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在系统中，可能会有多片网口，工作在不同的网段，同时有不同的网关，socket需要绑定其中的一个网卡，进行网络的通信。#define INTERFAXENAME "eth1" struct ifreq interface; strncpy(interface.ifr_ifrn.ifrn_name, INTERFAXENAME, sizeof(INTERFAXENAME)); if (setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE, (char *)&interface, sizeof(interface)) < 0) { perror("SO_BINDTODEVICE failed"); } demo程序如下： #include网络调试助手：#include #include #include #include #include #include #include #include #include #include #define BUF_SIZE 1024#define INTERFAXENAME "eth1"int sock;void * network_recv_thread(void * arg){ int n = 0; char buff[BUF_SIZE]; struct sockaddr_in peer; int len = sizeof(peer); while(1) { n = recvfrom(sock, buff, BUF_SIZE, 0, (struct sockaddr *)&peer, &len); if (n>0) { buff[n] = 0; printf("received:"); puts(buff); } else if (n==0) { printf("server closed\n"); close(sock); break; } else if (n == -1) { perror("recvfrom"); close(sock); break; } } return NULL;}int main(int argc, char *argv[]){ int ret = 0; if (argc != 3) { printf("Usage: %s ip port\n", argv[0]); exit(1); } printf("This is a UDP client\n"); if ( (sock=socket(AF_INET, SOCK_DGRAM, 0)) <0) { perror("socket"); exit(1); } struct ifreq interface; strncpy(interface.ifr_ifrn.ifrn_name, INTERFAXENAME, sizeof(INTERFAXENAME)); if (setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE, (char *)&interface, sizeof(interface)) < 0) { perror("SO_BINDTODEVICE failed"); } struct sockaddr_in addr; addr.sin_family = AF_INET; addr.sin_port = htons(atoi(argv[2])); addr.sin_addr.s_addr = inet_addr(argv[1]); if (addr.sin_addr.s_addr == INADDR_NONE) { printf("Incorrect ip address!"); close(sock); exit(1); } pthread_t pid; ret = pthread_create(&pid, NULL,network_recv_thread, NULL); if (ret) { printf("Create pthread error!\n"); return 0; } char buff[BUF_SIZE]; int n = 0; while (1) { gets(buff); n = sendto(sock, buff, strlen(buff), 0, (struct sockaddr *)&addr, sizeof(addr)); if (n < 0) { perror("sendto"); close(sock); break; } } pthread_join(pid, NULL); return 0;}
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