kernel: socket: Add POSIX setsockopt()

This commit introduces the kernel-side implementation of setsockopt()
for setting options on a socket file descriptor. See POSIX
setsockopt() for more information.

https://pubs.opengroup.org/onlinepubs/9690949499/functions/setsockopt.html

Signed-off-by: Ian Moffett <ian@osmora.org>

2 files changed, 140 insertions, 0 deletions

diff --git a/sys/include/sys/socket.h b/sys/include/sys/socket.h
index c82ae4e..9224542 100644
--- a/sys/include/sys/socket.h
+++ b/sys/include/sys/socket.h
@@ -69,6 +69,10 @@ typedef uint32_t socklen_t;
 /* Socket types */
 #define SOCK_STREAM 1
 
+/* Socket option names */
+#define SO_RCVTIMEO 0           /* Max time recv(2) waits */
+#define _SO_MAX     1           /* Max socket options */
+
 struct sockaddr_un {
     sa_family_t sun_family;
     char sun_path[108];
@@ -149,12 +153,22 @@ struct cmsg_list {
     uint8_t is_init : 1;
 };
 
+/*
+ * Socket option that may be applied to
+ * sockets on the system.
+ */
+struct sockopt {
+    socklen_t len;
+    char data[];
+};
+
 struct ksocket {
     int sockfd;
     union {
         struct sockaddr sockaddr;
         struct sockaddr_un un;
     };
+    struct sockopt *opt[_SO_MAX];
     struct proc *owner;
     struct cmsg_list cmsg_list;
     struct sockbuf buf;
@@ -174,6 +188,8 @@ scret_t sys_sendmsg(struct syscall_args *scargs);
 
 int socket(int domain, int type, int protocol);
 int bind(int sockfd, const struct sockaddr *addr, socklen_t len);
+
+int setsockopt(int sockfd, int level, int name, const void *v, socklen_t len);
 int connect(int sockfd, const struct sockaddr *addr, socklen_t len);
 
 ssize_t send(int sockfd, const void *buf, size_t size, int flags);
diff --git a/sys/kern/kern_socket.c b/sys/kern/kern_socket.c
index 02c58be..55b7668 100644
--- a/sys/kern/kern_socket.c
+++ b/sys/kern/kern_socket.c
@@ -31,6 +31,7 @@
 #include <sys/sio.h>
 #include <sys/systm.h>
 #include <sys/proc.h>
+#include <sys/time.h>
 #include <sys/namei.h>
 #include <sys/sched.h>
 #include <sys/errno.h>
@@ -47,6 +48,17 @@
 static struct vops socket_vops;
 
 /*
+ * This table maps socket option names to
+ * lengths of their underlying structure.
+ *
+ * This is used for bounds/length checking within
+ * setsockopt()
+ */
+static size_t sockopt_lentab[_SO_MAX] = {
+    [ SO_RCVTIMEO ] = sizeof(struct timeval)
+};
+
+/*
  * Get a kernel socket structure from a
  * file descriptor.
  *
@@ -101,6 +113,7 @@ static int
 socket_reclaim(struct vnode *vp)
 {
     struct ksocket *ksock;
+    struct sockopt *opt;
 
     /* Is this even a socket? */
     if (vp->type != VSOCK) {
@@ -112,6 +125,15 @@ socket_reclaim(struct vnode *vp)
         return -EIO;
     }
 
+    /* Free up any used options */
+    for (int i = 0; i < _SO_MAX; ++i) {
+        opt = ksock->opt[i];
+        if (opt != NULL) {
+            dynfree(opt);
+            ksock->opt[i] = NULL;
+        }
+    }
+
     fd_close(ksock->sockfd);
     mutex_free(ksock->mtx);
     dynfree(ksock);
@@ -185,6 +207,46 @@ connect_domain(int sockfd, struct ksocket *ksock, struct sockaddr_un *un)
 }
 
 /*
+ * Wait until data is received for the
+ * recv() function.
+ *
+ * @sockfd: Socket we are waiting on
+ *
+ * Returns zero on success, otherwise a less
+ * than zero value is returned.
+ */
+static int
+socket_rx_wait(int sockfd)
+{
+    struct ksocket *ksock;
+    struct sockopt *opt;
+    struct timeval tv;
+    int error;
+
+    if (ksock == NULL) {
+        return -EINVAL;
+    }
+
+    error = get_ksock(sockfd, &ksock);
+    if (error < 0) {
+        return error;
+    }
+
+    /*
+     * If the socket does not have this option set,
+     * we will assume that there is no timeout value.
+     */
+    opt = ksock->opt[SO_RCVTIMEO];
+    if (opt == NULL) {
+        return -1;
+    }
+
+    memcpy(&tv, opt->data, opt->len);
+    sched_suspend(NULL, &tv);
+    return 0;
+}
+
+/*
  * Send data to socket - POSIX send(2) core
  *
  * @sockfd: File descriptor that backs this socket
@@ -397,6 +459,68 @@ bind(int sockfd, const struct sockaddr *addr, socklen_t len)
 }
 
 /*
+ * Set socket options - POSIX setsockopt(3) core
+ *
+ * @sockfd: File descriptor of socket
+ * @level: Protocol level
+ * @v: Options value
+ * @len: Length of data pointed to by 'v'
+ */
+int
+setsockopt(int sockfd, int level, int name, const void *v, socklen_t len)
+{
+    struct ksocket *ksock;
+    struct sockopt *opt;
+    size_t exp_len;
+    int error;
+
+    /* Must have a valid fd */
+    if (sockfd < 0) {
+        return -EBADF;
+    }
+
+    /* Ensure value and length are valid */
+    if (v == NULL || len == 0) {
+        return -EINVAL;
+    }
+
+    /* Verify the name */
+    if (name >= _SO_MAX) {
+        return -EINVAL;
+    }
+
+    /* Grab a new socket */
+    if ((error = get_ksock(sockfd, &ksock)) < 0) {
+        return error;
+    }
+
+    /* Clamp the input length as needed */
+    exp_len = sockopt_lentab[name];
+    if (len > exp_len) {
+        len = exp_len;
+    }
+
+    /*
+     * Here we will grab the socket options. If it is
+     * NULL, we'll need to allocate one.
+     */
+    if ((opt = ksock->opt[name]) == NULL) {
+        opt = dynalloc(sizeof(*opt) + len);
+
+        if (opt == NULL) {
+            return -ENOMEM;
+        }
+
+        opt->len = len;
+        ksock->opt[name] = opt;
+    }
+
+    memcpy(opt->data, v, len);
+    opt->len = len;
+    return 0;
+}
+
+/*
  * Connect to a socket
  *
  * @sockfd: File descriptor to connect