簡單的Linux下原生socket的tcp程序及其修改

一個簡單的Linux下原生socket的tcp程序及其修改，最初參考網上資料完成如下：

1. /*
2. * tcpserver.c
3. *Author:coder_xia
4. * Description:a simple tcp server
5. */
7. #include <sys/socket.h>
8. #include <netinet/in.h> //sockaddr_in
9. #include <arpa/inet.h> //inet_addr
10. #include <unistd.h> //close
12. #include <stdio.h>
13. #include <stdlib.h>
14. #include <string.h>
16. #define BUFFERSIZE 128
17. #define TCPPORT 8001
18. #define BACKLOG 5 //max connection number
20. int main(void) {
21. int server_sockfd, client_sockfd;
22. int addr_len, result, recv_len, on = 1;
23. struct sockaddr_in server_address;
24. struct sockaddr_in client_address;
25. char recvbuf[BUFFERSIZE];
27. //init address
28. server_address.sin_family = AF_INET;
29. server_address.sin_addr.s_addr = htonl(INADDR_ANY);
30. server_address.sin_port = htons(TCPPORT);
31. addr_len = sizeof(struct sockaddr_in);
33. //new server socket
34. server_sockfd = socket(AF_INET, SOCK_STREAM, 0);
35. if (-1 == server_sockfd) {
36. perror("socket");
37. exit(EXIT_FAILURE);
38. }
39. //Enable address reuse
40. result = setsockopt(server_sockfd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));
41. //bind and listen
42. result = bind(server_sockfd, (struct sockaddr*)&server_address, addr_len);
43. if (-1 == result) {
44. perror("bind");
45. close(server_sockfd);
46. exit(EXIT_FAILURE);
47. }
48. result = listen(server_sockfd, BACKLOG);
49. if (-1 == result) {
50. perror("listen");
51. close(server_sockfd);
52. exit(EXIT_FAILURE);
53. }
55. while (1) {
56. memset(recvbuf, 0, BUFFERSIZE);
57. printf("server is waiting\n");
58. //Accept a connection, accept will block here,
59. //so ,there's no need to sleep in this loop like in udp
60. client_sockfd = accept(server_sockfd, (struct sockaddr*)&client_address, &addr_len);
61. //recv message from client
62. recvrecv_len = recv(client_sockfd, recvbuf, BUFFERSIZE, 0);
63. if (-1 == recv_len) { //error while recv
64. perror("recv");
65. close(client_sockfd);
66. close(server_sockfd);
67. exit(EXIT_FAILURE);
68. } else if (0 == recv_len) { //peer closed the socket
69. close(client_sockfd);
70. close(server_sockfd);
71. exit(EXIT_FAILURE);
72. }
73. printf("server receieve : %s\n", recvbuf);
74. printf("server port : %d\n", ntohs(server_address.sin_port));
75. printf("client port : %d\n", ntohs(client_address.sin_port));
76. printf("client addr : %s\n", inet_ntoa(client_address.sin_addr));
77. //send to client via client_sockfd
78. result = send(client_sockfd, recvbuf, recv_len, 0);
79. if (-1 == result) {
80. perror("send");
81. close(client_sockfd);
82. close(server_sockfd);
83. exit(EXIT_FAILURE);
84. }
85. }
86. close(server_sockfd);
87. return 0;
88. }