstat64(12, {st_mode=S_IFREG|0644, st_size=46, ...}) = 0

mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb6fba000

read(12, "search hurray.com.cnnnameserver "..., 4096) = 46

read(12, "", 4096) = 0

close(12) = 0

munmap(0xb6fba000, 4096) = 0

socket(PF_UNIX, SOCK_STREAM, 0) = 12

connect(12, {sa_family=AF_UNIX, path="/var/run/.nscd_socket"}, 110) = -1 ENOENT (No such file or directory)

close(12) = 0

open("/etc/host.conf", O_RDONLY) = 12

fstat64(12, {st_mode=S_IFREG|0644, st_size=17, ...}) = 0

mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb6fba000

read(12, "order hosts,bindn", 4096) = 17

read(12, "", 4096) = 0

close(12) = 0

munmap(0xb6fba000, 4096) = 0

futex(0xb71a1a20, FUTEX_WAKE, 2147483647) = 0

open("/etc/hosts", O_RDONLY) = 12

fcntl64(12, F_GETFD) = 0

fcntl64(12, F_SETFD, FD_CLOEXEC) = 0

fstat64(12, {st_mode=S_IFREG|0644, st_size=175, ...}) = 0

mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb6fba000

read(12, "# Do not remove the following li"..., 4096) = 175

read(12, "", 4096) = 0

close(12) = 0

munmap(0xb6fba000, 4096) = 0

open("/opt/oracle/product/9.2.0/lib/libnss_dns.so.2", O_RDONLY) = -1 ENOENT (No such file or directory)

open("/lib/tls/libnss_dns.so.2", O_RDONLY) = -1 ENOENT (No such file or directory)

open("/lib/i686/libnss_dns.so.2", O_RDONLY) = -1 ENOENT (No such file or directory)

open("/lib/libnss_dns.so.2", O_RDONLY) = 12

read(12, "7ELF0"..., 512) = 512

fstat64(12, {st_mode=S_IFREG|0755, st_size=18632, ...}) = 0

old_mmap(NULL, 17100, PROT_READ|PROT_EXEC, MAP_PRIVATE, 12, 0) = 0xb6fb6000

old_mmap(0xb6fba000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, 12, 0x3000) = 0xb6fba000

close(12) = 0

open("/opt/oracle/product/9.2.0/lib/libresolv.so.2", O_RDONLY) = -1 ENOENT (No such file or directory)

open("/lib/tls/libresolv.so.2", O_RDONLY) = -1 ENOENT (No such file or directory)

open("/lib/i686/libresolv.so.2", O_RDONLY) = -1 ENOENT (No such file or directory)

open("/lib/libresolv.so.2", O_RDONLY) = 12

read(12, "7ELF0("..., 512) = 512

fstat64(12, {st_mode=S_IFREG|0755, st_size=76508, ...}) = 0

old_mmap(NULL, 73604, PROT_READ|PROT_EXEC, MAP_PRIVATE, 12, 0) = 0xb6fa4000

old_mmap(0xb6fb3000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, 12, 0xf000) = 0xb6fb3000

old_mmap(0xb6fb4000, 8068, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0xb6fb4000

close(12) = 0

socket(PF_INET, SOCK_DGRAM, IPPROTO_IP) = 12

connect(12, {sa_family=AF_INET, sin_port=htons(53), sin_addr=inet_addr("208.113.151.109")}, 28) = 0

send(12, "4#wwwanysqlcom", 31, 0) = 31

gettimeofday({1161746697, 286025}, NULL) = 0

poll([{fd=12, events=POLLIN, revents=POLLIN}], 1, 5000) = 1

ioctl(12, FIONREAD, [74]) = 0

recvfrom(12, "4#10wwwanysqlcom"..., 1024, 0,

{sa_family=AF_INET, sin_port=htons(53), sin_addr=inet_addr("208.113.151.109")}, [16]) = 74

close(12) = 0

gettimeofday({1161746697, 290245}, NULL) = 0

getrusage(RUSAGE_SELF, {ru_utime={0, 40000}, ru_stime={0, 20000}, ...}) = 0

getrusage(RUSAGE_SELF, {ru_utime={0, 40000}, ru_stime={0, 20000}, ...}) = 0

gettimeofday({1161746697, 291553}, NULL) = 0

write(10, "56470001S"..., 701) = 701

read(7, "5^t@"..., 2064) = 141

gettimeofday({1161746697, 294898}, NULL) = 0

getrusage(RUSAGE_SELF, {ru_utime={0, 40000}, ru_stime={0, 20000}, ...}) = 0

getrusage(RUSAGE_SELF, {ru_utime={0, 40000}, ru_stime={0, 20000}, ...}) = 0

gettimeofday({1161746697, 295496}, NULL) = 0

getrusage(RUSAGE_SELF, {ru_utime={0, 40000}, ru_stime={0, 20000}, ...}) = 0

gettimeofday({1161746697, 295847}, NULL) = 0

gettimeofday({1161746697, 295981}, NULL) = 0

lseek(9, 1024, SEEK_SET) = 1024

read(9, "$07@JV`it~2500"..., 512) = 512

lseek(9, 47104, SEEK_SET) = 47104

read(9, "f^Px4y0z3{"..., 512) = 512

gettimeofday({1161746697, 297024}, NULL) = 0

write(10, "2"..., 130) = 130

read(7,

Process 14701 detached在这个信息中,我们注意到Oracle顺序访问了如下文件来完成地址定位:

open("/etc/resolv.conf", O_RDONLY) = 12

open("/etc/host.conf", O_RDONLY) = 12

open("/etc/hosts", O_RDONLY) = 12首先获取域名解析服务器,在根据host.conf文件确定解析顺序,因为缺省hosts文件优先,又继续读取/etc/hosts文件。

如果hosts文件存在解析关系,则返回信息;如果不存在,则继续问询DNS服务器,获得解析地址,如果不能解析,则会出错:

SQL> select UTL_INADDR.get_host_address('www.a.com') from dual;

select UTL_INADDR.get_host_address('www.a.com') from dual

*

ERROR at line 1:

ORA-29257: host www.a.com unknown

ORA-06512: at "SYS.UTL_INADDR", line 35

ORA-06512: at "SYS.UTL_INADDR", line 40

ORA-06512: at line 1

也就是说,UTL_INADDR的数据获取已经不依赖于数据库信息了,而SYS_CONTEXT的信息获取仍然来自数据库内部。 这就是UTL_INADDR包的工作原理。

查看本文来源

婴儿发烧物理降温
小孩有点咳嗽怎么办
宝宝咳嗽流鼻涕怎么办
宝宝感冒鼻塞流鼻涕咳嗽吃什么药
猜你会喜欢的
猜你会喜欢的