intro.ps

早期freebsd实现

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(sender2)272.45 155.6 Q 252 135.6 252 171.6 DL 324 135.6 252 135.6 DL 324 171.6
324 135.6 DL 252 171.6 324 171.6 DL(sender3)380.45 155.6 Q 360 135.6 360 171.6
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207.6 288 171.6 DL 288 207.6 286.2 200.4 DL 288 207.6 289.8 200.4 DL(sendmail)
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288 279.6 289.8 272.4 DL(mailer1)164.725 299.6 Q 144 279.6 144 315.6 DL 216
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279.6 DL 252 315.6 324 315.6 DL(mailer3)380.725 299.6 Q 360 279.6 360 315.6 DL
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180 171.6 DL 252 207.6 244.728 206.016 DL 252 207.6 246.384 202.776 DL 324
207.6 396 171.6 DL 324 207.6 329.616 202.776 DL 324 207.6 331.272 206.016 DL
180 279.6 252 243.6 DL 180 279.6 185.616 274.776 DL 180 279.6 187.272 278.016
DL 396 279.6 324 243.6 DL 396 279.6 388.728 278.016 DL 396 279.6 390.384
274.776 DL(Figure 1 \212 Sendmail System Structure.)208 346.8 Q 77 358.8 72
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DL 504 358.8 499 358.8 DL F0 2.5(2. O)72 394.8 R(VER)-.5 E(VIEW)-.55 E 2.5
(2.1. System)87 418.8 R(Or)2.5 E(ganization)-.1 E/F2 10/Times-Italic@0 SF
(Sendmail)127 435 Q F1 .874(neither interf)3.374 F .874
(aces with the user nor does actual mail deli)-.1 F -.15(ve)-.25 G(ry).15 E
5.873(.R)-.65 G(ather)431.241 435 Q 3.373(,i)-.4 G 3.373(tc)459.484 435 S .873
(ollects a)470.077 435 R .619(message generated by a user interf)102 447 R .619
(ace program \(UIP\) such as Berk)-.1 F(ele)-.1 E(y)-.15 E F2(Mail)3.12 E F1
3.12(,M)C 3.12(S[)427.6 447 S(Crock)439.61 447 Q .62(er77b], or)-.1 F 1.428
(MH [Borden79], edits the message as required by the destination netw)102 459 R
1.427(ork, and calls appropriate)-.1 F .28(mailers to do mail deli)102 473 R
-.15(ve)-.25 G .281(ry or queueing for netw).15 F .281(ork transmission)-.1 F
/F3 7/Times-Roman@0 SF(1)364.275 469 Q F1 5.281(.T)367.775 473 S .281
(his discipline allo)381.666 473 R .281(ws the inser)-.25 F(-)-.2 E 1.354
(tion of ne)102 485 R 3.854(wm)-.25 G 1.354(ailers at minimum cost.)161.642 485
R 1.354(In this sense)6.354 F F2(sendmail)3.853 E F1 1.353
(resembles the Message Processing)3.853 F(Module \(MPM\) of [Postel79b].)102
497 Q F0 2.5(2.2. Interfaces)87 521 R(to the Outside W)2.5 E(orld)-.75 E F1
.041(There are three w)127 537.2 R(ays)-.1 E F2(sendmail)2.541 E F1 .041
(can communicate with the outside w)2.541 F .042(orld, both in recei)-.1 F .042
(ving and)-.25 F 1.195(in sending mail.)102 549.2 R 1.194
(These are using the con)6.194 F -.15(ve)-.4 G 1.194(ntional UNIX ar).15 F
1.194(gument v)-.18 F 1.194(ector/return status, speaking)-.15 F(SMTP o)102
561.2 Q -.15(ve)-.15 G 2.5(rap).15 G(air of UNIX pipes, and speaking SMTP o)
162.53 561.2 Q -.15(ve)-.15 G 2.5(ra).15 G 2.5(ni)348.03 561.2 S
(nterprocess\(or\) channel.)358.31 561.2 Q F0 2.5(2.2.1. Ar)102 585.2 R
(gument v)-.1 E(ector/exit status)-.1 E F1 .52(This technique is the standard \
UNIX method for communicating with the process.)142 601.4 R 3.02(Al)5.52 G(ist)
494.55 601.4 Q .442(of recipients is sent in the ar)117 613.4 R .441(gument v)
-.18 F(ector)-.15 E 2.941(,a)-.4 G .441
(nd the message body is sent on the standard input.)299.491 613.4 R(An)117
625.4 Q .351(ything that the mailer prints is simply collected and sent back t\
o the sender if there were an)-.15 F(y)-.15 E 2.621(problems. The)117 637.4 R
-.15(ex)2.621 G .121(it status from the mailer is collected after the message \
is sent, and a diagnostic).15 F(is printed if appropriate.)117 649.4 Q .32 LW
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208 678.8 DL 216 678.8 212 678.8 DL/F4 5/Times-Roman@0 SF(1)93.6 689.2 Q/F5 8
/Times-Roman@0 SF -.12(ex)3.2 K(cept when mailing to a \214le, when).12 E/F6 8
/Times-Italic@0 SF(sendmail)2 E F5(does the deli)2 E -.12(ve)-.2 G(ry directly)
.12 E(.)-.52 E EP
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/F0 10/Times-Bold@0 SF 192.28(SMM:9-4 SENDMAIL)72 60 R 2.5<8a41>2.5 G 2.5(nI)
383.99 60 S(nter)395.94 60 Q(netw)-.15 E(ork Mail Router)-.1 E 2.5(2.2.2. SMTP)
102 96 R -.1(ove)2.5 G 2.5(rp).1 G(ipes)186.52 96 Q/F1 10/Times-Roman@0 SF .774
(The SMTP protocol [Postel82] can be used to run an interacti)142 112.2 R 1.074
-.15(ve l)-.25 H .774(ock-step interf).15 F .774(ace with)-.1 F .507
(the mailer)117 124.2 R 5.507(.A)-.55 G .506(subprocess is still created, b)
175.461 124.2 R .506(ut no recipient addresses are passed to the mailer via)-.2
F .075(the ar)117 136.2 R .075(gument list.)-.18 F .075(Instead, the)5.075 F
2.575(ya)-.15 G .075
(re passed one at a time in commands sent to the processes stan-)249.805 136.2
R .19(dard input.)117 148.2 R(An)5.19 E .19(ything appearing on the standard o\
utput must be a reply code in a special format.)-.15 F F0 2.5(2.2.3. SMTP)102
172.2 R -.1(ove)2.5 G 2.5(ra).1 G 2.5(nI)185.96 172.2 S(PC connection)197.91
172.2 Q F1 .366(This technique is similar to the pre)142 188.4 R .366
(vious technique, e)-.25 F .366(xcept that it uses a 4.2bsd IPC chan-)-.15 F
.953(nel [UNIX83].)117 200.4 R .953(This method is e)5.953 F .953
(xceptionally \215e)-.15 F .952
(xible in that the mailer need not reside on the)-.15 F(same machine.)117 212.4
Q(It is normally used to connect to a sendmail process on another machine.)5 E
F0 2.5(2.3. Operational)87 236.4 R(Description)2.5 E F1 .228(When a sender w)
127 252.6 R .228(ants to send a message, it issues a request to)-.1 F/F2 10
/Times-Italic@0 SF(sendmail)2.729 E F1 .229(using one of the three)2.729 F
1.028(methods described abo)102 264.6 R -.15(ve)-.15 G(.).15 E F2(Sendmail)
6.028 E F1 1.028(operates in tw)3.528 F 3.528(od)-.1 G 1.028(istinct phases.)
325.706 264.6 R 1.028(In the \214rst phase, it collects)6.028 F .612
(and stores the message.)102 276.6 R .612(In the second phase, message deli)
5.612 F -.15(ve)-.25 G .612(ry occurs.).15 F .612(If there were errors during)
5.612 F 1.59(processing during the second phase,)102 288.6 R F2(sendmail)4.09 E
F1 1.59(creates and returns a ne)4.09 F 4.09(wm)-.25 G 1.59
(essage describing the)415.84 288.6 R
(error and/or returns an status code telling what went wrong.)102 300.6 Q F0
2.5(2.3.1. Ar)102 324.6 R(gument pr)-.1 E(ocessing and addr)-.18 E(ess parsing)
-.18 E F1(If)142 340.8 Q F2(sendmail)3.321 E F1 .821
(is called using one of the tw)3.321 F 3.322(os)-.1 G .822
(ubprocess techniques, the ar)320.66 340.8 R .822(guments are \214rst)-.18 F
.797(scanned and option speci\214cations are processed.)117 352.8 R .796
(Recipient addresses are then collected, either)5.796 F .717(from the command \
line or from the SMTP RCPT command, and a list of recipients is created.)117
364.8 R .347(Aliases are e)117 376.8 R .347
(xpanded at this step, including mailing lists.)-.15 F .347(As much v)5.347 F
.346(alidation as possible of the)-.25 F 1.001
(addresses is done at this step: syntax is check)117 388.8 R 1.002
(ed, and local addresses are v)-.1 F 1.002(eri\214ed, b)-.15 F 1.002
(ut detailed)-.2 F .709
(checking of host names and addresses is deferred until deli)117 400.8 R -.15
(ve)-.25 G(ry).15 E 5.708(.F)-.65 G(orw)388.946 400.8 Q .708
(arding is also performed)-.1 F(as the local addresses are v)117 412.8 Q
(eri\214ed.)-.15 E F2(Sendmail)142 429 Q F1 .307
(appends each address to the recipient list after parsing.)2.807 F .307
(When a name is aliased)5.307 F .322(or forw)117 441 R .322(arded, the old nam\
e is retained in the list, and a \215ag is set that tells the deli)-.1 F -.15
(ve)-.25 G .322(ry phase to).15 F .479(ignore this recipient.)117 453 R .479
(This list is k)5.479 F .479(ept free from duplicates, pre)-.1 F -.15(ve)-.25 G
.48(nting alias loops and duplicate).15 F(messages deli)117 465 Q -.15(ve)-.25
G(rd to the same recipient, as might occur if a person is in tw).15 E 2.5(og)
-.1 G(roups.)428.12 465 Q F0 2.5(2.3.2. Message)102 489 R(collection)2.5 E F2
(Sendmail)142 505.2 Q F1 .454(then collects the message.)2.954 F .454
(The message should ha)5.454 F .754 -.15(ve a h)-.2 H .453(eader at the be).15
F(ginning.)-.15 E .778(No formatting requirements are imposed on the message e)
117 517.2 R .778(xcept that the)-.15 F 3.278(ym)-.15 G .778(ust be lines of te)
427.708 517.2 R(xt)-.15 E .78(\(i.e., binary data is not allo)117 529.2 R 3.28
(wed\). The)-.25 F .779(header is parsed and stored in memory)3.28 F 3.279(,a)
-.65 G .779(nd the body of)443.613 529.2 R(the message is sa)117 541.2 Q -.15
(ve)-.2 G 2.5(di).15 G 2.5(nat)204.97 541.2 S(emporary \214le.)222.19 541.2 Q
3.227 -.8(To s)142 557.4 T 1.627(implify the program interf).8 F 1.628
(ace, the message is collected e)-.1 F -.15(ve)-.25 G 4.128(ni).15 G 4.128(fn)
420.536 557.4 S 4.128(oa)432.994 557.4 S 1.628(ddresses were)446.562 557.4 R
-.25(va)117 569.4 S 2.5(lid. The).25 F(message will be returned with an error)
2.5 E(.)-.55 E F0 2.5(2.3.3. Message)102 593.4 R(deli)2.5 E -.1(ve)-.1 G(ry).1
E F1 -.15(Fo)142 609.6 S 2.618(re).15 G .117
(ach unique mailer and host in the recipient list,)162.798 609.6 R F2(sendmail)
2.617 E F1 .117(calls the appropriate mailer)2.617 F(.)-.55 E .619
(Each mailer in)117 621.6 R -.2(vo)-.4 G .619(cation sends to all users recei)
.2 F .619(ving the message on one host.)-.25 F .62(Mailers that only)5.62 F
(accept one recipient at a time are handled properly)117 633.6 Q(.)-.65 E .47
(The message is sent to the mailer using one of the same three interf)142 649.8
R .47(aces used to submit a)-.1 F 1.465(message to sendmail.)117 661.8 R 1.465
(Each cop)6.465 F 3.965(yo)-.1 G 3.965(ft)263.925 661.8 S 1.465
(he message is prepended by a customized header)274 661.8 R 6.465(.T)-.55 G(he)
494.56 661.8 Q 1.455(mailer status code is caught and check)117 673.8 R 1.455
(ed, and a suitable error message gi)-.1 F -.15(ve)-.25 G 3.955(na).15 G 3.955
(sa)448.115 673.8 S(ppropriate.)460.4 673.8 Q .589(The e)117 685.8 R .589(xit \
code must conform to a system standard or a generic message \(\231Service una)
-.15 F -.25(va)-.2 G(ilable\232\)).25 E(is gi)117 697.8 Q -.15(ve)-.25 G(n.).15
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/F0 10/Times-Bold@0 SF(SENDMAIL \212 An Inter)72 60 Q(netw)-.15 E
(ork Mail Router)-.1 E(SMM:9-5)462.9 60 Q 2.5(2.3.4. Queueing)102 96 R -.25(fo)
2.5 G 2.5(rr).25 G(etransmission)192.4 96 Q/F1 10/Times-Roman@0 SF .209(If the\
 mailer returned an status that indicated that it might be able to handle the \
mail later)142 112.2 R(,)-.4 E/F2 10/Times-Italic@0 SF(sendmail)117 124.2 Q F1
(will queue the mail and try ag)2.5 E(ain later)-.05 E(.)-.55 E F0 2.5
(2.3.5. Retur)102 148.2 R 2.5(nt)-.15 G 2.5(os)165.73 148.2 S(ender)177.12
148.2 Q F1 .588(If errors occur during processing,)142 164.4 R F2(sendmail)
3.088 E F1 .589(returns the message to the sender for retrans-)3.088 F 3.133
(mission. The)117 176.4 R .632(letter can be mailed back or written in the \
\214le \231dead.letter\232 in the sender')3.133 F 3.132(sh)-.55 G(ome)486.78
176.4 Q(directory)117 190.4 Q/F3 7/Times-Roman@0 SF(2)153.1 186.4 Q F1(.)156.6
190.4 Q F0 2.5(2.4. Message)87 214.4 R(Header Editing)2.5 E F1 1.756
(Certain editing of the message header occurs automatically)127 230.6 R 6.756
(.H)-.65 G 1.756(eader lines can be inserted)391.456 230.6 R .41
(under control of the con\214guration \214le.)102 242.6 R .41
(Some lines can be mer)5.41 F .41(ged; for e)-.18 F .41
(xample, a \231From:\232 line and)-.15 F 2.5<6199>102 254.6 S
(Full-name:\232 line can be mer)113.38 254.6 Q
(ged under certain circumstances.)-.18 E F0 2.5(2.5. Con\214guration)87 278.6 R
(File)2.5 E F1 .798(Almost all con\214guration information is read at runtime \
from an ASCII \214le, encoding macro)127 294.8 R .679
(de\214nitions \(de\214ning the v)102 306.8 R .678
(alue of macros used internally\), header declarations \(telling sendmail the)
-.25 F 1.009(format of header lines that it will process specially)102 318.8 R
3.509(,i)-.65 G 1.009(.e., lines that it will add or reformat\), mailer)320.398
318.8 R .478(de\214nitions \(gi)102 330.8 R .478(ving information such as the \
location and characteristics of each mailer\), and address)-.25 F(re)102 342.8
Q .428(writing rules \(a limited production system to re)-.25 F .429
(write addresses which is used to parse and re)-.25 F(write)-.25 E
(the addresses\).)102 354.8 Q 2.828 -.8(To i)127 371 T(mpro).8 E 1.528 -.15