wget: add support for https using "openssl s_client" as a helper

www.kernel.org started redirecting http:// to https://
making https support mandatory for any auto build scripts.

function                                             old     new   delta
wget_main                                           2631    2971    +340
parse_url                                            409     471     +62
.rodata                                           115607  115626     +19
P_HTTPS                                                -       6      +6
P_HTTP                                                 -       5      +5
P_FTP                                                  -       4      +4
------------------------------------------------------------------------------
(add/remove: 3/0 grow/shrink: 3/0 up/down: 436/0)             Total: 436 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 92 insertions, 26 deletions

diff --git a/networking/wget.c b/networking/wget.c
index 7ca947aec..dfea3d4d2 100644
--- a/networking/wget.c
+++ b/networking/wget.c
@@ -47,10 +47,13 @@ struct host_info {
         char *allocated;
         const char *path;
         char       *user;
+        const char *protocol;
         char       *host;
         int         port;
-        smallint    is_ftp;
 };
+static const char P_FTP[] = "ftp";
+static const char P_HTTP[] = "http";
+static const char P_HTTPS[] = "https";
 
 
 /* Globals */
@@ -219,7 +222,7 @@ static FILE *open_socket(len_and_sockaddr *lsa)
         /* glibc 2.4 seems to try seeking on it - ??! */
         /* hopefully it understands what ESPIPE means... */
         fp = fdopen(fd, "r+");
-        if (fp == NULL)
+        if (!fp)
                 bb_perror_msg_and_die(bb_msg_memory_exhausted);
 
         return fp;
@@ -274,23 +277,31 @@ static void parse_url(const char *src_url, struct host_info *h)
         free(h->allocated);
         h->allocated = url = xstrdup(src_url);
 
-        if (strncmp(url, "ftp://", 6) == 0) {
-                h->port = bb_lookup_port("ftp", "tcp", 21);
-                h->host = url + 6;
-                h->is_ftp = 1;
-        } else
-        if (strncmp(url, "http://", 7) == 0) {
-                h->host = url + 7;
+        h->protocol = P_FTP;
+        p = strstr(url, "://");
+        if (p) {
+                *p = '\0';
+                h->host = p + 3;
+                if (strcmp(url, P_FTP) == 0) {
+                        h->port = bb_lookup_port(P_FTP, "tcp", 21);
+                } else
+                if (strcmp(url, P_HTTPS) == 0) {
+                        h->port = bb_lookup_port(P_HTTPS, "tcp", 443);
+                        h->protocol = P_HTTPS;
+                } else
+                if (strcmp(url, P_HTTP) == 0) {
  http:
-                h->port = bb_lookup_port("http", "tcp", 80);
-                h->is_ftp = 0;
-        } else
-        if (!strstr(url, "//")) {
+                        h->port = bb_lookup_port(P_HTTP, "tcp", 80);
+                        h->protocol = P_HTTP;
+                } else {
+                        *p = ':';
+                        bb_error_msg_and_die("not an http or ftp url: %s", sanitize_string(url));
+                }
+        } else {
                 // GNU wget is user-friendly and falls back to http://
                 h->host = url;
                 goto http;
-        } else
-                bb_error_msg_and_die("not an http or ftp url: %s", sanitize_string(url));
+        }
 
         // FYI:
         // "Real" wget 'http://busybox.net?var=a/b' sends this request:
@@ -472,6 +483,56 @@ static FILE* prepare_ftp_session(FILE **dfpp, struct host_info *target, len_and_
         return sfp;
 }
 
+static int spawn_https_helper(const char *host, unsigned port)
+{
+        char *allocated = NULL;
+        int sp[2];
+        int pid;
+
+        if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) != 0)
+                /* Kernel can have AF_UNIX support disabled */
+                bb_perror_msg_and_die("socketpair");
+
+        if (!strchr(host, ':'))
+                host = allocated = xasprintf("%s:%u", host, port);
+
+        pid = BB_MMU ? xfork() : xvfork();
+        if (pid == 0) {
+                /* Child */
+                char *argv[6];
+
+                close(sp[0]);
+                xmove_fd(sp[1], 0);
+                xdup2(0, 1);
+                /*
+                 * TODO: develop a tiny ssl/tls helper (using matrixssl?),
+                 * try to exec it here before falling back to big fat openssl.
+                 */
+                /*
+                 * openssl s_client -quiet -connect www.kernel.org:443 2>/dev/null
+                 * It prints some debug stuff on stderr, don't know how to suppress it.
+                 * Work around by dev-nulling stderr. We lose all error messages :(
+                 */
+                xmove_fd(2, 3);
+                xopen("/dev/null", O_RDWR);
+                argv[0] = (char*)"openssl";
+                argv[1] = (char*)"s_client";
+                argv[2] = (char*)"-quiet";
+                argv[3] = (char*)"-connect";
+                argv[4] = (char*)host;
+                argv[5] = NULL;
+                BB_EXECVP(argv[0], argv);
+                xmove_fd(3, 2);
+                bb_perror_msg_and_die("can't execute '%s'", argv[0]);
+                /* notreached */
+        }
+
+        /* parent process */
+        free(allocated);
+        close(sp[1]);
+        return sp[0];
+}
+
 static void NOINLINE retrieve_file_data(FILE *dfp)
 {
 #if ENABLE_FEATURE_WGET_STATUSBAR || ENABLE_FEATURE_WGET_TIMEOUT
@@ -644,7 +705,8 @@ static void download_one_url(const char *url)
         /* Use the proxy if necessary */
         use_proxy = (strcmp(G.proxy_flag, "off") != 0);
         if (use_proxy) {
-                proxy = getenv(target.is_ftp ? "ftp_proxy" : "http_proxy");
+                proxy = getenv(target.protocol == P_FTP ? "ftp_proxy" : "http_proxy");
+//FIXME: what if protocol is https? Ok to use http_proxy?
                 use_proxy = (proxy && proxy[0]);
                 if (use_proxy)
                         parse_url(proxy, &server);
@@ -704,27 +766,31 @@ static void download_one_url(const char *url)
         /*G.content_len = 0; - redundant, got_clen = 0 is enough */
         G.got_clen = 0;
         G.chunked = 0;
-        if (use_proxy || !target.is_ftp) {
+        if (use_proxy || target.protocol != P_FTP) {
                 /*
                  *  HTTP session
                  */
                 char *str;
                 int status;
 
-
-                /* Open socket to http server */
-                sfp = open_socket(lsa);
+                /* Open socket to http(s) server */
+                if (target.protocol == P_HTTPS) {
+                        int fd = spawn_https_helper(server.host, server.port);
+                        sfp = fdopen(fd, "r+");
+                        if (!sfp)
+                                bb_perror_msg_and_die(bb_msg_memory_exhausted);
+                } else
+                        sfp = open_socket(lsa);
 
                 /* Send HTTP request */
                 if (use_proxy) {
-                        fprintf(sfp, "GET %stp://%s/%s HTTP/1.1\r\n",
-                                target.is_ftp ? "f" : "ht", target.host,
+                        fprintf(sfp, "GET %s://%s/%s HTTP/1.1\r\n",
+                                target.protocol, target.host,
                                 target.path);
                 } else {
-                        if (option_mask32 & WGET_OPT_POST_DATA)
-                                fprintf(sfp, "POST /%s HTTP/1.1\r\n", target.path);
-                        else
-                                fprintf(sfp, "GET /%s HTTP/1.1\r\n", target.path);
+                        fprintf(sfp, "%s /%s HTTP/1.1\r\n",
+                                (option_mask32 & WGET_OPT_POST_DATA) ? "POST" : "GET",
+                                target.path);
                 }
 
                 fprintf(sfp, "Host: %s\r\nUser-Agent: %s\r\n",