Beginnings of network support.

TODO: rewrite to be addressfamily-independent.  (getaddrinfo)

src/Makefile

@@ -0,0 +1 @@
+CFLAGS=-g -std=c99

src/net.c

@@ -0,0 +1,86 @@
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <stdarg.h>
+#include <errno.h>
+#include <poll.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#define MAX_CLIENTS 2
+#define SRV_FDS 1
+
+int servsock;
+struct pollfd pollfds[SRV_FDS+MAX_CLIENTS];
+int nclients = 0;
+
+int
+errx(int eval, const char *fmt, ...) {
+  va_list ap;
+  vfprintf(stderr, fmt, ap);
+  exit(eval);
+}
+
+int
+net_server(int port) {
+  struct sockaddr_in serveraddr;
+  serveraddr.sin_family = AF_INET;
+  serveraddr.sin_addr.s_addr = htonl(INADDR_ANY);
+  serveraddr.sin_port = htons(port);
+  
+  servsock=socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
+  if (servsock<0)
+    errx(1, "socket: %s", strerror(errno));
+  if (bind(servsock, (struct sockaddr *)&serveraddr, sizeof(serveraddr)) < 0)
+    errx(1, "bind port %d: %s", port, strerror(errno));
+  if (listen(servsock, 10) < 0)
+    errx(1, "listen: %s", strerror(errno));
+  pollfds[0].fd=servsock;
+  pollfds[0].events=POLLIN|POLLERR|POLLHUP;
+  for (int i=SRV_FDS; i<(SRV_FDS+MAX_CLIENTS); i++) {
+    pollfds[0].fd=-1;
+    pollfds[0].events=0;
+  }
+}
+
+
+int
+net_poll() {
+  int npoll;
+  npoll=poll(pollfds, SRV_FDS+MAX_CLIENTS, -1);
+  if (npoll<0)
+    errx(1, "poll: %s", strerror(errno));
+  if (pollfds[0].revents) {
+    struct sockaddr_in clientaddr;
+    int cfd;
+    socklen_t slen;
+    cfd=accept(servsock, (struct sockaddr *)&clientaddr, &slen);
+    if (cfd<0)
+      errx(1, "accept: %s", strerror(errno));
+    // FIXME log, shout, or something
+    if (nclients>MAX_CLIENTS) {
+#define STR_SERVER_FULL "Sorry, the server is full"
+      write(cfd, STR_SERVER_FULL, sizeof(STR_SERVER_FULL)-1);
+      close(cfd);
+    } else {
+      int i;
+      for (i=SRV_FDS; i<(SRV_FDS+MAX_CLIENTS); i++)
+	if (pollfds[i].fd=-1) break;
+      pollfds[i].fd=cfd;
+      pollfds[i].events=POLLIN|POLLERR|POLLHUP;
+      nclients++;
+    }
+    npoll--;
+  }
+  for (int i=SRV_FDS; npoll && i<(SRV_FDS+MAX_CLIENTS); i++) {
+    if (pollfds[SRV_FDS+i].revents) {
+      int n;
+      char buf[100];
+      n=read(pollfds[SRV_FDS+i].fd, &buf, sizeof(buf));
+      // parse buf
+      // handle disconnections
+    }
+  }
+}