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Implement userspace tool : vwifi-tool
An userspace tool vwifi-tool which can display the status of driver and allow users to specify blocklist. According to #48, we want a tool which can configure user-specific blocklist to filter unwanted packets from certain interfaces. This tool will show the status of vwifi driver by reading from `/sys/module/vwifi/initstate`, users can only set blocklist for vwifi driver when it's loaded. Users can use vwifi-tool with command line options which is enabled by `getopt()` to set or unset user-specific blocklist pair. The blocklist will be coppied and sent to the vwifi driver via netlink socket. Resolves: #48
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,191 @@ | ||
| #include <getopt.h> | ||
| #include <linux/netlink.h> | ||
| #include <stdbool.h> | ||
| #include <stdio.h> | ||
| #include <stdlib.h> | ||
| #include <string.h> | ||
| #include <sys/socket.h> | ||
| #include <unistd.h> | ||
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| #define MAX_PAYLOAD 1024 | ||
| #define LINE_LENGTH 20 | ||
| #define MAX_BLOCKLIST_PAIR 5 | ||
| #define VWIFI_STATUS_FILE "/sys/module/vwifi/initstate" | ||
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| /* The function aims to check the status of vwifi kernel module */ | ||
| bool vwifi_status_check() | ||
| { | ||
| FILE *fp = fopen(VWIFI_STATUS_FILE, "r"); | ||
| if (!fp) { | ||
| printf("vwifi status : not loaded\n"); | ||
| return false; | ||
| } | ||
|
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| char read_buf[LINE_LENGTH]; | ||
| fgets(read_buf, LINE_LENGTH, fp); | ||
| read_buf[strcspn(read_buf, "\n")] = | ||
| 0; /* Remove newline character from string */ | ||
| if (!strcmp("live", read_buf)) | ||
| printf("vwifi status : live\n"); | ||
| else { | ||
| printf("vwifi status : %s\n", read_buf); | ||
| return false; | ||
| } | ||
| return true; | ||
| } | ||
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| /* Check if command line options are specified */ | ||
| bool opt_set(int d, int s, int c) | ||
| { | ||
| return d || s || c; | ||
| } | ||
|
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||
| /* Check whether the number of source interfaces matches with the number of | ||
| * destination interfaces */ | ||
| bool blocklist_pair_check(int src_len, int dest_len) | ||
| { | ||
| return src_len == dest_len; | ||
| } | ||
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||
| /* Copy destination and source interface pair into blocklist buffer */ | ||
| bool blocklist_make(char *blocklist, | ||
| char *dest[], | ||
| char *src[], | ||
| int blocklist_len) | ||
| { | ||
| for (int i = 0; i < blocklist_len; i++) { | ||
| char tmp[LINE_LENGTH] = {'\0'}; | ||
| snprintf(tmp, LINE_LENGTH, "%s %s %s\n", dest[i], "blocks", src[i]); | ||
| if (strlen(tmp) + strlen(blocklist) < NLMSG_SPACE(MAX_PAYLOAD)) | ||
| strcat(blocklist, tmp); | ||
| else { | ||
| printf( | ||
| "Error: Blocklist size exceeds the maximum size of buffer\n"); | ||
| return false; | ||
| } | ||
| } | ||
| return true; | ||
| } | ||
|
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| /* Send blocklist to kernel using netlink socket */ | ||
| bool blocklist_send(char *blocklist) | ||
| { | ||
| int sock_fd = socket(PF_NETLINK, SOCK_RAW, NETLINK_USERSOCK); | ||
| if (sock_fd < 0) { | ||
| printf("Error: Can't open socket\n"); | ||
| return false; | ||
| } | ||
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| struct sockaddr_nl src_addr = { | ||
| .nl_family = AF_NETLINK, | ||
| .nl_pid = getpid(), | ||
| }; | ||
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| bind(sock_fd, (struct sockaddr *) &src_addr, sizeof(src_addr)); | ||
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| struct sockaddr_nl dest_addr = { | ||
| .nl_family = AF_NETLINK, | ||
| .nl_pid = 0, | ||
| .nl_groups = 0, | ||
| }; | ||
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| struct nlmsghdr *nlh = | ||
| (struct nlmsghdr *) calloc(1, NLMSG_SPACE(MAX_PAYLOAD)); | ||
| nlh->nlmsg_len = NLMSG_SPACE(MAX_PAYLOAD); | ||
| nlh->nlmsg_pid = getpid(); | ||
| nlh->nlmsg_flags = 0; | ||
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| strncpy(NLMSG_DATA(nlh), blocklist, NLMSG_SPACE(MAX_PAYLOAD)); | ||
|
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| struct iovec iov = { | ||
| .iov_base = (void *) nlh, | ||
| .iov_len = nlh->nlmsg_len, | ||
| }; | ||
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| struct msghdr msg = { | ||
| .msg_name = (void *) &dest_addr, | ||
| .msg_namelen = sizeof(dest_addr), | ||
| .msg_iov = &iov, | ||
| .msg_iovlen = 1, | ||
| }; | ||
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| printf("Configuring blocklist for vwifi...\n"); | ||
| sendmsg(sock_fd, &msg, 0); | ||
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| recvmsg(sock_fd, &msg, 0); | ||
| printf("Message from vwifi: %s\n", (char *) NLMSG_DATA(nlh)); | ||
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| close(sock_fd); | ||
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| return true; | ||
| } | ||
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| int main(int argc, char *argv[]) | ||
| { | ||
| /* Get opt arguments from command line to configure blocklist */ | ||
| char *dest[MAX_BLOCKLIST_PAIR], *src[MAX_BLOCKLIST_PAIR], | ||
| blocklist_pair[MAX_BLOCKLIST_PAIR][LINE_LENGTH]; | ||
| int blocklist_len = 0, dest_len = 0, src_len = 0, clear = 0; | ||
| int c; | ||
|
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| while ((c = getopt(argc, argv, "d:s:ch")) != -1) { | ||
| switch (c) { | ||
| case 'd': | ||
| dest[dest_len++] = optarg; | ||
| break; | ||
| case 's': | ||
| src[src_len++] = optarg; | ||
| break; | ||
| case 'c': | ||
| clear = 1; | ||
| break; | ||
| case 'h': | ||
| printf( | ||
| "vwifi-tool: A userspace tool which supports more " | ||
| "user-specific utilization for vwifi\n\n"); | ||
| printf("Usage:\n\n"); | ||
| printf("\tvwifi-tool [arguments]\n\n"); | ||
| printf("The arguments are:\n\n"); | ||
| printf("\t-d Destination interface name\n"); | ||
| printf("\t-s Source interface name\n"); | ||
| printf("\t-c Clear blocklist\n"); | ||
| return 0; | ||
| default: | ||
| printf("Invalid arguments\n"); | ||
| break; | ||
| } | ||
| } | ||
|
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| if (!vwifi_status_check()) | ||
| exit(1); | ||
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| /* When no options are specified, simply display the status of vwifi */ | ||
| if (!opt_set(dest_len, src_len, clear)) | ||
| return 0; | ||
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| if (!clear && !blocklist_pair_check(src_len, dest_len)) { | ||
| printf("Destination number doesn't match with Source number\n"); | ||
| exit(1); | ||
| } | ||
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| blocklist_len = | ||
| clear ? 0 | ||
| : (dest_len < MAX_BLOCKLIST_PAIR ? dest_len : MAX_BLOCKLIST_PAIR); | ||
|
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| /* Copy blocklist pair into message buffer */ | ||
| char buffer[NLMSG_SPACE(MAX_PAYLOAD)]; | ||
| memset(buffer, '\0', sizeof(buffer)); | ||
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| if (!blocklist_make(buffer, dest, src, blocklist_len)) | ||
| exit(1); | ||
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| if (!clear) | ||
| printf("blocklist:\n%s", buffer); | ||
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| /* Send blocklist buffer to kernel */ | ||
| if (!blocklist_send(buffer)) | ||
| exit(1); | ||
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| return 0; | ||
| } |
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