xref: /unit/src/nxt_socket_msg.h (revision 2555:6380c3e7e6a5)
1 /*
2  * Copyright (C) NGINX, Inc.
3  */
4 
5 #ifndef _NXT_SOCKET_MSG_H_INCLUDED_
6 #define _NXT_SOCKET_MSG_H_INCLUDED_
7 
8 #if (NXT_HAVE_UCRED)
9 #include <sys/un.h>
10 #endif
11 
12 
13 #if (NXT_HAVE_UCRED)
14 #define NXT_CRED_USECMSG    1
15 #define NXT_CRED_CMSGTYPE   SCM_CREDENTIALS
16 #define NXT_CRED_GETPID(u)  (u->pid)
17 
18 typedef struct ucred        nxt_socket_cred_t;
19 
20 #elif (NXT_HAVE_MSGHDR_CMSGCRED)
21 #define NXT_CRED_USECMSG    1
22 #define NXT_CRED_CMSGTYPE   SCM_CREDS
23 #define NXT_CRED_GETPID(u)  (u->cmcred_pid)
24 
25 typedef struct cmsgcred     nxt_socket_cred_t;
26 #endif
27 
28 #if (NXT_CRED_USECMSG)
29 #define NXT_OOB_RECV_SIZE                                                     \
30     (CMSG_SPACE(2 * sizeof(int)) + CMSG_SPACE(sizeof(nxt_socket_cred_t)))
31 #else
32 #define NXT_OOB_RECV_SIZE                                                     \
33     CMSG_SPACE(2 * sizeof(int))
34 #endif
35 
36 #if (NXT_HAVE_MSGHDR_CMSGCRED)
37 #define NXT_OOB_SEND_SIZE                                                     \
38     (CMSG_SPACE(2 * sizeof(int)) + CMSG_SPACE(sizeof(nxt_socket_cred_t)))
39 #else
40 #define NXT_OOB_SEND_SIZE                                                     \
41     CMSG_SPACE(2 * sizeof(int))
42 #endif
43 
44 
45 typedef struct {
46     size_t  size;
47     u_char  buf[NXT_OOB_RECV_SIZE];
48 } nxt_recv_oob_t;
49 
50 
51 typedef struct {
52     size_t  size;
53     u_char  buf[NXT_OOB_SEND_SIZE];
54 } nxt_send_oob_t;
55 
56 
57 /**
58  * The nxt_sendmsg is a wrapper for sendmsg.
59  * The oob struct must be initialized using nxt_socket_msg_oob_init().
60  */
61 NXT_EXPORT ssize_t nxt_sendmsg(nxt_socket_t s, nxt_iobuf_t *iob,
62     nxt_uint_t niob, const nxt_send_oob_t *oob);
63 
64 /**
65  * The nxt_recvmsg is a wrapper for recvmsg.
66  * The oob buffer must be consumed by using nxt_socket_msg_oob_get().
67  */
68 NXT_EXPORT ssize_t nxt_recvmsg(nxt_socket_t s,
69     nxt_iobuf_t *iob, nxt_uint_t niob, nxt_recv_oob_t *oob);
70 
71 
72 nxt_inline struct cmsghdr *
NXT_CMSG_NXTHDR(struct msghdr * msgh,struct cmsghdr * cmsg)73 NXT_CMSG_NXTHDR(struct msghdr *msgh, struct cmsghdr *cmsg)
74 {
75 #if !defined(__GLIBC__) && defined(__clang__)
76 #pragma clang diagnostic push
77 #pragma clang diagnostic ignored "-Wsign-compare"
78 #endif
79     return CMSG_NXTHDR(msgh, cmsg);
80 #if !defined(__GLIBC__) && defined(__clang__)
81 #pragma clang diagnostic pop
82 #endif
83 }
84 
85 
86 nxt_inline void
nxt_socket_msg_oob_init(nxt_send_oob_t * oob,int * fds)87 nxt_socket_msg_oob_init(nxt_send_oob_t *oob, int *fds)
88 {
89     int             nfds;
90     struct cmsghdr  *cmsg;
91 
92 #if (NXT_HAVE_MSGHDR_CMSGCRED)
93     cmsg = (struct cmsghdr *) (oob->buf);
94     /*
95      * Fill all padding fields with 0.
96      * Code in Go 1.11 validate cmsghdr using padding field as part of len.
97      * See Cmsghdr definition and socketControlMessageHeaderAndData function.
98      */
99     nxt_memzero(cmsg, sizeof(struct cmsghdr));
100 
101     cmsg->cmsg_len = CMSG_LEN(sizeof(nxt_socket_cred_t));
102     cmsg->cmsg_level = SOL_SOCKET;
103     cmsg->cmsg_type = NXT_CRED_CMSGTYPE;
104 
105     oob->size = CMSG_SPACE(sizeof(nxt_socket_cred_t));
106 
107 #else
108     oob->size = 0;
109 #endif
110 
111     nfds = (fds[0] != -1 ? 1 : 0) + (fds[1] != -1 ? 1 : 0);
112 
113     if (nfds == 0) {
114         return;
115     }
116 
117     cmsg = (struct cmsghdr *) (oob->buf + oob->size);
118 
119     nxt_memzero(cmsg, sizeof(struct cmsghdr));
120 
121     cmsg->cmsg_len = CMSG_LEN(nfds * sizeof(int));
122     cmsg->cmsg_level = SOL_SOCKET;
123     cmsg->cmsg_type = SCM_RIGHTS;
124 
125     /*
126      * nxt_memcpy() is used instead of simple
127      *   *(int *) CMSG_DATA(&cmsg.cm) = fd;
128      * because GCC 4.4 with -O2/3/s optimization may issue a warning:
129      *   dereferencing type-punned pointer will break strict-aliasing rules
130      *
131      * Fortunately, GCC with -O1 compiles this nxt_memcpy()
132      * in the same simple assignment as in the code above.
133      */
134     nxt_memcpy(CMSG_DATA(cmsg), fds, nfds * sizeof(int));
135 
136     oob->size += CMSG_SPACE(nfds * sizeof(int));
137 }
138 
139 
140 nxt_inline nxt_int_t
nxt_socket_msg_oob_get_fds(nxt_recv_oob_t * oob,nxt_fd_t * fd)141 nxt_socket_msg_oob_get_fds(nxt_recv_oob_t *oob, nxt_fd_t *fd)
142 {
143     size_t          size;
144     struct msghdr   msg;
145     struct cmsghdr  *cmsg;
146 
147     msg.msg_control = oob->buf;
148     msg.msg_controllen = oob->size;
149 
150     for (cmsg = CMSG_FIRSTHDR(&msg);
151          cmsg != NULL;
152          cmsg = NXT_CMSG_NXTHDR(&msg, cmsg))
153     {
154         size = cmsg->cmsg_len - CMSG_LEN(0);
155 
156         if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_RIGHTS) {
157             if (nxt_slow_path(size != sizeof(int) && size != 2 * sizeof(int))) {
158                 return NXT_ERROR;
159             }
160 
161             nxt_memcpy(fd, CMSG_DATA(cmsg), size);
162 
163             return NXT_OK;
164         }
165     }
166 
167     return NXT_OK;
168 }
169 
170 
171 nxt_inline nxt_int_t
nxt_socket_msg_oob_get(nxt_recv_oob_t * oob,nxt_fd_t * fd,nxt_pid_t * pid)172 nxt_socket_msg_oob_get(nxt_recv_oob_t *oob, nxt_fd_t *fd, nxt_pid_t *pid)
173 {
174     size_t          size;
175     struct msghdr   msg;
176     struct cmsghdr  *cmsg;
177 
178     if (oob->size == 0) {
179         return NXT_OK;
180     }
181 
182 #if (NXT_CRED_USECMSG)
183     *pid = -1;
184 #endif
185 
186     msg.msg_control = oob->buf;
187     msg.msg_controllen = oob->size;
188 
189     for (cmsg = CMSG_FIRSTHDR(&msg);
190          cmsg != NULL;
191          cmsg = NXT_CMSG_NXTHDR(&msg, cmsg))
192     {
193         size = cmsg->cmsg_len - CMSG_LEN(0);
194 
195         if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_RIGHTS) {
196             if (nxt_slow_path(size != sizeof(int) && size != 2 * sizeof(int))) {
197                 return NXT_ERROR;
198             }
199 
200             nxt_memcpy(fd, CMSG_DATA(cmsg), size);
201 
202 #if (!NXT_CRED_USECMSG)
203             break;
204 #endif
205         }
206 
207 #if (NXT_CRED_USECMSG)
208         else if (cmsg->cmsg_level == SOL_SOCKET
209                  && cmsg->cmsg_type == NXT_CRED_CMSGTYPE)
210         {
211             nxt_socket_cred_t  *creds;
212 
213             if (nxt_slow_path(size != sizeof(nxt_socket_cred_t))) {
214                 return NXT_ERROR;
215             }
216 
217             creds = (nxt_socket_cred_t *) CMSG_DATA(cmsg);
218             *pid = NXT_CRED_GETPID(creds);
219         }
220 #endif
221     }
222 
223 #if (NXT_CRED_USECMSG)
224     /* For platforms supporting credential passing, it's enforced */
225     if (nxt_slow_path(*pid == -1)) {
226         return NXT_ERROR;
227     }
228 #endif
229 
230     return NXT_OK;
231 }
232 
233 
234 #endif /* _NXT_SOCKET_MSG_H_INCLUDED_ */
235