文章目錄

• • 1 本地字節流套接字
  • • 1.1 示例代碼
  • 2 本地數據報套接字
  • • 2.1 示例代碼

1 本地字節流套接字

1.1 示例代碼

服務端：

#include "lib/common.h"int main(int argc, char **argv) {if (argc != 2) {error(1, 0, "usage: unixstreamserver <local_path>");}int listenfd, connfd;socklen_t clilen;struct sockaddr_un cliaddr, servaddr;listenfd = socket(AF_LOCAL, SOCK_STREAM, 0);if (listenfd < 0) {error(1, errno, "socket create failed");}char *local_path = argv[1];unlink(local_path);bzero(&servaddr, sizeof(servaddr));servaddr.sun_family = AF_LOCAL;strcpy(servaddr.sun_path, local_path);if (bind(listenfd, (struct sockaddr *) &servaddr, sizeof(servaddr)) < 0) {error(1, errno, "bind failed");}if (listen(listenfd, LISTENQ) < 0) {error(1, errno, "listen failed");}clilen = sizeof(cliaddr);if ((connfd = accept(listenfd, (struct sockaddr *) &cliaddr, &clilen)) < 0) {if (errno == EINTR)error(1, errno, "accept failed"); /* back to for() */elseerror(1, errno, "accept failed");}char buf[BUFFER_SIZE];while (1) {bzero(buf, sizeof(buf));if (read(connfd, buf, BUFFER_SIZE) == 0) {printf("client quit");break;}printf("Receive: %s", buf);char send_line[MAXLINE];sprintf(send_line, "Hi, %s", buf);int nbytes = sizeof(send_line);if (write(connfd, send_line, nbytes) != nbytes)error(1, errno, "write error");}close(listenfd);close(connfd);exit(0);}

注意：

• 關于本地文件路徑，需要明確一點，它必須是“絕對路徑”，這樣的話，編寫好的程序可以在任何目錄里被啟動和管理。如果是“相對路徑”，為了保持同樣的目的，這個程序的啟動路徑就必須固定，這樣一來，對程序的管理反而是一個很大的負擔。

客戶端程序：

#include "lib/common.h"int main(int argc, char **argv) {if (argc != 2) {error(1, 0, "usage: unixstreamclient <local_path>");}int sockfd;struct sockaddr_un servaddr;sockfd = socket(AF_LOCAL, SOCK_STREAM, 0);if (sockfd < 0) {error(1, errno, "create socket failed");}bzero(&servaddr, sizeof(servaddr));servaddr.sun_family = AF_LOCAL;strcpy(servaddr.sun_path, argv[1]);if (connect(sockfd, (struct sockaddr *) &servaddr, sizeof(servaddr)) < 0) {error(1, errno, "connect failed");}char send_line[MAXLINE];bzero(send_line, MAXLINE);char recv_line[MAXLINE];while (fgets(send_line, MAXLINE, stdin) != NULL) {int nbytes = sizeof(send_line);if (write(sockfd, send_line, nbytes) != nbytes)error(1, errno, "write error");if (read(sockfd, recv_line, MAXLINE) == 0)error(1, errno, "server terminated prematurely");fputs(recv_line, stdout);}exit(0); }

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2 本地數據報套接字

2.1 示例代碼

服務器端：

#include "lib/common.h"int main(int argc, char **argv) {if (argc != 2) {error(1, 0, "usage: unixdataserver <local_path>");}int socket_fd;socket_fd = socket(AF_LOCAL, SOCK_DGRAM, 0);if (socket_fd < 0) {error(1, errno, "socket create failed");}struct sockaddr_un servaddr;char *local_path = argv[1];unlink(local_path);bzero(&servaddr, sizeof(servaddr));servaddr.sun_family = AF_LOCAL;strcpy(servaddr.sun_path, local_path);if (bind(socket_fd, (struct sockaddr *) &servaddr, sizeof(servaddr)) < 0) {error(1, errno, "bind failed");}char buf[BUFFER_SIZE];struct sockaddr_un client_addr;socklen_t client_len = sizeof(client_addr);while (1) {bzero(buf, sizeof(buf));if (recvfrom(socket_fd, buf, BUFFER_SIZE, 0, (struct sockadd *) &client_addr, &client_len) == 0) {printf("client quit");break;}printf("Receive: %s \n", buf);char send_line[MAXLINE];bzero(send_line, MAXLINE);sprintf(send_line, "Hi, %s", buf);size_t nbytes = strlen(send_line);printf("now sending: %s \n", send_line);if (sendto(socket_fd, send_line, nbytes, 0, (struct sockadd *) &client_addr, client_len) != nbytes)error(1, errno, "sendto error");}close(socket_fd);exit(0); }

客戶端：

#include "lib/common.h"int main(int argc, char **argv) {if (argc != 2) {error(1, 0, "usage: unixdataclient <local_path>");}int sockfd;struct sockaddr_un client_addr, server_addr;sockfd = socket(AF_LOCAL, SOCK_DGRAM, 0);if (sockfd < 0) {error(1, errno, "create socket failed");}bzero(&client_addr, sizeof(client_addr)); /* bind an address for us */client_addr.sun_family = AF_LOCAL;strcpy(client_addr.sun_path, tmpnam(NULL));if (bind(sockfd, (struct sockaddr *) &client_addr, sizeof(client_addr)) < 0) {error(1, errno, "bind failed");}bzero(&server_addr, sizeof(server_addr));server_addr.sun_family = AF_LOCAL;strcpy(server_addr.sun_path, argv[1]);char send_line[MAXLINE];bzero(send_line, MAXLINE);char recv_line[MAXLINE];while (fgets(send_line, MAXLINE, stdin) != NULL) {int i = strlen(send_line);if (send_line[i - 1] == '\n') {send_line[i - 1] = 0;}size_t nbytes = strlen(send_line);printf("now sending %s \n", send_line);if (sendto(sockfd, send_line, nbytes, 0, (struct sockaddr *) &server_addr, sizeof(server_addr)) != nbytes)error(1, errno, "sendto error");int n = recvfrom(sockfd, recv_line, MAXLINE, 0, NULL, NULL);recv_line[n] = 0;fputs(recv_line, stdout);fputs("\n", stdout);}exit(0); }

注意：

• 需要將本地套接字 bind 到本地一個路徑上，然而 UDP 客戶端程序是不需要這么做的。本地數據報套接字這么做的原因是，它需要指定一個本地路徑，以便在服務器端回包時，可以正確地找到地址；而在 UDP 客戶端程序里，數據是可以通過 UDP 包的本地地址和端口來匹配的。

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