#include #include #include #include #include #include #include #include #include #define SRV_IP "127.0.0.1" #define PORT 9930 #define BUFLEN 512 #define NPACK 10 enum { SINGLE, PARALLEL } mode = PARALLEL; int do_fork = 0; int pipefds[2]; int server(void) { struct sockaddr_in si_me, si_other; int s, i; socklen_t slen = sizeof(si_other); char buf[BUFLEN]; if ((s = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) == -1) { fprintf(stderr, "socket() failed\n"); exit(1); } memset((char*)&si_me, 0, sizeof(si_me)); si_me.sin_family = AF_INET; si_me.sin_port = htons(PORT); si_me.sin_addr.s_addr = htonl(INADDR_ANY); if (bind(s, (struct sockaddr*)&si_me, sizeof(si_me)) == -1) { fprintf(stderr, "bind() failed\n"); exit(1); } if (mode == PARALLEL) { close(pipefds[0]); char byte = 0; write(pipefds[1], &byte, 1); } if (do_fork) { if (fork() > 0) { close(s); wait(NULL); return 0; } } for (i = 0; i < NPACK; i++) { if (recvfrom(s, buf, BUFLEN, 0, (struct sockaddr*)&si_other, &slen) == -1) { fprintf(stderr, "recvfrom() failed\n"); exit(1); } printf("Received packet from %s:%d\nData: %s\n", inet_ntoa(si_other.sin_addr), ntohs(si_other.sin_port), buf); } close(s); if (do_fork) exit(0); return 0; } int client(void) { struct sockaddr_in si_other; int s, i; socklen_t slen = sizeof(si_other); char buf[BUFLEN] = "hi"; int res; if (mode == PARALLEL) { close(pipefds[1]); char byte = 0; read(pipefds[0], &byte, 1); } if ((s = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) == -1) { fprintf(stderr, "socket() failed\n"); exit(1); } if (do_fork) { if (fork() > 0) { close(s); wait(NULL); return 0; } } memset((char*)&si_other, 0, sizeof(si_other)); si_other.sin_family = AF_INET; si_other.sin_port = htons((PORT)); if (inet_aton(SRV_IP, &si_other.sin_addr) == 0) { fprintf(stderr, "inet_aton() failed\n"); exit(1); } for (i = 0; i < 10; i++) { printf("Sending packet %d\n", i); sprintf(buf, "This is packet %d", i); if ((res = sendto(s, buf, BUFLEN, 0, (struct sockaddr*)&si_other, slen)) == -1) { fprintf(stderr, "sendto() failed\n"); exit(1); } } close(s); if (do_fork) exit(0); return 0; } int main(int argc, char** argv) { if (argc > 1) { if (strcmp(argv[1], "client") == 0) { mode = SINGLE; client(); return 0; } if (strcmp(argv[1], "server") == 0) { mode = SINGLE; server(); return 0; } if (strcmp(argv[1], "fork") == 0) { do_fork = 1; goto old; } } else { old: pipe(pipefds); int pid = fork(); if (pid == 0) client(); else { server(); waitpid(pid, NULL, -1); } } return 0; }