Initial commit

1 files changed, 303 insertions, 0 deletions

diff --git a/server.c b/server.c
new file mode 100644
index 0000000..d867b59
--- /dev/null
+++ b/server.c
@@ -0,0 +1,303 @@
+#include "server.h"
+#include <fcntl.h>
+#include <sys/select.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <unistd.h>
+#include <errno.h>
+#include <signal.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+struct server
+{
+    int fd;
+
+    struct server_client
+    {
+        int fd;
+        bool write;
+    } *c;
+
+    size_t n;
+};
+
+int server_close(struct server *const s)
+{
+    int ret = 0;
+
+    if (!s)
+        return 0;
+    else if (s->fd >= 0)
+        ret = close(s->fd);
+
+    free(s);
+    return ret;
+}
+
+int server_client_close(struct server *const s, struct server_client *const c)
+{
+    int ret = 0;
+
+    for (size_t i = 0; i < s->n; i++)
+    {
+        struct server_client *ref = &s->c[i];
+
+        if (c == ref)
+        {
+            if ((ret = close(c->fd)))
+            {
+                fprintf(stderr, "%s: close(2): %s\n",
+                    __func__, strerror(errno));
+                return -1;
+            }
+            else if (s->n - 1)
+            {
+                memcpy(ref, ref + 1, s->n - i);
+
+                if (!(s->c = realloc(s->c, (s->n - 1) * sizeof *s->c)))
+                {
+                    fprintf(stderr, "%s: realloc(3): %s\n",
+                        __func__, strerror(errno));
+                    return -1;
+                }
+            }
+            else
+            {
+                free(s->c);
+                s->c = NULL;
+            }
+
+            s->n--;
+            break;
+        }
+    }
+
+    return ret;
+}
+
+int server_read(void *const buf, const size_t n, struct server_client *const c)
+{
+    const ssize_t r = read(c->fd, buf, n);
+
+    if (r < 0)
+        fprintf(stderr, "%s: read(2): %s\n", __func__, strerror(errno));
+
+    return r;
+}
+
+int server_write(const void *const buf, const size_t n,
+    struct server_client *const c)
+{
+    const ssize_t w = write(c->fd, buf, n);
+
+    if (w < 0)
+        fprintf(stderr, "%s: write(2): %s\n", __func__, strerror(errno));
+
+    return w;
+}
+
+static struct server_client *alloc_client(struct server *const s)
+{
+    struct sockaddr_in addr;
+    socklen_t sz = sizeof addr;
+    const int fd = accept(s->fd, (struct sockaddr *)&addr, &sz);
+
+    if (fd < 0)
+    {
+        fprintf(stderr, "%s: accept(2): %s\n",
+            __func__, strerror(errno));
+        return NULL;
+    }
+
+    const int flags = fcntl(fd, F_GETFL);
+
+    if (flags < 0)
+    {
+        fprintf(stderr, "%s: fcntl(2) F_GETFL: %s\n",
+            __func__, strerror(errno));
+        return NULL;
+    }
+    else if (fcntl(fd, F_SETFL, flags | O_NONBLOCK))
+    {
+        fprintf(stderr, "%s: fcntl(2) F_SETFL: %s\n",
+            __func__, strerror(errno));
+        return NULL;
+    }
+    else if (!(s->c = realloc(s->c, (s->n + 1) * sizeof *s->c)))
+    {
+        fprintf(stderr, "%s: realloc(3): %s\n",
+            __func__, strerror(errno));
+        return NULL;
+    }
+
+    s->c[s->n] = (const struct server_client)
+    {
+        .fd = fd
+    };
+
+    return &s->c[s->n++];
+}
+
+void server_client_write_pending(struct server_client *const c,
+    const bool write)
+{
+    c->write = write;
+}
+
+static volatile sig_atomic_t do_exit;
+
+static void handle_signal(const int signum)
+{
+    do_exit = 1;
+}
+
+struct server_client *server_select(struct server *const s, bool *const io,
+    bool *const exit)
+{
+    int nfds = -1;
+    fd_set rfds, wfds;
+
+    *io = *exit = false;
+
+    FD_ZERO(&rfds);
+    FD_ZERO(&wfds);
+
+    for (size_t i = 0; i < s->n; i++)
+    {
+        const struct server_client *const c = &s->c[i];
+        const int fd = c->fd;
+
+        FD_SET(fd, &rfds);
+
+        if (c->write)
+            FD_SET(fd, &wfds);
+
+        if (fd > nfds)
+            nfds = fd;
+    }
+
+    FD_SET(s->fd, &rfds);
+
+    if (s->fd > nfds)
+        nfds = s->fd;
+
+    const int res = select(nfds + 1, &rfds, &wfds, NULL, NULL);
+
+    if (res < 0)
+    {
+        if (do_exit)
+            *exit = true;
+        else
+            fprintf(stderr, "%s: select(2): %s\n", __func__, strerror(errno));
+
+        return NULL;
+    }
+    else if (FD_ISSET(s->fd, &rfds))
+        return alloc_client(s);
+
+    for (size_t i = 0; i < s->n; i++)
+    {
+        struct server_client *const c = &s->c[i];
+
+        if (FD_ISSET(c->fd, &rfds) || FD_ISSET(c->fd, &wfds))
+        {
+            *io = true;
+            return c;
+        }
+    }
+
+    fprintf(stderr, "%s: unlisted fd\n", __func__);
+    return NULL;
+}
+
+static int init_signals(void)
+{
+    struct sigaction sa =
+    {
+        .sa_handler = handle_signal,
+        .sa_flags = SA_RESTART
+    };
+
+    sigemptyset(&sa.sa_mask);
+
+    if (sigaction(SIGINT, &sa, NULL))
+    {
+        fprintf(stderr, "%s: sigaction(2) SIGINT: %s\n",
+            __func__, strerror(errno));
+        return -1;
+    }
+    else if (sigaction(SIGTERM, &sa, NULL))
+    {
+        fprintf(stderr, "%s: sigaction(2) SIGINT: %s\n",
+            __func__, strerror(errno));
+        return -1;
+    }
+
+    return 0;
+}
+
+struct server *server_init(const unsigned short port)
+{
+    struct server *const s = malloc(sizeof *s);
+
+    if (!s)
+    {
+        fprintf(stderr, "%s: malloc(3): %s\n", __func__, strerror(errno));
+        goto failure;
+    }
+
+    *s = (const struct server)
+    {
+        .fd = socket(AF_INET, SOCK_STREAM, 0)
+    };
+
+    if (s->fd < 0)
+    {
+        fprintf(stderr, "%s: socket(2): %s\n", __func__, strerror(errno));
+        goto failure;
+    }
+    else if (init_signals())
+    {
+        fprintf(stderr, "%s: init_signals failed\n", __func__);
+        goto failure;
+    }
+
+    const struct sockaddr_in addr =
+    {
+        .sin_family = AF_INET,
+        .sin_port = htons(port)
+    };
+
+    enum {QUEUE_LEN = 10};
+
+    if (bind(s->fd, (const struct sockaddr *)&addr, sizeof addr))
+    {
+        fprintf(stderr, "%s: bind(2): %s\n", __func__, strerror(errno));
+        goto failure;
+    }
+    else if (listen(s->fd, QUEUE_LEN))
+    {
+        fprintf(stderr, "%s: listen(2): %s\n", __func__, strerror(errno));
+        goto failure;
+    }
+
+    struct sockaddr_in in;
+    socklen_t sz = sizeof in;
+
+    if (getsockname(s->fd, (struct sockaddr *)&in, &sz))
+    {
+        fprintf(stderr, "%s: getsockname(2): %s\n", __func__, strerror(errno));
+        goto failure;
+    }
+
+    printf("Listening on port %hu\n", ntohs(in.sin_port));
+    return s;
+
+failure:
+    server_close(s);
+    return NULL;
+}