以此纪念刚开始在linux上学习网络编程的失败-_-!
以此纪念刚开始在linux上学习网络编程的失败-_-!
write by 九天雁翎(JTianLing) -- www.jtianling.com
从一开始的学习到现在，我的Ubuntu 8.04服务器版本就从来没有正常的跑过一个服务器程序，亏它还是服务器版本的，郁闷的我要死。目前为止的正常的服务器端网络程序都是在Windows下运行成功的，比如第一次那个daytime服务器，都是靠着移植到windows下才能成功，不过不停的调试啊，调试啊，gdb倒是熟悉了不少，还顺便熟悉了一堆的网络调试工具，linux下的netstat,tcpdump，windows下的Wireshark（linux因为没有X window，所以用不了）倒是真熟悉了很多，我都真不知道这样的死Ubuntu对于学习是好是坏了，假如没有碰到这么多问题的话，我不会调试一个那样简单的程序那么多次，不会这样的进一步熟悉那些特别简单的套接口API,真是，郁闷了。
中间发帖求救，有人说是防火墙，我配置了半天也没有反应，直接将ufw,iptables什么的都卸载了，结果还是不行！
最新的调试结果就是netstat显示的确服务器端listen成功了， tcpdump可以看到客户端的发送的SYN包，但是就是服务器不回ACK包，郁闷的客户端所以总是不停的发送几次SYN包，然后connect failed了，奇怪的家伙，我今晚准备下个ubuntu的普通版本试一下，服务器版本可能为了安全做了太多的手脚，我配置linux的能力又那么弱-_-!光学些bash,makefile什么的，对于配置文件的修改实在是不行，不然我也不会为了samba的配置郁闷到死，然后干脆传输文件都直接改用WinSCP，通过SSH传输，而不是通过共享了。唉。。。。。还是公司好，有管理员。
ubuntu普通版本还不行，我就只好换回FC了。。。。刚才看了一下已经到10了-_-!我上一次用的时候还是FC6呢，那时候4，5张盘，现在FC10只有1CD了，最近的操作系统瘦身工程进行的还挺彻底。要知道，连最最老的经典的RH9那时候都是4张盘。
呵呵，其实想起来，看的其实是UNIX的书，弄个真正的UNIX，比如FreeBSD什么的应该也挺不错的，可惜最近工作那个忙的啊。。。。都快吐血了，游戏快要上大规模的内测了，老总，总监催进度催的我一天头是大的，刚开始弄游戏的主逻辑服务器，第二天就要我设计并添加模块-_-!实在是@#%#$^@#$^$%@&$%基本上就那句话，不能上硬着头皮眯着眼睛也要上！唉。。。。所以嘛，还是暂时收收心吧。。。好好把网络编程学好都不错了，连Linux都没有弄转，呵呵，还是老实点好。
以下是我痛苦的调试经历：-_-!
@ubuntu:~$ netstat -a
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 *:13000 *:* LISTEN
@ubuntu:~$ netstat -a
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 *:daytime *:* LISTEN
@ubuntu:~$ netstat -a
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 *:9877 *:* LISTEN
三个不同的程序，都是卡在listen上。。。。
@ubuntu:~/test/testclient$ ./test 127.0.0.1
connet failed.
@ubuntu:~/test/testclient$ ./test 127.0.0.1
connet failed.
可怜的客户端啊。。。一次一次的connet failed
其实它实在不停的尝试的。。。。
一次：
@ubuntu:~$ sudo tcpdump port 9877
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 96 bytes
22:04:03.173472 IP 192.168.0.158.46269 > localhost.9877: S 1088742785:1088742785(0) win 5840 <mss 1460,sackOK,timestamp 95154 0,nop,wscale 4>
22:04:06.171580 IP 192.168.0.158.46269 > localhost.9877: S 1088742785:1088742785(0) win 5840 <mss 1460,sackOK,timestamp 95904 0,nop,wscale 4>
两次：
@ubuntu:~$ sudo tcpdump port 9877 -vv
tcpdump: listening on eth0, link-type EN10MB (Ethernet), capture size 96 bytes
22:05:09.022315 IP (tos 0x0, ttl 64, id 16507, offset 0, flags [DF], proto TCP (6), length 60) 192.168.0.158.46270 > localhost.9877: S, cksum 0xef4b (correct), 2110715003:2110715003(0) win 5840 <mss 1460,sackOK,timestamp 111616 0,nop,wscale 4>
22:05:12.019572 IP (tos 0x0, ttl 64, id 16508, offset 0, flags [DF], proto TCP (6), length 60) 192.168.0.158.46270 > localhost.9877: S, cksum 0xec5d (correct), 2110715003:2110715003(0) win 5840 <mss 1460,sackOK,timestamp 112366 0,nop,wscale 4>
22:05:18.019572 IP (tos 0x0, ttl 64, id 16509, offset 0, flags [DF], proto TCP (6), length 60) 192.168.0.158.46270 > localhost.9877: S, cksum 0xe681 (correct), 2110715003:2110715003(0) win 5840 <mss 1460,sackOK,timestamp 113866 0,nop,wscale 4>
22:05:30.019593 IP (tos 0x0, ttl 64, id 16510, offset 0, flags [DF], proto TCP (6), length 60) 192.168.0.158.46270 > localhost.9877: S, cksum 0xdac9 (correct), 2110715003:2110715003(0) win 5840 <mss 1460,sackOK,timestamp 116866 0,nop,wscale 4>
22:05:54.019575 IP (tos 0x0, ttl 64, id 16511, offset 0, flags [DF], proto TCP (6), length 60) 192.168.0.158.46270 > localhost.9877: S, cksum 0xc359 (correct), 2110715003:2110715003(0) win 5840 <mss 1460,sackOK,timestamp 122866 0,nop,wscale 4>
22:06:42.019581 IP (tos 0x0, ttl 64, id 16512, offset 0, flags [DF], proto TCP (6), length 60) 192.168.0.158.46270 > localhost.9877: S, cksum 0x9479 (correct), 2110715003:2110715003(0) win 5840 <mss 1460,sackOK,timestamp 134866 0,nop,wscale 4>
6 packets captured
6 packets received by filter
0 packets dropped by kernel
三次：
@ubuntu:~$ sudo tcpdump port 13000 -vv
[sudo] password for xqh:
tcpdump: listening on eth0, link-type EN10MB (Ethernet), capture size 96 bytes
22:44:49.480945 IP (tos 0x0, ttl 64, id 10118, offset 0, flags [DF], proto TCP (6), length 60) 192.168.0.158.60205 > localhost.13000: S, cksum 0xebc4 (correct), 793636653:793636653(0) win 5840 <mss 1460,sackOK,timestamp 706731 0,nop,wscale 4>
22:44:52.479579 IP (tos 0x0, ttl 64, id 10119, offset 0, flags [DF], proto TCP (6), length 60) 192.168.0.158.60205 > localhost.13000: S, cksum 0xe8d6 (correct), 793636653:793636653(0) win 5840 <mss 1460,sackOK,timestamp 707481 0,nop,wscale 4>
22:44:58.479574 IP (tos 0x0, ttl 64, id 10120, offset 0, flags [DF], proto TCP (6), length 60) 192.168.0.158.60205 > localhost.13000: S, cksum 0xe2fa (correct), 793636653:793636653(0) win 5840 <mss 1460,sackOK,timestamp 708981 0,nop,wscale 4>
22:45:10.479576 IP (tos 0x0, ttl 64, id 10121, offset 0, flags [DF], proto TCP (6), length 60) 192.168.0.158.60205 > localhost.13000: S, cksum 0xd742 (correct), 793636653:793636653(0) win 5840 <mss 1460,sackOK,timestamp 711981 0,nop,wscale 4>
22:45:34.479596 IP (tos 0x0, ttl 64, id 10122, offset 0, flags [DF], proto TCP (6), length 60) 192.168.0.158.60205 > localhost.13000: S, cksum 0xbfd2 (correct), 793636653:793636653(0) win 5840 <mss 1460,sackOK,timestamp 717981 0,nop,wscale 4>
22:46:22.479584 IP (tos 0x0, ttl 64, id 10123, offset 0, flags [DF], proto TCP (6), length 60) 192.168.0.158.60205 > localhost.13000: S, cksum 0x90f2 (correct), 793636653:793636653(0) win 5840 <mss 1460,sackOK,timestamp 729981 0,nop,wscale 4>
22:49:22.209124 IP (tos 0x0, ttl 64, id 2573, offset 0, flags [DF], proto TCP (6), length 60) 192.168.0.158.49879 > localhost.13000: S, cksum 0x20c8 (correct), 778754316:778754316(0) win 5840 <mss 1460,sackOK,timestamp 774913 0,nop,wscale 4>
22:49:25.207577 IP (tos 0x0, ttl 64, id 2574, offset 0, flags [DF], proto TCP (6), length 60) 192.168.0.158.49879 > localhost.13000: S, cksum 0x1dda (correct), 778754316:778754316(0) win 5840 <mss 1460,sackOK,timestamp 775663 0,nop,wscale 4>
22:49:31.207570 IP (tos 0x0, ttl 64, id 2575, offset 0, flags [DF], proto TCP (6), length 60) 192.168.0.158.49879 > localhost.13000: S, cksum 0x17fe (correct), 778754316:778754316(0) win 5840 <mss 1460,sackOK,timestamp 777163 0,nop,wscale 4>
22:49:43.207579 IP (tos 0x0, ttl 64, id 2576, offset 0, flags [DF], proto TCP (6), length 60) 192.168.0.158.49879 > localhost.13000: S, cksum 0x0c46 (correct), 778754316:778754316(0) win 5840 <mss 1460,sackOK,timestamp 780163 0,nop,wscale 4>
22:50:07.207588 IP (tos 0x0, ttl 64, id 2577, offset 0, flags [DF], proto TCP (6), length 60) 192.168.0.158.49879 > localhost.13000: S, cksum 0xf4d5 (correct), 778754316:778754316(0) win 5840 <mss 1460,sackOK,timestamp 786163 0,nop,wscale 4>
22:50:55.207580 IP (tos 0x0, ttl 64, id 2578, offset 0, flags [DF], proto TCP (6), length 60) 192.168.0.158.49879 > localhost.13000: S, cksum 0xc5f5 (correct), 778754316:778754316(0) win 5840 <mss 1460,sackOK,timestamp 798163 0,nop,wscale 4>
记住，就算我不改一个字，原《UNIX Network Programming》第一卷第三版一书的源程序（我试过4，5个前面几章的例子了），都是可以编译，可以运行，但是状况都是同样的。。。那就是connect不会成功。-_-!
处于对于原程序的一丝不信任，我自己重写了一些程序，但是几乎同样的程序，在Windows下相当的正常，但是在Ubuntu 8.04服务器版本上，还是同样的状况！！有没有人可以给我个解释啊。。。。。朝闻道夕死可矣。。。。。
举个例子，比如，linux下的两个程序：
服务器端：
1 #include <stdio.h>
2 #include <stdlib.h>
3 #include <sys/socket.h>
4 #include <sys/time.h>
5 #include <time.h>
6 #include <netinet/in.h>
7 #include <errno.h>
8 #include <string.h>
9 #include <unistd.h>
10
11
12 #define MAXLINE 1000
13 int main(int argc, char* argv[])
14 {
15 int listenfd, connfd;
16 struct sockaddr_in servaddr;
17 //char buff[MAXLINE] = {0};
18 //time_t ticks;
19
20 listenfd = socket(AF_INET, SOCK_STREAM, 0);
21 if(0 == listenfd)
22 {
23 printf("socket Error./n");
24 return -1;
25 }
26
27 memset(&servaddr, 0, sizeof(servaddr));
28 servaddr.sin_family = AF_INET;
29 servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
30 servaddr.sin_port = htons(13000); /* daytime server */
31
32 if( 0 != bind(listenfd, (struct sockaddr*)&servaddr, sizeof(servaddr)))
33 {
34 printf("bind error./n");
35 close(listenfd);
36 return -1;
37 }
38
39 if( 0 != listen(listenfd, 10))
40 {
41 printf("listen error./n");
42 close(listenfd);
43 return -1;
44 }
45
46 printf("listen right./n");
47
48 char buffRecv[MAXLINE] = {0};
49 connfd = accept(listenfd, (struct sockaddr*)NULL, NULL);
50
51 printf("have accept./n");
52
53 while(true)
54 {
55 int n = 0;
56 if( 0 == (n = read(connfd, buffRecv, MAXLINE)) )
57 {
58 printf("recv failed/n");
59 break;
60 }
61 buffRecv[n] = 0;
62 if( 0 == (n = write(connfd, buffRecv, strlen(buffRecv))) )
63 {
64 printf("send failed./n");
65 break;
66 }
67 fputs(buffRecv, stdout);
68 }
69 close(connfd);
70 exit(0);
71 }
72
客户端：
1 #include <stdio.h>
2 #include <stdlib.h>
3 #include <sys/socket.h>
4 #include <sys/time.h>
5 #include <time.h>
6 #include <netinet/in.h>
7 #include <errno.h>
8 #include <string.h>
9 #include <unistd.h>
10 #include <arpa/inet.h>
11
12 #define MAXLINE 1000
13
14 void str_cli(FILE *fp, int sockfd)
15 {
16 char sendline[MAXLINE] = {0};
17 char recvline[MAXLINE] = {0};
18 while ( (fgets(sendline, MAXLINE, fp)) != NULL)
19 {
20
21 if(0 == send(sockfd, sendline, strlen(sendline), 0))
22 {
23 printf("send failed./n");
24 break ;
25 }
26 }
27 close(sockfd);
28 }
29
30 int main(int argc, char* argv[])
31 {
32 if (argc != 2)
33 {
34 printf("usage: tcpcli <IPaddress>");
35 exit(1);
36 }
37
38 int sockfd = 0;
39 sockfd = socket(AF_INET, SOCK_STREAM, 0);
40
41 struct sockaddr_in servaddr;
42 memset(&servaddr, 0, sizeof(servaddr));
43 servaddr.sin_family = AF_INET;
44 servaddr.sin_addr.s_addr = inet_addr(argv[1]);
45 servaddr.sin_port = htons(13000); /* daytime server */
46
47 if( 0 != connect(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr)))
48 {
49 printf("connet failed./n");
50 close(sockfd);
51 return -1;
52 }
53
54 str_cli(stdin, sockfd); /* do it all */
55 exit(0);
56 }
57
就这么简单的程序，硬是成功不了，何解？
几乎同样的程序，比如：
服务器端：
#include "Winsock2.h"
//#include "python.h"
//void CallPython(const char* apszPy)
//{
// Py_Initialize();
//
// PyRun_SimpleString(apszPy);
//
// Py_Finalize();
//}
#define MAXLINE 1000
int main(int argc, char **argv)
{
WORD wVersionRequested;
WSADATA wsaData;
int err;
wVersionRequested = MAKEWORD( 2, 2 );
// windows下此初始化为必须
err = WSAStartup( wVersionRequested, &wsaData );
if ( err != 0 ) {
return -1;
}
SOCKET listenfd, connfd;
struct sockaddr_in servaddr;
char buff[MAXLINE];
time_t ticks;
listenfd = socket(AF_INET, SOCK_STREAM, 0);
if(INVALID_SOCKET == listenfd)
{
printf("socket Error: %d",WSAGetLastError());
return -1;
}
ZeroMemory(&servaddr, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
servaddr.sin_port = htons(13); /* daytime server */
bind(listenfd, (struct sockaddr*)&servaddr, sizeof(servaddr));
listen(listenfd, SOMAXCONN);
char buffRecv[MAXLINE] = {0};
connfd = accept(listenfd, (struct sockaddr*)NULL, NULL);
while(true)
{
int n = 0;
if( 0 == (n = recv(connfd, buffRecv, MAXLINE,0)) )
{
printf("recv failed, Error Code: %d", WSAGetLastError());
break;
}
buffRecv[n] = 0;
// CallPython(buffRecv);
if( 0 == (n = send(connfd, buffRecv, strlen(buffRecv),0)) )
{
printf("send failed, Error Code: %d", WSAGetLastError());
break;
}
fputs(buffRecv, stdout);
}
closesocket(connfd);
}
客户端：
#include "Winsock2.h"
#include "errno.h"
#include "stdlib.h"
#define MAXLINE 1000
void str_cli(FILE *fp, SOCKET sockfd)
{
char sendline[MAXLINE] = {0};
char recvline[MAXLINE] = {0};
while ( (fgets(sendline, MAXLINE, fp)) != NULL)
{
if(SOCKET_ERROR == send(sockfd, sendline, strlen(sendline), 0))
{
printf("send failed, Error Code: %d", WSAGetLastError());
break ;
}
}
closesocket(sockfd);
}
int main(int argc, char **argv)
{
WORD wVersionRequested = 0;
WSADATA wsaData;
int err;
wVersionRequested = MAKEWORD( 2, 2 );
// windows下此初始化为必须，实际包含加载WinsockDLL的过程
err = WSAStartup( wVersionRequested, &wsaData );
if ( err != 0 ) {
return -1;
}
SOCKET sockfd;
struct sockaddr_in servaddr;
if (argc != 2)
{
printf("usage: tcpcli <IPaddress>");
exit(1);
}
sockfd = socket(AF_INET, SOCK_STREAM, 0);
ZeroMemory(&servaddr, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(13);
servaddr.sin_addr.s_addr = inet_addr(argv[1]);
if( SOCKET_ERROR == connect(sockfd, (struct sockaddr *) &servaddr, sizeof(servaddr)))
{
printf("connet failed, Error Code: %d", WSAGetLastError());
closesocket(sockfd);
return -1;
}
str_cli(stdin, sockfd); /* do it all */
system("pause");
exit(0);
}
就是运行的那么正常-_-!给我个解释？。。。。。另外，虽然做了写了好几个服务器了，我最近才知道。。原来。。。recv,send本来就是标准的套接口API。。。。我一直以为这些都是windows扩展的-_-!《Unix Network Programming》书以前只看了前面一点，因为前面用的都是read,write接口来写套接字，所以嘛。。。呵呵，误解了，以前还常喊windows下用的recv,send很奇怪呢-_-!太无知了，所以嘛，还是要好好学习底层知识才行。。。不能太依赖于公司的网络框架了，虽然那个框架写的真是不赖。。。好用的很。。。
有在Ubuntu 8.04版本上成功accept的兄弟，请告知怎么样配置的。。。。
以此纪念刚开始在linux上学习网络编程的失败-_-!
write by 九天雁翎(JTianLing) -- www.jtianling.com
Posted By 九天雁翎 at 九天雁翎的博客 on 2009年02月17日