tests/echo-server.c

   1 /* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil -*-
   2  *
   3  * echo-server.c --- Simple echo server for testing purposes.
   4  *
   5  */
   6
   7 /* TODO: IPv6 support, port to Winsock */
   8
   9 #include <stdio.h>
  10 #include <stdlib.h>
  11 #include <time.h>
  12 #include <ctype.h>
  13 #include <string.h>
  14
  15 #ifdef _WIN32
  16 #include <windows.h>
  17 #include <Winsock2.h>
  18 #include <Ws2tcpip.h>
  19 #else
  20 #include <unistd.h>
  21 #include <errno.h>
  22 #include <sys/types.h>
  23 #include <sys/socket.h>
  24 #include <netinet/in.h>
  25 #include <arpa/inet.h>
  26 #include <sys/select.h>
  27 #endif
  28
  29 #define DEFAULT_PORT 7
  30 #define BACKLOG 10
  31 #define MAXCONS FD_SETSIZE
  32
  33 static int
  34 sendallto(int s, char *buf, int len, struct sockaddr *to, socklen_t tolen)
  35 {
  36     int sent = 0;
  37     int left = len;
  38
  39     while (sent < len) {
  40         int n = sendto(s, buf+sent, left, 0, to, tolen);
  41         if (n == -1) { return -1; }
  42         sent += n;
  43         left -= n;
  44     }
  45
  46     return 0;
  47 }
  48
  49 static char time_str[9];
  50
  51 static const char* timestamp()
  52 {
  53     time_t now = time(NULL);
  54     struct tm *tms = localtime(&now);
  55     strftime(time_str, (sizeof time_str)-1, "%T", tms);
  56     return time_str;
  57 }
  58
  59 int main(int argc, char *argv[])
  60 {
  61     int fds[MAXCONS];
  62     struct sockaddr_in addrs[MAXCONS];
  63     int conns = 0;
  64     int local_port, listenfd, dgramfd;
  65     struct sockaddr_in local;
  66     socklen_t sin_size = sizeof(struct sockaddr_in);
  67
  68     switch (argc) {
  69     case 1: local_port = DEFAULT_PORT; break;
  70     case 2: local_port = strtol(argv[1], NULL, 10); break;
  71     default:
  72         fprintf(stderr, "Usage: %s [port number]\n", argv[0]);
  73         fprintf(stderr, "The default port is: %d.\n", DEFAULT_PORT);
  74         exit(1);
  75     }
  76
  77     if (local_port <= 0 || local_port > 65535) {
  78         fprintf(stderr, "Error: invalid port number.\n");
  79         exit(1);
  80     }
  81
  82     printf("[%s] listening on port %d\n", timestamp(), local_port);
  83
  84     if ((listenfd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
  85         perror("socket");
  86         exit(1);
  87     }
  88
  89     fds[conns++] = listenfd;
  90
  91     if ((dgramfd = socket(AF_INET, SOCK_DGRAM, 0)) == -1) {
  92         perror("dgram socket");
  93         exit(1);
  94     }
  95
  96     fds[conns++] = dgramfd;
  97
  98     local.sin_family = AF_INET;
  99     local.sin_port = htons(local_port);
 100     local.sin_addr.s_addr = INADDR_ANY;
 101     memset(local.sin_zero, 0, sizeof local.sin_zero);
 102
 103     if (bind(listenfd, (struct sockaddr *) &local, sin_size) == -1) {
 104         perror("bind");
 105         exit(1);
 106     }
 107
 108     if (bind(dgramfd, (struct sockaddr *) &local, sin_size) == -1) {
 109         perror("dgram bind");
 110         exit(1);
 111     }
 112
 113     if (listen(listenfd, BACKLOG) == -1) {
 114         perror("listen");
 115         exit(1);
 116     }
 117
 118     for (;;) {
 119         int fd, max_fd, i, j, n;
 120         fd_set readfds;
 121         char buf[4096];
 122
 123         FD_ZERO(&readfds);
 124         for (i = 0, max_fd = -1; i < conns; i++) {
 125             if (fds[i] > max_fd)
 126                 max_fd = fds[i];
 127             FD_SET(fds[i], &readfds);
 128         }
 129
 130         if (select(max_fd+1, &readfds, NULL, NULL, NULL) == -1) {
 131             perror("select");
 132             exit(1);
 133         }
 134
 135         if (FD_ISSET(listenfd, &readfds)) {
 136             fd = accept(listenfd, (struct sockaddr *) &addrs[conns], &sin_size);
 137
 138             if (fd == -1) {
 139                 perror("accept");
 140                 continue;
 141             } else {
 142                 printf("[%s] accepted connection from %s (fd: %d)\n",
 143                        timestamp(), inet_ntoa(addrs[conns].sin_addr), fd);
 144                 fds[conns++] = fd;
 145             }
 146         }
 147
 148         for (i = 1; i < conns; i++) {
 149             if (FD_ISSET(fds[i], &readfds)) {
 150                 sin_size = sizeof(struct sockaddr_in);
 151                 n = recvfrom(fds[i], buf, (sizeof buf)-1, 0,
 152                              (struct sockaddr *) &addrs[i], &sin_size);
 153                 if (n == -1) {
 154                     perror("recvfrom");
 155                     goto error;
 156                 }
 157
 158                 // n == 0? huh hmm..
 159                 if (n == 0) goto error;
 160
 161                 printf("[%s] got %d bytes from %s (%s) ", timestamp(),
 162                        n, inet_ntoa(addrs[i].sin_addr),
 163                        i == 1 ? "udp" : "tcp");
 164
 165                 for (j = 0; j < n; j++) {
 166                     if (j % 75 == 0)
 167                         printf("\n  ");
 168
 169                     if (isprint(buf[j]))
 170                         putchar(buf[j]);
 171                     else
 172                         printf("[0x%x]", buf[j]);
 173
 174                     //putchar(isprint(buf[j]) ? buf[j] : '?');
 175                 }
 176
 177                 if (sendallto(fds[i], buf, n, (struct sockaddr *) &addrs[i],
 178                               sizeof(struct sockaddr_in)) == -1) {
 179                     perror("\nsendto");
 180                     goto error;
 181                 }
 182
 183                 printf("\n  (echoed)\n");
 184                 continue;
 185
 186             error:
 187                 if (i == 1) continue;
 188                 printf("[%s] removing fd %d from set\n", timestamp(), fds[i]);
 189                 close(fds[i]);
 190                 for (j = i+1; j < conns; j++) {
 191                     fds[j-1] = fds[j];
 192                     addrs[j-1] = addrs[j];
 193                 }
 194                 conns--;
 195             }
 196         }
 197     }
 198
 199     return 0;
 200 }