sock.c

#include "sock.h"
#include "ftpfs.h"

#include <asm/uaccess.h>
#include <linux/net.h>
#include <linux/slab.h>
#include <linux/in.h>
#include <linux/version.h>

int sock_send(struct socket *sock, const void *buf, int len) {
    struct iovec iov;
    struct msghdr msg;
    int ret;
    mm_segment_t old_fs = get_fs();
    set_fs(get_ds());

    iov.iov_base = (void*)buf;
    iov.iov_len = len;
    memset(&msg, 0, sizeof(msg));
#if LINUX_VERSION_CODE < KERNEL_VERSION(3, 19, 0)
    msg.msg_iov = &iov;
    msg.msg_iovlen = 1;
#else
    iov_iter_init(&msg.msg_iter, WRITE, &iov, 1, len);
#endif
#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 1, 0)
    ret = sock_sendmsg(sock, &msg, len);
#else
    ret = sock_sendmsg(sock, &msg);
#endif

    set_fs(old_fs);
    return ret;
}

int sock_recv(struct socket *sock, void *buf, int size) {
    struct iovec iov;
    struct msghdr msg;
    int ret;
    mm_segment_t old_fs = get_fs();
    set_fs(get_ds());

    iov.iov_base = buf;
    iov.iov_len = size;
    memset(&msg, 0, sizeof(msg));
#if LINUX_VERSION_CODE < KERNEL_VERSION(3,19,0)
    msg.msg_iov = &iov;
    msg.msg_iovlen = 1;
#else
    iov_iter_init(&msg.msg_iter, READ, &iov, 1, 1);
#endif
    ret = sock_recvmsg(sock, &msg, size, 0);

    set_fs(old_fs);
    return ret;
}

int sock_readline(struct socket *sock, char **buf) {
    int size = 4096, read = 0, ret;
    char *tmp;
    /* allocate an initial buffer of size 4096 */
    *buf = kmalloc(size, GFP_KERNEL);
    if (*buf == NULL)
        return -ENOMEM;

    while (1) {
        /* read 1 char every time */
        ret = sock_recv(sock, *buf + read, 1);
        if (ret <= 0) {
            kfree(*buf);
            return ret;
        }
        read++;
        if ((*buf)[read - 1] == '\n') {
            (*buf)[read] = 0;
            return read;
        }
        /* not enough space, allocate a buffer of doubled size and copy data */
        if (read == size - 1) {
            tmp = kmalloc(size * 2, GFP_KERNEL);
            if (tmp == NULL) {
                kfree(*buf);
                return -ENOMEM;
            }
            memcpy(tmp, *buf, read);
            kfree(*buf);
            *buf = tmp;
            size *= 2;
        }
    }
}

static unsigned short _htons(unsigned short port) {
    unsigned short s0 = port & (unsigned short)0x00ff;
    unsigned short s1 = port & (unsigned short)0xff00;
    pr_debug("got the port %d\n", (s0 << 8) + s1);
    return (s0 << 8) + s1;
}

static void _inet_aton(const char* ip, unsigned int *res) {
    unsigned int s[4];
    int i;
    sscanf(ip, "%u.%u.%u.%u", s, s + 1, s + 2, s + 3);
    *res = 0;
    for (i = 0; i < 4; i++) *res |= s[i] << (8 * i);
    pr_debug("%u.%u.%u.%u\n", s[0], s[1], s[2], s[3]);
    pr_debug("got the ip %u\n", *res);
}

struct sockaddr_in* cons_addr(const char* ip) {
    struct sockaddr_in *addr = kmalloc(sizeof(struct sockaddr_in), GFP_KERNEL);
    if (addr) {
        addr->sin_family = AF_INET;
        addr->sin_port = _htons(FTP_PORT);
        _inet_aton(ip, &addr->sin_addr.s_addr);
    }
    return addr;
}