s_client: Add basic proxy authentication support

1) Add two new flags (-proxy_user & -proxy_pass) to s_client to add support for basic (base64) proxy authentication.
2) Add a "Proxy-Connection: Keep-Alive" HTTP header which is a workaround for some broken proxies which otherwise close the connection when entering tunnel mode (eg Squid 2.6).

Reviewed-by: Paul Dale <paul.dale@oracle.com>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/7975)

1 files changed, 76 insertions, 5 deletions

diff --git a/apps/s_client.c b/apps/s_client.c
index 51001d5766..d788b89dee 100644
--- a/apps/s_client.c
+++ b/apps/s_client.c
@@ -74,6 +74,7 @@ static void print_stuff(BIO *berr, SSL *con, int full);
 static int ocsp_resp_cb(SSL *s, void *arg);
 #endif
 static int ldap_ExtendedResponse_parse(const char *buf, long rem);
+static char *base64encode (const void *buf, size_t len);
 
 static int saved_errno;
 
@@ -590,7 +591,8 @@ typedef enum OPTION_choice {
     OPT_V_ENUM,
     OPT_X_ENUM,
     OPT_S_ENUM,
-    OPT_FALLBACKSCSV, OPT_NOCMDS, OPT_PROXY, OPT_DANE_TLSA_DOMAIN,
+    OPT_FALLBACKSCSV, OPT_NOCMDS, OPT_PROXY, OPT_PROXY_USER, OPT_PROXY_PASS,
+    OPT_DANE_TLSA_DOMAIN,
 #ifndef OPENSSL_NO_CT
     OPT_CT, OPT_NOCT, OPT_CTLOG_FILE,
 #endif
@@ -608,6 +610,8 @@ const OPTIONS s_client_options[] = {
     {"bind", OPT_BIND, 's', "bind local address for connection"},
     {"proxy", OPT_PROXY, 's',
      "Connect to via specified proxy to the real server"},
+    {"proxy_user", OPT_PROXY_USER, 's', "UserID for proxy authentication"},
+    {"proxy_pass", OPT_PROXY_PASS, 's', "Proxy authentication password source"},
 #ifdef AF_UNIX
     {"unix", OPT_UNIX, 's', "Connect over the specified Unix-domain socket"},
 #endif
@@ -894,8 +898,10 @@ int s_client_main(int argc, char **argv)
     STACK_OF(X509_CRL) *crls = NULL;
     const SSL_METHOD *meth = TLS_client_method();
     const char *CApath = NULL, *CAfile = NULL;
-    char *cbuf = NULL, *sbuf = NULL;
-    char *mbuf = NULL, *proxystr = NULL, *connectstr = NULL, *bindstr = NULL;
+    char *cbuf = NULL, *sbuf = NULL, *mbuf = NULL;
+    char *proxystr = NULL, *proxyuser = NULL;
+    char *proxypassarg = NULL, *proxypass = NULL;
+    char *connectstr = NULL, *bindstr = NULL;
     char *cert_file = NULL, *key_file = NULL, *chain_file = NULL;
     char *chCApath = NULL, *chCAfile = NULL, *host = NULL;
     char *port = OPENSSL_strdup(PORT);
@@ -1075,6 +1081,12 @@ int s_client_main(int argc, char **argv)
             proxystr = opt_arg();
             starttls_proto = PROTO_CONNECT;
             break;
+        case OPT_PROXY_USER:
+            proxyuser = opt_arg();
+            break;
+        case OPT_PROXY_PASS:
+            proxypassarg = opt_arg();
+            break;
 #ifdef AF_UNIX
         case OPT_UNIX:
             connect_type = use_unix;
@@ -1619,7 +1631,17 @@ int s_client_main(int argc, char **argv)
 #endif
 
     if (!app_passwd(passarg, NULL, &pass, NULL)) {
-        BIO_printf(bio_err, "Error getting password\n");
+        BIO_printf(bio_err, "Error getting private key password\n");
+        goto end;
+    }
+
+    if (!app_passwd(proxypassarg, NULL, &proxypass, NULL)) {
+        BIO_printf(bio_err, "Error getting proxy password\n");
+        goto end;
+    }
+
+    if (proxypass != NULL && proxyuser == NULL) {
+        BIO_printf(bio_err, "Error: Must specify proxy_user with proxy_pass\n");
         goto end;
     }
 
@@ -2322,7 +2344,31 @@ int s_client_main(int argc, char **argv)
             BIO *fbio = BIO_new(BIO_f_buffer());
 
             BIO_push(fbio, sbio);
-            BIO_printf(fbio, "CONNECT %s HTTP/1.0\r\n\r\n", connectstr);
+            BIO_printf(fbio, "CONNECT %s HTTP/1.0\r\n", connectstr);
+            /* 
+             * Workaround for broken proxies which would otherwise close
+             * the connection when entering tunnel mode (eg Squid 2.6)
+             */
+            BIO_printf(fbio, "Proxy-Connection: Keep-Alive\r\n");
+
+            /* Support for basic (base64) proxy authentication */
+            if (proxyuser != NULL) {
+                size_t l;
+                char *proxyauth, *proxyauthenc;
+
+                l = strlen(proxyuser);
+                if (proxypass != NULL)
+                    l += strlen(proxypass);
+                proxyauth = app_malloc(l + 2, "Proxy auth string");
+                snprintf(proxyauth, l + 2, "%s:%s", proxyuser, (proxypass != NULL) ? proxypass : "");
+                proxyauthenc = base64encode(proxyauth, strlen(proxyauth));
+                BIO_printf(fbio, "Proxy-Authorization: Basic %s\r\n", proxyauthenc); 
+                OPENSSL_clear_free(proxyauth, strlen(proxyauth));
+                OPENSSL_clear_free(proxyauthenc, strlen(proxyauthenc));
+            }
+
+            /* Terminate the HTTP CONNECT request */
+            BIO_printf(fbio, "\r\n");
             (void)BIO_flush(fbio);
             /*
              * The first line is the HTTP response.  According to RFC 7230,
@@ -3128,6 +3174,8 @@ int s_client_main(int argc, char **argv)
     OPENSSL_clear_free(cbuf, BUFSIZZ);
     OPENSSL_clear_free(sbuf, BUFSIZZ);
     OPENSSL_clear_free(mbuf, BUFSIZZ);
+    if (proxypass != NULL)
+        OPENSSL_clear_free(proxypass, strlen(proxypass));
     release_engine(e);
     BIO_free(bio_c_out);
     bio_c_out = NULL;
@@ -3467,4 +3515,27 @@ static int ldap_ExtendedResponse_parse(const char *buf, long rem)
     return ret;
 }
 
+/*
+ * BASE64 encoder: used only for encoding basic proxy authentication credentials
+ */
+static char *base64encode (const void *buf, size_t len)
+{
+    int i;
+    size_t outl;
+    char  *out;
+
+    /* Calculate size of encoded data */
+    outl = (len / 3);
+    if (len % 3 > 0)
+        outl++;
+    outl <<= 2;
+    out = app_malloc(outl + 1, "base64 encode buffer");
+
+    i = EVP_EncodeBlock((unsigned char *)out, buf, len);
+    assert(i <= (int)outl);
+    if (i < 0)
+        *out = '\0'; 
+    return out;
+}
+
 #endif                          /* OPENSSL_NO_SOCK */